Canopy Temperature Depression Research Articles

Variation in Physiological Traits of Blackgram (Vigna mungo L.) Genotypes under High Temperature Stress

Background: Blackgram is one of the important short duration pulse crop which is sensitive to high temperatures. The rising global temperatures are threatening the yield of blackgram by altering the physiological processes at cellular level. Keeping this in view, the present investigation was carried out for better understanding of genotypic variability and the physiological mechanisms governing heat stress tolerance which can help in identifying heat tolerant blackgram genotypes that can yield better under climate change scenarios. Methods: Thirty blackgram genotypes selected from temperature induction response technique were evaluated for physiological efficiency under natural high temperature conditions during summer, 2022 and 2023. Field experiment was conducted at Agricultural College Farm, Acharya N.G Ranga Agricultural University, Agricultural College, Bapatla. Physiological and yield parameters were recorded at flowering and the data were analyzed statistically and pooled. Result: Significant genetic variability was observed among the blackgram genotypes with respect to all the physiological traits under high temperature stress conditions. Among the 30 genotypes tested for thermotolerance, the genotypes TBG-129, PU-1804, LBG-1015, PU-31 and TBG-104 were found to withstand high temperature stress at reproductive stage by maintaining higher total chlorophyll, carotenoids, chlorophyll stability index, total biomass production, cooler canopies resulting into higher canopy temperature depression, less membrane injury index values and higher yield. Correlation analysis revealed a strong positive correlation for all the physiological traits with seed yield except membrane injury index under heat stress conditions. The PCA results revealed considerable variability among the traits accounting for 82.65% of total variability. The genotypes TBG-129, PU-1804, LBG-1015 and TBG-104 can be potentially used as donors in the breeding programmes for the development of heat tolerant genotypes.

Effect of plant architecture on the responses of canopy temperature and water use to population density in winter wheat

AbstractRevealing how plant architecture affects the responses of canopy temperature depression (CTD), water use (WU), and grain yield to population density (PD) in wheat (Triticum aestivum L.) would help explore a water‐saving pathway related to managing population. This study was conducted over three consecutive years under rainfed and supplemental irrigation conditions. The flat‐leafed Jinmai 47 and upright‐leafed Jing 411 genotypes were grown at high population density (HD), medium population density (MD), and low population density (LD); seeding rates were 450, 675, and 900 seeds m−2, respectively). CTD peaked at MD in Jinmai 47 but reached the highest at HD in Jing 411. WU generally increased with increasing PD but remained unchanged from LD to MD in Jinmai 47 under the two water conditions, while it remained unchanged from MD to HD under supplemental irrigation condition in Jing 411. Yield increased with increasing density in both genotypes under the two water conditions. It is thus clear that Jinmai 47 gained higher yield but did not consume more water at MD than at LD under the two water conditions; Jing 411 obtained higher yield at the expense of similar amount of water at HD than at MD under supplemental irrigation condition. The grain yield and WU responses of wheat crops to PD implied that through appropriately adjusting PD in combination with plant architecture and water condition, the dual goals of optimizing yield and effectively saving irrigation water could be realized synchronously.

Response of stomatal conductance to plant water stress in buffalograss seed production: Observation with UAV thermal infrared imagery

Stomatal conductance (gs) is an indicator that allows for direct evaluation of plant water status, but it is challenging to achieve rapid monitoring in large-scale fields due to limitations in observation methods. Here this study was conducted to identify the thresholds of gs with different target yields and develop a gs-based water stress diagnostic model for buffalograss (Buchloe dactyloides (Nutt.) Engelm.) using UAV thermal infrared imagery for buffalograss in 2022 and 2023. The results of the field experiment demonstrated that the gs rapidly response to changes in the water stress status of buffalograss. The thresholds of gs were 403 and 385 mmol m−2 s−1 for the vegetative and reproductive growth stages, respectively, with the target seed yield of 1224 kg ha−1. The gs values were classified into three levels for the vegetative growth and four levels for the in reproductive growth stage of buffalograss, respectively. The canopy temperature depression response to water stress is consistent with the gs. Based on this relationship, this study developed a gs-based diagnostic model with a random forest algorithm for buffalograss. Furthermore, a spital map of gs was created using UAV thermal infrared imagery. The modification test results indicated that the model made a good estimation of gs were good with normalized root mean square errors of 15% in the vegetative stage and 11% in the reproductive stage, respectively. Therefore, it is feasible to use thermal infrared imagery for monitoring gs and evaluating the water stress of plants in buffalograss fields.

