Light Interception Research Articles

Variation in shoot architecture traits and their relationship to canopy coverage and light interception in soybean (Glycine max)

BackgroundIn soybeans, faster canopy coverage (CC) is a highly desirable trait but a fully covered canopy is unfavorable to light interception at lower levels in the canopy with most of the incident radiation intercepted at the top of the canopy. Shoot architecture that influences CC is well studied in crops such as maize and wheat, and altering architectural traits has resulted in enhanced yield. However, in soybeans the study of shoot architecture has not been as extensive.ResultsThis study revealed significant differences in CC among the selected soybean accessions. The rate of CC was found to decrease at the beginning of the reproductive stage (R1) followed by an increase during the R2-R3 stages. Most of the accessions in the study achieved maximum rate of CC between R2-R3 stages. We measured Light interception (LI), defined here as the ratio of Photosynthetically Active Radiation (PAR) transmitted through the canopy to the incoming PAR or the radiation above the canopy. LI was found to be significantly correlated with CC parameters, highlighting the relationship between canopy structure and light interception. The study also explored the impact of plant shape on LI and CO2 assimilation. Plant shape was characterized into distinct quantifiable parameters and by modeling the impact of plant shape on LI and CO2 assimilation, we found that plants with broad and flat shapes at the top maybe more photosynthetically efficient at low light levels, while conical shapes were likely more advantageous when light was abundant. Shoot architecture of plants in this study was described in terms of whole plant, branching and leaf-related traits. There was significant variation for the shoot architecture traits between different accessions, displaying high reliability. We found that that several shoot architecture traits such as plant height, and leaf and internode-related traits strongly influenced CC and LI.ConclusionIn conclusion, this study provides insight into the relationship between soybean shoot architecture, canopy coverage, and light interception. It demonstrates that novel shoot architecture traits we have defined here are genetically variable, impact CC and LI and contribute to our understanding of soybean morphology. Correlations between different architecture traits, CC and LI suggest that it is possible to optimize soybean growth without compromising on light transmission within the soybean canopy. In addition, the study underscores the utility of integrating low-cost 2D phenotyping as a practical and cost-effective alternative to more time-intensive 3D or high-tech low-throughput methods. This approach offers a feasible means of studying basic shoot architecture traits at the field level, facilitating a broader and efficient assessment of plant morphology.

Agronomic and physiological characteristics of high yield and nitrogen use efficient varieties of rice: Comparison between two near‐isogenic lines

AbstractIncreasing the application of nitrogen fertilizer is the main approach to increase rice production, but it also brings problems of environmental pollution and increases agricultural production costs. Cultivating high‐yielding and high nitrogen use efficiency (NUE) rice varieties is an important approach to solving this problem. The rice varieties carrying dep1 (dense and erect panicle 1) have both high grain yield and high NUE. However, their plant traits have not been fully explored. In this study, two rice near‐isogenic lines carrying dep1 (NIL‐DEP1 and NIL‐dep1) were grown in paddy fields under 0, 120 and 270 kg N ha−1. We analyzed agronomic traits of panicle type, plant type, leaves and roots, and physiological traits of vascular bundles, photosynthetic rate and carbon and nitrogen transport. The results showed that the NIL‐dep1 exhibited higher grain yield and NUE than NIL‐DEP1, mainly due to the higher spikelet number per panicle, grain filling percentage and dry matter production. Compared with NIL‐DEP1, NIL‐dep1 had improved flag leaf morpho–physiological traits, including erect flag leaves, greater leaf thickness and specific leaf weight, higher root dry weight, root length, root volume and root surface area, and a better canopy structure, as reflected by a lower light interception percent and canopy extinction coefficient, leading to better photosynthetic performance and dry matter production. In addition, NIL‐dep1 exhibited better vascular bundle traits of peduncle and enhanced dry matter, stem carbon and nitrogen translocation during grain filling. In conclusion, NIL‐dep1 had high grain yield and NUE by improved agronomic and physiological traits and increasing carbon and nitrogen translocation during grain filling. These traits mentioned above could be used to select and breed high grain yield with high NUE rice varieties.

