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In modern orchard systems, the tree canopy is designed to ensure homogeneity in fruit quality. However, even in those crops there are some variables that affect the fruit maturation process and fruit quality properties. The aim of this work was to determine if canopy layer (upper vs. lower), fruit shoot position (grouped vs. individual) and orientation (west vs. east) affect fruit quality attributes of 'Sanguinelli' blood oranges. Thus, different quality traits, such as weight, internal colour (IC), external colour (EC), total soluble solids (TSS), titratable acidity (TA) and maturity index (MI) were determined for this purpose. Results showed that fruit weight, internal colour, TA and MI were influenced by the number of fruits per shoot. In this sense, the highest values of weight, IC and MI were found in the grouped fruits, while the highest values in TA were in the individual fruits. Regarding the EC and TSS, they were strongly related to the canopy layer, since the highest values were found in fruit located at the upper parts of the canopy. On the contrary, the orientation did not have a significant effect on fruit quality properties. Therefore, consistent differences in quality traits of 'Sanguinelli' blood oranges fruits were observed depending on canopy layer and number of fruits per shoot. [ABSTRACT FROM AUTHOR]

Introduction: Clementine mandarins are categorised as non-climacteric fruit because they do not exhibit an increase in respiration rate and ethylene production during ripening. Recent studies have suggested that abscisic acid (ABA), a distinct ripening hormone, plays a pivotal role in the postharvest behaviour of this fruit. The present study aimed to identify biomarkers for enhancing the postharvest durability and flavour retention of imported 'Nadorcott' clementines (Citrus reticulata Blanco). To achieve this goal, an experiment was designed to investigate pre- and post-harvest factors influencing quality of clementine fruit, encompassing both physiological and biochemical aspects. Furthermore, the study investigated the role of ABA and ABA catabolites in the fruit senescence process. Methods: Clementines from four different canopy positions, i.e. upper outside, upper inside, lower outside, and lower inside, were manually harvested at different horticultural maturity. The study was conducted over two harvest times, specifically in March (mid-season) and April (end of season). Harvested fruit samples were stored for six weeks in a cold room with temperature and relative humidity set at 8.5±0.5 °C and 85±2%, respectively. Various physiological (i.e. respiration rate), organoleptic (i.e. rind colour, total soluble solids, and titratable acidity) and biochemical (i.e. individual sugars and organic acids, abscisic acid and its catabolites) variables were measured bi-weekly. Sensory evaluation and consumer survey were conducted during the fourth week of storage. Results and discussion: At the end of storage, fruit located on the inside of the canopy had a significantly higher respiration rate and lower concentration of sugars than outside fruit, resulting in a shorter shelf-life. At the same time, inside fruit showed a higher concentration of ABA and ABA catabolites than outside fruit, coinciding with a lower consumer acceptance score for external appearance, aroma, and flavour. For the first time, the key biomarkers affecting resilience and flavour retention, notably the higher ABA concentration and lower sugar levels in inner canopy fruit, resulting in a shorter shelf-life and reduced consumer acceptance were unveiled. This research not only provides valuable insights for the citrus industry but also unveils the intricate relationship between fruit quality, ABA, and ABA catabolites during senescence and consumer acceptance. [ABSTRACT FROM AUTHOR]

In modern orchard systems, the tree canopy is designed to ensure homogeneity in fruit quality. However, even in those crops there are some variables that affect the fruit maturation process and fruit quality properties. The aim of this work was to determine if canopy layer (upper vs. lower), fruit shoot position (grouped vs. individual) and orientation (west vs. east) affect fruit quality attributes of ‘Sanguinelli’ blood oranges. Thus, different quality traits, such as weight, internal colour (IC), external colour (EC), total soluble solids (TSS), titratable acidity (TA) and maturity index (MI) were determined for this purpose. Results showed that fruit weight, internal colour, TA and MI were influenced by the number of fruits per shoot. In this sense, the highest values of weight, IC and MI were found in the grouped fruits, while the highest values in TA were in the individual fruits. Regarding the EC and TSS, they were strongly related to the canopy layer, since the highest values were found in fruit located at the upper parts of the canopy. On the contrary, the orientation did not have a significant effect on fruit quality properties. Therefore, consistent differences in quality traits of ‘Sanguinelli’ blood oranges fruits were observed depending on canopy layer and number of fruits per shoot.

IntroductionClementine mandarins are categorised as non-climacteric fruit because they do not exhibit an increase in respiration rate and ethylene production during ripening. Recent studies have suggested that abscisic acid (ABA), a distinct ripening hormone, plays a pivotal role in the postharvest behaviour of this fruit. The present study aimed to identify biomarkers for enhancing the postharvest durability and flavour retention of imported ‘Nadorcott’ clementines (Citrus reticulata Blanco). To achieve this goal, an experiment was designed to investigate pre- and post-harvest factors influencing quality of clementine fruit, encompassing both physiological and biochemical aspects. Furthermore, the study investigated the role of ABA and ABA catabolites in the fruit senescence process.MethodsClementines from four different canopy positions, i.e. upper outside, upper inside, lower outside, and lower inside, were manually harvested at different horticultural maturity. The study was conducted over two harvest times, specifically in March (mid-season) and April (end of season). Harvested fruit samples were stored for six weeks in a cold room with temperature and relative humidity set at 8.5±0.5 °C and 85±2%, respectively. Various physiological (i.e. respiration rate), organoleptic (i.e. rind colour, total soluble solids, and titratable acidity) and biochemical (i.e. individual sugars and organic acids, abscisic acid and its catabolites) variables were measured bi-weekly. Sensory evaluation and consumer survey were conducted during the fourth week of storage.Results and discussionAt the end of storage, fruit located on the inside of the canopy had a significantly higher respiration rate and lower concentration of sugars than outside fruit, resulting in a shorter shelf-life. At the same time, inside fruit showed a higher concentration of ABA and ABA catabolites than outside fruit, coinciding with a lower consumer acceptance score for external appearance, aroma, and flavour. For the first time, the key biomarkers affecting resilience and flavour retention, notably the higher ABA concentration and lower sugar levels in inner canopy fruit, resulting in a shorter shelf-life and reduced consumer acceptance were unveiled. This research not only provides valuable insights for the citrus industry but also unveils the intricate relationship between fruit quality, ABA, and ABA catabolites during senescence and consumer acceptance.

Water use efficiency (WUE) relates two important processes of the plant atmosphere continuum namely carbon assimilation (via photosynthesis) and water utilization (via transpiration). Our desire to trade-off WUE between accurate measurement at leaf level (WUEL) and effective implementation at plant level (WUEP) demands accurate scaling relations. Conventional mid-day, fully expanded, single-leaf measurements of WUEL are found to be poorly correlated with WUEP, thus questioning the applicability of scaling relations. This research is aimed at obtaining optimal time-window and canopy position to characterize and upscale WUEL for effective field level implementation. Leaf gas exchange parameters were monitored in a rainfed Cotton field at five canopy positions for one crop cycle, and further correlated with WUEP considering individual measurements as well as their spatial averages. Optimal time-window showing highest correlation with WUEP has occurred during 15:00 to 16:00 h irrespective of leaf position and growth stage. Deviation with mid-day measurements of WUEL are largely attributed to stomatal regulation of water vapour via unregulated water stress conditions. Scaling relations between WUEL and WUEP are linear with correlation strengths ranging from 0.52 (west bottom) to 0.80 (plant top). At leaf level, WUE is controlled by variations in photosynthetic photon flux density (ρ = 0.80) and vapour pressure deficit (ρ = 0.78), whereas at plant level, WUE is controlled by relative humidity (ρ = 0.77) and net solar radiation (ρ = 0.85). Our findings can help in developing alternate water management strategies to improve WUE in rainfed Cotton fields of tropical humid climate.