Sensor-based precision nutrient and irrigation management enhances the physiological performance, water productivity, and yield of soybean under system of crop intensification.

Sensor-based decision tools provide a quick assessment of nutritional and physiological health status of crop, thereby enhancing the crop productivity. Therefore, a 2-year field study was undertaken with precision nutrient and irrigation management under system of crop intensification (SCI) to understand the applicability of sensor-based decision tools in improving the physiological performance, water productivity, and seed yield of soybean crop. The experiment consisted of three irrigation regimes [I1: standard flood irrigation at 50% depletion of available soil moisture (DASM) (FI), I2: sprinkler irrigation at 80% ETC (crop evapo-transpiration) (Spr 80% ETC), and I3: sprinkler irrigation at 60% ETC (Spr 60% ETC)] assigned in main plots, with five precision nutrient management (PNM) practices{PNM1-[SCI protocol], PNM2-[RDF, recommended dose of fertilizer: basal dose incorporated (50% N, full dose of P and K)], PNM3-[RDF: basal dose point placement (BDP) (50% N, full dose of P and K)], PNM4-[75% RDF: BDP (50% N, full dose of P and K)] and PNM5-[50% RDF: BDP (50% N, full P and K)]} assigned in sub-plots using a split-plot design with three replications. The remaining 50% N was top-dressed through SPAD assistance for all the PNM practices. Results showed that the adoption of Spr 80% ETC resulted in an increment of 25.6%, 17.6%, 35.4%, and 17.5% in net-photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), and intercellular CO2 concentration (Ci), respectively, over FI. Among PNM plots, adoption of PNM3 resulted in a significant (p=0.05) improvement in photosynthetic characters like Pn (15.69 µ mol CO2 m-2 s-1), Tr (7.03m mol H2O m-2 s-1), Gs (0.175 µmol CO2 mol-1 year-1), and Ci (271.7mol H2O m2 s-1). Enhancement in SPAD (27% and 30%) and normalized difference vegetation index (NDVI) (42% and 52%) values were observed with nitrogen (N) top dressing through SPAD-guided nutrient management, helped enhance crop growth indices, coupled with better dry matter partitioning and interception of sunlight. Canopy temperature depression (CTD) in soybean reduced by 3.09-4.66°C due to adoption of sprinkler irrigation. Likewise, Spr 60% ETc recorded highest irrigation water productivity (1.08kg ha-1 m-3). However, economic water productivity (27.5 INR ha-1 m-3) and water-use efficiency (7.6kg ha-1 mm-1 day-1) of soybean got enhanced under Spr 80% ETc over conventional cultivation. Multiple correlation and PCA showed a positive correlation between physiological, growth, and yield parameters of soybean. Concurrently, the adoption of Spr 80% ETC with PNM3 recorded significantly higher grain yield (2.63t ha-1) and biological yield (8.37t ha-1) over other combinations. Thus, the performance of SCI protocols under sprinkler irrigation was found to be superior over conventional practices. Hence, integrating SCI with sensor-based precision nutrient and irrigation management could be a viable option for enhancing the crop productivity and enhance the resource-use efficiency in soybean under similar agro-ecological regions.

Micrometeorological Comparison of Canopy Temperature between Two Wheat Cultivars Grown under Irrigation in a Hot Environment in Sudan

A thorough exploration of the micrometeorological aspects influencing canopy temperature in contrasting wheat cultivars can unveil the specific mechanisms of adaptation to heat stress. However, information on wheat microclimates in hot environments for crop improvement is lacking. Here, we used a micrometeorological method to investigate wheat’s response to high temperatures. Field experiments were conducted in the Gezira Scheme, Sudan, to compare two high-yielding heat-tolerant cultivars, Imam and Bohaine, in terms of canopy temperature depression (CTD), air temperature gradient (ATG), and vapor pressure gradient (VPG) from a 2 m height to canopy level. The maximum air temperature at 2 m during the main growing season was 37 °C. Air temperature at canopy level was mostly lower in the Imam field than in the Bohaine field, and it was positively correlated with and higher than radiometric canopy surface temperature. The maximum CTD during the reproductive stage was 4.7–6.5 °C in the Bohaine field and 5.0–7.2 °C in the Imam field. ATG was also larger in the Imam field, attributed to the greater leaf area of the Imam canopy, as presumed from the NDVI difference between fields. ATG was negatively correlated with VPG in both fields, and the relationship was stronger at lower nighttime wind speeds and weaker at higher daytime wind speeds. These results indicate that the micrometeorological approach can be used to compare cultivars in high-temperature environments.