Physiological efficiency of grapevine canopies having varying geometries: Seasonal and diurnal whole canopy gas exchange assessment under well-watered and water deficit conditions

Grapevine training systems should be thoroughly examined to contribute to vineyards more resilient to climate change. This study was conducted on 18 three-year-old fruiting Sangiovese vines grown in pots outdoors with canopies trained to a vertical shoot positioned (VSP) spur-pruned cordon, a single high wire (SHW), and a Pergola (P) training system. Whole-canopy net CO2 exchange rate (NCER) and transpiration (T) were monitored by an enclosure system on a 24/7 basis from DOY 179–249. All vines were kept well-watered (WW) from DOY 179 to DOY 199, and the water supply was first reduced to 50% (DOY200–204) and then to 35% (DOY 205–214) before final rewatering (DOY 215–217). Vegetative growth, yield components, and grape composition were also assessed. Seasonal gas exchange on a per vine basis reflected vine size given as total leaf area (LA) varying from 2.5 to 3.1 m2; however, when diurnal trends of NCER/LA and T/LA within the WW and rewatering periods were considered, the good correlations found with the modeled total canopy light interception (TCLI) in SHW and P, were not confirmed in VSP. In all canopy geometries, the best predictor of NCER/LA was the total direct light intensity, whereas T/LA was linearly and closely correlated with air VPD. In terms of NCER/LA during the WW period, SHW had 24% higher rates than VSP and P. Under progressive water stress, SHW again exhibited higher drought resilience, while NCER and T were severely reduced in VSP and P. Severe stress also caused lower light saturation points and quantum yield in VSP and P. Under similar yield levels, P reached the best fruit maturity. In terms of photosynthetic efficiency and adaptive response to increasing water stress, the SHW performed best. Results extrapolated at the field level indicate the P system as the most rewarding.

Eastern Gamagrass Model Simulation Parameters for Diverse Ecotypes: Leaf Area Index, Light Extinction Coefficient, and Radiation Use Efficiency

Eastern gamagrass (Tripsacum dactyloides) is highly palatable, ideal for grazing and hay production in the United States. It is deep rooted and resilient, tolerant of flooding and drought. Objectives of this study were to develop plant parameters for different ecotypes of this grass. Data collected in field plots of diverse ecotypes included biomass, leaf area index (LAI), light extinction coefficient (k), and radiation use efficiency (RUE). Average LAI was 1.06 and average k was −1.05. The power response of k to LAI offers a new approach to simulating light interception at very low LAI values and throughout the range of LAI values of these ecotypes and similar grass species. The RUE values, which ranged from 1.16 to 4.31 g/MJ, highlight the immense diversity of eastern gamagrass. The high RUE values for the most productive ecotypes emphasizes the importance of this grass species for hay and grazing. While not as large as switchgrass (Panicum virgatum) values, it is still a prominent forage species that even is comparable to maize (Zea mays L.) in productivity when expressed as radiation use efficiency. These results are an important step in developing relationships and parameters to simulate the different ecotypes of this grass with process-based models.

MiniRead: A simple and inexpensive do-it-yourself device for multiple analyses of micro-organism growth kinetics.

Fitness in micro-organisms can be proxied by growth parameters on different media and/or temperatures. This is achieved by measuring optical density at 600 nm using a spectrophotometer, which measures the effect of absorbance and side scattering due to turbidity of cells suspensions. However, when growth kinetics must be monitored in many 96-well plates at the same time, buying several 96-channel spectrophotometers is often beyond budgets. The MiniRead device presented here is a simple and inexpensive do-it-yourself 96-well temperature-controlled turbidimeter designed to measure the interception of white light via absorption or side scattering through liquid culture medium. Turbidity is automatically recorded in each well at regular time intervals for up to several days or weeks. Output tabulated text files are recorded into a micro-SD memory card to be easily transferred to a computer. We propose also an R package which allows (1) to compute the nonlinear calibration curves required to convert raw readings into cell concentration values, and (2) to analyze growth kinetics output files to automatically estimate proxies of growth parameters such as lag time, maximum growth rate, or cell concentration at the plateau.