This study attempts to clarify the effect of canopy position on the physico-chemical parameters of apples cv. Braeburn. The experiments were carried out on fruit from the inner and outer part of the canopy in two growing seasons and at two harvest dates. Light measurements revealed that the average value of photo active radiation (PAR) for the inside and outside canopy amounted to 30.3 μmol/m2/s and 133.7 μmol/m2/s, respectively. Production year and canopy position significantly influenced ground color parameters a*, b*, C*, and h°, while the harvest date influenced all color parameters studied. For additional (red blush) coloration, the production year significantly influenced only the L* parameter, harvest date influenced all color parameters, and canopy position influenced L, a*, and C*. Only the fruits of the second harvest date showed more intense additional (red blush) coloration. The production year significantly affected fruit mass, firmness, total soluble solids (SSC), titratable acidity (TA), SSC/TA ratio, DPPH radical scavenging assay (AOP), total phenolic content (TPC), and total flavonoid content (TFC). The harvest date significantly influenced fruit mass, SSC, TA, SSC/TA, AOP, TPC, and TFC. The canopy position significantly influenced SSC, TA, AOP, TPC, and TFC. Regarding mineral content, the production year significantly affected the content of Fe, Ni, Cu, and Ca and the K/Ca ratio. The harvest date significantly affected Fe, Cu, Sr, K and K/Ca. The canopy position affected Fe, Ni, Zn, Sr, Ca, and K/Ca ratio, with a clear significant trend regarding the effect of canopy position only for Ca content (first and second year of the second harvest date) and K/Ca ratio (first year of both harvest dates). PCA analyses identified distinguishing features between apples, with differences defined specifically by AOP, TPC, TFC, Rb, Sr, Ca, and K/Ca on the PC 1 and Mn, Fe, Ni, Cu, and Zn on PC 2. [ABSTRACT FROM AUTHOR]

This study was conducted to identify reliable science-based maturity indices for ‘Lamb Hass’ avocado fruit and evaluate the effect of harvest maturity on the fruit postharvest performance. Fruits were harvested from outside and inside canopy positions at early and mid-season for quality assessment. The results showed that the canopy position had a highly significant effect (p .05) between the early and mid-season fruit, whilst significant differences in OC were found between the two harvesting stages. In both harvesting stages, the canopy positions did not affect the rate of fruit mass loss. Nonetheless, the overall analysis showed that early season fruit had a significantly (p .05) on the fruit softening rate as insignificant differences between the two harvesting stages were observed. In both the harvesting stages, inside canopy fruit were characterized by a higher concentration of mannoheptulose and perseitol than the outside canopy fruit. The early and mid-season fruit also differed significantly (p

‘Honeycrisp’ is a popular apple cultivar, but it is prone to several disorders, especially bitter pit. Previously reported models for predicting bitter pit are biased, indicating that the models are missing one or more important predictor variables. To identify additional variables that may improve bitter pit prediction, a study was undertaken to investigate the influence of canopy position, spur characteristics, and individual fruit characteristics on bitter pit development. ‘Honeycrisp’ trees from two orchards over 2 years provided four combinations of orchards and years. Fruits were sampled from spurs at different canopy positions and with varying bourse shoot lengths and numbers of fruits and leaves. Following cold storage, bitter pit was assessed in three ways: 1) bitter pit severity was recorded as the number of pits per fruit, 2) bitter pit was recorded as a binomial response (yes, no) for each fruit, and 3) the incidence of bitter pit was recorded as the proportion of fruit developing bitter pit. As a result of the high fruit-to-fruit variation, bitter pit severity was associated with canopy position or spur characteristics to a lesser extent than bitter pit incidence. Bitter pit incidence was generally greater for fruits developing on spurs with only one fruit and spurs from the lower canopy. Binomial data were analyzed with a generalized linear mixed model. Fruit harvested from trees with heavy crop loads, and those developing on spurs with multiple fruit and spurs with long bourse shoots had the lowest probability of developing bitter pit. Regardless of how bitter pit was assessed, bitter pit related positively to fruit weight (FW), but the relationship usually depended on other variables such as canopy position, fruit per spur, and leaves per spur. The advantages of fitting binomial data with logistic regression models are discussed.

Camellia oleifera is an economic tree species in southern China and is famous for its oil. The surrounding climate is filtered by the tree itself, resulting in the canopy microclimate, which affects the growth and fruit quality of C. oleifera. This study investigated the effect of canopy positions on microclimate and fruit growth, maturation and qualities by comparing the differences in canopy position. This study also considered the relationship between microclimate and fruit qualities during the oil conversion period. The fruit qualities and microclimate were studied by dividing the canopy into two vertical layers and horizontal layers, creating the following canopy positions: upper outer canopy (UO), upper inner canopy (UI), lower outer canopy (LO) and lower inner canopy (LI). The light intensity increased significantly from inside to outside and from top to bottom in the canopy; however, there were no significant differences in temperature and relative humidity. At maturity, the moisture content of fruits and kernels in UO and LO was approximately <5% of those in UI and LI. The soluble sugar content increased by 10.90%, 8.47% and 6.84% in UO, UI and LO in November, while no significant change was observed in LI. The kernel oil content (KOC) obtained a higher value in UO and UI at maturity. However, KOC decreased by 5.16%, 3.02%, 3.10% and 0.67% in UO, UI, LO and LI in November. Light intensity in September and October was correlated, and temperature and relative humidity in August and September were correlated. [ABSTRACT FROM AUTHOR]

Soybean production can be affected by heat (HS) and water stress (WS). However, studies on effects of stresses combination under field conditions are still scarce. The objective of this study was to evaluate the impact of HS, WS and their interaction (HS × WS) during seed filling on seed weight, seed growth rate (SGR) and seed filling duration (SFD) of same phenological age pods from different canopy positions. Two soybean genotypes were exposed to four treatments during seed filling: control (irrigated plots at ambient temperature), HS (plots under temperatures >32°C for 6 hr/day during 15 days), WS (plots under 25% of soil water content, during entire seed filling) and HS × WS. Stresses interaction caused similar responses to WS alone, decreasing yield and its components (seed number and weight), as well as seed weight for each canopy position (SWCP), SGR and SFD. Non‐significant effect of irrigated HS and non‐additive effects was observed in HS × WS plots, exhibiting WS a dominant effect over HS. The SWCP strongly correlated with SGR, exhibiting upper position a trend to higher SWCP than lower one. Seed maximum water content and pod weight, positively associated with SWCP, indicated seed metabolic limitations under WS and HS × WS. Our results advance in the understanding of SW determination under abiotic stresses and highlight the importance of identifying pods of same phenological age to establish accurate comparisons between seeds from different canopy positions. [ABSTRACT FROM AUTHOR]

Citrus fruits contain numerous beneficial bioactive compounds including vitamin C, phenolic compounds, flavonoids, carotenoids, and sugars which have high nutritional and antioxidant value. Some factors such as the canopy position of the fruit and fruit size affect the quality and quantity of these compounds. The aim of this study was to investigate the effect of canopy position and fruit size on morphophysiological and biochemical properties of Thomson orange fruit. In the first experiment, fruits with medium and uniform size were harvested from inside and outside canopy positions of the tree. In the second experiment, after harvest the fruits were grouped into three sizes of small, medium, and large. Traits such as weight, volume, length, and width of fruit, skin color, skin thickness, extract content, dry matter percentage, TA, TSS, TSS/TA, total chlorophyll and total carotenoids, antioxidant capacity, phenolic acid content, vitamin C, total sugars, and reducing sugars were evaluated on the peel and pulp of fruit along with a panel test. Results revealed that fruit volume, peel thickness, TSS/TA, a* value, CCI value, peel antioxidant capacity, and peel total sugars were higher in the fruits from the external canopy position while TA, L*, C*, h°, and b* in the fruits from internal canopies were significantly higher. Fruit size had a significant effect on physical parameters of fruit, CCI, h°, juice, and dry matter while it did not affect the quality and chemical traits of fruit. The results of this study showed that orange fruit with a position outside the crown and a large size has a significant increase in extract content, actual volume, average fruit diameter, aroma, taste, and sweetness compared to the position inside the crown with a small size.