Monitoring of drought stress and transpiration rate using proximal thermal and hyperspectral imaging in an indoor automated plant phenotyping platform

BackgroundThermography is a popular tool to assess plant water-use behavior, as plant temperature is influenced by transpiration rate, and is commonly used in field experiments to detect plant water deficit. Its application in indoor automated phenotyping platforms is still limited and mainly focuses on differences in plant temperature between genotypes or treatments, instead of estimating stomatal conductance or transpiration rate. In this study, the transferability of commonly used thermography analysis protocols from the field to greenhouse phenotyping platforms was evaluated. In addition, the added value of combining thermal infrared (TIR) with hyperspectral imaging to monitor drought effects on plant transpiration rate (E) was evaluated.ResultsThe sensitivity of commonly used TIR indices to detect drought-induced and genotypic differences in water status was investigated in eight maize inbred lines in the automated phenotyping platform PHENOVISION. Indices that normalized plant temperature for vapor pressure deficit and/or air temperature at the time of imaging were most sensitive to drought and could detect genotypic differences in the plants’ water-use behavior. However, these indices were not strongly correlated to stomatal conductance and E. The canopy temperature depression index, the crop water stress index and the simplified stomatal conductance index were more suitable to monitor these traits, and were consequently used to develop empirical E prediction models by combining them with hyperspectral indices and/or environmental variables. Different modeling strategies were evaluated, including single index-based, machine learning and mechanistic models. Model comparison showed that combining multiple TIR indices in a random forest model can improve E prediction accuracy, and that the contribution of the hyperspectral data is limited when multiple indices are used. However, the empirical models trained on one genotype were not transferable to all eight inbred lines.ConclusionOverall, this study demonstrates that existing TIR indices can be used to monitor drought stress and develop E prediction models in an indoor setup, as long as the indices normalize plant temperature for ambient air temperature or relative humidity.

Skipping irrigation at pre- and post-anthesis stages influences grain yield and starch contents of bread wheat derived from synthetic or landraces

AbstractThis study aims to evaluate the role of genetic diversity originated from three-way crosses of landraces and synthetic bread wheat derivatives attempted with elite cultivars to identify the genotypes having better grain yield as well as better starch contents under flowering stage drought stress. In total, 50 genotypes comprised of 47 derivatives of landraces and synthetics, and three standard varieties were grown in the fields of CIMMYT, Obregon following alpha lattice design with two replications. Drought stress was imposed by stopping the irrigation before anthesis and post-anthesis stages. Different traits related to physiological adaptations, earliness, grain yield and starch contents were decreased under drought stress except amylose which increased significantly. Canopy temperature depression was not significantly affected by drought stress. Further, we identified strong correlation of grain yield with plant height, normalized difference in vegetation index, plant maturity, spike length, grain number and thousand grain weight but negative with canopy temperature depression. Non-significant correlation of amylose and amylopectin was recorded with grain yield. Results revealed that genetic diversity derived from landraces and synthetic bread wheat can improve grain yield and starch contents but simultaneous improvement of both is elusive.

Assessment of Genetic Variability for Morpho-physiological and Yield Traits in Bread Wheat (Triticum aestivum L.)

In order to estimate genetic variability parameters for seventeen traits of wheat, 28 F1s were obtained by crossing 8 parents in 8×8 diallel fashion, excluding reciprocals and evaluation trial was laid down in randomised complete block design at Pantnagar, Uttarakhand. Analysis of variance revealed that highly significant differences between genotypes exist for all seventeen characters. Eleven out of seventeen characters were observed to exhibit elevated values for both the PCV and GCV. The observed phenotypic coefficient of variation (PCV) values was determined to be greater than the genotypic coefficient of variation (GCV) values, indicating that the expression of traits is comparatively less influenced by environmental factors. A significant degree of heritability, along with a notable genetic advance, was observed for various traits, including flag leaf area, followed by grain yield, biological yield, canopy temperature depression (CTD), harvest index, tillers per plant, peduncle length, grains per spike, awn length, plant height, grain filling duration, spikelet per spike, spike length, and normalised difference vegetation index (NDVI) content. This study has thus identified significant genetic variability in wheat traits, highlighted traits with high heritability and genetic advance, and suggested that these traits could be targeted for improvement in wheat breeding programs.