Methylmercury photodegradation in paddy water: An overlooked process mitigating methylmercury risks

Photodegradation is critical to reduce the potent neurotoxic methylmercury (MeHg) in water and its subsequent accumulation along food chains. However, this process has been largely ignored in rice paddies, which are hotspots of MeHg production and receive about a quarter of the world's developed freshwater resources. Here, we reported that significant MeHg photodegradation, primarily mediated by hydroxyl radicals, occurs in the overlying water during rice growth. By incorporating field-measured light interception into a rice paddy biogeochemistry model, as well as photodegradation rates obtained from 42 paddy soils stretching ∼3500 km across China, we estimated that photodegradation reduced MeHg concentrations in paddy water and rice by 82 % and 11 %, respectively. Without photodegradation, paddy water could be a significant MeHg source for downstream ecosystems, with an annual export of 178 − 856 kg MeHg to downstream waters in China, the largest rice producer. These findings suggest that photodegradation in paddy water is critical for preventing greater quantities of MeHg entering human food webs.

Mowing and nitrogen management guidelines for superior rice ratoon yields

Forage-grain ratoon rice (FG-RR) is a dual-cropping system, with forage harvested in the initial season and grain during the regeneration phase. While it is known that the timing of mowing and nitrogen (N) fertilization are key drivers that influence FG-RR production, physiological mechanisms ensuing mowing and N fertilizer application remain unclear. We conducted field experiments in 2021 and 2022 to investigate the yield and growth characteristics of ratooned crops (RC) under various mowing treatments (heading, milk-ripening, dry-ripening and maturity) using three N levels (135, 270, and 405 kg ha−1), two rice genotypes, Taoyouxiangzhan (TYXZ) and Liangyou 6326 (LY6326). Our results demonstrate a significant increase in ratoon yield when mowing occurred at heading or milk-ripening stages compared with maturity, with a yield increase of 2.2-fold when mowing occurred at heading. Early mowing stages increased stubble biomass (up to 73 %) and non-structural carbohydrate (up to 198 %) compared with that at maturity. Mowing at heading or milk-ripening improved accumulated temperature and light exposure, and when coupled with higher N application (270 kg ha−1 N), amplified ratoon ability to recover. Collectively, these factors raised leaf area index, canopy light interception and biomass. Hierarchical partitioning analysis underscored the substantial yet indirect influence of environmental drivers of ratoon yield, alongside a direct driver of growth, particularly thermal sum. We conclude that mowing at heading and milk-ripening with 270 kg ha−1 N elicits optimal ratoon yield with forage production, although further studies are required to determine how these guidelines vary across environments.

Quantifying water-use efficiency in plant canopies with varying leaf angle and density distribution.

Variation in architectural traits related to the spatial and angular distribution of leaf area can have considerable impacts on canopy-scale fluxes contributing to water-use efficiency (WUE). These architectural traits are frequent targets for crop improvement and for improving the understanding and predictions of net ecosystem carbon and water fluxes. A three-dimensional, leaf-resolving model along with a range of virtually generated hypothetical canopies were used to quantify interactions between canopy structure and WUE by examining its response to variation of leaf inclination independent of leaf azimuth, canopy heterogeneity, vegetation density and physiological parameters. Overall, increasing leaf area index (LAI), increasing the daily-averaged fraction of leaf area projected in the sun direction (Gavg) via the leaf inclination or azimuth distribution and increasing homogeneity had a similar effect on canopy-scale daily fluxes contributing to WUE. Increasing any of these parameters tended to increase daily light interception, increase daily net photosynthesis at low LAI and decrease it at high LAI, increase daily transpiration and decrease WUE. Isolated spherical crowns could decrease photosynthesis by ~60 % but increase daily WUE ≤130 % relative to a homogeneous canopy with equivalent leaf area density. There was no observed optimum in daily canopy WUE as LAI, leaf angle distribution or heterogeneity was varied. However, when the canopy was dense, a more vertical leaf angle distribution could increase both photosynthesis and WUE simultaneously. Variation in leaf angle and density distributions can have a substantial impact on canopy-level carbon and water fluxes, with potential trade-offs between the two. These traits might therefore be viable target traits for increasing or maintaining crop productivity while using less water, and for improvement of simplified models. Increasing canopy density or decreasing canopy heterogeneity increases the impact of leaf angle on WUE and its dependent processes.

