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The use of non-destructive, continuous, and rapid canopy temperature (T c) indices for crop stress diagnosis is of significant importance for improving crop water productivity (WP). However, the comprehensive applicability of the crop water stress index (CWSI), grounded in T c , in diagnosing both single and combined water and salt stress, as well as characterizing physiological and growth traits, remains inadequately explored. We aim to investigate the ability of CWSI to diagnose single and combined water and salt stress and to test whether a non-water stress baseline (NWSB) with or without growth stage and genotype differences influences CWSI to characterise maize leaf physiological and growth traits. Here, we measured the T c using infrared radiation thermometers of two maize genotypes (XY335 and ZD958) under both single and combined water and salt stress over two growing seasons, compared the differences of NWSB in three growth stages, and established CWSI. Our analysis involved scrutinizing the differences in characterizing crop physiology and growth traits between CWSI calculated using NWSB with and without growth stage differentiations. Our findings indicated that T c is modulated by an interplay of soil water content, VPD, and soil salinity. The NWSB exhibited variations with both growth stage (p slope < 0.001) and genotype (p slope or p intercept < 0.01). The CWSI can diagnose single and combined water and salt stress suffered by maize. Under no stress, and single and combined water and salt stress, CWSI was significantly correlated with stomatal conductance (R2 ≥ 0.31, p < 0.1) and net photosynthetic rate (R2 ≥ 0.38, p < 0.1), rather than with hydraulic traits. The mean CWSI across the entire growth period closely correlated with leaf area index (LAI), canopy photosynthetically active radiation interception, biomass, yield, and evapotranspiration across varying treatments (R2 ≥ 0.54, p < 0.1). Contrary to CWSI derived from NWSB without growth stage variations, utilizing CWSI with growth stage distinctions better characterized physiological traits, while the former was more suitable for delineating yield and WP. This research underscores the efficacy of CWSI for stress diagnosis and the evaluation of gas exchange and productivity in maize under both single and combined soil water-salt stress. This investigation significantly propels forward the implementation of crop-centric irrigation strategies aimed at optimizing water utilization efficiency. • Canopy temperature is modulated by soil water content, vapor pressure deficit, and soil salinity. • Non-water stress baseline (NWSB) exhibited variations upon both growth stage and genotype. • Crop water stress index (CWSI) can diagnose single and combined water-salt stress in maize. • CWSI from growth-stage-specific NWSB well indicated stomatal conductance and photosynthesis. • CWSI from NWSB without growth stage variations well indicated yield and crop water productivity. [ABSTRACT FROM AUTHOR]

Sugarcane breeding is resource-intensive and time-consuming, and could benefit substantially from the integration of aerial phenotyping (AP) for rapidly identifying genotypes with superior yield traits. The study aimed to assess the feasibility of using AP to enhance sugarcane breeding by rapidly identifying genotypes with superior yield traits. The specific objectives of the study were to: (1) assess the impacts of canopy cover and stomatal conductance on stalk dry mass yield (SDM); (2) assess the feasibility of estimating these traits with aerially sensed normalized difference vegetation index (NDVI) and canopy temperature (Tc); (3) evaluate the potential for predicting SDM from NDVI and Tc; (4) formulate best AP procedures. The study comprised a replicated field trial near Komatipoort, South Africa, with 54 genotypes grown under well-watered and water deficit conditions. Traits were measured on the ground (canopy cover and stomatal conductance) and remotely sensed from the air with a drone (NDVI and Tc) throughout the plant and first ratoon crops, and SDM was measured at harvest. Measurements were categorized by crop water status and extent of canopy cover, and phenotypic trait correlations were analyzed for these different categories. The study confirmed canopy cover and stomatal conductance as influential traits for determining SDM. Canopy cover could be used as a proxy for identifying high- and low-yielding genotypes early on in water stress-free crops. Findings suggest that high stomatal conductance benefits well-watered crops, while relatively low conductance could be advantageous in dry environments, though further investigation is needed. Canopy cover was predicted well from NDVI at partial canopy for well-watered crops, while the prediction of stomatal conductance from Tc lacked reliability. It was concluded that NDVI and Tc could be used to identify high- and low-yielding genotypes when measured earlier on in the growth cycle for well-watered crops. Results also showed potential for using water treatment differences in Tc and SDM to identify drought tolerant genotypes. Lastly, the study highlighted methodological challenges and insights for future agronomic trait prediction using AP techniques. The findings of this study will be used in further testing in the early stages of the breeding programme along with the breeding populations, ultimately helping to manage breeding strategies for target environments. This has the potential to enhance breeding efficiency and ultimately genetic gains towards productive sugarcane cultivars for the future. [ABSTRACT FROM AUTHOR]