Assessment of genetic variation among wheat genotypes for drought tolerance utilizing microsatellite markers and morpho-physiological characteristics

Drought is a major abiotic stress that severely limits sustainable wheat (Triticum aestivum L.) productivity via morphological and physio-biochemical alterations of cellular processes. The complex nature and polygenic control of drought tolerance traits make breeding tolerant genotypes quite challenging. However, naturally occurring variabilities among wheat germplasm resources could potentially help combating drought. The present study was conducted to assess the drought tolerance of 18 Bangladeshi hexaploid wheat genotypes, focusing on the identification of potent sources of diversity by combining microsatellite markers, also known as single sequence repeat markers, and morpho-physiological characteristics that might help accelerating wheat crop improvement programs. Initially, the genotypes were evaluated using 25 microsatellite markers followed by an on-field evaluation of 7 morphological traits (plant height, spike number, spike length, grains per spike, 1000-grain weight, grain yield, biological yield) and 6 physiological traits (SPAD value, membrane stability index, leaf relative water content, proline content, canopy temperature depression, and leaf K+ ion content). The field-trial was conducted in a factorial fashion of 18 wheat genotypes and two water regimes (control and drought) following a split-plot randomized complete block design. Regardless of genotype, drought was significantly damaging for all the tested traits; however, substantial variability in drought stress tolerance was evident among the genotypes. Spike length, 1000-grain weight, SPAD value, leaf relative water content, canopy temperature depression, proline content, and potassium (K+) ion content were the most representative of drought-induced growth and yield impairments and also correlated well with the contrasting ability of genotypic tolerance. Microsatellite markers amplified 244 alleles exhibiting 79% genetic diversity. Out of 25 markers, 23 was highly polymorphic showing 77% average polymorphism. Morpho-physiological trait-based hierarchical clustering and microsatellite marker-based neighbor-jointing clustering both revealed three genotypic clusters with 71% co-linearity between them. In both cases, the genotypes Kanchan, BAW-1147, BINA Gom 1, BARI Gom 22, BARI Gom 26, and BARI Gom 33 were found to be comparatively more tolerant than the other tested genotypes, showing potential for cultivation in water-deficit environments. The findings of this study would contribute to the present understanding of drought tolerance in wheat and would provide a basis for future genotype selection for drought-tolerant wheat breeding programs.

Monitoring and Investigating the Change Patterns of Major Growth Parameters of Almond (Badam) Trees under Different Irrigation Conditions

Knowledge of the response of growth parameters of almond (Badam) trees to different water supply conditions is important for Badam production. To identify growth parameters that are sensitive to water deficit in almond trees, field experiments were conducted during a median water year to monitor the major growth characteristics of almond trees under different irrigation conditions in Shache County, Xinjiang, China. A field (in-situ) monitoring system was also constructed using various sensors for the continuous and non-destructive monitoring of the growth parameters, such as soil water in the root zone, canopy temperature depression, trunk diameter, and fruit diameter of almond trees. The results confirmed the reliability of the monitoring system. Both canopy temperature depression and the diameter shrinkage of the trunk and fruit were significantly negatively correlated (r values ranging from −0.996 to −0.823) with the irrigation water quantity. This correlation was observed from the young fruit stage to the maturation stage of almond trees, under irrigation conditions representing 50–100% of crop evapotranspiration (ETc). These parameters were sensitive (|r| ≥ 0.778) to the water deficit status of almond trees from 14:00 to 18:00 in sunny weather. These results can provide both technical and theoretical support for real-time non-destructive assessment of the water deficit status of almond trees.