This study was conducted to identify reliable science-based maturity indices for 'Lamb Hass' avocado fruit and evaluate the effect of harvest maturity on the fruit postharvest performance. Fruits were harvested from outside and inside canopy positions at early and mid-season for quality assessment. The results showed that the canopy position had a highly significant effect (p <.001) on all maturity parameters: dry matter (DM) content, moisture content (MC) and oil content (OC). The outside canopy fruit were more mature (30% DM, 70% MC, 14.9% OC) than those harvested from the inside canopy (28.9% DM, 71.1% MC, 11.75% OC) at minimum maturity. However, fruit DM and MC did not differ significantly (p >.05) between the early and mid-season fruit, whilst significant differences in OC were found between the two harvesting stages. In both harvesting stages, the canopy positions did not affect the rate of fruit mass loss. Nonetheless, the overall analysis showed that early season fruit had a significantly (p <.001) higher fruit mass loss rate than the mid-season fruit. Notably, fruit maturity did not have a significant effect (p >.05) on the fruit softening rate as insignificant differences between the two harvesting stages were observed. In both the harvesting stages, inside canopy fruit were characterized by a higher concentration of mannoheptulose and perseitol than the outside canopy fruit. The early and mid-season fruit also differed significantly (p <.05) in phenolic content; with the mid-season fruit having a high phenolic content (2.7 µm/g) than the early season fruit (1.8 µm/g), suggesting the possibility of increased mesocarp discolouration with the advancement in maturity. These findings will be a valuable tool to assist growers in assessing fruit readiness for harvest and understanding the influence of maturity on the fruit postharvest behavior. [ABSTRACT FROM AUTHOR]

Camellia oleifera Abel. is an economically important plant for edible oils. To investigate the importance of wild bee abundance at different canopy and spatial scale for fruit set of Camellia oleifera, we evaluated the relationship of bee abundance with fruit set using yellow pan trap, with additional focus on distance and wild bee abundance counts at a farm in China for 2 years. We found that yellow traps collected 95% more individual bees than the second‐best (pink) trap colour. Looking across canopy positions, the number of wild bees (including Colletes gigas, Andrena camellia, Andrena striata, Andrena hunanensis and Andrena chekiangensis) varied significantly in each year. The fruit set also varied significantly based on canopy position. In 2018, there was with an average fruit set of 34.13% in the lower canopy, 54.30% in the middle canopy and 47.41% in the upper canopy. In 2019, fruit set was 29.67% in the lower canopy, 54.15% in the middle canopy and 47.36% in the upper canopy. Comparing inter‐annual changes, only the fruit set and number of bees in the low canopy showed significant differences between 2018 and 2019. Fruit set and wild bee abundance were positively correlated in all canopy layers in each year, and there was an interactive effect between canopy and bee abundance on fruit set. Across 205 trees, growth indicators, crown size and tree height, increased significantly from 2018 to 2019, but the fruit set did not increase with the significant increase in the number of flowers. From the spatial perspective, wild bee abundance and fruit set were positively correlated, but fruit set was negatively correlated with distance from a large bee nesting aggregation nearby. Among the variables investigated, bee abundance seems to have the strongest influence on fruit set in C. oleifera. [ABSTRACT FROM AUTHOR]

Questions: Studies in alpine environments have highlighted dominant facilitative effects of cushion species for diversity. Many fewer studies have assessed the effects of cushion shrubs in drier and less cold mountain habitats and how these effects vary within the shrub canopy and with increasing drought stress with exposure and disturbance by fire. Location: A mountain steppe of the Golestan National Park in the semi-arid climate of northeast Iran. Methods: We quantified the cover of understorey species at the center and edge of the canopy of the thorny cushion shrub Onobrychis cornuta and in paired open areas, in north and south exposures and unburned and burned plots, two years after a fire. Soil chemical variables and moisture were measured in treatments. We quantified cushions' center and edge effects on understorey species cover with the Relative Interaction Index (RII). Treatment effects on RII cover were analyzed with generalized linear mixed-effects models (GLMM) and species composition with Correspondence Analysis. Results: In unburned plots, competition for cover was very high at cushion centers and strongly decreased at cushion edges. Exposure stress did not affect competition in unburned plots. Fire slightly decreased competition but only at center cushion shrub position and at south exposure. Species composition was mostly affected by exposure and fire treatments, although there was subtle variation in species composition among patches due to fire. Cushion position, fire and exposure treatments affected soil moisture and chemical variables, but soil changes did not explain cushion effects on understorey cover and their variations along treatments. Conclusions: The effects of the cushion shrub were highly negative and in particular at cushion center, likely due to interference and competition for light in a dry and not too cold environment. Fire only slightly decreased competition in the short term, likely due to the delayed response of understorey species to disturbance induced by fire. [ABSTRACT FROM AUTHOR]

Wood density is strongly related to key aspects of tree physiological performance. While many studies have examined wood density in different parts of trees, for a variety of reasons, there are very few studies that have compared within-tree density variation across many trees, of many species, drawn from a large geographic area. Here, a large data set representing thousands of trees of 78 species/genera, drawn from hundreds of sites in the Eastern United States, was compiled and analyzed to explore branch to main stem wood basic density relationships. It was expected that differences in stem vs. branch wood density among trees would be due to both genetic constraints and plastic responses in wood properties, due to tree growth responses to external environments. The results show a wide tree-to-tree variation in average branch density, relative to main stem density. However, there was a general pattern for overstory tree species to have high tree branch density relative to stem density at lower stem densities, and a declining branch to stem wood density ratio as stem density increased. Evergreen gymnosperms showed the strongest change in branch to stem wood density ratios over the range of stem wood densities and deciduous angiosperms the least; deciduous gymnosperms showed an intermediate pattern, but with generally higher branch- than stem- wood densities. More cold-hearty, shade-tolerant/drought-intolerant, evergreen gymnosperms, growing at higher latitudes, showed higher branch to stem density ratios than more shade-intolerant/drought tolerant evergreen gymnosperms growing at lower latitudes. Across all trees, canopy position had a significant influence on branch to stem density relationships, with higher branch to stem density ratios for canopy dominant trees and successively lower branch to stem density ratios for trees in successively inferior canopy positions (in terms of light availability). Understory tree species, which remain in the forest understory at maximum height, showed generally lower branch than stem densities over a wide range of stem densities. The results suggested that tradeoffs between mechanical safety and whole-tree hydraulic conductance are driving within-tree differences in wood density and highlighted the need for more detailed examinations of within-tree density variation at the whole-tree level.

Several studies have looked at how individual environmental factors influence needle morphology in conifer trees, but interacting effects between drought and canopy position have received little attention. In this study, we characterized morphological responses to experimentally induced drought stress in sun exposed and shaded current-year Norway spruce needles. In the drought plot trees were suffering mild drought stress, with an average soil water potential at 50 cm depth of -0.4 MPa. In general, morphological needle traits had greater values in sun needles in the upper canopy than in shaded needles in the lower canopy. Needle morphology 15 months after the onset of drought was determined by canopy position, as only sun needle morphology was affected by drought. Thus, canopy position was a stronger morphogenic factor determining needle structure than was water availability. The largest influence of mild drought was observed for needle length, projected needle area and total needle area, which all were reduced by ~27% relative to control trees. Needle thickness and needle width showed contrasting sensitivity to drought, as drought only affected needle thickness (10% reduction). Needle dry mass, leaf mass per area and needle density were not affected 15 months after the onset of mild drought. Our results highlight the importance of considering canopy position as well as water availability when comparing needle structure or function between conifer species. More knowledge about how different canopy parts of Norway spruce adapt to drought is important to understand forest productivity under changing environmental conditions.

