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In the global context of population growth and climate change, monitoring crops is necessary to sustain agriculture and conserve natural resources. While many studies have demonstrated the ability of optical and SAR remotely sensed data to estimate crop parameters, these data have not been compared or combined to predict crop phenological stages. Despite the high sensitivity of SAR polarimetric data to crop phenological stages, no study has used high temporal resolution data. The freely available SAR Sentinel-1 (S-1) and optical Sentinel-2 (S-2) time series provide a unique opportunity to monitor crop phenology at a high spatial resolution on a weekly basis. The objective of this study was to evaluate the potential of S-1 data alone, S-2 data alone, and their combined use to predict wheat and rapeseed phenological stages. We first analyzed temporal profiles of spectral bands, vegetation indices and leaf area index (LAI) derived from S-2 data, and backscattering coefficients and polarimetric indicators derived from S-1 data. Then, an incremental procedure was used to estimate the contribution of S-1 and S-2 features to the classification of principal and secondary phenological stages of wheat and rapeseed. Results for both crops showed that the classification obtained with combined S-1 & 2 data (mean kappa = 0.53–0.82 and 0.74–0.92 for wheat and rapeseed, respectively) was more accurate than those obtained with S-2 data alone (mean kappa = 0.54–0.75 and 0.67–0.86 for wheat and rapeseed, respectively) or S-1 data alone (mean kappa = 0.48–0.61 and 0.61–0.64 for wheat and rapeseed, respectively). Combining S-1 & 2 data allowed better identification of the beginning and end of tillering for wheat and the beginning and end of ripening for rapeseed. Among S-2 features, the most important were LAI for wheat and the NDVI for rapeseed. For both crops, the S2REP index was one of the most important vegetation indices, while MCARI was less important. For S-1 features, results highlighted the large contribution of the backscatter ratio (σ◦VH:σ◦VV) and the value of using polarimetric indicators (Shannon entropy and span) to monitor rapeseed and wheat phenology. The main novelties of this work are the use of S-1 polarimetric indicators to identify phenological stages of wheat and rapeseed and the mapping of wheat and rapeseed secondary phenological stages using remotely sensed data.

Crop health management systems can be designed according to practices that help to reduce crop losses by restricting pathogen development and promoting host plant growth. A good understanding of pathogen and host dynamics, which are interdependent, is therefore needed. In this article, we used a holistic approach to explain the behavior of coffee leaf rust (CLR), a major coffee disease. We monitored coffee plant and CLR dynamics simultaneously in plots under different disease management and agroforestry systems. Diseased leaves were also collected to characterize inoculum stock and rust life stages (latent rust area, area with uredospores, necrosis due to rust) through picture analysis. We used structural equation modeling to obtain an overview of CLR pathosystem functioning on a plant scale. This overview integrates processes such as disease dilution by host leaf renewal, direct and indirect effects of fruit load on CLR development, antagonistic effects of shading depending on rust life stages, the tonic effect of copper-based fungicides on leaf retention, and effects on rust life stages depending on fungicide types. From our results, we also deduced that the inoculum stock could be calculated in unsprayed plots from the rust area with uredospores, with uredospores at 58 × 103 cm−2, on average.

International audience; The vulnerability of forest species and tree populations to climate change is related to the exposure of the ecosystem to extreme climatic conditions and to the adaptive capacity of the population to cope with those conditions. Adaptive capacity is a relatively under-researched topic within the forest science community and there is an urgent need to understand to what extent particular combinations of traits have been shaped by natural selection under climatic gradients, potentially resulting in adaptive multi-trait associations. Thus, our aim was to quantify genetic variation in several leaf and woody traits that may contribute to multi-trait associations in which intraspecific variation could represent a source for species adaptation to climate change. A multi-trait approach was performed using nine Quercus petraea provenances originating from different locations that cover most of the species' distribution range over Europe and that were grown in a common garden. Multiple adaptive differences were observed between oak provenances but also some evolutionary stasis. Also, our results revealed higher genetic differentiation in traits related to phenology and growth than in those related to xylem anatomy, physiology and hydraulics for which no genetic differentiation was observed. The multiple associations between those traits and climate variables resulting from multivariate and path analyses suggest a multi-trait association largely involving phenological and growth traits for Quercus petraea. © The Author(s) 2019. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

To understand how various factors influence phenological patterns like fruit production and the extent of phenological variability as survival strategy in different environments, fruit production of shea trees was studied in different agroclimatic zones (North Sudanian, South Sudanian and North Guinean) in Mali. Three sites were selected for this study and in each site; two stands (field and fallow) were concerned. For each stand, three “land use history or land management" i.e. new fields/fallows (1-5 years), medium (6-10 years) and old (10 years) were considered and permanent plots of 0.25 ha were established. 60 adult shea trees (DBH) ? 10 cm) were selected by site and monitored for fruit production assessment. The nested analysis of variance on the yield showed a significant site effect and significant effect of land use history within stand. However, stand effect within site was not significant. Factors like site and land management (land use history) appear to be determinant for fruit production of V. paradoxa. The site of Mperesso in the South Sudanian zone showed the highest fruit mean yield (11 kg/tree), significantly higher than the fruit mean yield observed at Daelan (7 kg/tree) in the North Sudanian zone and that observed at Nafégué (6 kg/tree) in the North Guinean zone. For field stand, old fields showed highest mean yield in all sites. For fallow stand, old fallows showed the lowest mean yield in most of cases. Different pattern was observed between field and fallow stands regarding the effect of land management. More fields are aged, more they influence positively fruit production whereas more fallows are aged, and more they influence negatively fruit production. This study highlighted the importance of land management practices and therefore, any domestication program to be successful should consider the potential effect of management practices.

Dacryodes edulis (G. Don) H.J. Lam is an underexploited oil-bearing fruit tree highly appreciated in the Central Africa rainforest. To improve horticultural management and provide relevant data to scientists for physiological studies, the reproductive phenology of D. edulis as well as their fruit (safou) development and ripening indexes has been defined and correlated to climatic conditions. Changes in safou were assessed in four production localities in Cameroon. Fruit-set-to-ripening time was evaluated over 2 consecutive production years. Four fruits developmental and ripening stages and their durations were determined as follows: The putative cell division (1–2 weeks); putative elongation (10–14 weeks); pre-ripening (2–7 weeks); and ripening phases (3–5 weeks). Rainfall, average, and cumulative temperatures were found to be correlated with the chronology of reproductive phenophases. The average temperature during the period ranging from the floral bud emergence to the fruit set can be used to predict the thermal time. Similarly, the average ambient temperature during the period from floral bud emergence to anthesis can help to determine the temperature to be cumulated during the ripening phase. These findings are considerable contributions that could help producers to enhance the industrial management of safou sector, reduce fruit perishability, and better control their harvesting time.

The quinoa pest Copitarsia incommoda (Walker, Lepidoptera: Noctuidae) is a cause of significant damage, and it is thus critical for Andean countries to have access to phenological models to maintain production and food safety. These models are key components in pest control strategies in the context of global warming and in the development of sustainable production integrating agroecological concepts. Phenological models are mainly based on outlining the relationship between temperature and development rate. In this study, we investigated the combined effect of protein content within the diet (artificial diet; artificial diet with −20% protein; artificial diet with +20% protein; natural quinoa diet) and temperature (12, 16.9, 19.5, 22.7, 24.6°C) as drivers of the development rate. Our study supports the literature, since temperature was found to be the main driver of the development rate. It highlights the significant role played by protein content and its interaction with temperature (significant effects of temperature, diet, and diet:temperature on development time using GLMs for all foraging life stages). We discuss the implications of such drivers of the development rate for implementing and applying phenological models that may benefit from including factors other than temperature. While performance curves such as development rate curves obtained from laboratory experiments are still a useful basis for phenological development, we also discuss the need to take into account the heterogeneity of the insect response to environmental factors. This is critical if pest control practices are to be deployed at the optimal time.

Machine learning (ML) has great potential to drive scientific discovery by harvesting data from images of herbarium specimens—preserved plant material curated in natural history collections—but ML techniques have only recently been applied to this rich resource. ML has particularly strong prospects for the study of plant phenological events such as growth and reproduction. As a major indicator of climate change, driver of ecological processes, and critical determinant of plant fitness, plant phenology is an important frontier for the application of ML techniques for science and society. In the present article, we describe a generalized, modular ML workflow for extracting phenological data from images of herbarium specimens, and we discuss the advantages, limitations, and potential future improvements of this workflow. Strategic research and investment in specimen-based ML methods, along with the aggregation of herbarium specimen data, may give rise to a better understanding of life on Earth.