Silicon improves root system and canopy physiology in wheat under drought stress

Abstract Aims Root system is an important regulator for unevenly distributed below-ground resource acquisition. In a rainfed cropping environment, drought stress (DS) significantly restricts root growth and moisture uptake capacity. The fact that silicon (Si) alleviates DS in wheat is widely reported, but its effects on the wheat root system remain unclear. Methods The present study investigated the effect of pre-sowing Si treatment on two contrasting wheat cultivars (RAC875, drought-tolerant; Kukri, drought-susceptible) at early growth stages. The cultivars were grown in a glasshouse in a complete randomized design with four replications and two watering treatments. Various root traits and physiological data, including non-destructive infrared thermal imaging for water stress indices, were recorded. Results Under DS and Si (DSSi), Kukri had a significant increase in primary root length (PRL,44%) and lateral root length (LRL,28.1%) compared with RAC875 having a substantial increase in PRL (35.2%), but non-significant in LRL. The Si-induced improvement in the root system positively impacted canopy physiology and significantly enhanced photosynthesis, stomatal conductance and transpiration in Kukri and RAC875 under DSSi. Canopy temperature was reduced significantly in Kukri (4.24%) and RAC875 (6.15%) under DSSi, while canopy temperature depression was enhanced significantly in both the cultivars (Kukri,78.6%; RAC875, 58.6%) under DSSi. Conclusion These results showed that Si has the potential to influence below-ground traits, which regulate the moisture uptake ability of roots for cooler canopy and improved photosynthesis under DS. It also suggests a future direction to investigate the underlying mechanisms involved in wheat’s Si-induced root growth and moisture uptake ability.

Safflower (Carthamus tinctorius L.) crop adaptation to residual moisture stress: conserved water use and canopy temperature modulation are better adaptive mechanisms.

Oilseeds with high productivity and tolerance to various environmental stresses are in high demand in the food and industrial sectors. Safflower, grown under residual moisture in the semi-arid tropics, is adapted to moisture stress at certain levels. However, a substantial reduction in soil moisture has a significant impact on its productivity. Therefore, assessing genetic variation for water use efficiency traits like transpiration efficiency (TE), water uptake, and canopy temperature depression (CTD) is essential for enhancing crop adaptation to drought. The response of safflower genotypes (n = 12) to progressive soil moisture depletion was studied in terms of water uptake, TE, and CTD under a series of pot and field experiments. The normalised transpiration rate (NTR) in relation to the fraction of transpirable soil water (FTSW) varied significantly among genotypes. The genotypes A-1, Bhima, GMU-2347, and CO-1 had higher NTR-FTSW threshold values of 0.79 (R2 = 0.92), 0.74 (R2 = 0.96), 0.71 (R2 = 0.96), and 0.71 (R2 = 0.91), respectively, whereas GMU-2644 had the lowest 0.38 (R2 = 0.93). TE was high in genotype GMU-2347, indicating that it could produce maximum biomass per unit of water transpired. At both the vegetative and reproductive stages, significant positive relationships between TE, SPAD chlorophyll metre reading (SCMR) (p < 0.01) and CTD (p < 0.01) were observed under field conditions by linear regression. The genotypes with high FTSW-NTR thresholds, high SCMR, and low CTD may be useful clues in identifying a genotype's ability to adapt to moisture stress. The findings showed that the safflower genotypes A-1, Bhima, GMU-2347, and CO-1 exhibited an early decline and regulated water uptake by conserving it for later growth stages under progressive soil water depletion.

Prioritization of Physio-Biochemical Selection Indices and Yield-Attributing Traits toward the Acquisition of Drought Tolerance in Chickpea (Cicer arietinum L.).

Chickpea is widely grown in rainfed areas of developing countries because of its nutritional abundance and adaptability. To overcome the environmental effect of drought on yield, a characteristic-linked selection strategy is proved as well-thought-out and advantageous for the development of drought-tolerant cultivars. To precisely understand the contribution of various physio-biochemical and yield-attributing traits toward drought tolerance in chickpea (Cicer arietinum L.), forty chickpea genotypes were evaluated in the years 2020-2021 and 2021-2022 under normal irrigated as well as drought-stressed conditions. Among the studied genotypes, genotype ICC4958 retained the highest chl content (0.55 mg g-1 FW), minimal electrolyte leakage, and superoxide dismutase (1.48 U/mg FW) and peroxidase (2.21 µmol/min/g FW) activities while cultivar JG11 maintained the maximum relative water content and proline accumulation. The principal-component-based biplots prioritized the physio-biochemical and yield-accrediting characteristics based on their association significance and contribution to terminal drought tolerance. Under drought stress, grain yield per plant was depicted to have a strongly positive association with canopy temperature depression, catalase, superoxide dismutase, and peroxidase activities as well as total soluble sugar, proline, and chlorophyll content, along with the numbers of pods and biological yield per plant. These identified physio-biochemical and yield-attributing traits can be further deployed to select drought-tolerant chickpea genotypes for the breeding of climate-smart chickpea genotypes.