The response of understory trees to climate variability is key to understanding current and future forest dynamics. However, analyses of climatic effects on tree growth have primarily focused on the upper canopy, leaving understory dynamics unresolved. We analyzed differences in climate sensitivity based on canopy position of four common tree species (Acer rubrum, Fagus grandifolia, Quercus rubra, and Tsuga canadensis) using growth information from 1,084 trees across eight sites in the northeastern United States. Effects of canopy position on climate response varied, but were significant and often nonlinear, for all four species. Compared to overstory trees, understory trees showed stronger reductions in growth at high temperatures and varied shifts in precipitation response. This contradicts the prevailing assumption that climate responses, particularly to temperature, of understory trees are buffered by the overstory. Forest growth trajectories are uncertain in compositionally and structurally complex forests, and future demography and regeneration dynamics may be misinferred if not all canopy levels are represented in future forecasts. [ABSTRACT FROM AUTHOR]

Lemon (Citrus limon L.) is one of the most cultivated citrus fruit in South Africa. In citrus packhouses, fruit are coated with commercial synthetic waxes to enhance shelflife. However, the use of waxes has been linked to peteca spot (PS) incidence in lemons. This study evaluated the efficacy of chitosan (CH) and carboxymethyl cellulose (CMC) incorporated with moringa leaf extracts (M) on reducing peteca spot incidence on 'Eureka' lemon. A total of 500 'Eureka' lemons were harvested from outside and inside canopy positions from a commercial orchard in KwaZulu-Natal, South Africa. Fruit were assigned to five coating treatments, namely; control, 1% M + CMC, 1% CMC, 1% CH and 1% M + CH. After coating, fruit were transferred into a cold room with delivery air temperature set at 3 °C for 12 weeks to induce the disorder. At each sampling week, peteca spot incidence, fruit physicochemical and phytochemical properties including color, mass, vitamin C, carotenoids, TSS, TA and phenolics were measured. The results showed that coating treatments and canopy position significantly affected PS incidence. Fruit coated with M + CMC, CMC, CH were less susceptible to PS development in both inside and outside canopy compared to the control and M + CH coated fruit. Coating treatments significantly affected phenolic and flavonoid concentration. Moreover, coating treatments significantly reduced mass loss, ascorbic acid loss and delayed color change of fruit. The results found in this study demonstrated the ability of either M + CMC, CMC, or CH as coating treatments for reducing PS in 'Eureka' lemon. [ABSTRACT FROM AUTHOR]

Summary: Iron (Fe) and zinc (Zn) deficiencies are a global human health problem that may worsen by the growth of crops at elevated atmospheric CO2 concentration (eCO2). However, climate change will also involve higher temperature, but it is unclear how the combined effect of eCO2 and higher temperature will affect the nutritional quality of food crops. To begin to address this question, we grew soybean (Glycine max) in a Temperature by Free‐Air CO2 Enrichment (T‐FACE) experiment in 2014 and 2015 under ambient (400 μmol mol−1) and elevated (600 μmol mol−1) CO2 concentrations, and under ambient and elevated temperatures (+2.7°C day and +3.4°C at night). In our study, eCO2 significantly decreased Fe concentration in soybean seeds in both seasons (−8.7 and −7.7%) and Zn concentration in one season (−8.9%), while higher temperature (at ambient CO2 concentration) had the opposite effect. The combination of eCO2 with elevated temperature generally restored seed Fe and Zn concentrations to levels obtained under ambient CO2 and temperature conditions, suggesting that the potential threat to human nutrition by increasing CO2 concentration may not be realized. In general, seed Fe concentration was negatively correlated with yield, suggesting inherent limitations to increasing seed Fe. In addition, we confirm our previous report that the concentration of seed storage products and several minerals varies with node position at which the seeds developed. Overall, these results demonstrate the complexity of predicting climate change effects on food and nutritional security when various environmental parameters change in an interactive manner. Significance statement: Mineral deficiencies are a global health problem that may be exacerbated by crop growth at elevated atmospheric CO2 concentration (eCO2) that can reduce micronutrient concentrations in grains and seeds. However, our soybean studies suggest that the potential threat to human nutrition by increasing CO2 concentration may not be realized when plants grow at eCO2 and higher temperatures that more realistically mimic future climate conditions. [ABSTRACT FROM AUTHOR]

Abstract: A range of environmental factors regulate tree growth; however, climate is generally thought to most strongly influence year‐to‐year variability in growth. Numerous dendrochronological (tree‐ring) studies have identified climate factors that influence year‐to‐year variability in growth for given tree species and location. However, traditional dendrochronology methods have limitations that prevent them from adequately assessing stand‐level (as opposed to species‐level) growth. We argue that stand‐level growth analyses provide a more meaningful assessment of forest response to climate fluctuations, as well as the management options that may be employed to sustain forest productivity. Working in a mature, mixed‐species stand at the Howland Research Forest of central Maine, USA, we used two alternatives to traditional dendrochronological analyses by (1) selecting trees for coring using a stratified (by size and species), random sampling method that ensures a representative sample of the stand, and (2) converting ring widths to biomass increments, which once summed, produced a representation of stand‐level growth, while maintaining species identities or canopy position if needed. We then tested the relative influence of seasonal climate variables on year‐to‐year variability in the biomass increment using generalized least squares regression, while accounting for temporal autocorrelation. Our results indicate that stand‐level growth responded most strongly to previous summer and current spring climate variables, resulting from a combination of individualistic climate responses occurring at the species‐ and canopy‐position level. Our climate models were better fit to stand‐level biomass increment than to species‐level or canopy‐position summaries. The relative growth responses (i.e., percent change) predicted from the most influential climate variables indicate stand‐level growth varies less from to year‐to‐year than species‐level or canopy‐position growth responses. By assessing stand‐level growth response to climate, we provide an alternative perspective on climate–growth relationships of forests, improving our understanding of forest growth dynamics under a fluctuating climate. [ABSTRACT FROM AUTHOR]

The present study involved measurements of the stable carbon isotope composition (δ13C) and intrinsic water-use efficiency (iWUE) of three C3 leguminous Prosopis spp. (P. juliflora, P. cineraria, and P. pallida) foliage at different canopy positions (east and west) from saline (SLH) and non-saline habitats (NSH). Integrated measurements of the stable carbon isotope composition (δ13C) of plant tissue were broadly used to study iWUE, taking into consideration the effect of leaf age and canopy position on C isotope discrimination. Mature foliage of P. pallida from an SLH with a west canopy position had significantly higher δ13C (less negative) than that from NSH. On the west side, Δ13C values ranged from 17.8‱ (P. pallida) to 22.31‱ (P. juliflora) for a west canopy position, while they varied from 18.05‱ (P. pallida) to 22.4‱ (P. cineraria) on the east canopy side. Because the patterns are similar for the three Prosopis species, the difference in carbon isotope discrimination (Δ13C) between the canopy position (west and east) is relatively consistent among species and sites, ranging between 17.8 ± 4.43‱ for the young foliage in the west and 18.05 ± 4.35‱ for the east canopy position. The iWUE of P. pallida was twice that of P. cineraria. The iWUE of P. juliflora was higher from NSH than SLH. Mature leaves possessed a higher iWUE than the young leaves. We concluded that exotic P. juliflora and P. pallida have higher iWUE values than the native P. cineraria, which might be due to the rapid below-ground development of plant roots in the Arabian deserts of the United Arab Emirates (UAE). This could enable the alien species access to deeper humid soil layers or water resources.

Understanding the vertical pattern of leaf traits across plant canopies provide critical information on plant physiology, ecosystem functioning and structure and vegetation response to climate change. However, the impact of vertical canopy position on leaf spectral properties and subsequently leaf traits across the entire spectrum for multiple species is poorly understood. In this study, we examined the ability of leaf optical properties to track variability in leaf traits across the vertical canopy profile using Partial Least Square Discriminatory Analysis (PLS-DA). Leaf spectral measurements together with leaf traits (nitrogen, carbon, chlorophyll, equivalent water thickness and specific leaf area) were studied at three vertical canopy positions along the plant stem: lower, middle and upper. We observed that foliar nitrogen (N), chlorophyll (Cab), carbon (C), and equivalent water thickness (EWT) were higher in the upper canopy leaves compared with lower shaded leaves, while specific leaf area (SLA) increased from upper to lower canopy leaves. We found that leaf spectral reflectance significantly (P ≤ 0.05) shifted to longer wavelengths in the 'red edge' spectrum (685-701 nm) in the order of lower > middle > upper for the pooled dataset. We report that spectral bands that are influential in the discrimination of leaf samples into the three groups of canopy position, based on the PLS-DA variable importance projection (VIP) score, match with wavelength regions of foliar traits observed to vary across the canopy vertical profile. This observation demonstrated that both leaf traits and leaf reflectance co-vary across the vertical canopy profile in multiple species. We conclude that canopy vertical position has a significant impact on leaf spectral properties of an individual plant's traits, and this finding holds for multiple species. These findings have important implications on field sampling protocols, upscaling leaf traits to canopy level, canopy reflectance modelling, and subsequent leaf trait retrieval, especially for studies that aimed to integrate hyperspectral measurements and LiDAR data. [ABSTRACT FROM AUTHOR]