Citrus classification remains an unresolved problem. In the first part of this chapter, after a short description of their morphological characters, the justification for the separation of the “true citrus” group into six genera is discussed, based on their reproductive biology and plastome phylogenetics. It is concluded that all true citrus plus the genus Oxanthera should be joined within the genus Citrus. Moreover, despite full sexual compatibility between the Citrus species sensu Swingle, the phenotypic and molecular differentiation between the ancestral taxa (C. maxima, C. medica, C. micrantha, C. reticulata) of the cultivated forms fit with phylogenetic species concepts based on diagnosability and monophyly. In the second part, after an historical perspective, the species rank of the genus Citrus is discussed based on the recent phylogenomic data and a new concept is proposed for citrus classification. Finally, in the third part, the phenotypical diversity of the Asian ancestors of edible citrus and of the most important horticultural groups of interspecific origins is presented after a discussion of the implication of the reticulate evolution coupled with apomixis on the phenotypical diversity structure of edible Citrus.

AGAP; International audience; In West Africa Sudano-Sahelian zone, sorghum sensitivity to photoperiod is a major trait for flowering adjustment toward the end of the rainy season. This trait ensures that conditions for crop development are optimal. Improving the understanding of the genetic control of flowering time in sorghum is thus an important step toward breeding climate resilient varieties for meeting the challenge of climate smart agriculture. In the wake of green revolution, most sorghum breeders eliminated photoperiod sensitivity to develop early maturing varieties. The evidence is now that simultaneous improvement of production, yield stability and grain quality requires the development of photoperiod-sensitive varieties. A segregating sorghum population derived from a cross between two photoperiod sensitive elite parents was evaluated in three different locations and five environments. CERES crop model was applied to decompose the flowering time of each genotype into basic vegetative phase, critical photoperiod and photoperiod sensitivity. Phenology and model derived variables were used for genetic analysis. The three model parameters were controlled by specific genomic regions. A major QTL affecting critical photoperiod was identified, whereas only independent minor QTLs were found for basic vegetative phase and photoperiod sensitivity. Candidate gene analysis in the major QTL region allowed us to propose a candidate gene (ELF3) involved in the circadian clock as a key regulator of flowering time in photoperiod-sensitive sorghum. Our findings provide critical information supporting the development of photoperiod-sensitive genotypes specifically adapted to climate variability encountered in Sudano-Sahelian zone.

A quantitative method was tested to describe crown phenophases in relation to water content and to secondary growth in ring-porous species, based on the hypothesis that new shoots require hydrated tissues to maintain the necessary turgor for extension, leading to a reduction in dry matter content (DMC). We collected a three-year-old branch from 11 Quercus pyrenaica Willd. trees at 10-day intervals to estimate DMC of newly developing buds, leaves, and twigs, and processed two opposite stem microcores for xylogenesis. Branch phenophases and shoot length were recorded in the field. The DMC of all organs decreased during crown development, with a minimum in early June, followed by a gradual increase up to initial values in late September. The shoot extension period concurred with the lowest DMC, but also with the beginning of earlywood maturation in the main stem, suggesting a high tissue hydration only when earlywood vessels become functional to fulfill enough water requirements for shoot and leaf extension. These results confirm the usefulness of DMC to accurately quantify the phenology of primary growth from bud swelling up to full leaf extension, as a complement to qualitative methods. This variation in DMC appears to be linked to secondary growth as a result of earlywood vessel development.

Apple tree bloom onset in Germany has advanced by 2 days/decade in 1951-2014 and by 3 days/decade in 1988-2014, behaving similarly in respect to its evolution since 1951 and its sensitivity to temperature to other species’ phenological spring phases. The evolution however was not linear; by conducting a split moving-window dissimilarity analysis (SMWDA) we were able to detect the “break-period” 1987-1989 which coincides with a breakpoint that has been identified in the phases of the North Atlantic Oscillation (NAO). We observed distinct spatial patterns with apple bloom advancing from southwest to northeast and, most interestingly, a longitudinal gradient in the trend of apple bloom onset revealed by a probabilistic principal components analysis (PPCA). In the period of 1951-2014, plants located in the east displayed a much stronger trend (‑16.53 days on average) than those in the western part of the country (‑6.74 days on average). This pattern seems to be linked to patterns in temperature which is highly correlated to apple bloom onset (best one predictor model: mean temperature March to May, R² = 0.82, ‑6 days/°C): the coldest regions exhibit the strongest warming trends and the greatest advances in apple bloom onset., Les dates de floraison des pommiers en Allemagne ont en moyenne avancé de 2 jours/décade de 1951 à 2014 et de 3 jours/décade de 1988 à 2014, en accord avec l’évolution des phases phénologiques d’autres espèces. Cependant, cette évolution n’a pas été linéaire : en réalisant une analyse de dissimilarité d’une fenêtre glissante fractionnée (SMWDA), nous avons détecté une période de rupture entre 1987 et 1989 qui coïncide avec un point de rupture qui a été identifié dans les phases de l’oscillation nord-atlantique (ONA). Nous avons également pu constater une structuration spatiale : la floraison des pommiers progresse du sud-ouest du pays au nord-est ; en termes de variabilité interannuelle des dates de floraison, il existe, superposé à un mode principal commun à l’ensemble du pays, un gradient longitudinal qui a été révélé par une analyse probabiliste en composantes principales (PPCA). Entre 1951 et 2014, la tendance à la précocité est plus marquée à l’est du pays (en moyenne ‑16,53 jours) qu’à l’ouest (en moyenne ‑6,74 jours) et la floraison des pommiers est très étroitement liée à la variabilité des températures moyennes de mars à mai (R² = 0,82 ; ‑6 jours/°C). Les régions les plus froides montrent les tendances les plus importantes au réchauffement et à la précocité de la floraison.

International audience; In the Toba Highlands of North Sumatra (Indonesia), coffee production (Coffea arabica L. var. Sigarar Utang) is an important outcome for smallholders; however, the attack of the coffee berry borer (CBB) Hypothenemus hampei, is an obstacle for the development of coffee cultivation in this area. This pest causes great economic losses produced by the development of its offspring inside the coffee berries, making it difficult to control. This concerning situation has led us to consider the development of a CBB control strategy, but beforehand, it was necessary to acquire key information on the phenology of the coffee tree and its implication on the bioecology of the pest. Thus, two study designs were set up, one comprising six plots with two different age classes and the other corresponding to a single plot dedicated only to the study of short distance dispersal of CBB. Part of this study focused on the phenology of the coffee trees and showed that berry production mainly takes place in the upper parts of the trees and significantly decreases with tree age. Due to the equatorial climate, berries were practically always present. Berries were produced following two major flowering periods and some minor ones distributed over the year, and harvested at regular intervals. Berry distribution on the branches varied over time. Dynamics of infestations by CBB showed that ripe berries were more infested than unripe berries because they had been exposed longer to CBB attacks, that older trees were more exposed than younger trees and that infestation was evenly distributed along branches. In addition, internode pedestrian dispersal of CBBs was shown to occur, but considerably less frequently than airborne dispersal. In conclusion, it appears that in the agro-climatic context of the Toba region, the virtual year-round presence of berries - which fosters CBB infestations and CBB short-distance dispersal - is a constraint that must be taken into consideration for designing future pest management measures. To this end, it will be necessary in particular to evaluate the potential of trapping mainly used in tropical areas and to put into practice the sanitation harvesting applied in other countries.