Identification of Climate-Smart Bread Wheat Germplasm Lines with Enhanced Adaptation to Global Warming.

Bread wheat (Triticum aestivum L.) is widely grown in sub-tropical and tropical areas and, as such, it is exposed to heatstress especially during the grain filling period (GFP). Global warming has further affected its production and productivity in these heat-stressed environments. We examined the effects of heatstress on 18 morpho-physiological and yield-related traits in 96 bread wheat accessions. Heat stress decreased crop growth and GFP, and consequently reduced morphological and yield-related traits in the delayed sown crop. A low heat susceptibility index and high yield stability were used for selecting tolerant accessions. Under heatstress, the days to 50% anthesis, flag-leaf area, chlorophyll content, normalized difference vegetation index (NDVI), thousand grain weight (TGW), harvest index and grain yield were significantly reduced both in tolerant and susceptible accessions. The reduction was severe in susceptible accessions (48.2% grain yield reduction in IC277741). The plant height, peduncle length and spike length showeda significant reduction in susceptible accessions, but a non-significant reduction in the tolerant accessions under the heatstress. The physiological traits like the canopy temperature depression (CTD), plant waxiness and leaf rolling were increased in tolerant accessions under heatstress. Scanning electron microscopy of matured wheat grains revealed ultrastructural changes in endosperm and aleurone cells due to heat stress. The reduction in size and density of large starch granules is the major cause of the yield and TGW decrease in the heat-stress-susceptible accessions. The most stable and high-yielding accessions, namely, IC566223, IC128454, IC335792, EC576707, IC535176, IC529207, IC446713 and IC416019 were identified as the climate-smart germplasm lines. We selected germplasm lines possessing desirable traits as potential parents for the development of bi-parent and multi-parent mapping populations.

Farklı Çevrelerde Yetiştirilen Bazı Ekmeklik Buğday Çeşitlerinin (Triticum aestivum L.) Bazı Fizyolojik ve Verim Özelliklerinin Değerlendirilmesi

This study aimed to evaluate the performance of some bread wheat varieties in different environments, and to reveal the relationships between some physiological parameters and yield and yield components. Three bread wheat varieties, (Namely, Basribey 95, Alibey, and Kaşifbey 95), were used as plant materials. Field experiments were conducted during the 2009-2010 and 2010-2011 growing seasons in Aydın and Menemen locations. The experimental layout was a RCBD with three replications at each location and year. In the study, canopy temperature depression (CTD), chlorophyll content (CC), stomatal conductance (SC), grain yield (GY), plant height (PH), spike number per square meter (S/m2), thousand kernel weight (TKW), test weight (TW), grain number per spike (G/S), single spike yield (SSY), number of days to heading (DHE), were examined. CTD in ZGS 65 had a decisive role in gaining high grain yield. Also, CC in ZGS 65 and ZGS 71 might be defined as an important physiological traits. On the other hand, the contribution of the SC parameter determined in ZGS 55, ZGS 65 and ZGS 71 to the yield depends on the environment. Those parameters could be selection criteria for high-yield wheat breeding due to positive and significant correlations with grain yield. And also SC and CC parameters might be used in yield estimation on wheat.

Genetic diversity assessment of Grewia tenax (Forssk.) Fiori. germplasm for fodder and other economic traits in hot-arid Kachchh region of India