In mature walnut trees, mono-cyclic shoots are the main bearing structure and are thus fundamental for tree productivity. In this line, a study was carried out in three commercial “Chandler” walnut orchards, located in the central valley of Chile. In each orchard, eight mature trees were selected and eighteen mono-cyclic shoots were marked according to three fruit load categories (shoots bearing one fruit (F1), shoots bearing two fruits (F2), shoots bearing three fruits (F3)). These shoots were distributed in three zones of the canopy (upper, lower-exposed, lower-shaded). This resulted in 432 marked shoots in the total of the experiment, in which the effect of position and fruit load on length, diameter, leaf area and specific leaf weight were studied. In addition, multilinear regression models for fruit diameter as a function of the above-mentioned characteristics were performed. The results indicate that the production of two or more fruits per shoot is associated with an average shoot length of 12.7 cm, an average shoot diameter of 8.1 mm and an average leaf area of 1034.7 cm 2 . Linear models indicate that length and specific leaf weight significantly explain fruit size for all shoot categories. In addition, the leaf area, and leaf area plus basal diameter of the shoot, are significantly related to fruit size (equatorial diameter) for shoots with two and three fruits, respectively. According to the results of this study, the tree’s upper and lower-exposed zones offer shoots with greater potential to produce more and larger fruits per shoot than the lower-shaded canopy zone. Thus, the morphological characteristics of the shoot (diameter, length and leaf area, among others) are directly related to a greater number and size of fruits, and therefore higher productivity. [ABSTRACT FROM AUTHOR]

Attractive peel colour and quality development in Kinnow (Citrus nobilis Lour x Citrus deliciosa Tenara) is a prime requisite for its fair market price. The objective of study was to find out the impact of canopy position, date of harvesting and nutrition on yield and quality of Kinnow mandarin. A field experiment was conducted in a four year old Kinnow orchard using factorial randomized block design with three replications. There were nine treatments comprised of various N, P, K levels and one control; two canopy positions (external and internal) and three harvesting dates (06.12.13, 26.12.13 and 16.01.14). Statistical analysis using SAS 9.3 software and Tukey's HSD test revealed the significance of various treatments, canopy positions and harvesting dates (P

Citrus fruits are an important diet for human health by providing some nutritional and antioxidant components, especially ascorbic acid (AsA). As the major antioxidant compound, the concentration of AsA is an important nutritional quality indicator for citrus fruit and its derivative products. Although the emphasis is on vitamin C content of harvested citrus fruit, this review of literature focuses on preharvest factors affecting this nutritional quality variable. The literature reviewed in this study showed that the content of AsA in citrus fruits is influenced by numerous preharvest factors including genotype, cultural practices, climatic conditions, fruit maturity and postharvest management. To better understand the mechanism underlying the vitamin C content of different citrus fruits, the introduction of this paper will first provide an overview of major proposed biosynthetic pathways and genes encoding for enzymes involved in AsA biosynthesis and oxidation. The review will then concentrate on the current state of knowledge regarding inherent genetic, environmental, fertilization, maturity and harvesting factors affecting AsA of citrus fruits. Some suggestions for future research are also highlighted. [ABSTRACT FROM AUTHOR]

Leaf-level photosynthetic processes and their environmental dependencies are critical for estimating CO2 uptake from the atmosphere. These estimates use biochemical-based models of photosynthesis that require accurate Rubisco kinetics. We investigated the effects of canopy position, elevated atmospheric CO2 [eC; ambient CO2 (aC)+240 ppm] and elevated air temperature (eT; ambient temperature (aT)+3 °C) on Rubisco content and activity together with the relationship between leaf N and Vcmax (maximal Rubisco carboxylation rate) of 7 m tall, soil-grown Eucalyptus globulus trees. The kinetics of E. globulus and tobacco Rubisco at 25 °C were similar. In vitro estimates of Vcmax derived from measures of E. globulus Rubisco content and kinetics were consistent, although slightly lower, than the in vivo rates extrapolated from gas exchange. In E. globulus, the fraction of N invested in Rubisco was substantially lower than for crop species and varied with treatments. Photosynthetic acclimation of E. globulus leaves to eC was underpinned by reduced leaf N and Rubisco contents; the opposite occurred in response to eT coinciding with growth resumption in spring. Our findings highlight the adaptive capacity of this key forest species to allocate leaf N flexibly to Rubisco and other photosynthetic proteins across differing canopy positions in response to future, warmer and elevated [CO2] climates. [ABSTRACT FROM AUTHOR]

Nitrogen (N) and water availability are the two crucial factors confining tree growth and forest productivity. Irrigation, fertilization, and combined fertigation are commonly applied to plantation forests for improving productivity. However, how xylem vasculature responds to these management practices remains poorly understood. Here we investigated the responses of tree growth, xylem anatomical structure, and hydraulics of the upper, middle, and lower canopy branches in a 6-year-old Populus tomentosa plantation subjected to four years of irrigation and fertigation treatments. The results showed that an improvement in tree growth only occurred in the irrigation treatment while the addition of N in fertigation treatments did not have a cumulative effect on tree growth. Most of the xylem anatomical traits, including vessel hydraulic diameter (D h), vessel density (VD), vessel fraction (VF), double vessel wall thickness (t), potential specific sapwood hydraulic conductivity (K p), fiber wall to lumen ratio (T f / D f), vessel wall reinforcement (t / b)2, and wood density (WD) all showed conserved plasticity to long-term irrigation and fertigation, despite different tree growth rate, implying that aboveground biomass accumulation may have decoupled from the branch-level xylem traits. Besides, the alterations of other factors, including stomatal regulation strategy and crown structure with soil water and N availabilities, might better explain the variation in tree growth. In contrast, greater variations in branch xylem traits were detected across canopy layers. The upper canopy showed greater hydraulic safety characterized by narrower and denser vessels, higher cell wall to lumen ratio, and higher wood density compared to the lower canopy, while hydraulic efficiency (K p) remained constant across the crown, thus highlighting the priority of hydraulic safety over efficiency in the construction of branch xylem. Overall, our study revealed the response pattern of P. tomentosa xylem structure to long-term water and N management, which facilitates a comprehensive understanding on the mechanisms underpinning the influence of water and nutrients regulation on the performance of fast-growing tree species' plantations. • Responses of branch xylem traits to irrigation and fertigation were tested. • Soil water availability was the primary factor confining tree growth. • Branch xylem anatomy and hydraulics showed limited phenotypic plasticity. • Hydraulic safety rather than efficiency drove branch xylem construction. [ABSTRACT FROM AUTHOR]

The position of fruit within the pear tree canopy may affect fruit quality characteristics. The objective of this study was to determine whether outer and inner canopy ‘Forelle’ pears differ in quality attributes and how these differences relate to consumer preference when stored for 9, 12 and 16 weeks at −0.5 °C in air and ripened for 7 days at 20 °C. Fruit firmness, size, colour, total soluble solids concentration (TSS), titratable acidity (TA), internal ethylene concentration, dry matter concentration (DMC) as well as the incidence of mealiness were determined after each cold storage period and subsequent ripening. The flavour and texture of the pear samples were assessed by a trained panel and consumer groups scored pears for eating quality and appearance. In 2011, inner canopy pears that were cold stored for 12 and 16 weeks and ripened were preferred for eating quality. Mealiness was generally low in inner canopy pears and significantly lower than in outer canopy pears. Mealiness was low for both canopy positions after 16 weeks cold storage plus ripening. While the preference for inner canopy pears after 12 weeks storage may relate to the lower incidence of mealiness, reasons for the preference after 16 weeks cold storage are uncertain. In 2012, the incidence of mealiness in outer canopy pears was double that of inner canopy pears, which may explain the general consumer preference for inner canopy pears. The canopy position effect was less in 2012 when fruit were picked at more optimal firmness (±6.4 kg) compared to harvesting at pre-optimum firmness (±7.9 kg) in 2011. Mealiness levels decreased from 9 and 12 weeks cold storage to 16 weeks cold storage in 2012. This study therefore supports the mandatory 12 weeks cold storage period at −0.5 °C for ‘Forelle’ pears to ensure optimum eating quality. In light of the above, inner canopy ‘Forelle’ pears should not be viewed as inferior to outer canopy pears. The consistent differences in mealiness incidence between inner and outer canopy ‘Forelle’ pears opens up a new avenue for investigating mealiness development. [ABSTRACT FROM AUTHOR]