Low night and high day temperatures during sensitive reproductive stages cause spikelet sterility in rice. Phenotyping of tolerance traits in the field is difficult because of temporal interactions with phenology and organ temperature differing from ambient. Physiological models can be used to separate these effects. A 203-accession indica rice diversity panel was phenotyped for sterility in ten environments in Senegal and Madagascar and climate data were recorded. Here we report on sterility responses while a companion study reported on phenology. The objectives were to improve the RIDEV model of rice thermal sterility, to estimate response traits by fitting model parameters, and to link the response traits to genomic regions through genome-wide association studies (GWAS). RIDEV captured 64% of variation of sterility when cold acclimation during vegetative stage was simulated, but only 38% when it was not. The RIDEV parameters gave more and stronger quantitative trait loci (QTLs) than index variables derived more directly from observation. The 15 QTLs identified at P

Phenology and time of flowering are crucial determinants of rice adaptation to climate variation. A previous study characterized flowering responses of 203 diverse indica rices (the ORYTAGE panel) to ten environments in Senegal (six sowing dates) and Madagascar (two years and two altitudes) under irrigation in the field. This study used the physiological phenology model RIDEV V2 to heuristically estimate component traits of flowering such as cardinal temperatures (base temperature (Tbase) and optimum temperature), basic vegetative phase, photoperiod sensitivity and cold acclimation, and to conduct a genome-wide association study for these traits using 16 232 anonymous single-nucleotide polymorphism (SNP) markers. The RIDEV model after genotypic parameter optimization explained 96% of variation in time to flowering for Senegal alone and 91% for Senegal and Madagascar combined. The latter was improved to 94% by including an acclimation parameter reducing Tbase when the crop experienced low temperatures during early vegetative development. Eighteen significant (P

Background and Aims Mango (Mangifera indica L.) is the fifth most widely produced fruit in the world. Its cultivation, mainly in tropical and sub-tropical regions, raises a number of issues such as the irregular fruit production across years, phenological asynchronisms that lead to long periods of pest and disease susceptibility, and the heterogeneity of fruit quality and maturity at harvest. To address these issues, we developed an integrative functional–structural plant model that synthesizes knowledge about the vegetative and reproductive development of the mango tree and opens up the possible simulation of cultivation practices. Methods We designed a model of architectural development in order to precisely characterize the intricate developmental processes of the mango tree. The appearance of botanical entities was decomposed into elementary stochastic events describing occurrence, intensity and timing of development. These events were determined by structural (position and fate of botanical entities) and temporal (appearance dates) factors. Daily growth and development of growth units and inflorescences were modelled using empirical distributions and thermal time. Fruit growth was determined using an ecophysiological model that simulated carbon- and water-related processes at the fruiting branch scale. Key Results The model simulates the dynamics of the population of growth units, inflorescences and fruits at the tree scale during a growing cycle. Modelling the effects of structural and temporal factors makes it possible to simulate satisfactorily the complex interplays between vegetative and reproductive development. The model allowed the characterization of the susceptibility of mango tree to pests and the investigatation of the influence of tree architecture on fruit growth. Conclusions This integrative functional–structural model simulates mango tree vegetative and reproductive development over successive growing cycles, allowing a precise characterization of tree phenology and fruit growth and production. The next step is to integrate the effects of cultivation practices, such as pruning, into the model.

International audience; The objective of this study was to evaluate the effect of banana phenological stages on the chlorophyll content of its leaves in order to assess possible restrictions on the potential use of remote sensing for nutritional diagnoses when phenological stages cannot be discriminated on images. Chlorophyll measurements were made with a Dualex sensor at different positions on banana leaves with different ranks on the plant, on plants at different phenological stages and located in different fields of a commercial farm. The effect of these factors was studied using mixed models with nested factors and the results showed that they have a significant effect on the chlorophyll content. It is therefore suggested to take into account the diversity of phenological stages in banana fields before considering nutritional diagnoses services based on remote sensing.

Rubber ( Hevea brasiliensis ) growing in Latin America is severely limited by South American Leaf Blight, a disease caused by the Ascomycete fungus Microcyclus ulei , recently renamed Pseudocercospora ulei . Sustainable ways of controlling it may be genetic, using resistant cultivars, or may consist in seeking so-called “escape zones”, where disease incidence is low thanks to climatic conditions unsuitable for the fungus. After identifying one such zone on the Pacific coast of Ecuador, between 2006 and 2014 we used an 8.2 ha trial to compare the agronomic performance of ten rubber clones originating from Asia and Africa. The study focused on tree growth, susceptibility to the disease and clone phenology. For most of the assessed clones, the results obtained over 8 months showed good adaptability and a good agronomic performance during the immature period, so that tapping could begin on the earliest trees at 6½ years. An examination of the monthly values for climatic factors such as rainfall, relative humidity, minimum temperature and dew point temperature, showed that conditions during the dry season, which lasted 5 months, were detrimental to P. ulei fungus development, even though the mean relative humidity of the driest months did not fall below 75%. In addition, between September and December, the minimum temperature remained above the dew point temperature, preventing dew formation on the leaf surface. These conditions enabled the trees to complete their natural refoliation without any risk of parasite pressure, and to conserve a foliar density over 90% up to natural defoliation the following year. The results obtained during the early growing phase, i.e. the immature phase, confirmed the suitability of this zone for rubber growing, especially for materials with a high yield potential, despite their known susceptibility to the disease. These escape zones consequently offer an undeniable alternative for developing rubber, due to a low phytosanitary risk arising from P. ulei .

Recent outbreaks of highly pathogenic avian influenza virus (AIV) in birds, humans and other mammalian species calls for a better understanding of virus dynamics in wild bird species and populations that act as maintenance hosts. Host ecology influences the transmission of pathogens and can be used to explore and infer pathogen dynamics. Most of the ecological processes proposed to explain AIV transmission in wild birds have been derived from studies conducted in the temperate and boreal regions of the northern hemisphere. We evaluate the role of two key drivers of AIV dynamics in a waterfowl community in Zimbabwe (southern Africa): (1) the recruitment of young birds and (2) the seasonal aggregation of birds. We analyse the seasonal variation of AIV prevalence in waterfowl and overlay these data with the phenology of reproduction and the seasonal variation in the local abundance of these species. We find that the breeding period of southern Afrotropical waterfowl species is more extended and somewhat less synchronized among species in the community than is the case in temperate and boreal waterfowl communities. Young birds are recorded at most times of the year, and these immunologically naive individuals can therefore act as new hosts for AIV throughout the year within the wild bird population. Although host aggregation peaks in the cold-dry to hot-dry season, birds still aggregate throughout the year and this potentially spreads the opportunities for first infection of juveniles and other naive birds temporally. We did not find a relationship between season, AIV prevalence in waterfowl, the influx of juveniles or the gradual aggregation of birds during the dry season. Therefore, the main drivers of AIV dynamics (juvenile influx and host abundance/aggregation), although present in Afrotropical regions, could not explain the AIV seasonal patterns in our study in contrast to results reported from temperate and boreal regions. These differences imply variation in the risk of AIV circulation in waterfowl and in the risk of spread to poultry, other animals or humans. (Resume d'auteur)

High-yielding rice varieties (HYV) show strong compensation among sequentially developed yield components (YC). This phenotypic plasticity has adaptive value but for crop improvement, more information is needed on its effects on yield. SAMARA, a deterministic crop model predicting trait-trait and trait-environment interactions by simulating morphogenetic processes and competition among sinks for assimilates, was developed to study crop phenotypic plasticity. Dynamics of YC and morphology were observed on the HYV IR72 planted at standard and 4-fold greater density in 4 environments in the Philippines in 2012/13. Data for other years/seasons were obtained for model validation. Sequential path analysis was used to determine the phenotypic plasticity of traits consecutively contributing to yield. Tiller number at flowering (R2 = 0.94) and maturity (R2 = 0.84) and grain yield (R2 = 0.77) were predicted accurately for independent datasets. The model also predicted accurately density effects on aboveground dry weight (agdw), plant height, leaf size, spikelet number per panicle and filling percentage. Tiller and leaf mortality were over-estimated under high density. Overall, the model predicted satisfactorily the sequential compensation processes among YCs. They led to stable grain yield despite large morphological differences among density treatments and environments. Sensitivity analysis of simulation outcomes vs. variation in crop parameters indicated that modified genotypic tillering ability, phyllochron or leaf size had little effect on final grain yield because of compensations by other traits, although IR72 appeared to have an optimal combination of parameter values. Larger effects on grain yield were predicted for variation of parameters affecting the sensitivity of leaf and tiller mortality to assimilate resources and the ability to mobilize stem non-structural carbohydrates during grain filling. The model will be used next to perform physiological trait dissection and plasticity analyses for diverse genotypes.