Grewia tenax (Forssk.) Fiori. belongs to the family Tiliaceae, an underutilized shrub in arid and semi-arid regions. The maximum distribution of G. tenax population was recorded in Nakhtarana (38%), Bhuj (32%), and Mandvi (15%). Morpho-physiological trait variation of germplasm viz., plant height ranged from 70 to 162.4 cm, canopy spread from 79.7 to 175.8 cm2, leaf area from 3.1 to 8. 3 cm2, relative water content from 33.3 to 72.4% and canopy temperature depression was ranged from 0.6 to 7.0ºC. The fodder traits such as above-ground biomass (AGB) varied from 0.4 to 2.9 kg/plant, with a lot of variation in crude protein (2.2- 15.2%), NDF (37.2- 64.2%), and ADF (12.0- 47.6%) contents. The fruit traits viz., fruit length ranged from 4.9 to 6.7 mm, fruit diameter 4.1 to 5.9 mm, pulp 24.0 to 46.0%, TSS 6.5 to 11.4°B, and pH 3.2 to 4.8. Based on the overall assessment, genotypes GT-2, GT-3, GT-14, and GT-15 were found the most promising. A high coefficient of variation was recorded for nitrogen (72.5%), AGB/plant (60.4%), crude protein (57.2%), and Canopy temperature depression (47.9%). Cluster analysis assembled the genotypes into two major clusters with two sub-clusters each, affirming the presence of a high amount of genetic variability between the tested genotypes. The principal component analysis revealed that first 10 Eigen PC explained 85.95% of the total variation. Biplot between PC1 and PC2 demonstrated that genotypes GT-15, GT-1, GT-3, GT-11, GT-13, GT-29, GT-32, GT-33 and GT-36 were much distinct from each other.

Evaluation of bread wheat (Triticum aestivum L.) genotypes for drought tolerance using morpho-physiological traits under drought-stressed and well-watered conditions.

Increasing frequency of drought spells occasioned by changing climatic conditions, coupled with rise in demand for bread wheat, calls for the development of high yielding drought resilient genotypes to enhance bread wheat production in areas with moisture deficit. This study was designed to identify and select drought-tolerant bread wheat genotypes using morpho-physiological traits. One hundred and ninety-six bread wheat genotypes were evaluated in greenhouse and field experiments, under well-watered (80% of field capacity) and drought-stressed (35% of field capacity) conditions, for two years. Data were collected on five morphological traits (flag leaf size, flag leaf angle, flag leaf rolling, leaf waxiness and resistance to diseases) and 14 physiological traits. Relative water content (RWC), Excised leaf water retention (ELWR), Relative water loss (RWL), Leaf membrane stability index (LMSI), as well as Canopy temperature depression (CTD) at heading (CTDH), anthesis (CTDA), milking (CTDM), dough stage (CTDD) and ripening (CTDR) were estimated. Similarly, leaf chlorophyll content (SPAD reading) was recorded at heading (SPADH), anthesis (SPADA), milking (SPADM), dough stage (SPADD), and ripening (SPADR). Significant (p<0.01) genotypic differences were found for the traits under both well-watered and drought-stressed conditions. Associations of RWL with SPADH, SPADA, SPADM, SPADD and SPADR were significant (p<0.01) and negative under both watering regimes. The first three principal components accounted for 92.0% and 88.4% of the total variation under well-watered and drought-stressed conditions, respectively and comprised all the traits. The traits CTDD, CTDM, CTDR, SPADH, SPADA, SPADM, SPADD and SPADR with genotypes Alidoro, ET-13A2, Kingbird, Tsehay, ETBW 8816, ETBW 9027, ETBW9402, ETBW 8394 and ETBW 8725 were associated under both conditions. Genotypes with narrow flag leaves, erect flag leaf angles, fully rolled flag leaves, heavily waxed leaves, and resistant to disease manifested tolerance to drought stress. The identified traits and genotypes could be exploited in future breeding programmes for the development of bread wheat genotypes with tolerance to drought.

Potential of Melia dubia-wheat based agroforestry system to cope up with climate change

Climate change has impact on agricultural production, because it raises CO2 levels in the atmosphere, which leads to higher temperatures. Agroforestry systems aid in climate change adaptation and mitigation by providing relatively lower temperature beneath the tree canopy. Therefore, diversified agricultural systems are needed to be identified and studied throughout the world that can help annual crops in providing better survival conditions with least effects on yield. Although food crop output in agroforestry systems is lower than in open regions, agroforestry is seen to be capable of supporting food security, soil and water conservation, land use diversification, and micronutrient adequacy and most importantly climate change mitigation. The present study showed that all the tree parameters (i.e., tree DBH, tree height and canopy spread) recorded in the intercropped conditions (Melia dubia based agroforestry system) were found higher compared to the trees devoid of intercrops. Trees with intercrops showed more canopy spread, tree height and DBH (6.9 m, 16.3m, 56.6 m) as compared to pure stand (6.6 m, 16.2 m, 55.6 m) of Melia dubia trees. The canopy temperature depression (CTD) of wheat crop grown with Melia dubia trees was -5.58 0C whereas; -5.27 0C CTD was recorded in non-shaded conditions. Significantly higher biological yield was observed in wheat variety HD 3086 in open and intercropped conditions (134.9 q/ha and 100.5 q/ha respectively). Study revealed that M. dubia based agroforestry provides trees to perform better in intercropped conditions and provides favourable environment for the crop growing beneath in terms of lowering temperature and maintaining apt moisture to the crop raised beneath.