Homoeologous exchanges contribute to branch angle variations in rapeseed: Insights from transcriptome, QTL-seq and gene functional analysis.

Branch angle (BA) is a critical morphological trait that significantly influences planting density, light interception and ultimately yield in plants. Despite its importance, the regulatory mechanism governing BA in rapeseed remains poorly understood. In this study, we generated 109 transcriptome data sets for 37 rapeseed accessions with divergent BA phenotypes. Relative to adaxial branch segments, abaxial segments accumulated higher levels of auxin and exhibited lower expression of six TCP1 homologues and one GA20ox3. A co-expression network analysis identified two modules highly correlated with BA. The modules contained homologues to known BA control genes, such as FUL, YUCCA6, TCP1 and SGR3. Notably, a homoeologous exchange (HE), occurring at the telomeres of A09, was prevalent in large BA accessions, while an A02-C02 HE was common in small BA accessions. In their corresponding regions, these HEs explained the formation of hub gene hotspots in the two modules. QTL-seq analysis confirmed that the presence of a large A07-C06 HE (~8.1 Mb) was also associated with a small BA phenotype, and BnaA07.WRKY40.b within it was predicted as candidate gene. Overexpressing BnaA07.WRKY40.b in rapeseed increased BA by up to 20°, while RNAi- and CRISPR-mediated mutants (BnaA07.WRKY40.b and BnaC06.WRKY40.b) exhibited decreased BA by up to 11.4°. BnaA07.WRKY40.b was exclusively localized to the nucleus and exhibited strong expression correlations with many genes related to gravitropism and plant architecture. Taken together, our study highlights the influence of HEs on rapeseed plant architecture and confirms the role of WRKY40 homologues as novel regulators of BA.

Completing the picture of field-grown cereal crops: a new method for detailed leaf surface models in wheat.

The leaf angle distribution (LAD) is an important structural parameter of agricultural crops that influences light interception, radiation fluxes and consequently plant performance. Therefore, LAD and its parametrized form, the Beta distribution, is used in many photosynthesis models. However, in field cultivations, these parameters are difficult to assess and cereal crops in particular pose challenges since their leaves are thin, flexible, and often bent and twisted around their own axis. To our knowledge, there is only a very limited set of methods currently available to calculate LADs of field-grown cereal crops that explicitly takes these special morphological properties into account. In this study, a new processing pipeline is introduced that allows for the generation of realistic leaf surface models and the analysis of LADs of field-grown cereal crops from 3D point clouds. The data acquisition is based on a convenient stereo imaging setup. The approach was validated with different artificial targets and results on the accuracy of the 3D reconstruction, leaf surface modeling and calculated LAD are given. The mean error of the 3D reconstruction was below 1mm for an inclination angle range between 0° and 75° and the leaf surface could be quantified with an average accuracy of 90%. The concordance correlation coefficient (CCC) of 99.6% (p-value = [Formula: see text]) indicated a high correlation between the reconstructed inclination angle and the identity line. The LADs for bent leaves were reconstructed with a mean error of 0.21° and a standard deviation of 1.55°. As an additional parameter, the insertion angle was reconstructed for the artificial leaf model with an average error < 5°. Finally, the method was tested with images of field-grown cereal crops and Beta functions were approximated from the calculated LADs. The mean CCC between reconstructed LAD and calculated Beta function was 0.66. According to Cohen, this indicates a high correlation. This study shows that our image processing pipeline can reconstruct the complex leaf shape of cereal crops from stereo images. The high accuracy of the approach was demonstrated with several validation experiments including artificial leaf targets. The derived leaf models were used to calculate LADs for artificial leaves and naturally grown cereal crops. This helps to better understand the influence of the canopy structure on light absorption and plant performance and allows for a more precise parametrization of photosynthesis models via the derived Beta distributions.