The combined production of grain and sugar by sorghum requires efficient leaf C acquisition (source) and allocation to productive sinks, namely the stem and the panicle. Photoperiod sensitivity, which regulates plant phenology and growth, is also likely to be a key regulator of such C source-sink relationships, while it is crucial to drought adaptation. This study set out to evaluate the contribution of plant leaf area and stem growth to the production of grain and sugar by sweet, photoperiodic sorghum depending on the sowing date and post-flowering water availability. Twelve West African accessions were studied in the field in Senegal during two consecutive rainy seasons, comparing two sowing dates and post-anthesis water regimes (irrigated, or not). Plant growth and development were monitored weekly up to flowering. Organ size and biomass, stem juiciness and sweetness were characterized at flowering and maturity. At flowering, early sowing enhanced plant leaf area, stem dry weight and sugar production, and plant leaf area expressed per unit of stem dry weight was positively correlated to stem sweetness, suggesting that a high pre-flowering source-to-sink ratio favors early sugar accumulation. Overall, a late sowing date reduced sugar and grain production more than post-anthesis drought, whereas early sowing enhanced both types of production. No post-anthesis competition was found between grain filling and stem sugar accumulation. However, under drought conditions, the maintenance of combined production was better for the most leaf stay-green accessions. It is suggested that the combined production of sugar and grain by sweet, photoperiodic sorghum in response to the sowing date and post-anthesis drought is firstly sink-driven but that source (plant leaf area) dynamics can enhance stem sugar accumulation and its maintenance under drought conditions. These results provide further insight into the traits to be combined in dual-purpose ideotypes dedicated to drought-prone environments.

Ecuador has an outstanding diversity of palm species, some of which have been well studied, certain others remain an enigma, however. A particular case is the American oil palm, Elaeis oleifera (Kunth) Cortés, first recorded in Ecuador in 1986. The genus Elaeis has a trans-Atlantic (Africa-America) distribution, with E. oleifera from the Neotropics, and E. guineensis Jacq. from Africa. It has been hypothesized that E. oleifera derives from populations of E. guineensis, which diverged 15 million years ago. At the local level, the populations of E. oleifera have a disjunct distribution, with isolated populations in Central America, the Amazonia basin, the Guianas, Chocó and the Caribbean Cost of Colombia and Venezuela, frequently associated with human or archaeological settlements. Despite the spatial and historical separation between the two species, there are no reproductive barriers to the generation of fertile hybrids. This important reproductive characteristic has allowed E. oleifera to become a major source of genetic variation for the improvement and adaptability of commercial populations of E. guineensis throughout the tropics. The Ecuadorian populations of E. oleifera from Taisha, with morphological, reproductive and agronomically important biochemical characteristics, have been used for the creation of commercial hybrids, which today are planted in many tropical regions.

Background and Aims Fine roots play a major role in the global carbon cycle through respiration, exudation and decomposition processes, but their dynamics are poorly understood. Current estimates of root dynamics have principally been observed in shallow soil horizons (2.5 m) root growth occurred at two distinct periods, at bud break in spring and throughout the winter i.e., after leaf fall. In contrast, shallow roots grew mainly during the spring-summer period. Maximum root elongation rates ranged from 1 to 2 cm day−1 depending on soil depth. Most root mortality occurred in upper soil layers whereas only 10 % of fine roots below 4 m died over the study period. Fine root lifespan was longer in thicker and in deeper roots with the lifespan of the thinnest roots (0.0–0.5 mm) increasing from 129 days in the topsoil to 190 at depths > 2.5 m. Conclusions The unexpected growth of very deep fine roots during the winter months, which is unusual for a deciduous tree species, suggests that deep and shallow roots share different physiological strategies and that current estimates based on the shortest root growth periods (i.e., during spring and summer) may be underestimating root production. Although high fine root turnover rates might partially result from the minirhizotron approach used, our results help gain insight into some of the factors driving soil organic carbon content.

Wheat and rice are the most important food crops in agriculture providing around 50% of all calories consumed in the human diet. While both are C3 species, the evolution and domestication of wheat and rice occurred in very different environments, resulting in diverse anatomical and metabolic adaptation. This review focuses on the current understanding of their adaptation in an agronomic context. The similarities and differences between wheat and rice are discussed, focusing on traits related to phenology, photosynthesis, assimilate partitioning, and lodging resistance, these being the main abiotic drivers of yield expression in most agro-ecosystems. Currently, there are significant knowledge gaps in the major biological processes that account not only for differential adaption among cultivars within each species, but even between the two species. By addressing what is known as well as where gaps exist in a comparative context, this review aims to highlight translational research approaches that could provide insights into the genetic improvement of both crops. (Resume d'auteur)

Sweet sorghum is highly coveted to contribute and take up food and energy challenges. A collection of 84 West Africa landraces mostly from Senegal and four control cultivars were screened to identify relevant accessions and trait combination for multi-purpose (sugar/grain/biomass). The implication of photoperiod sensitivity was particularly addressed. A total of 20 traits related to phenology, morphology, grain and sugar production were assessed in two sowing dates (July and August) at CNRA Bambey in Senegal. Late sowing resulted in shortened vegetative phase and a significant decrease in traits related to plant size, stem sugar, biomass and grain productions. Broad-sense heritability was moderate to high for most of the phenology, morphology, grain and sugar-related traits, suggesting their interest for breeding. All the traits related to plant size were positively correlated with plant sugar production except plant height. A cluster analysis identified three groups contrasting in their ability to combine sugar, grain or fodder production based on 18 traits measured for the early sowing. Clusters I and III were suitable for one purpose: grain and sugar, respectively. Cluster II was the most suitable for multi-purpose, showing the best trade-off among grain, sugar and vegetative biomass production. The best accessions for stem sugar yield belonged to durra, caudatum and their intermediate types. The relationship between internode size and sweetness should be further studied, in particular exploring their relationship with internode tissue anatomy. Further studies are also needed to evaluate the role that stay-green can play in sugar yield maintenance under post-flowering drought. (Resume d'auteur)

It is crucial to understand the adaptive mechanisms of woody plants facing periodic drought to assess their vulnerability to the increasing climate variability predicted in the Sahel. Guiera senegalensis J.F.Gmel is a semi-evergreen Combretaceae commonly found in Sahelian rangelands, fallows and crop fields because of its value as an agroforestry species. We compared canopy leafing, and allometric measurements of leaf area, stem area and stem length and their relationships with leaf water potential, stomatal conductance (gs) and soil-to-leaf hydraulic conductance (KS-L), in mature and current-year resprouts of G. senegalensis in Sahelian Niger. In mature shrubs, seasonal drought reduced the ratio of leaf area to cross-sectional stem area (AL : AS), mainly due to leaf shedding. The canopy of the current-year resprouts remained permanently leafed as the shrubs produced leaves and stems continuously, and their AL : AS ratio increased throughout the dry season. Their KS–L increased, whereas gs decreased. West, Brown and Enquist's (WBE) model can thus describe allometric trends in the seasonal life cycle of undisturbed mature shrubs, but not that of resprouts. Annual clear cutting drives allometric scaling relationships away from theoretical WBE predictions in the current-year resprouts, with scaling exponents 2.5 times greater than those of mature shrubs. High KS-L (twice that of mature shrubs) supports this intensive regeneration process. The adaptive strategy described here is probably common to many woody species that have to cope with both severe seasonal drought and regular disturbance over the long term.

Night temperature (NT) increases faster than day temperature with global warming and this may have strong implications for crop yield. One of the assumptions is the increase in night respiration and thus the increase in carbon losses over time. Some rice cultivars (indica, aus and japonica types) were grown in the field in the Philippines and in heated greenhouses in Montpellier, France, to quantify the response of respiration to increased NT and its implication at crop level. Increased NT by 3.8 and 5.4 °C over the whole crop cycle in two greenhouse experiments and by 1.9 °C in the field from 33 days after transplanting up to maturity using a free-air-controlled enhancement increased night respiration rate significantly. Overall, the cost in CH 2 O of night respiration over crop duration was 17 to 20% (field) and 8 to 18% (greenhouse) of the potential shoot dry matter (including that lost by respiration). Additional respiratory burden due to increased NT was only 1 to 7% of the potential shoot dry matter at maturity, and was not associated with significant loss in additional dry matter. The absence of any dry matter reduction with increased NT within indica cultivars questions the assumptions of recent papers.