Highlights • We used commercial production fields (>1,000 m2 per plot) to compare different planting geometries in corn. • Compared to ESP, alternative geometries decreased canopy temperature but increased harvest index and kernel weight. • Grain yield increased significantly only when both kernel weight and kernel number were higher for alternative geometries. • Alternative geometries may reduce corn production risks under water-limited conditions. Abstract Selection of an appropriate planting geometry is important for determining crop yield under water-limited conditions. Four studies, consisting of six experiments, were conducted to investigate the feasibility of alternative planting geometries for sustainable corn ( Zea mays L.) production on a commercial scale. Clump (three plants clustered), cluster (five plants clustered), and skip-row (one row planted, one row skipped) geometries were tested against the commonly used evenly spaced planting within the row (ESP) geometry under limited irrigation and/or dryland conditions. Among the four studies, harvest index (HI) for alternative geometries was significantly higher (9–18%) in three of them compared to ESP. Aboveground biomass and grain yield showed mixed results. Although kernel weight for alternative geometries was significantly higher (2–10%) in all studies, grain yield was significantly higher only when kernel number was also higher for alternative geometries. Decreased HI in ESP was mainly due to more tillers because tillers increased vegetative mass, but did not contribute to grain yield. Plants in ESP had 0.57–1.81 tillers plant−1, but the plants in cluster geometry had only 0.22–0.48 tillers plant-1. Canopy temperature (CT) between planting geometries was compared in two studies, where plants in ESP had higher CT (32.2–39.4 °C) than those in clusters (30.7–38.5 °C). Although alternative geometries did not always increase the yield, decreased tillers, reduced CT, and increased HI and kernel weight associated with the alternative geometries may help to reduce corn production risk under water-limited environments. [ABSTRACT FROM AUTHOR]

Crop models are useful tools to investigate climate change impacts and suitable adaptations strategies on crops. In order to evaluate the impact of climate change on peanut yield in Senegal, a solution of the SIMPLACE crop modelling framework using the Lintul5 crop model together with a T c model and FAO-56 based approach to simulate evapotranspiration was used with consideration of T c versus T a in driving heat stress with output from four regional climate models (RCMs) and two climate change scenarios (RCP4.5 and RCP8.5). Results from six field experiments at two sites (Bambey and Nioro) in Senegal in the dry seasons of 2014 and 2015 and the rainy season of 2014, were used for calibration and evaluation for two peanut varieties. Our calibration and evaluation exercise revealed that simulation skill was markedly improved when T c was considered under irrigated, dry season conditions during which time the plants were subject to periodic heat stress. Under future climatic conditions, positive changes of up to 2.4% for RCP4.5 and 8.3% for RCP8.5 for seed yield were found when increasing [CO 2 ] is taken into account for the period 2016–2045 in dry season. While, in rainy season seed yield increased by 11.0% for RCP4.5 and 19.0% for RCP8.5. The effect of climate change on seed yield was negative in the dry season where maximum T a is often higher than 38 °C compared to the rainy season in particular when T a is used for simulating heat stress effects. It is concluded that climate change could have limited negative impacts on peanut yield in Senegal due to the effect of elevated [CO 2 ]. However, simulated T c should be used instead of T a to accurately account for heat stress impact on peanut especially during the dry season. [ABSTRACT FROM AUTHOR]