Enigmatic fossil plants with three-dimensional, arborescent-growth architecture from the earliest Carboniferous of New Brunswick, Canada

The evolution of arborescence in Devonian plants, followed by their architectural radiation in the Carboniferous, is a transition fundamental to Earth-system processes and ecological development. However, this evolutionary transition in trees is based on preserved trunks, of which only a few known specimens possess crowns. We describe Mississippian-aged (Tournaisian) trees with a unique three-dimensional crown morphology from New Brunswick, Canada. The trees were preserved by earthquake-induced, catastrophic burial of lake-margin vegetation. The tree architecture consists of an unbranched, 16-cm-diameter trunk with compound leaves arranged in spirals of ∼13 and compressed into ∼14cm of vertical trunk length. Compound leaves in the upper ∼0.75m of the trunk measure >1.75m in length and preserve alternately arranged secondary laterals beginning at 0.5m from the trunk; the area below the trunk bears only persistent leaf bases. The principal specimen lacks either apical or basal sections, although an apex is preserved in another. Apically, the leaves become less relaxed toward horizontal and are borne straight at an acute angle at the crown. The compact leaf organization and leaf length created a crown volume of >20-30 m3. This growth strategy likely maximized light interception and reduced resource competition from groundcover. From their growth morphology, canopy size, and volume, we propose that these fossils represent the earliest evidence of arborescent subcanopy-tiering. Moreover, although systematically unresolved, this specimen shows that Early Carboniferous vegetation was more complex than realized, signaling that it was a time of experimental, possibly transitional and varied, growth architectures.

Mustard ‘Amara’ Benefits from Superelevated CO2 While Adapting to Far-red Light Over Time

Compared with the ambient Earth carbon dioxide concentration (≈415 μmol⋅mol–1), the International Space Station has superelevated carbon dioxide (≈2800 μmol⋅mol–1), which can be a stressor to certain crops. Far-red light can drive plant photosynthesis and increase extension growth and biomass. However, the effects of far-red light under superelevated carbon dioxide are unclear. We grew hydroponic mustard (Brassica carinata) ‘Amara’ seedlings in four growth chambers using a randomized complete block design with two carbon dioxide concentrations (415 and 2800 μmol⋅mol–1), two lighting treatments, and two blocks at temperature and relative humidity set points of 22 °C and 40%, respectively. Each growth chamber had two lighting treatments at the same total photon flux density of 200 μmol⋅m–2⋅s–1. Under the same blue and green light at 50 μmol⋅m–2⋅s–1 each, plants received either red light at 100 μmol⋅m–2⋅s–1 or red + far-red light at 50 μmol⋅m–2⋅s–1 each. At day 15 after planting, far-red light did not influence shoot fresh or dry mass at 415 μmol⋅mol–1 carbon dioxide, but decreased both parameters by 22% to 23% at 2800 μmol⋅mol–1 carbon dioxide. Increasing the carbon dioxide concentration increased shoot fresh and dry mass 27% to 49%, regardless of the lighting treatment. Far-red light decreased leaf area by 16% at 2800 μmol⋅mol–1 carbon dioxide, but had no effect at 415 μmol⋅mol–1 carbon dioxide. Increasing the carbon dioxide concentration increased leaf area by 21% to 33%, regardless of far-red light. Regardless of the carbon dioxide concentration, far-red light promoted stem elongation and decreased chlorophyll concentrations by 39% to 42%. These responses indicate far-red light elicited a crop-specific shade avoidance response in mustard ‘Amara’, increasing extension growth but decreasing leaf area, thereby reducing light interception and biomass. In addition, carbon dioxide enrichment up to 2800 μmol⋅mol–1 increased the biomass of mustard ‘Amara’ but decreased the biomass of other crops, indicating crop-specific tolerance to superelevated carbon dioxide. In conclusion, mustard ‘Amara’ seedlings benefit from superelevated carbon dioxide, but exhibit growth reduction under far-red light under superelevated carbon dioxide.

Genetic regulation of self-organizing azimuthal canopy orientations and their impacts on light interception in maize.