UMR AGAP - équipe AFEF - Architecture et fonctionnement des espèces fruitières; International audience; In plants, carbon source–sink relationships are assumed to affect their reproductive effort. In fruit trees, carbon source–sink relationships are likely to be involved in their fruiting behavior. In apple, a large variability in fruiting behaviors exists, from regular to biennial, which has been related to the within-tree synchronization vs desynchronization of floral induction in buds. In this study, we analyzed if carbon assimilation, availability and fluxes as well as shoot growth differ in apple genotypes with contrasted behaviors. Another aim was to determine the scale of plant organization at which growth and carbon balance are regulated. The study was carried out on 16 genotypes belonging to three classes: (i) biennial, (ii) regular with a high production of floral buds every year and (iii) regular, displaying desynchronized bud fates in each year. Three shoot categories, vegetative and reproductive shoots with or without fruits, were included. This study shows that shoot growth and carbon balance are differentially regulated by tree and shoot fruiting contexts. Shoot growth was determined by the shoot fruiting context, or by the type of shoot itself, since vegetative shoots were always longer than reproductive shoots whatever the tree crop load. Leaf photosynthesis depended on the tree crop load only, irrespective of the shoot category or the genotypic class. Starch content was also strongly affected by the tree crop load with some adjustments of the carbon balance among shoots since starch content was lower, at least at some dates, in shoots with fruits compared with the shoots without fruits within the same trees. Finally, the genotypic differences in terms of shoot carbon balance partly matched with genotypic bearing patterns. Nevertheless, carbon content in buds and the role of gibberellins produced by seeds as well as the distances at which they could affect floral induction should be further analyzed.

Short-rotation plantations are extending worldwide due to the increased demand for pulp and wood. Reliable estimations of recent expansion of short-rotation plantation areas and associated land use changes are a prerequisite to assess their environmental impact on regional carbon and water cycles, and on climate. A binary classification methodology using MODerate resolution Imaging Spectroradiometer (MODIS) 16-day 250 m NDVI time series was developed and applied to classify Eucalyptus plantations across Brazil. The identification of Eucalyptus plantations specific patterns in the time series was based on the calculation of matching functions between the NDVI time series and a ~ 2 years long reference time series. Among the seven tested matching functions, the bounding envelope was the most successful. This method was robust to residual noise on the NDVI time series, and a threshold coefficient for the binary classification was adjusted using an omission-commission criteria. With this method, it was possible to detect any presence of Eucalyptus between 2003 and 2009 at monthly time-steps, including the periods of bare soils between two rotations that are typically 6-7 years long. The dates of first afforestation, of clear-cut at the end of a rotation, and of re-planting at the beginning of a new rotation were retrieved from the NDVI time series with a precision of ~ 66 days. The final almost continuous tri-dimensional map (space and time) was validated with three different datasets, from local to regional data. All three datasets gave similarly high global accuracy statistics, but a global underestimation of Eucalyptus areas compared to large scales census was observed. Discrepancies and way to improve the Eucalyptus area estimates were discussed in this study. The developed methodology could be applied to other short-rotation tree plantations.

Context[br/] Parasites can induce strong effects on their host’s growth, not only as a result of host resource exploitation (growth loss) but also with a potential adaptive value for host (tolerance response) and themselves (increased transmission).[br/] [br/] Aims[br/] We assessed these three types of phenotypic changes in oak seedlings infected by powdery mildew.[br/] [br/] Methods[br/] A manipulative field experiment with three levels of parasite inoculum was designed in order to tease apart infection from genetic effects on oak growth. Seedlings were monitored during 3 years for height growth, phenology and infection.[br/] [br/] Results[br/] Powdery mildew infection induced both significant growth loss and qualitative changes in plant architecture. The most striking and unexpected change was increased growth polycyclism in infected seedlings. This benefitted both the host as a form of compensation for infection-caused height loss, and the pathogen, by increasing sporulation.[br/] [br/] Conclusion[br/] The study highlights the effect of parasites in the expression of plant phenotypic traits, such as phenology and ultimately tree architecture. Both host tolerance and parasitic manipulation may be involved in the observed changes in growth patterns. These results suggest a complex interplay between development and defence in trees and emphasize the need to better assess tolerance mechanisms when considering the defence strategies of trees against pathogens.

Crop phenology is essential for evaluating crop production in the food insecure regions of West Africa. The aim of the paper is to study whether satellite observation of plant phenology are consistent with ground knowledge of crop cycles as expressed in agro-simulations. We used phenological variables from a MODIS Land Cover Dynamics (MCD12Q2) product and examined whether they reproduced the spatio-temporal variability of crop phenological stages in Southern Mali. Furthermore, a validated cereal crop growth model for this region, SARRA-H (System for Regional Analysis of Agro-Climatic Risks), provided precise agronomic information. Remotely-sensed green-up, maturity, senescence and dormancy MODIS dates were extracted for areas previously identified as crops and were compared with simulated leaf area indices (LAI) temporal profiles generated using the SARRA-H crop model, which considered the main cropping practices. We studied both spatial (eight sites throughout South Mali during 2007) and temporal (two sites from 2002 to 2008) differences between simulated crop cycles and determined how the differences were indicated in satellite-derived phenometrics. The spatial comparison of the phenological indicator observations and simulations showed mainly that (i) the satellite-derived start-of-season (SOS) was detected approximately 30 days before the model-derived SOS; and (ii) the satellite-derived end-of-season (EOS) was typically detected 40 days after the model-derived EOS. Studying the inter-annual difference, we verified that the mean bias was globally consistent for different climatic conditions. Therefore, the land cover dynamics derived from the MODIS time series can reproduce the spatial and temporal variability of different start-of-season and end-of-season crop species. In particular, we recommend simultaneously using start-of-season phenometrics with crop models for yield forecasting to complement commonly used climate data and provide a better estimate of vegetation phenological changes that integrate rainfall variability, land cover diversity, and the main farmer practices.

Introduction. African fruit production, as well as regional and international fruit trade, have experienced heavy economic losses over the past decade due to the damage caused by fruit flies, especially B. invadens Drew Tsuruta & White (Tephritidae: Diptera). Bactrocera invadens attacks fruits belonging to numerous botanical families, several of which are of great economic importance. The females of these flies generally lay their eggs in mature fruits, but some can lay in green-immature fruits. Materials and methods. The influence of the species, variety and phenology of fruits on the fruit attractiveness to B. invadens and the elicitation of B. invadens egg- laying behaviour were studied in the laboratory. Fruits harvested regularly during the years 2008 and 2009 from orchards in the Niayes area (Senegal) were exposed to gravid females in cages set for the different factors tested. The exposed fruits were then incubated and the pupae emerging from them were counted. Results and discussion. Bactrocera invadens females laid eggs in ripe fruits. Within the same fruit species, the variety plays an important role in egg-laying preference. Hence, among the mango varieties tested, the Peche variety hosted the highest number of pupae per fruit, while the Palmer variety hosted the lowest number. Comparison among different fruit species showed that mature papaya was more infested than mature mango or citrus. Furthermore, flies were unable to develop on lime. Conclusion. Our study showed that B. invadens can infest green and ripe host fruits, and even immature abscised fruits. Consequently, management of this pest must include preventive measures in the development and implementation of an integrated management system. Senegal / Mangifera indica / Carica papaya / Citrus / fruits / phenology / maturity / Tephritidae / Bactrocera invadens / oviposition La phenologie des fruits d'agrumes, mangues et papayes influence les preferences de ponte de Bactrocera invadens (Diptera : Tephritidae).

a b s t r a c t Two major cultivated cotton species, Gossypium hirsutum (Gh) and G. barbadense (Gb) contribute to the bulk of cotton fiber production worldwide (95%). These species are largely inter-fertile and each displays a series of distinctive characteristics in terms of numerous botanical features and, more importantly, in their agronomic performance, adaptability and overall fiber quality. A recombinant inbred line (RIL) pop- ulation derived from an inter-specific cross between Gh and Gb, used previously for QTL mapping of fiber quality characteristics, has also been evaluated over 6 sites and 2 years for various plant morphological, phenological and yield component traits. A total of 27 traits were assessed across a varying number of locations (up to 6 locations, in Australia, USA, Brazil, Cameroon, Belgium and France) and years, represent- ing up to 10 different combinations. Variability in many of these traits was observed among the RILs and they frequently showed transgression. One hundred and sixty six significant QTLs, covering the 27 traits, were detected by composite interval mapping when using individual datasets. Cases of confirmation of localizations of individual QTLs from different data sets were detected in 27 instances, indicating that the 166 individual QTLs in this study could be represented by a maximum of 121 chromosome positions. QTL were shared between traits related to hairiness (22 individual QTLs), plant morphology of vegetative (29 QTLs) and reproductive (37 QTLs) parts, phenology (17 QTLs), and yield-related traits (61 QTLs). This is the first report of QTL mapping in cotton for various within-boll yield-related traits assessed on a per-seed basis, including fiber mass per unit of seed surface area (5 QTLs), calculated number of fibers per seed (2 QTLs) or per unit of seed surface area (1 QTL). This report confirms the importance of considering such basic yield components in selection for better yielding cotton varieties.