Film mulching with deficit irrigation is considered an effective way to maximize water productivity and ensure a stable crop yield in the arid region of Northwest China. Deficit irrigation requires precise knowledge of crop response to drought conditions, whereas the canopy temperature and the related crop water stress index (CWSI) monitor crop water stress status. Although canopy temperature and CWSI are closely related to meteorological conditions, cultivation measure and crop growing conditions, it is unclear how film mulching influences the canopy temperature and CWSI. A two-year field experiment was conducted in a maize field with three irrigation levels and different film mulching conditions, i.e., non-mulching, plastic film mulching and biodegradable film mulching treatments, in the Shiyang River Basin of Northwest China. The study aimed to quantify the effects of film mulching on canopy temperature and CWSI, as well as to compare CWSI values obtained from the nearby meteorological station data (CWSI_M), and in situ (field) measurements (CWSI_I). The results showed that plastic film and biodegradable film significantly (p < 0.05) reduced the canopy temperature. The non-water-stressed baseline based on the air temperature and relative humidity of the nearby meteorological station was significantly (p < 0.05) different from those of the field measurement at both the vegetative and the reproductive stages. No significant differences in the non-water-stressed baselines (p > 0.05) were observed among different film mulching conditions. CWSI was calculated using the air temperature and relative humidity data from the aforementioned two sources. The results revealed showing that CWSI_I better correlated with the crop yields of various treatments when compared to CWSI_M. Irrigation scheduling based on CWSI_I could save 83 mm of irrigation amount. This underscore the preference of using CWSI_I (if available) as the primary choice for irrigation scheduling. These findings highlight the impact of meteorological and planting conditions on the canopy temperature, non-water-stressed baseline and CWSI, which may be valuable for diagnosing crop water status more accurately by regional water managers. • Plastic & biodegradable films notably lowered maize canopy temperature. • Various film mulching types show no significant difference in non-water-stressed baselines (NWSBs). • NWSBs exhibit significant difference in two meteorological data sources (500 m apart). • Calculating irrigation amount by crop water stress index (in-situ meteorological data) saves 83 mm. [ABSTRACT FROM AUTHOR]

Wheat breeding has improved drought tolerance over the years. However, our knowledge on drought tolerance in relation to the diurnal pattern of canopy temperature (CT) and grain yield is limited. A three-season wheat field study ending 2012, 2015, and 2016 was conducted at Bushland, Texas to investigate the relationship between canopy temperature depression (CTD) and yield during the grain filling period. For each season, 20 elite wheat genotypes were grown under dryland conditions, and CT was measured by Smart Crop wireless IRT sensors every 15 min continuously for 12–15 days during mid-grain filling (∼10–25 days after flowering). There was a genotypic variation for CTD regardless of time of the day; however, the variation was more evident during the day time (10:00–18:00 h), with the smallest CTD (i.e., warmer canopy) at 14:00–15:00 h. In a dry season of 2012, TAM 304, TAM 112, Dumas, and Hatcher had greater CTD (i.e., cooler canopy) than other genotypes. In two wet/near normal seasons (2015 and 2016) Duster, TAM 111, TAM 110, TAM 112, and TAM 105 had greater CTD. There was a significant (P < 0.05) positive linear relationship between grain yield and day-time CTD. Hence, a cooler plant canopy during the mid-grain filling in winter wheat appears to be an important indicator of greater drought tolerance and yield under dryland condition. This knowledge may help breeders to conduct high-throughput field phenotyping in large breeding populations. [ABSTRACT FROM AUTHOR]