Plant Architecture Influences the Population Transpiration and Canopy Temperature in Winter Wheat Genotypes

To study how plant architecture affects the canopy traits and water use of wheat, the Triticum aestivum L. population is expected to provide important information for cultivar improvement and the ideal population structure establishment for conserving water without causing an enormous grain yield loss. This study was conducted for three consecutive growing seasons using two genotypes with contrasting plant architectures as the materials, the upright-leafed compact type Jing 411 and the flat-leafed loose type Jinmai 47. The population-scale transpiration (PT) and soil evaporation (E) were partitioned from the evapotranspiration (ET) using micro-lysimeters, and the canopy traits population density and the canopy temperature depression (CTD) were also monitored during the period from the jointing to early grain filling stage—the largest water requirement period of wheat crops. Jinmai 47 showed a lower E than Jing 411, but a similar PT and ET, though it had a higher population density at the sowing density. The total evapotranspiration (TET) for the whole growing season was also similar in the two genotypes. This indicated that Jinmai 47 performed better in water conservation than Jing 411. With a similar PT and TET, however, Jinmai 47 showed a rather larger CTD and a significantly higher grain yield than Jing 411. If the higher population density and higher leaf net photosynthetic rate could explain its higher grain yield, the higher leaf stomotal conductance and transpiration rate and the higher population density could not explain the similar PT, ET and TET to Jing 411. Presumably, the involvement of the plant architecture disrupted the original higher transpiration–larger CTD relation, and broke up the prevailing saving water-losing yield concept. Thus, the study might suggest the important water saving value of the flat-leafed loose architecture in wheat crops and demonstrate the possibility of conserving irrigation water without causing serious grain yield loss by taking advantage of the distinct plant architecture to establish an appropriate population structure.

Effects of different tillage on morpho-physiological traits of dryland chickpea (Cicer arietinum L.)

The study of different types of tillage can be effective in promoting conservation agriculture for chickpea cultivation. The present experiment was conducted to study the effects of different soil management (reduced tillage (RT), no-tillage (NT), and conventional tillage (CT)) on morpho-physiological characteristics of chickpea in a complete randomized block design field experiment with three replications during the 2017–2019 cropping seasons. In this experiment effects of soil management on mycorrhizal colonization and sporulation, rhizobium nodules, relative leaf water content, leaf area index, chlorophyll and carotenoids, chlorophyll fluorescence, canopy temperature, enzymes, proline, hydrogen peroxide, malondialdehyde, leaf soluble proteins, carbohydrates, and leaf P and N content were investigated in early grain filling were evaluated. The highest activity of antioxidant enzymes including catalase (0.066 U/mg−1Protein min−1), peroxidase (1.22 U/mg−1Protein min−1), and superoxide dismutase (0.69 U/mg−1Protein min−1) were observed in the plants grown under CT practice, while the lowest were observed under NT system. In NT, the lowest amounts of malondialdehyde and carotenoids were retrieved compared to the conventional tillage. CT determined a reduction in chlorophyll in leaves compared to RT (13 %) and NT (36.2 %), respectively. The highest rate of canopy temperature depression occurred in no-tillage system. The highest remobilization from stems to seeds was respectively obtained from conventional tillage, reduced tillage and no-tillage treatments. In no-tillage, leaf area index, quantum efficiency of PSII (chlorophyll fluorescence), relative water content, leaf nitrogen, and leaf phosphorus increased compared to reduced tillage and conventional tillage, respectively. The rate of colonization and sporulation of mycorrhizal fungi and the number of rhizobium nodules significantly increased under NT compared to RT and CT systems. The results in this experiment showed that the NT system improved relative leaf water content, reduced antioxidant enzymes, and positive effects on measured morpho-physiological traits increased the yield and stability of chickpea compared to RT and CT systems under rainfed conditions.