Earth system models currently use a discretized representation of vegetation, grouping together the whole world species into a dozen of Plant Functional Types (PFT), whose characteristics (traits) are fixed. This rigidity does not allow to accurately represent the evolution of ecosystems and their associated bio-geochemical cycles, while vegetation is facing stronger environnemental and anthropogenic pressures. Three complementary approaches based on functional traits were tested in order to improve the representation of forests in the dynamic global vegetation model ORCHIDEE. Based on a hierarchical classification of species, the first approach is to increase the number of PFTs. The second approach extrapolates observed traits for each PFT from empirical relationships calibrated against different environmental variables. The last one uses the photosynthesis coordination theory which allows the estimation of functional traits in optimal photosynthesis conditions. In addition, this study explores the capacity of a global model to represent functional traits when optimized against a given carbon flux. Increasing the number of PFTs significantly improves the estimations of stand characteristics and their spatial distribution by more than 50 %. The two other approaches managed to reproduce realistics traits distributions and higlighted the ``buffer'' role of traits plasticity on futur carbon fluxes. Some weaknesses of the model linked to phenological processes, biomass allocation or hydric stress, emerged for conifers species. This led to the implementation of an explicit representation of the phenology for evergreen needleleaves PFTs in ORCHIDEE, which can now reproduce the LAI dynamic observed from remote sensing data. Finally, the ORCHIDEE model cannot be calibrated with in situ observations, emphasizing the theoretical approach to simulate continuous traits distributions. However, the assimilation of observed carbon fluxes allows to bridge the gap between traits measured at the leaf scale and the canopy. It reproduced consistent trait distributions with observations, and led to trait-trait and trait-environment relationships similar to those observed at the leaf scale., Dans les modèles globaux de la biosphère continentale, toute la végétation mondiale est généralement représentée par une dizaine de grand groupes fonctionnels (PFT-Plant Functional Type), dont les caractéristiques (traits) sont fixes. Cette rigidité ne permet pas de représenter correctement l'évolution de la végétation face aux pressions environnementales et anthropiques grandissantes, et est à l'origine de nombreuses incertitudes pour l'estimation des cycles bio-géochimiques associés. Trois approches complémentaires axées sur l'utilisation des traits fonctionnels ont été explorées à l'aide du modèle dynamique global de végétation ORCHIDEE afin d'améliorer la représentation des PFTs forestiers. La première approche consiste à augmenter le nombre de PFTs à partir d'une classification hiérarchique des espèces. La seconde approche permet d'extrapoler les traits observés pour chaque PFT existant grâce à des relations empiriques calibrées à partir de plusieurs variables environnementales. La dernière approche utilise la théorie de la coordination de la photosynthèse afin d'estimer des distributions continues de traits en conditions optimales de photosynthèse. En parallèle, cette étude s'interroge sur les capacité d'un modèle global à représenter correctement les traits fonctionnels lorsqu'il est optimisé pour un flux de carbone. L'augmentation du nombre de PFTs permet d'améliorer significativement les caractéristiques et la représentativité spatiale des peuplements simulés de plus de 50 %. Les deux autres approches permettent d'estimer des distributions de traits réalistes et mettent en évidence un rôle ``tampon'' important de la plasticité des traits sur les flux de carbone futurs. Les trois approches abordées ont mis en évidence certaines faiblesses du modèle liées à la représentation de la phénologie, de l'allocation de la biomasse ou encore du stress hydrique pour les conifères. Ces résultats ont menés à la mise en place d'une représentation explicite des processus phénologiques pour les conifères sempervirents dans ORCHIDEE, qui à présent reproduit les dynamiques de LAI observées par télédétection. Enfin, le modèle ORCHIDEE ne peux pas être paramétré avec des observations directes de traits, privilégiant l'approche théorique pour simuler les distributions de traits. Cependant, l'assimilation de données d'observations de flux de carbone permet de faire le lien entre les traits mesurés à l'échelle foliaire et leur intégration à l'échelle de la canopée. Elle permet de retrouver des distributions de traits cohérentes avec les observations, ainsi que des relations trait-trait et trait-environnement qui sont observées à l'échelle foliaire.

A major barrier for the scientific community of climate change biologists is the spatial mismatch between the size of organisms and the resolution at which global climate data are collected and modelled. Thus, the development of integrative and quantitative tools for the monitoring and spatial characterization of microclimates across spatial scales is a key issue for climate change ecologists. We proposed an integrative toolbox for quantifying the spatial heterogeneity in surface temperatures by bringing together procedures of unmanned aerial vehicles, thermal imagery, orthomosaic, GIS classification and spatial metrics. This toolbox permits to yield high-resolution visual and infrared orthoimages that are processed into a GIS for selecting surfaces of interest in the landscape (e.g. soil, vegetation). Then, the thermal matrices of selected surfaces (i.e. temperature values of the pixels belonging to the selected surfaces only) are processed within r to generate a variety of thermal landscape metrics (e.g. thermal patch richness and density, thermal aggregation and cohesion index). We applied this toolbox to the thermal characterization of mountainous agricultural landscapes in Ecuador with implications for ectothermic pest dynamics. UAV flights at a height of 60 m above-ground level allowed us to acquired high-resolution visual and thermal images (1 and 5 cm/pixel, respectively) for 12 potato fields with a mean surface of 1017 ± 117 m2. Landscape metrics on plant and soil surfaces showed that crop phenology drives the spatial patterns of surface temperatures and strongly modifies the overall thermal ecology of crop fields, with potential implications for ectothermic pest occurrence and dynamics. Overall, our toolbox affords a timely and innovative methodological framework to better assess the thermal heterogeneity of natural landscapes across a wide range of spatial scales. In particular, this toolbox would be of topical interest for ecologists trying to bridge the gap between the resolution of their climatic data and the body size of their study organisms. (Resume d'auteur)

International audience; Grain yield in any given environment is determined by yield components developed at different phenophases. Yield components are influenced by the environmental conditions the plant experiences during the respective phases. The final yield of a given cultivar depends on the interaction between geno-type and its responses to environmental conditions. Hence, it is necessary to evaluate the plasticity in yield components formation while selecting genotype for a given environment. For this, we conducted field trials comprising 10 upland rice genotypes representing a large share of genetic variation, with two sowing dates in two consecutive years in three altitudinal locations creating 12 environments in Madagascar. Crop duration, grain yield and yield components (tillers per hill, panicles per tiller, grains per panicle, sterility, grain weight) were strongly affected by sowing dates, location, year and genotypes. Sowing date and years resulted in comparatively more variable environments in high and low altitudes than in mid altitude. Yield stability across environments reflected the target environments the geno-types were originally selected for. Variation in grain yield among planting dates within altitudes was not mainly due to temperature but rather to the combinations of abiotic factors the genotypes experi-enced during the different phenological stages duringwhich the different yield componentswere formed. Yield components and their contribution to environmentally induced yield penalties were analyzed in detail. The contribution of individual yield components to final yield changed with the environmen-tal conditions the rice experienced during the development stages. This effect may have a stronger influence on final yield than the genetic control of the individual yield components. New combina-tions of traits are required to better exploit the environmental potential which may only be possible via advanced crop models simulating the environmental effects on yield components and their inter-dependencies to develop ideotypes for the target environments thus guiding breeding and selection efforts.

The present study investigates the genetic determinism of flowering and maturity dates, two traits highly affected by global climate change. Flowering and maturity dates were evaluated on five progenies from three Prunus species, peach, apricot and sweet cherry, during 3–8 years. Quantitative trait locus (QTL) detection was performed separately for each year and also by integrating data from all years together. High heritability estimates were obtained for flowering and maturity dates. Several QTLs for flowering and maturity dates were highly stable, detected each year of evaluation, suggesting that they were not affected by climatic variations. For flowering date, major QTLs were detected on linkage groups (LG) 4 for apricot and sweet cherry and on LG6 for peach. QTLs were identified on LG2, LG3, LG4 and LG7 for the three species. For maturity date, a major QTL was detected on LG4 in the three species. Using the peach genome sequence data, candidate genes underlying the major QTLs on LG4 and LG6 were investigated and key genes were identified. Our results provide a basis for the identification of genes involved in flowering and maturity dates that could be used to develop cultivar ideotypes adapted to future climatic conditions., This work was partially supported by the ISAFRUIT Project funded by the European Commission—Food Quality and Safety of the 6th Framework Program of RTD (No. FP6-FOOD-CT-2006-016279).