In order to explore the plant factors facilitating better adaptation of soybean to high temperatures, genotypic variability till the beginning of seed filling (R5) were examined with reference to biomass production, relative transpiration activity and relevant plant factors under a tropical environment. Twenty-nine (in 2014 and 2015) and 20 (in 2016) soybean cultivars of temperate (Japan and USA) and tropical (Indonesia-old, Indonesia-modern, and Others) origin were grown in Serang, Banten (2014 and 2015; Experiment 1) and in Bogor, West Java (2016; Experiment 2), Indonesia. In Experiment 1, aboveground biomass at R5 (TDW R5 ) of the temperate cultivars was one-third to one-fourth of that of the tropical cultivars. This was associated with less than half the amount of the cumulative intercepted radiation to R5 (CIR R5 ) due to their shorter growth duration and lower value of the mean fraction of canopy light interception till R5 (mean F VE-R5 ). In addition, the radiation use efficiency (RUE) at R5 of the temperate cultivars was also as low as 0.54 g MJ −1 , as compared to 0.87 g MJ −1 in the tropical cultivars. The value of canopy temperature minus air temperature (CTd), as an indicator of relative transpiration activity, of temperate cultivars was markedly larger than that of the tropical cultivars, indicating lower transpiration activity in temperate cultivars, which was associated with the low RUE. In Experiment 2, greater activity of transpiration in tropical cultivars was attributed to their higher stomatal conductance ( g s ) and greater stomatal density ( N stoma ) of upper leaves than that in those from the temperate regions. These results indicate that low biomass production in temperate cultivars occurs not only due to the cumulative intercepted radiation in the canopy but also due to low RUE and that the low RUE in temperate cultivars is associated with low gas exchange activity, in which leaf morphological traits are involved. Within temperate cultivars, US cultivars tended to perform better than the Japanese cultivars with respect to gas exchange activity. [ABSTRACT FROM AUTHOR]

Despite widespread application in studying climate change impacts, most crop models ignore complex interactions among air temperature, crop and soil water status, CO 2 concentration and atmospheric conditions that influence crop canopy temperature. The current study extended previous studies by evaluating T c simulations from nine crop models at six locations across environmental and production conditions. Each crop model implemented one of an empirical (EMP), an energy balance assuming neutral stability (EBN) or an energy balance correcting for atmospheric stability conditions (EBSC) approach to simulate T c . Model performance in predicting T c was evaluated for two experiments in continental North America with various water, nitrogen and CO2 treatments. An empirical model fit to one dataset had the best performance, followed by the EBSC models. Stability conditions explained much of the differences between modeling approaches. More accurate simulation of heat stress will likely require use of energy balance approaches that consider atmospheric stability conditions. [ABSTRACT FROM AUTHOR]

To mitigate the possible yield reduction of winter wheat under climate change in the North China Plain (NCP), cultivars with traits that could offset the negative effects of several deteriorating weather factors in the future should be developed. This study used 16 recently certified cultivars of winter wheat each season for five seasons from 2011 to 2016 under three irrigation treatments (I0: without irrigation; I1: moderate irrigation; and I2: well water supply) to examine the agronomic traits of winter wheat that may be able to reduce the negative effects of abiotic stress. Yield variation up to 32% was observed during the five seasons, indicating the significant effects of seasonal weather conditions. The yield difference among the cultivars reached 33%, indicating the benefit of selecting a better cultivar to minimize the negative effects of weather and water deficit. Cultivars with higher seed numbers per area and greater biomass usually gave better grain production under all three water supply conditions. Under good water supply conditions, sunshine duration during the vegetative growth stage significantly affected the spike numbers per area and seed numbers per spike. Diurnal temperature range (DTR) during the grain-fill stage was positively related to the seed weight. Cultivars with higher leaf photosynthetic rates and earlier anthesis dates had an advantage to relieve the influence of climate change and produced higher yield. Due to the reduced rainfall and increased atmospheric evaporation potential under the climate change background, for winter wheat grown under limited water supply, cultivars with a higher kernel Δ 13 C, a lower canopy temperature and a larger root system usually produced a higher yield. In general, for winter wheat grown under good water supply conditions, cultivars that had higher efficiency in dry matter assimilation and allocation performed better. Under dry conditions, cultivars with a high ability to use the soil water stored before sowing had an advantage that allowed them to produce a higher yield. [ABSTRACT FROM AUTHOR]