BACKGROUND Light and water are major factors in fruit development and quality. In this study, the effect of water and light in Olea europaea trees on volatile organic compounds ( VOCs) in olive oil was studied over 2 years. Mature fruits were harvested from three zones of the canopy with different light exposure (64%, 42% and 30% of incident light) of trees subjected to full, deficit or complementary irrigation. VOCs were determined by SPME GC-MS and analysed by principal component analysis followed by discriminant analysis to partition treatment effects. RESULTS Fruit fresh weight and mesocarp oil content decreased in zones where intercepted light was less. Low light levels significantly slowed down fruit maturation, whereas conditions of water deficit accelerated the maturation process. The presence of cyclosativene and α-muurulene was associated with water deficit, nonanal, valencene with full irrigation; α-muurulene, ( E)-2-hexanal were related to low light conditions, while trans-β-ocimene, α-copaene, ( Z)-2-penten-1-ol, hexanal and nonanal to well exposed zones. The year strongly affected the VOC profile of olive oil. CONCLUSION This is the first report on qualitative changes in VOCs induced by light environment and/or water status. This information is valuable to better understand the role of environmental factors on the sensory quality of virgin olive oil. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

This study was performed on hybrid aspen saplings growing at the Free Air Humidity Manipulation site in Estonia. We investigated changes in wood anatomy and hydraulic conductivity in response to increased air humidity. Two hydraulic traits (specific conductivity and leaf-specific conductivity) and four anatomical traits of stem wood - relative vessel area (VA), vessel density (VD), pit area and pit aperture area- were influencedbythe humidity manipulation. Stem hydraulic traits decreased in the apical direction, whereas branch hydraulic characteristics tended to be greatest in mid-canopy, associated with branch size. A reduction in VD due to increasing humidity was accompanied by a decrease in vessel lumen diameter, hydraulically weighted mean diameter (D[sub h]), xylem vulnerability index and theoretical hydraulic conductivity. VA and D[sub h] combined accounted for 87.4% of the total variation in k[sub t] of branches and 85.5% of that in stems across the treatments. Characters of branch vessels were more stable, and only the vessel-grouping index (the ratio of the total number of vessels to the total number of vessel groupings) was dependent on the interactive effect of the treatment and canopy position. Our results indicate that the increasing atmospheric humidity predicted for high latitudes will result in moderate changes in the structure and functioning of the hybrid aspen xylem. [ABSTRACT FROM AUTHOR]

Stem injection techniques can be used to introduce 15N into trees to overcome a low variation in natural abundance and label biomass with a distinct 15N signature, but have tended to target small and young trees, of a variety of species, with little replication. We injected 98 atom% 15N ammonium nitrate (NH4NO3) solution into 13 mature, 9- to 13-m tall edge-profile Sitka spruce trees in order to produce a large quantity of labelled litter, examining the distribution of the isotope throughout the canopy after felling in terms of both total abundance of 15N and relative distribution of the isotope throughout individual trees. Using a simple mass balance of the canopy alone, based on observed total needle biomass and modelled branch biomass, all of the isotope injected was accounted for, evenly split between needles and branches, but with a high degree of variability both within individual trees, and among trees. Both 15N abundance and relative within-canopy distribution were biased towards the upper and middle crown in foliage. Recovery of the label in branches was much more variable than in needles, possibly due to differences in nitrogen allocation for both growth and storage, which differ seasonally between foliage and woody biomass. [ABSTRACT FROM AUTHOR]

• The high acidity in bottom fruit is due to citrate but not malate, which is associated with low light intensity and low temperature. • High citrate content in bottom fruits is explained by low expression of degradation genes, high expression of biosynthesis and proton pump genes. • Low malate content in bottom fruits is explained by low expression of biosynthesis genes and high expression of degradation genes. Organic acids are key metabolites for diverse fruit flavoring and vital for fruit quality measures. Their contents are significantly varied regarding the canopy position. However, the underlying mechanism is still unclear. In this study by using Citrus raticulata cv. Bendizao as research material, a significant 2-fold increase in citrate content and a 2-fold decrease in malate content were noticed in bottom-canopy fruits subjected to less light and low temperature compared to top-canopy fruits. Moreover, transcript levels of genes like citrate synthase (CS1), aconitate hydratase genes (ACO1 and ACO2), NAD-dependent malic enzyme gene (NAD-ME) and malate dehydrogenase genes (MDH1 and MDH2) were significantly higher, while transcript levels of other genes such as citrate utilization genes (ACL2, ACL3 and ACO3), malate synthase gene (MS) and cytosolic NAD-dependent malate dehydrogenase gene (cytNAD-MDH) were significantly lower in bottom-canopy fruits compared to top-canopy fruits. Additionally, transcript levels of proton pump genes (CsPHs and VHA), two transporter genes (MATE and ALMT9), and four transcription factor genes (MYB73, Noemi, MYC-N , and bHLH) were significantly higher, while mRNA levels of two transcription factor genes (MYB10 and WRKY14) and transporter genes (CsCit1 and ALMT9-like) were significantly lower in bottom-canopy fruits than those in top-canopy fruits. Taken together, the variance of organic acid profiles in the canopy could be attributed to the microclimate change, which comprehensively influences the organic acid accumulation-related genes' transcript levels; reduced malate accumulation in bottom-canopy fruits is mainly due to the minimal expression of MS and cytNAD-MDH , and high expression of malate utilization genes (MDH and NAD - ME), while the higher citrate content in the bottom-canopy fruits is probably due to the enhanced vacuolar storage through increasing vacuolar proton pump genes and MATE transcript levels, and the minimal citrate degradation and efflux through decreasing ACL2, ACL3, ACO3 and CsCit1 transcript levels. [ABSTRACT FROM AUTHOR]

Key message: Across sites in Brazil and Hawaii, LMA and N were strongly correlated with height and shade index, respectively, which may help simplify canopy function modeling of Eucalyptus plantations. Abstract: Within tree canopies, leaf mass per area (LMA) and leaf nitrogen per unit area ( N) commonly increase with height. Previous research has suggested that these patterns occur as a strategy to optimize carbon gain by allocating available resources to upper canopy leaves that are exposed to greater light availability. We tested three hypotheses about the influences of height, shade index (a proxy for light), and stand age on LMA and leaf nitrogen for even-aged Eucalyptus saligna and Eucalyptus grandis × urophylla plantations in Brazil and Hawaii, USA, spanning most of the environmental conditions found across 19.6 million ha of Eucalyptus spp. plantations around the world. Shade index was developed by incorporating canopy depth (inner-crown shading) and a tree height ratio relative to neighbor trees (shading from other trees). Across all sites and ages, leaf height accounted for 45 % of the variation in LMA, whereas shade index accounted for only 6 %. A combination of both factors was slightly better in accounting for LMA variation than height alone. LMA-height relationships among sites were strongest under greater light availability and in older stands. Leaf nitrogen per unit mass ( N) consistently decreased with shade index, whereas N showed no consistent pattern with height or shade index. These relationships indicate that N is primarily driven by light, while height is the primary driver for LMA. The general relationships between LMA and leaf N across all sites may simplify canopy function modeling of E. saligna and E. grandis × urophylla plantations. [ABSTRACT FROM AUTHOR]

Highlights: [•] Vis/NIRS models for prediction of mandarin postharvest rind quality were validated. [•] Rind carbohydrates associated with rind breakdown disorder were predicted. [•] Spiking of models with few samples from prediction set improved model performance. [•] The robustness of PLS models across two seasons and four orchards was demonstrated. [•] Models developed using collective data of all orchards and seasons performed better. [Copyright &y& Elsevier]