Matching phenology with prevalent abiotic and biotic conditions is a prerequisite for varietal adaptation to the environment. That is particularly important in the context of climate change because an increase in temperature is most likely to modify the precocity of the varieties. The forecast of flowering time in photoperiod- sensitive sorghum is complex as flowering depends on temperature, day length and soil fertility. The objectives of this work were to quantify effects of latitude on the development of selected sorghum varieties and to verify the precision of our models to predict sorghum maturity. A field experiment at three locations along the latitudinal gradient in Mali with staggered sowing dates (SDs) was conducted. Seven sorghum cultivars covering a wide range of the diversity of cultivated sorghums in Mali were sown on the 10 of June, July and August in 2009 and 2010. Duration of the vegetative phase strongly decreased with latitude. Although the maximum day length difference between locations was < 8 min, for some varieties, we observed a reduction in crop duration of up to 3 weeks. Some varieties were photoperiod insensitive at one location but became photoperiod sensitive at another. The effect of latitude on the phenology is underestimated by the existing models. To determine the optimal areas for the varieties in West Africa and to forecast the effects of climate change, a correction of the simulation coefficients taking account of latitude is proposed. But, in the end, it will be necessary to develop a new model that will be able to predict the effects of both SD and latitude. More research is needed to understand physiological response mechanisms of the pronounced latitude effects on sorghum phenology. (Resume d'auteur)

Context In tropical areas, studies based on the retrospective analysis of tree development have focused principally on growth ring research. The interpretation of primary growth markers is overlooked although it opens perspectives to provide long time-series on tree-crown development. Aims This study focused on Parkia velutina, an emergent tree of neotropical rain forests. Our objectives were (1) to characterize the phenological cycle of this species, and (2) to identify temporally interpretable morphological and anatomical markers. Methods We collected dominant branches in 14 adult trees and identified growth markers that limit longitudinal and radial increments. We coupled this approach with a 2-year phenological survey of 20 trees. Results Leaf shedding, growth unit elongation and growth ring formation define the phenological cycle. At tree scale, this cycle is synchronous and affects all axes. At population scale, trees can be desynchronized. This cycle is annual despite some slight variability. Successive growth units and growth rings are easily identifiable. Conclusion Dating a branch by counting the number of growth units or growth rings is possible in many years with a reasonable error. Nevertheless, estimating their precise month of formation in order to study climatic influences remains difficult.

Contact: berville@supagro.inra.fr; The genetic base of sunflower elite lines is very narrow, due to many years of selection and breeding. To broaden the genetic diversity of the cultivated sunflower, in 1995 73 wild sunflower populations were crossed with 3 cultivated lines (Testers), and 219 hybrid offspring's were evaluated in the field. GCA and SCA effects were computed suggesting for all traits a genetic potential for improvement through selection. Study of the hybrids revealed that the wild accessions bear different genetic abilities to combine with the testers for traits of morphological architecture, phenology and yield (seed weight and seed oil). The variance due to GCA and SCA showed that gene action was additive for days to flowering, branching and plant height. Genotypes derived from the same geographic origin may have either good or poor general combing ability. The correlation between GCA and per se genotype performance was positive for all traits except for seed oil content. This was the first attempt to evaluate wild-cultivated hybrids in sunflower on a large scale and will be the starting point for the management of hybrid Helianthus annuus populations for breeding. GCA and SCA estimations will facilitate the definition of strategies to manage and exploit the natural diversity for this crop

Carolus Linnaeus a ete le pere des reseaux phenologiques modernes. Dans son ouvrage " Philosophia Botanica ", il a decrit des methodes permettant d'elaborer des calendriers annuels des plantes precisant l'ouverture des feuilles, la floraison, la fructification et la chute des feuilles, le tout associe a des observations climatologiques " de facon a montrer les differences selon les regions " (Schnelle, 1955). Le Programme GLOBE (Global Learning and Observations to Benefit the Environment, www.globe.gov) fonde en 1998, a reconnu la valeur des observations phenologiques dans l'education, et encourage les etudiants a prendre des mesures valides sur le plan scientifique dans les domaines de l'atmosphere, de l'hydrologie, des sols et de la couverture vegetale/phenologie, associant la recherche scientifique et l'education. La description detaillee des etapes de croissance de plantes utiles, suivie d'une codification adequate, facilite la communication entre les scientifiques et les chercheurs, lorsque par ex. de nouvelles decouvertes scientifiques doivent etre transferees sous forme de procedures de gestion, ou lorsque des experiences menees sur un site de culture doivent etre adaptees a un autre site. Nous decrivons les etapes de la croissance d'especes de cacaoyers (Theobroma sp.) dans le monde entier afin de preparer les informations qui serviront de base a la gestion de la production, a des comparaisons d'etudes epidemiologiques de maladies, de schemas de croissance suivant differents facteurs environnementaux et de parametres genetiques specifiques a certains clones. La codification suit l'echelle " BBCH etendue " (BBCH = Biologische Bundesantalt, Bundessortenamt and CHemische Industrie, Allemagne), un systeme numerique qui distingue les etapes de croissance principale, secondaire et tertiaire. Chaque etape de croissance presentee, de la germination des semences jusqu'au developpement de la cime et a la recolte, est mise en correlation avec les pratiques de gestion generales. Cette echelle sera tres utile aux cacaoculteurs et aux chercheurs du monde entier pour permettre une meilleure communication, une planification plus efficace des pratiques de gestion et des experimentations. (Resume d'auteur)

Dry weight is used to estimate growth for modelling purposes. Dry weight is commonly derived from fresh weight, which is easily measurable, and dry matter content (DMC). DMC depends on plant physiology and may be variable among organs. DMC distribution within a tree and its sources of variability are poorly investigated, particularly in mango. The objectives of this work were (i) to determine the distribution of DMC among the organs of an irrigated mango tree, and (ii) to assess to which extent the individual plant, the drying method (freeze-drying or oven-drying), the phenological stage and irrigation affect DMC. A distribution of DMC among 22 organs of irrigated whole mango tree has been presented, from fine roots to inflorescences. The drying method did not affect DMC measurement, but the sampling procedure did: radial core samples in woody organs over-estimated DMC. Taproot had the highest DMC (53.4%) which did not differ significantly from DMC of the main woody structure, from stump to scaffolds. Individual plant did not affect DMC of organs, on the contrary to phenological stage. Irrigation affected DMC of taproot, fine and medium roots at the end of harvest, probably in relation to carbohydrate mobilization and soil water status. Our results are used to formulate practical recommendations for sampling procedures, and suggest further studies on carbohydrate cycle in mango. (Resume d'auteur)

UMR DAP équipe AFEF Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Over the last 40 years, perceptible advances in dates of flowering stages have been observed in apple and pear trees growing in three cropping areas in France and one in Switzerland. The time-course variation of dates of flowering stages was established for eight chronological sequences. Our aim was to propose a statistical modelling framework for such sequences with the objective of characterizing the relationship between flowering advances in fruit trees and global warming. After an exploratory analysis, change-point models were applied to multivariate and univariate sequences. The results clearly support the occurrence of a significant abrupt change in the time-course variation of flowering dates at the end of the 1980s toward more frequent early dates, the most probable change instant being between 1988 and 1989. The coincidence between this abrupt change in phenological variations and marked increases in temperature recorded particularly in France at the end of the 1980s led us to consider the flowering advances in apple and pear trees as impacts of global warming. The suddenness in the response to global warming could be explained by changes in rates for completion of chilling and heat requirements, successively essential to the development of floral primordia within buds. In all cropping areas, annual mean temperatures had suddenly increased since 1988 (1.1–1.3 ◦C), but including noticeable monthly differences. Particularly, warming was clearly more pronounced in February and March (mean temperature increases of 1.6 ◦C) corresponding to the main period of heat requirements, than in November and December (0.8 ◦C) corresponding to the main period of chilling requirements. So marked temperature increases during the heat phase would have suddenly resulted in more frequent years with relatively short duration for completion of the heat requirements and consequently more frequent early flowering years, despite some years with relatively long duration of chilling requirements.