Rice crops are one of the world's major consumers of irrigation water. With water becoming more limited, water-saving aerobic production (AP) systems may provide an alternative to traditional flooded culture. Genotypes with narrow root cone angle (RCA) and subsequently deeper rooting systems are hypothesised as key for AP adaptation ensuring water uptake at depth. Using a recombinant inbred line (RIL) population and differential genotypes (narrow and wide RCA groups) derived from a Sherpa/IRAT109 cross, a glasshouse experiment and four field experiments with different water inputs in well-watered (WW, in two seasons), mild water deficit (MWD), and intermittent water deficit (IWD) conditions were carried out to characterise the relationship of RCA with grain yield (GY) and key physiological traits. Significant genotypic variation and group differences were found in root traits, canopy temperature and GY. Expression of genotypes with narrow RCA were found to be consistent across experiments and water availability conditions. Genotypes in the narrow RCA group produced a greater proportion of roots below 20 cm (7.4–17.7%), longer total root length (69.7%), cooler canopies (0.3–1.0 °C) and higher GY (14–62%) compared with wide RCA group. Two promising RILs were identified which expressed high GY in WW (12.0–13.4 t/ha) conditions while maintaining GY in IWD (up to 9.4 t/ha). Higher GY was obtained in genotypes with cooler canopies (r = −0.72) and narrow RCA (r = −0.39) in IWD. Narrower RCA was associated with higher total root length (r = −0.70) and higher stomatal conductance (r = −0.71) in the glasshouse and proportion of deep roots (r = −0.65) and cooler canopies (r = 0.66) in the field. To our knowledge, this was one of the foremost studies exploring and demonstrating such relationships in rice AP systems. Root traits determined in the field were congruent with the other root-related traits driving differences between RCA groups measured in the glasshouse providing confidence with the field phenotyping methods. This work demonstrated the advantage conferred by the development of narrow RCA in aerobic conditions, presented improved physiological understanding of RCA and with genomics assisted breeding, is considered valuable for the development of AP-adapted, sustainably produced rice. • Water saving AP system may provide alternative to traditional flooded rice culture. • RCA of genotypes was consistent across experiments in aerobic conditions. • Narrow RCA genotypes had deeper roots, cooler canopies and higher GY. • Potential to increase GY in AP systems by improving root system architecture. [ABSTRACT FROM AUTHOR]

Even brief periods of high temperatures occurring around flowering and during grain filling can severely reduce grain yield in cereals. Recently, ecophysiological and crop models have begun to represent such phenomena. Most models use air temperature ( T air ) in their heat stress responses despite evidence that crop canopy temperature ( T c ) better explains grain yield losses. T c can deviate significantly from T air based on climatic factors and the crop water status. The broad objective of this study was to evaluate whether simulation of T c improves the ability of crop models to simulate heat stress impacts on wheat under irrigated conditions. Nine process-based models, each using one of three broad approaches (empirical, EMP; energy balance assuming neutral atmospheric stability, EBN; and energy balance correcting for the atmospheric stability conditions, EBSC) to simulate T c , simulated grain yield under a range of temperature conditions. The models varied widely in their ability to reproduce the measured T c with the commonly used EBN models performing much worse than either EMP or EBSC. Use of T c to account for heat stress effects did improve simulations compared to using only T air to a relatively minor extent, but the models that additionally use T c on various other processes as well did not have better yield simulations. Models that simulated yield well under heat stress had varying skill in simulating T c . For example, the EBN models had very poor simulations of T c but performed very well in simulating grain yield. These results highlight the need to more systematically understand and model heat stress events in wheat. [ABSTRACT FROM AUTHOR]