Abstract: Daily dynamics of leaf (K L) and soil-to-branch hydraulic conductance (K S–B) was investigated in silver birch (Betula pendula Roth.) using evaporative flux method in situ: water potential drop was measured with a pressure chamber and evaporative flux was estimated as sap flux density measured with sap flow gauges. Canopy position had a significant (P < 0.001) effect on both K L and K S – B. Upper-canopy leaves exhibited 1.7 and soil-to-branch pathway 2.3 times higher hydraulic efficiency than those for lower-canopy. K L varied significantly with time of day: K L for both upper- and lower-canopy leaves was lowest in the morning and rose gradually achieving maximal values in late afternoon (4.75 and 3.38 mmol m−2 s−1 MPa−1, respectively). Relevant environmental factors affecting K L were photosynthetic photon flux density (Q P), air relative humidity (RH) and air temperature (T A). K S – B started rising in the morning and reached maximum in the lower canopy (1.44 mmol m−2 s−1 MPa−1) at 1300 h and in the upper canopy (2.52 mmol m−2 s−1 MPa−1) at 1500 h, decreasing afterwards. Environmental factors controlling K S – B were Ψ S and Q P. The diurnal patterns of K L reflect a combination of environmental factors and endogenous rhythms. The temporal pattern of K S – B refers to daily up- and down-regulation of hydraulic conductance of water transport pathway from soil–root interface to leaves with respect to changing irradiance. [Copyright &y& Elsevier]

Abstract: The use of diffuse reflectance visible and near infrared (Vis/NIR) spectroscopy was explored as a non-destructive technique to predict ‘Nules Clementine’ mandarin fruit susceptibility to rind breakdown (RBD) disorder by detecting rind physico-chemical properties of 80 intact fruit harvested from different canopy positions. Vis/NIR spectra were obtained using a LabSpec® spectrophotometer. Reference physico-chemical data of the fruit were obtained after 8 weeks of storage at 8°C using conventional methods and included RBD, hue angle, colour index, mass loss, rind dry matter, as well as carbohydrates (sucrose, glucose, fructose, total carbohydrates), and total phenolic acid concentrations. Principal component analysis (PCA) was applied to analyse spectral data to identify clusters in the PCA score plots and outliers. Partial least squares (PLS) regression was applied to spectral data after PCA to develop prediction models for each quality attribute. The spectra were subjected to a test set validation by dividing the data into calibration (n =48) and test validation (n =32) sets. An extra set of 40 fruit harvested from a different part of the orchard was used for external validation. PLS-discriminant analysis (PLS-DA) models were developed to sort fruit based on canopy position and RBD susceptibility. Fruit position within the canopy had a significant influence on rind biochemical properties. Outside fruit had higher rind carbohydrates, phenolic acids and dry matter content and lower RBD index than inside fruit. The data distribution in the PCA and PLS-DA models displayed four clusters that could easily be identified. These clusters allowed distinction between fruit from different preharvest treatments. NIR calibration and validation results demonstrated that colour index, dry matter, total carbohydrates and mass loss were predicted with significant accuracy, with residual predictive deviation (RPD) for prediction of 3.83, 3.58, 3.15 and 2.61, respectively. The good correlation between spectral information and carbohydrate content demonstrated the potential of Vis/NIR as a non-destructive tool to predict fruit susceptibility to RBD. [Copyright &y& Elsevier]

Leaf traits and physiology are species-specific and various with canopy position and leaf age. Leaf photosynthesis, morphology and chemistry in the upper and lower canopy positions of Pinus koraiensis Sieb. et Zucc and Quercus mongolica Fisch. ex Turoz in broadleaved Korean pine forest were determined in September 2009. Canopy position did not significantly affect light-saturated photosynthetic rate based on unit area ( P) and unit dry mass ( P), apparent quantum yield (α), light compensation point (LCP), light saturation point (LSP); total nitrogen (N), phosphorus (P), carbon (C), and chlorophyll content (Chl) per unit dry mass; leaf dry mass per unit area (LMA) and photosynthetic nitrogen-use efficiency (PNUE) for P. koraiensis current-year needles and Q. mongolica leaves. While in P. koraiensis one-year-old needles, P, P, α and LCP in the upper canopy were lower than those in the lower canopy. The needles of P. koraiensis had higher Cm and LMA than leaves of Q. mongolica, but P, Chl and PNUE showed opposite trend. There were no differences in P, LSP, N, and P between the two species. Needle age significantly influenced photosynthetic parameters, chemistry and LMA of P. koraiensis needles except LCP, LSP and C. In contrast to LMA, P, P, N, P, Chl, and PNUE of one-year-old needles were significantly lower than those of current-year needles for P. koraiensis. The negative correlations between LMA and P, N, P, Chl, and positive correlations between P and N, P, Chl were found for P. koraiensis current-year needles and Q. mongolica leaves. Our results indicate that leaf nitrogen and phosphorus contents and nutrient absorption from soil are similar for mature P. koraiensis and Q. mongolica growing in the same environment, while difference in carbon content between P. koraiensis and Q. mongolica may be attributed to inherent growth characteristics. [ABSTRACT FROM AUTHOR]

Host resistance is an efficient and effective component in integrated management of plant diseases. The aim of this study was to test whether Acibenzolar-S-methyl (ASM), Chitosan, Heads-up and Acetyl Salicylic Acid (ASA), known to induce resistance against various diseases, can help protect potato crop against brown leaf spot. The effect of these inducers, on two potato cultivars, Goldrush and FL1879 against Alternaria alternata, causal agent of brown leaf spot at two different field sites were evaluated. To determine the effects of the application of inducers on disease resistance, the foliage of the potato cultivars was sprayed with appropriate concentrations of ASA, chitosan, and ASM. Heads-up was also applied as a pre-plant treatment on potato tubers. The results obtained from the both field experiments indicated the highest yield performance was achieved in plots treated with ASM, followed by Heads-up and chitosan treatments. However, no significant difference in terms of tuber yield production has been noted between ASA treated potato foliage, and the untreated control plants. Results of experiments with detached leaves showed that there was a significant difference regarding disease index reduction between plots which been treated with defense inducers and untreated, inoculated plots. It was clear that on both potato cultivars, application of chitosan and ASM encouraged enhancement of the disease resistance compared to the ASA and Heads-up treatments. In the laboratory experiment, disease progress was recorded on leaves from three different heights of the crop canopy. The results indicated that disease severity was low in the apex, moderate in the middle and high in the lower parts of the crop, in both potato cultivars. These results suggest that chitosan and ASM may offer alternative methods for controlling brown leaf spot of potato. [ABSTRACT FROM AUTHOR]

Abstract: Adequate K, Mg and Ca supply is important to develop well-structured and functional cell walls and membranes in fruit, and insufficient levels or imbalances of these minerals are known to be involved in various postharvest disorders. Microclimatic variation exists in the ‘Nules Clementine’ mandarin tree canopy and results in lower photosynthetically active radiation (PAR) levels and temperature as well as a higher humidity inside the tree canopy. The aim of this experiment was to determine the impact of this variation in microclimate on accumulation patterns of K, Ca and Mg in the flavedo of the fruit rind during stages II and III of fruit development. Fruit mass, dimensions, rind colour development and mineral composition of the flavedo were measured to describe the condition of fruit borne on the outside and inside of the tree''s canopy. The data revealed that canopy position influenced mineral nutrient accumulation patterns in the flavedo. Outside fruit flavedo accumulated significantly higher concentrations of Ca and Mg in all three seasons (2005–2007). In contrast, inside fruit flavedo (shaded fruit) accumulated significantly higher levels of K compared with outside fruit flavedo. The accumulation of K and Ca differed from that of kiwifruit and apple in that Ca concentration increased and K decreased towards maturity. These results suggest that xylem, as in citrus leaves, is the main vasculature supply conduit to the citrus fruit flavedo for mineral nutrients. The reduction of transpiration potential by lower temperatures and higher humidity inside the canopy could be responsible for the reduced accumulation of Ca and Mg. The high K concentration of inside fruit flavedo is suggested to be a stress response, due to the low light levels, to maintain osmotic potential in the shaded rind tissue, and this imbalance could possibly lead to a reduction in rind condition, which manifests through rind breakdown symptom development. [Copyright &y& Elsevier]