Effects of photoperiod (PP) on panicle initiation (PI) of West African sorghums are essential for the crop's agro-ecological adaptation, but not well understood. Conventional models based on fixed PP thresholds (qualitative response) or additive signal accumulation (qualitative response) are able to predict flowering for only a limited range of conditions. Recently, an alternative concept was proposed based on thresholds that vary with plant age. Using this concept, this study develops a generic model of PP response of sorghum called “ Impatience ” because it implements decreasing day length requirements during prolonged wait states, or appetence, during the photoperiod sensitive phase (PSP). The model was applied to experimental field data obtained from sowing date experiments in Mali, in order to validate it and evaluate the range of genotypic response that can be explained with it. It predicted accurately the observations that (1) PI does not occur at any genotype specific day length, but instead, on increasingly long days as the PSP is extended; (2) PI occurs predominantly when day length decreases, or after summer solstice; (3) the duration of PSP increases linearly (but not always proportionally) when crops are sown earlier in the year; (4), a genotype specific sowing date exists in winter (cool season) or spring (hot dry season) after which PSP suddenly increases by up to 160 days (“break point”); (5), the largest variance of PSP occurs near the break point. Most genotypic variations of this complex pattern could be simulated by fitting only one of the four model parameters while using default values for the three other parameters. However, the model tended to underestimate the duration of PSP when it fell into the cool season, which might be explained by specific thermal effects or a specific inhibitory effect of increasing day length on PI in some genotypes. The ability of the model to discriminate among genotypes was used to devise a simple, model assisted phenotyping methodology. Genotypic parameters were determined by fitting two model parameters to measured dates of flag leaf ligule appearance for three sowing dates. Thus parameterized, the model predicted accurately the phenological patterns of contrasting materials observed in different experiments. The authors discuss the physiological probability of the model's underlying concepts, the need for further studies to develop them into a comprehensive theory, and possible applications in crop simulation and varietal selection.

La vitesse de développement des sorghos fortement photopériodiques et par conséquent tardifs adaptés aux savanes d'Afrique de l'Ouest est ralentie pendant les phases de montaison et de développement de la panicule. Cette lenteur du développement, exprimée par un long phyllochrone, ou temps écoulé entre l'apparition de deux feuilles successives, est en relation avec la taille limitée des panicules des sorghos tardifs. Par conséquent, une modification de la vitesse de développement de la plante pourrait être une voie pour augmenter le potentiel de rendement de ce type de variétés. La variabilité pour ce caractère a été recherchée dans la mini core collection de sorgho du Centre de coopération internationale en recherche agronomique pour le développement (Cirad) et n'a pas été décelée. Au contraire, les vitesses de développement sont apparues homogènes au sein de l'espèce. Aucune variation du phyllochrone initial, depuis la levée, n'a été montrée et en dépit de la grande variabilité du phyllochrone secondaire, exprimé pendant la montaison, il n'a pas été mis en évidence de différence significative entre variétés de même maturité. Le phyllochrone secondaire, fortement corrélé à la durée de la phase végétative, est apparu comme l'une des fonctions affectées par la réponse photopériodique.

Patterns of flowering and fruiting phenology are described for 30 native woody species (21 families) growing in maquis on the south of New Caledonia, south—western Pacific. Data were monthly recorded from August 2002 to July 2005 along a transect joining 337 individual plants. Flowering and fruiting were mostly annual. Flowering peaks appeared at the end of the dry season and, to a lesser extent, during the wet season. Fruiting peaks occurred during the wet season. Radiation duration and rainfall are assumed to be the climatic parameters that have the greatest influence on maquis plants phenology, respectively triggering flowering and fruiting. Three functional types of species are defined according to their phenological patterns, based on flowering duration and flowering synchronism. The expected effects of climate change on these functional types are discussed.

Il est couramment admis que la sécheresse en Afrique de l'Ouest a entraîné l'adoption par les paysans de variétés de sorgho plus précoces que les cultivars traditionnels. Pour mesurer l'évolution récente du cycle des sorghos du Mali, nous avons étudié la phénologie de deux collections de variétés locales prospectées à 20 ans d'intervalle en 1978 et en 2000. Les dates de début et de fin de saison des pluies ont été calculées pour tous les villages échantillonnés. La sensibilité des cultivars à la photopériode a été mesurée à l'aide d'un essai comportant deux dates de semis. Un modèle permet d'étudier l'adaptation des variétés au climat en tenant compte de la latitude et du régime des pluies de leurs zones d'origines. Le déficit pluviométrique n'a pas entraîné un raccourcissement important des cycles végétatifs. En 20 ans, le cycle moyen des cultivars locaux s'est raccourci de 5 jours. Pour des latitudes inférieures à 14° N, la grande majorité des cultivars sont photopériodiques, la floraison des variétés se produit dans les 20 jours qui précèdent la date moyenne de fin de la saison des pluies. Ce caractère permet d'optimiser l'alimentation en eau des cultures et d'éviter de nombreuses contraintes biotiques. Pour des latitudes supérieures ou égales à 14° N, la floraison moyenne coïncide avec la fin de saison. On note la présence simultanée de variétés tardives et précoces. Dans ces régions, la culture du sorgho dépend moins de la pluviométrie car les systèmes traditionnels valorisent des situations diversifiées et les reports d'eau sur les toposéquences. Cette diversité des cycles contribue à sécuriser la production agricole en zone aride. Ce travail permet de guider les programmes de sélection dans la définition d'idéotypes spécifiquement adaptés à la gamme d'environnements climatiques rencontrés dans la région.

Un programme de sélection a été monté au Mali avec pour objectif d'agir simultanément sur l'amélioration de la productivité et sur la conservation de la diversité génétique des sorghos locaux. La méthodologie proposée combine des méthodes de sélection récurrente et de sélection participative directement dans le milieu cible. Les critères de sélection se partagent en quatre grands groupes : l'adaptation au milieu, la productivité, la qualité et le maintien de la diversité génétique. L'élargissement de la base génétique à de nombreuses variétés locales a permis de monter la contribution des gènes des variétés locales à près de 70 % dans la population de base. Le photopériodisme confère aux variétés obtenues une grande plasticité phénologique, le matériel demeure performant quelle que soit la date de semis. Le tallage naturel des variétés locales a été préservé, ce qui permet au rendement d'atteindre 4 t/ha, même à faible densité de semis. Les progrès observés au cours de ce travail montrent que nous sommes encore loin d'avoir épuisé la diversité génétique de notre population de base. Deux voies d'amélioration se dessinent à court et moyen termes : l'introduction des caractères de stabilité propres aux variétés locales dans du matériel amélioré et l'introduction des caractères de productivité dans du matériel local.

The impact of human practices on the phenology of flowering was assessed for an important agroforestry tree species of the Sudano-Sahelian zone: Vitellaria paradoxa. Flowering was monitored at two sites in southern Mali over 2 years. At each site, the impact of agricultural practices on flowering phenology was assessed by comparing field, fallow and forest. The site effect and agricultural practices were significant for all the monitored variables. The proportion of individuals that flowered was 89% at Koumantou and 40% at MPeresso. About 98, 95 and 75% of individuals at Koumantou and 88, 12 and 20% at MPeresso flowered in the field, fallow and forest, respectively. The mean length of flowering ranged from 69 to 81 days at Koumantou and from 45 to 108 days at MPeresso. The mean number of days for the active phase ranged from 36 to 49 days at Koumantou and from 27 to 64 days at MPeresso. Koumantou's favourable climatic conditions resulted in better flowering ability and a higher probability of abundant flowering. Field appeared to provide better conditions than fallow and forest regarding flowering ability and probability of abundant flowering. How-ever, tree diameter did not affect flowering phenology. Agricultural practices appear to have a noticeable impact on the phenology of flowering of V. paradoxa. Trees flowered abundantly in the parkland and therefore increased gene flow via pollen and/or seeds and the dynamics of genetic diversity.

A species in the Bactrocera dorsalis (Hendel) complex was detected in Kenya during 2003 and classified as Bactrocera invadens Drew, Tsuruta & White. Having spread rapidly throughout Africa, it threatens agriculture due to crop damage and loss of market access. In a recent revision of the B. dorsalis complex, B. invadens was incorporated into the species B. dorsalis. The potential distribution of B. dorsalis has been previously modelled. However, previous models were based on presence data and did not incorporate information on the seasonal phenology of B. dorsalis, nor on the possible influence that irrigation may have on its distribution. Methyl eugenol-baited traps were used to collect B. dorsalis in Africa. Seasonal phenology data, measured as fly abundance throughout the year, was related to each location's climate to infer climatic growth response parameters. These functions were used along with African distribution records and development studies to fit the niche model for B. dorsalis, using independent global distribution records outside Africa for model validation. Areas at greatest risk of invasion by B. dorsalis are South and Central America, Mexico, southernmost USA, parts of the Mediterranean coast, parts of Southern and Eastern Australia and New Zealand's North Island. Under irrigation, most of Africa and Australia appear climatically suitable.