The efficiency of solar radiation interception contributes to the photosynthetic efficiency of crop plants. Light interception is a function of canopy architecture, including plant density; leaf number, length, width, and angle; and azimuthal canopy orientation. We report on the ability of some maize (Zea mays) genotypes to alter the orientations of their leaves during development in coordination with adjacent plants. Although the upper canopies of these genotypes retain the typical alternate-distichous phyllotaxy of maize, their leaves grow parallel to those of adjacent plants. A genome-wide association study (GWAS) on this parallel canopy trait identified candidate genes, many of which are associated with shade avoidance syndrome, including phytochromeC2. GWAS conducted on the fraction of photosynthetically active radiation (PAR) intercepted by canopies also identified multiple candidate genes, including liguleless1 (lg1), previously defined by its role in ligule development. Under high plant densities, mutants of shade avoidance syndrome and liguleless genes (lg1, lg2, and Lg3) exhibit altered canopy patterns, viz, the numbers of interrow leaves are greatly reduced as compared to those of nonmutant controls, resulting in dramatically decreased PAR interception. In at least the case of lg2, this phenotype is not a consequence of abnormal ligule development. Instead, liguleless gene functions are required for normal light responses, including azimuth canopy re-orientation.

Life history scaling in a tropical forest

Abstract Both tree size and life history variation drive forest structure and dynamics, but little is known about how life history frequency changes with size. We used a scaling framework to quantify ontogenetic size variation and assessed patterns of abundance, richness, productivity and light interception across life history strategies from &gt;114,000 trees in a primary, neotropical forest. We classified trees along two life history axes: a fast–slow axis characterized by a growth–survival trade‐off, and a stature–recruitment axis with tall, long‐lived pioneers at one end and short, short‐lived recruiters at the other. Relative abundance, richness, productivity and light interception follow an approximate power law, systematically shifting over an order of magnitude with tree size. Slow saplings dominate the understorey, but slow trees decline to parity with rapidly growing fast and long‐lived pioneer species in the canopy. Like the community as a whole, slow species are the closest to obeying the energy equivalence rule (EER)—with equal productivity per size class—but other life histories strongly increase productivity with tree size. Productivity is fuelled by resources, and the scaling of light interception corresponds to the scaling of productivity across life history strategies, with slow and all species near solar energy equivalence. This points towards a resource‐use corollary to the EER: the resource equivalence rule. Fitness trade‐offs associated with tree size and life history may promote coexistence in tropical forests by limiting niche overlap and reducing fitness differences. Synthesis. Tree life history strategies describe the different ways trees grow, survive and recruit in the understorey. We show that the proportion of trees with a pioneer life history strategy increases steadily with tree size, as pioneers become relatively more abundant, productive, diverse and capture more resources towards the canopy. Fitness trade‐offs associated with size and life history strategy offer a mechanism for coexistence in tropical forests.

Blue light strongly promotes de-etiolation over green, moderate over red, but have limited action over far-red lights in lettuce plants

The role of photoreceptors (phytochromes and cryptochromes) was evaluated in lettuce regarding (de)etiolation processes. The manipulation of light quality and intensity can modulate their activity and response and, consequently, promote morphophysiological changes in plants. To this end, lettuce plants were grown under controlled conditions at two photosynthetically active radiation levels (300 and 600 µmol m−2 s−1) and at different qualities, including white, blue, green, red and far-red light, as well as combinations, totaling 18 treatments. Biomass gain, internode length, light interception, pigment content, morpho-anatomical changes in the leaves and ultrastructural changes in the chloroplast and cell wall were evaluated. It was verified that in green, there was the highest degree of etiolation; however, the supplementation of blue promotes a strong de-etiolation process. In pure red (R), the plants were slightly less etiolated, but with limited action of blue in stimulating de-etiolation, and in R plus far-red (FR) (R:FR ratio was 0.33 in R + FR treatment), there was a strong degree of etiolation and weak action of blue on those set of treatments. In general, the plants submitted to the highest intensities of blue light, alone or in combination, approach the control phenotype (white light at total 300 µmol m−2 s−1; 18 % blue = 54 µmol m−2 s−1). The morpho-anatomical phenotype supports the hypothesis that blue light is capable of inhibiting or reducing etiolation-related responses, but the effects are dependent not only on the quality alone but also on the light intensity. Based on the known light-dependent response of phytochromes and cryptochromes, we suggest a weak interference of PHYB on CRY and a strong negative action of PHYA on CRY proteins.