Taking the dominant tree species Quercus mongolica in natural coniferous-broadleaved mixed forest in Changbai Mountains as test object, this paper studied the variations of leaf dry mass per unit area (LMA), leaf carbon (C), nitrogen (N), and phosphorus (P) contents per unit mass and per unit area, as well as the leaf N and P resorption efficiency and use efficiency at upper and lower canopy positions during growth season (from June to October). In the growth season, and at both upper and lower canopy positions, the LMA and leaf C content per unit area had obvi- ous monthly fluctuation, the leaf N and P contents per unit area had the similar monthly variation trend with the leaf N and P contents per unit mass, but the leaf N and P resorption efficiency per unit mass had no significant difference with the leaf N and P resorption efficiency per unit area. The leaf N resorption efficiency and use efficiency were less affected by canopy position, but the leaf P resorption efficiency and use efficiency were higher at upper canopy than at lower canopy. Under the scenario of future climate change, the higher survival and competitive capabilities of Q. mongol- ica would benefit the nutrient cycling in the test forest ecosystem [ABSTRACT FROM AUTHOR]

Abstract: The progressive postharvest disorder of ‘Nules Clementine’ mandarin (Citrus reticulata Blanco), referred to as rind breakdown (RBD), starts to develop during storage, about 3–5 weeks after harvest. Variation within the tree canopy, i.e. inside or outside canopy positions, as well as postharvest handling practices such as ethylene degreening, storage temperature and storage duration, were investigated for their influence on RBD incidence. Two experiments were conducted wherein fruit were subjected, in the first experiment, to ethylene degreening and a delay in commencement of cold storage (2004), and, in the second experiment, fruit were sampled from the inside and outside of the canopy and cold-stored at either −0.5°C or 7.5°C during 2005 and 2007. Rind pigment and carbohydrate contents as well as rind colour and RBD incidence were recorded during prolonged storage. The senescence-promoting treatments resulted in an increase in RBD incidence, except for storage at −0.5°C, which resulted in a lower occurrence of RBD. Overall, results indicated that the incidence of RBD was aggravated by senescence-promoting factors during the postharvest handling of fruit and this is thought to lead to the premature senescence of the flavedo. In addition, fruit position in the tree canopy during fruit development contributed significantly to RBD sensitivity, with inside fruit having significantly higher RBD incidence compared to outside fruit. [Copyright &y& Elsevier]

It is a well-described phenomenon that plant leaves respond to changes in light intensity and duration by adjusting leaf hydraulic efficiency, and there is current consensus that up- or down-regulation of water channels (aquaporins) in the plasma membrane of the bundle sheath and mesophyll cells play a central role in the underlying mechanisms. Recently, experimental evidence has been provided also for light-mediated changes of stem hydraulic conductance (Kstem) in field-grown laurel plants. This effect was attributed to differences in potassium ion concentration of xylem sap as a function of light conditions. In the present article, we report evidence obtained in silver birch (Betula pendula Roth), supporting the concept of light-mediated modulation of Kstem. Both canopy position (long-term effect) and current photosynthetic photon flux density (PPFD; short-term effect) had a significant impact (P < 0.001) on Kstem measured in shoots taken from the lower (shade shoots) and upper (sun shoots) third of the crowns of ∼25-year-old trees growing in a natural forest stand. The shade shoots responded more sensitively to light manipulation: Kstem increased by 51% in shade shoots and 26% in sun shoots when PPFD increased from 70 to 330 μmol m−2 s−1. In 4-year-old trees growing in a dense experimental plantation, Kstem, specific conductivity of branch-wood (kbw) and potassium ion concentration ([K+]) in xylem sap varied in accordance with canopy position (P < 0.001). Both Kstem and kbw increased considerably with light availability, increasing within the tree crowns from bottom to top; there was a strong relationship between mean values of Kstem and [K+] in hydraulically sampled branches. [ABSTRACT FROM AUTHOR]

This study investigates whether it is possible to simplify the complex influence of numerous species on leaf litter decomposition in a diverse tropical forest using functional classifications to predict litter quality, decomposition rate, and nutrient dynamics during decomposition, over a 2-yr period. Thirty-three lowland tropical forest plant species from contrasting growth forms (canopy trees, pioneer trees, lianas, palms, herbs) were studied. Twelve of 18 indices of litter quality varied significantly among growth forms, with canopy trees and palms showing lower litter quality than pioneer trees and herbs. Canopy leaves decomposed more slowly than understory leaves. Decomposition rate and mass loss trended greater ( P<0.1) in herbs and pioneer trees compared with other growth forms. There were no significant differences between monocots and dicots, and no phylogenetic signal for decomposition was observed. Significant correlations between continuous litter quality variables and decomposition rate were observed with correlation coefficients up to 0.72. Litter lignin:Mg, P concentration, and lignin:K, were the litter quality variables most related to decomposition rate. All elements showed significant negative correlations between initial litter concentration and percent remaining, but many elements showed significant correlation between percent element remaining and initial concentrations of other elements, indicating a stoichiometric balance between these elements during decomposition. The results show that although classification by growth form and canopy position are helpful for considering the ecosystem implications of changing community composition, litter quality traits provide additional predictive power for estimating the effects of species change on decomposition. Abstract in Spanish is available at [ABSTRACT FROM AUTHOR]

• Preharvest factors influence peach maturation and quality. • Fruit maturity must be controlled when evaluating preharvest factors. • Peach quality influence by preharvest factors can be accurately characterized by Vis-NIRS. • Light environment-related metabolic swifts facilitate peach quality development. • Carbon sufficiency and growing altitude prime metabolism and fruit quality. One primary reason worldwide peach consumption has been in steady decline throughout the past few decades is due to poor fruit quality. Fruit quality is developed in the orchard by optimizing preharvest factors and orchard practices. Several studies have been conducted to understand how these factors influence peach internal quality, but often fail to control for confounding variables. One particular confounding variable that is influenced by preharvest factors and directly impacts fruit quality is maturation. Pomological experiments investigating the impact of preharvest factors on internal fruit quality must compare fruit of equal maturity. Maturity assessment through destructive and subjective methods is not feasible nor efficient. The use of visual radiation (Vis) and near-infrared spectroscopy (NIRS) allowed the development of robust non-destructive tools for physiological maturity (index of absorbance difference, I AD) and internal fruit quality [dry matter content (DMC) and soluble solids concentration (SSC)] assessment simultaneously in a single scan. Recent studies investigated the impact of critical preharvest factors such as rootstock, canopy position, crop load and growing environment on peach fruit quality development and metabolism, while selecting for fruit of equal maturity. Studies on rootstock and canopy position revealed that the fruit's light environment was more influential in quality development and metabolic shifts than the genotype vigor or position alone. Fruit under sufficient carbon supply, which was determined by crop load, exhibited superior quality and phenotype when compared to carbon-starved fruit at harvest. Although, metabolite profile differences between distinct carbon supply conditions at harvest were minimal, when assessed at equal maturity. Early metabolic shifts under optimum carbon supply and optimum growing environment conditions may prime fruit quality at harvest. Catechin and sorbitol were associated with high-quality fruit, while amino acids and citric acid showcased relationships with inferior quality fruit. [ABSTRACT FROM AUTHOR]

Abstract: The effect of free-air ozone fumigation and crown position on antioxidants were determined in old-growth spruce (Picea abies) trees in the seasonal course of two consecutive years (2003 and 2004). Levels of total ascorbate and its redox state in the apoplastic washing fluid (AWF) were increased under double ambient ozone concentrations (2×O3), whilst ascorbate concentrations in needle extracts were unchanged. Concentrations of apoplastic and symplastic ascorbate were significantly higher in 2003 compared to 2004 indicating a combined effect of the drought conditions in 2003 with enhanced ozone exposure. Elevated ozone had only weak effects on total glutathione levels in needle extracts, phloem exudates and xylem saps. Total and oxidised glutathione concentrations were higher in 2004 compared to 2003 and seemed to be more affected by enhanced ozone influx in the more humid year 2004 compared to the combined effect of elevated ozone and drought in 2003 as observed for ascorbate. [Copyright &y& Elsevier]