In the extensive rice–wheat system of north-west (NW) India, harvesting is by large combines and the rice residues are normally burnt after harvest, followed by irrigation and intensive tillage prior to sowing wheat. While in-field retention of crop residues can play an important role in replenishing soil quality and reducing environmental pollution from stubble burning, until recently, there has been no suitable technology for seeding wheat in rice residues. To address this need, a series of machines (‘Happy Seeders’) was developed over the past 10 years, culminating in the development of version 2 of the 9-row Turbo Happy Seeder (v.2). The 9-row Turbo Happy Seeder(v.2) has a weight of 506 kg and can be operated by a 33.6 kW tractor at a work rate of 0.3 ha h −1 . Numerous on-farm trials show that yield of wheat sown into rice residues with the 9-row Turbo Happy Seeder is similar to or higher than yield with straw burning and conventional tillage prior to sowing, while providing many benefits to the farmer. These include greatly reduced fuel consumption and cost of crop establishment, and the ability to sow as soon as desired after harvest, ensuring the possibility of sowing at the optimum time and reducing the need for irrigation. However, adoption has been low to date, despite a 50% price subsidy. Constraints to adoption include the low window of operation of the machine (25 days per year), the low machine capacity compared with conventional seed drills, the inability to operate in wet straw, and the lack of straw spreaders on combine harvesters. Removal of subsidies for diesel and electricity (for pumping groundwater) and implementation of the policy banning in-field straw burning would help to accelerate adoption of technology for direct drilling wheat into rice residues. [ABSTRACT FROM AUTHOR]

Crop canopy temperature ( T c ) is associated with transpiration and T c has been used in crop water stress detection. This study investigates the effect of surface drip and furrow irrigation regimes on cotton T c . It outlines the relationship between T c and lint yield, fibre quality and both agronomic (WUE a , kg ha −1 mm −1 total applied water) and leaf level water-use efficiency (WUE l , μmol[CO 2 ] mmol[H 2 O] −1 ) in a high input, high yielding (>1800 kg ha −1 ) cotton system. Canopy temperature between flowering and crop maturity was monitored. Yield reductions occurred when T c exceeded 28 °C. Reductions in fibre length outside the ideal range (>28.6 mm) occurred when T c exceeded 31 °C, while desirable micronaire (3.8–4.5) was observed at T c between 25 and 32 °C. Desirable fibre quality and peak lint yield can be realised if an irrigation scheduling protocol maintains average canopy temperatures below 28 °C. However, maximum WUE a was observed at a higher average T c (30 °C) than peak lint yield (28 °C), which would correspond to a predicted 23% reduction in lint yield from the peak (3030 kg ha −1 ). Therefore, the trade-off between peak yield and WUE a needs to be considered in conjunction with irrigation water costs and availability when scheduling irrigations based on canopy temperature. [ABSTRACT FROM AUTHOR]

High-throughput precision phenotyping, using spectral reflectance measurements, has the potential to provide more information for making better-informed management decisions at the canopy scale in real time. Active and passive spectral reflectance sensors are available for ground-based remote sensing; however, they have not been compared in their performance for assessing the normalized relative canopy temperature (NRCT) and the grain yield of drought-stressed plants. In this study, five spectral passive and active reflectance sensors, including a hyperspectral passive sensor (HPS), a hyperspectral active sensor (HAS), an active flash sensor (AFS), the Crop Circle (CC) and the GreenSeeker (GS), were tested to assess the NRCT and grain yield of barley cultivars under mild and severe drought stress in 2012 and 2013. Simple linear regression and partial least squares regression models were used for analysing the spectral data. The results showed that the spectral indices of all sensors were more closely related to NRCT and grain yield under mild drought stress ( R 2 up to 0.70, significant correlation at p ≤ 0.001) than under severe drought stress ( R 2 up to 0.53, significant correlation at p ≤ 0.001). Closer relationships between three normalized water indices (NWI-1, NWI-3 and NWI-4) and NRCT and grain yield were obtained for the hyperspectral passive sensor compared to the same indices of the hyperspectral active sensor and the active flash sensor under both mild and severe drought stress. Multivariate analysis using partial least square regression improved the relationship ( R 2 up to 0.77, significant correlation at p ≤ 0.001) compared to the individual spectral indices and the single reflectance bands for each sensor. In conclusion, both the selection of adapted measurement devices and advanced statistical methods can improve assessments of NRCT and grain yield. [ABSTRACT FROM AUTHOR]