Effects of post-shooting sprays and bunch covering on yield attributes of Willium banana (Musa paradisiaca L.)

This research investigates the synergistic effects of post-shooting sprays and bunch covering materials on the growth, development, and yield of Willium banana (Musa paradisiaca L.). Gibberellic acid (GA3) at 100 mg/l emerges as a potent post-shooting spray, significantly enhancing bunch length, finger length, girth of finger, bunch weight, and overall fruit yield. The study highlights the pivotal role of GA3 in promoting both cell division and elongation, contributing to increased fruit size and weight. Non-woven material bag covering proves superior in creating an optimal microclimate, fostering enhanced air circulation, temperature control, and light interception. This material significantly boosts finger length, girth, bunch weight, and fruit yield. These findings provide valuable insights for banana cultivation, emphasizing the strategic use of GA3 and appropriate covering materials to optimize environmental conditions and hormonal balance for improved crop outcomes. The study contributes to the evolving field of banana cultivation practices and offers practical implications for enhancing fruit quality and yield.

Quantifying physiological contributions to yield loss in response to planting date in short-season cotton under a cotton[sbnd]wheat double-cropping system

Crop yield is primarily determined by physiological parameters, including light interception by the canopy (IPAR), radiation use efficiency (RUE), and harvest index (HI). However, little information is available about how these physiological parameters are impacted by planting date and what their contributions are to cotton yield loss. To evaluate the relative contribution of each physiological parameter to planting date-associated yield loss in cotton, an experiment was conducted during the 2019 to 2021 growing seasons at a field site in Anyang, Henan, China. Two contemporary cotton cultivars were grown in the field with four different planting dates (PDMAY10, PDMAY20, PDMAY30 and PDJUN10) for the growing seasons from 2019 to 2021. The measurements included climatic parameters, seed cotton yield, yield components, HI and biweekly leaf area index, light interception and biomass. First, seed cotton yield was significantly affected by the planting dates, with yields ranging from 1984 to 3388 kg ha−1, averaged across cultivars and years, while a significant difference between the first three planting dates was observed only in 2021. Second, the planting date significantly impacted the total light interception during the growing season (IPARtotal) and HI, while IPARtotal and HI decreased with the delayed planting date in all the years of the study. Compared to PDMAY10, IPARtotal was 0.34%, 13.2%, and 19.9% lower for PDMAY20, PDMAY30 and PDJUN10, respectively. Averaged across cultivars and years, PDMAY10 resulted in the highest HI value (0.28). The RUE gradually decreased as the planting date was delayed, but a significant difference in RUE between planting dates was observed only in 2021. Overall, among the three physiological yield-driving parameters, IPARtotal was a stronger contributor (46.9–47.0%) to the yield loss for PDJUN10 than PDMAY10 and PDMAY20. However, when compared to PDMAY30, HI was the greatest contributor, accounting for approximately 72.5% of the seed cotton yield loss for PDJUN10, followed by IPAR. We found that when cotton sowing in the Yellow River basin was postponed until June 10, the cotton yield was significantly reduced, and IPAR and HI were the main factors responsible for PDJUN10 yield loss on average. This study identified the most important functional traits for seed cotton yield response to planting date and has important reference value for stable cotton production.

Changes in light use efficiency explains why diversity effect on biomass production is lower at high planting density in mixed-species plantations of Eucalyptus grandis and Acacia mangium