Canopy temperature depression (CTD) has been used to estimate crop yield and drought tolerance. However, when to measure CTD for the best breeding selection efficacy has seldom been addressed. The objectives of this study were to evaluate CTD as a drought response measure, identify suitable crop stage for measurement and associated molecular markers. CTD was measured using an infrared camera on 59, 62, 69, 73, 76 and 82 days after sowing (DAS) and the grain yield, shoot biomass and harvest index (%). CTD recorded at 62 DAS was positively associated with the grain yield by 40% and shoot biomass by 27% and such association diminished gradually to minimum after 76 DAS. Moreover, CTD at 62 DAS also showed similar positive association with the grain yield recorded in two previous years ( r = 0.45***, 0.42***). Genome-wide and candidate gene based association analysis had revealed the presence of nine SSR, 11 DArT and three gene-based markers that varied across the six stages of observation. Two SSR markers were associated with CTD through crop phenology or grain yield while the rest were associated only with CTD for computing marker-trait associations (MTAs). The phenotypic variation explained by the markers was the highest at 62 DAS. These results confirm the importance of continued transpiration and the ability of the roots to supply stored soil water under terminal drought. The selection for grain yield through CTD is done best 15 days after the mean flowering time. [ABSTRACT FROM AUTHOR]

Highlights: [•] A major QTL, qDTY3.2 was mapped on chromosome 3 with consistent effect on grain yield across three seasons under both stress and control conditions. [•] We observed the effect of qDTY3.2 increases with increase in level of stress. [•] A clear grain yield advantage was found between with QTL lines and without QTL lines. [•] qDTY3.2 is also governing canopy temperature and seedling dry weight under stress conditions. [ABSTRACT FROM AUTHOR]

Abstract: Genetic progress in yield will increase if more traits conferring better agronomic and physiological performance are brought together in the same variety through full exploitation of genotyping and phenotyping techniques in breeding. A set of 288 spring wheat advanced lines was tested in different countries in North Africa, Western and South Asia, as well as in Mexico (total of 12 environments) to: identify high yielding germplasm adapted to the former regions; identify sources of variation for physiological traits; and test the ability of physiological traits to predict yield. A group of high yielding advanced lines has been selected in these environments, but significant genotype by environment interactions were observed and were significantly explained (21% of yield variation) by soil pH and air temperature. Associations between traits were dependent on the environment, specifically TKW was positively associated with yield in almost all environments however in Sudan, negative associations were observed. In contrast cooler CT was consistently associated with yield and the trait showed moderate heritability. Agronomic and physiological variables were able to predict 27% of yield variation across advanced lines (R 2% by ridge regression) using means of all environments and this model became more significant under stress environments (explaining around 34% of yield variation). Results suggested that if drought and heat adaptive traits are brought together in one genotype, yields can be further increased particularly in low yielding environments. [Copyright &y& Elsevier]

Abstract: Plant growth and soil water deficit can vary spatially and temporally in crop fields due to variation in soil properties and/or irrigation and crop management factors. We conducted field experiments with cotton (Gossypium hirsutum L.) over two seasons during 2007–2009 to test if infrared thermography can distinguish systematic variation in deficit irrigation applied to various parts of the field over time. Soil water content was measured with a neutron probe and thermal images of crop plants were taken with a thermal infrared camera. Leaf water potential and stomatal conductance were also measured on selected occasions. All measurements were made at fixed locations within three replicate plots of an irrigation experiment consisting of four soil-water deficit treatments. Canopy temperature related as well with soil water within the root zone of cotton as the stomatal conductance index derived from canopy temperature, but it neglected the effect of local and seasonal variation in environmental conditions. Similarities in the pattern of spatial variation in canopy temperature and soil water over the experimental field indicates that thermography can be used with stomatal conductance index to assess soil water deficit in cotton fields for scheduling of irrigation and to apply water in areas within the field where it is most needed to reduce water deficit stress to the crop. Further confidence with application of infrared thermography can be gained by testing our measurement approach and analysis with irrigation scheduling of other crops. [Copyright &y& Elsevier]

Abstract: Under Mediterranean environments, farmers usually prefer to sow barley rather than wheat as it is generally believed that barley yields more under stressful conditions. As terminal stresses such as high temperature and water are common constraints in Mediterranean regions, higher grain weight stability may confer a clear advantage in order to maintain higher yields. The objective of the present study was to compare the stability in terms of grain weight and its components for barley, bread wheat, and durum wheat, exploring a wide range of nitrogen and water availabilities in experiments conducted in a Mediterranean region. Grain weight ranged from 23.8 to 47.7mg grain−1, being higher for durum wheat than barley and bread wheat. Durum wheat presented higher variability both in maximum grain filling rate and duration of grain filling period than bread wheat or barley. The three species responded similarly in terms of grain nitrogen content to changes in the environmental conditions explored. It is concluded that in terms of grain weight barley is as stable as bread wheat. However, durum wheat presented a lower stability than barley and bread wheat. [Copyright &y& Elsevier]

Abstract: Nitrogen (N) fertilisation boosts the grain yield of wheat through its influence on yield components, phenology and leaf traits. Both crop growth and senescence are dependent on N supply, as are the number of kernels set per unit area and per ear, and the mean kernel size. A two-season trial of four semi-dwarf durum wheat cultivars, grown at two levels of N, was used to illustrate the effects of N on canopy temperature, leaf resistance and flag leaf senescence pattern under irrigated conditions in a Mediterranean climate, and to explore the consequences of these effects on the crop phenology, its yield and its yield components. The well-fertilised crop developed a larger leaf area index at anthesis and a lower leaf resistance, thus generating a lower canopy temperature and delayed anthesis. Its grain fill duration was shorter, in spite of its lower canopy temperature, presumably because the increased N availability resulted in the development of a stronger sink (more kernels per unit area and per ear), which was associated with earlier senescence, thereby shortening the duration of grain fill, and led to reduced kernel weight. [Copyright &y& Elsevier]

Abstract: Over the last century, most of the genetic gain in the grain yield of Italian durum has been achieved by an increase in the harvest index and promotion of flowering time. We report the indirect effects of this long-term selection on a number of leaf and canopy traits associated with photosynthesis. In a 2-year experiment, using different sowing dates and nitrogen regimes, these characters were assessed for a set of 20 cultivars released between 1900 and 2000. Leaf area, specific leaf area, specific leaf nitrogen content and stomatal resistance were all negatively correlated with year of release, whereas canopy temperature showed a positive correlation. The substantial reduction in plant height, by which the rise in harvest index was achieved, was partly responsible for the rise in canopy temperature, acting via its effect on aerodynamic resistance. Senescence, when expressed in thermal time after anthesis, was delayed for the modern cultivars, and this delay could be associated with a greater quantity of nitrogen allocated to the grain. The association of senescence onset with earliness suggests a likely role of increased earliness in delayed senescence. The yield increase over time was correlated with a decrease in stomatal resistance and in specific leaf nitrogen content. [Copyright &y& Elsevier]