Understanding the effect of planting densities and species proportions on light absorption and light use efficiency can help to improve the management of mixed-species forest plantations. Our study aimed to disentangle the role of light interception and light use efficiency (LUE) on the biomass production of Eucalyptus grandis (E), a highly productive species in tropical conditions, and Acacia mangium (A), a N2-fixing species, in monocultures and mixed-species plantations for contrasting planting densities. A randomized block experiment set up over 4 ha in southern Brazil was intensively monitored for 14 months at mid rotation. The absorbed photosynthetically active radiation (APAR) was simulated for each tree of the experiment using the tri-dimensional MAESPA model parameterized with detailed in situ measurements of tree and foliage. LUE for stem wood production was estimated as the ratio of measured stem biomass production (SBP) and simulated APAR. The APAR of Eucalyptus trees did not significantly differ between monocultures and mixed plantations, the reduction of Eucalyptus density being compensated by an increase in light absorption of Eucalyptus individuals. The LUE of Eucalyptus trees in monoculture and mixed-species stands was found to be comparable only at low planting densities. The replacement of Eucalyptus trees with Acacia trees resulted in a reduction in Eucalyptus LUE only at high planting density. The SBP of Eucalyptus trees was mainly explained by differences in APAR, while both APAR and LUE explained the SBP of Acacia trees. The maximum stand production was obtained with monoculture of Eucalyptus at high density and no mixture reached this productivity. Reducing the proportion of Eucalyptus in mixture lead to a substantial decrease in stand production at high planting density due to a decrease in LUE, while this stand production reduction was offset at low planting density, underlying a higher diversity effect at low planting density. In the perspective of increasing diversity in forest plantations to foster multifunctionality, mixed plantations of Acacia and Eucalyptus at low planting density can be an interesting option to maintain a relatively high productivity, which is similar to Eucalyptus monocultures at the same low planting density.

Performance of Summer Greengram (Vigna radiate L.) under Various Orientations in Semi-arid Region, Haryana (India)

Background: Summer green gram (Vigna radiata L.) commonly known as “moong” belongs to the Fabaceae family that currently is grown in different parts of the world and it has a significant role in nutrition in developing countries. It is a short-duration crop grown over a wide range of environments in India. Light interception and penetration as well as albedo are affected by row orientation. Methods: Line Quantum sensor (Model L1-191R) was used to measure PAR (400 nm-700 nm) at important phenophases at different orientations. In order to better understand how plants absorb light in different row orientations, such as North-South (NS), East-West (EW) and North-West-Southeast (NW-SE), a study was carried out at the Chaudhary Charan Singh Research Farm of Agricultural Meteorology at the Haryana Agricultural University in Hisar India during summer 2020 and 2021. Heat and radiation use efficiency measure at flowering, pod and physiological maturity by using weather data and other indices. Result: It was found that moong variety MH 421’s pod initiation stage was when PAR absorption was greatest, along with other factors including NW-SE orientation. Row orientation heat use efficiency ranges between (2.6 to 7.6 kg ha-1 °C day-1) and in variety (1.4 to 2.7 g MJ-1) and radiation use efficiency ranges between (1.4 to 2.8 g MJ-1) and in row orientation (1.4 to 2.7 g MJ-1) (2.7 to 7.7 kg ha-1 °C day-1). As a consequence, it was determined that diagonal row orientations generated better yield and yield attributes because PAR absorption was higher in such orientations. In dry and semi-arid areas, it can be used to produce food and forage.

Effects of surface geometry on light exposure, photoacclimation and photosynthetic energy acquisition in zooxanthellate corals.

Symbiotic corals display a great array of morphologies, each of which has unique effects on light interception and the photosynthetic performance of in hospite zooxanthellae. Changes in light availability elicit photoacclimation responses to optimize the energy balances in primary producers, extensively documented for corals exposed to contrasting light regimes along depth gradients. Yet, response variation driven by coral colony geometry and its energetic implications on colonies with contrasting morphologies remain largely unknown. In this study, we assessed the effect of the inclination angle of coral surface on light availability, short- and long-term photoacclimation responses, and potential photosynthetic usable energy. Increasing surface inclination angle resulted in an order of magnitude reduction of light availability, following a linear relationship explained by the cosine law and relative changes in the direct and diffuse components of irradiance. The light gradient induced by surface geometry triggered photoacclimation responses comparable to those observed along depth gradients: changes in the quantum yield of photosystem II, photosynthetic parameters, and optical properties and pigmentation of the coral tissue. Differences in light availability and photoacclimation driven by surface inclination led to contrasting energetic performance. Horizontally and vertically oriented coral surfaces experienced the largest reductions in photosynthetic usable energy as a result of excessive irradiance and light-limiting conditions, respectively. This pattern is predicted to change with depth or local water optical properties. Our study concludes that colony geometry plays an essential role in shaping the energy balance and determining the light niche of zooxanthellate corals.