Normal Irrigation Research Articles

Foliar salicylic acid application to mitigate the effect of drought stress on isabgol (Plantago ovata forssk)

The aim of this study was to identify the effect of drought stress on physiological and biochemical characteristics of isabgol and to clarify whether the foliar application of salicylic acid is able to mitigate the stress impacts. This study was carried out as a factorial field experiments at Gonbad Kavous, north-eastern Iran during the growing seasons of 2016 and 2017.The treatments were 3 regimes of irrigation, namely irrigation every week throughout the growth period based on field capacity (Non stress = NS), cut-off the irrigation at the seed filling stage for 60 days (Moderate stress = MS) and at the flowering stage for 50 days (Severe stress = SS). Salicylic acid (SA) application with three levels, 0 (distilled water spray), 0.4 and 0.8 mM SA per 5 m−2were assigned as the subplot treatments. Foliar application of salicylic acid was performed simultaneously with cut-off irrigation treatments (in three times).The studied traits included: membrane stability index, catalase activity, proline content, soluble sugars content, total phenol contents in plant leaves and seed yield. According to the results of the two-year experiment, the highest seed yield was obtained by foliar spraying of 0.8 mM salicylic acid at the moderate stress condition. Application of salicylic acid at a concentration of 0.8 mM improved the cell membrane stability from 71 to 98%, water productivity by 53–99 m3 ha−1, water used efficiency from 2 to 4 m3 ha−1the soluble sugar content from 62 to 125 mg g−1 DW and the total phenol content from 2 to 10 mg g−1 DW. In both years of the study, the highest catalase activity was recorded for the normal irrigation treatment under foliar application of 0.4 and 0.8 mM salicylic acid. Application of SA at 0.8 mM under MS and SS conditions increased seed yield, cell membrane stability, catalase activity and proline concentration compared to NS, which indicates the positive effect of this compound.

Linkage Mapping Reveals QTL for Flowering Time-Related Traits under Multiple Abiotic Stress Conditions in Maize.

Variation in flowering plays a major role in maize photoperiod adaptation during long-term domestication. It is of high value to investigate the genetic basis of maize flowering under a wide range of environmental conditions in order to overcome photoperiod sensitivity or enhance stress tolerance. A recombinant inbred line (RIL) population derived from a cross between Huangzaosi and Mo17, composed of 121 lines and genotyped by 8329 specifically developed markers, was field evaluated in two consecutive years under two planting densities (67,500 and 120,000 plants ha−1) and two water treatments (normal irrigation and drought stress at the flowering stage). The days to silking (DTS), days to anthesis (DTA), and anthesis to silking interval (ASI) were all evaluated. Within the RIL population, DTS and DTA expanded as planting density and water deficit increased. For DTA, DTS, ASI, and ASI-delay, a total of 22, 17, 21, and 11 QTLs were identified, respectively. More than two significant QTLs were identified in each of the nine chromosomal intervals. Under diverse conditions and locations, six QTLs (quantitative trait locus) for DTS and DTA were discovered in Chr. 8: 118.13–125.31 Mb. Three chromosome regions, Chr. 3: 196.14–199.89 Mb, Chr. 8: 169.02–172.46 Mb, and Chr. 9: 128.12–137.26 Mb, all had QTLs for ASI-delay under normal and stress conditions, suggesting their possible roles in stress tolerance enhancement. These QTL hotspots will promote early-maturing or multiple abiotic stress-tolerant maize breeding, as well as shed light on the development of maize varieties with a broad range of adaptations.

Unravelling the Effect of Triacontanol in Combating Drought Stress by Improving Growth, Productivity, and Physiological Performance in Strawberry Plants.

To explore the effects of triacontanol (TR) on drought tolerance of strawberry plants (cv Fertona), two field experiments were carried out to study the effects of three supplementary foliar TR rates (0, 0.5, and 1 ppm) under the following three levels of water irrigation: 11 m3/hectare (40% of water holding capacity (WHC) severe as a drought treatment, 22 m3/hectare (80% of WHC) as moderate drought stress, and normal irrigation with 27 m3/hectare (100% of WHC) server as a control treatment. TR treatments were applied five times after 30 days from transplanting and with 15-day intervals. The results showed that drought stress (40% and 80%) markedly decreased the growth, fruit yield, and chlorophyll reading, as well as the gas exchange parameters (net photosynthetic rate, stomatal conductance, and transpiration rate). Meanwhile, drought stress at a high rate obviously increased antioxidant enzyme activities such as superoxide dismutase (SOD), peroxidase (POX), and catalase (CAT) contents in the leaves of the strawberry plants. The moderate and high drought stress rates enhanced some strawberry fruit quality parameters such as total soluble solids (TSS), vitamin C, and anthocyanin content compared to the control. Additionally, TR increased the activities of SOD, POX, and CAT. TR treatment significantly increased the chlorophyll contents, gas exchange parameters (photosynthetic rate and stomatal conductance), and water use efficiency (WUE). Plant height, fruit weight, and total biomass were increased also via TR application. Total yield per plant was increased 12.7% using 1 ppm of TR compared with the control. In conclusion, our results suggested that TR application could relieve the adverse effects of drought stress on the growth of strawberry plants by enhancing the antioxidant enzymes, photosynthesis rate, and WUE of the leaves.

Adaptation of Salvia fruticosa, S. officinalis, S. ringens and interspecific hybrids in an extensive green roof under two irrigation frequencies

With the ultimate goal of introducing new species of sage to the green roof industry, the adaptation of the Mediterranean sage species Salvia fruticosa, S. officinalis, S. ringens and the interspecific hybrids S. fruticosa × S. ringens and S. officinalis × S. ringens was investigated, under normal and sparse irrigation in an extensive green roof in Athens, Greece. Rooted cuttings were planted (April 2021) on shallow (10 cm) substrate (grape-marc compost: perlite: pumice, 3:3:4, v/v) and irrigated when substrate moisture was 16-22% (normal irrigation) or 7-11% (sparse irrigation). All sage types established satisfactorily on the green roof, even under sparse irrigation, except S. fruticosa, which had the highest vegetative growth and at the end of the experiment (September 2021) showed the highest mortality rate regardless of irrigation frequency. Similar to the S. fruticosa response showed the S. fruticosa × S. ringens hybrid under normal irrigation. Both hybrids, S. fruticosa × S. ringens and S. officinalis × S. ringens had a lower mortality rate under sparse irrigation compared to the parental species. S. officinalis × S. ringens formed more lateral shoots than its parental species and had an almost spherical compact canopy, which is a nice feature for an ornamental plant. S. officinalis and S. ringens developed bigger horizontal diameter, which is valued for rapid substrate coverage in a green roof installation. All sage types flowered except S. fruticosa. All sage types showed higher values of stomatal resistance under sparse irrigation, while ΦPSIIo values under both irrigation frequencies indicated normal operation of the photosynthetic apparatus. S. officinalis, S. ringens and S. officinalis × S. ringens hybrid are highly recommended for sustainable extensive green roofs in arid/semi-arid regions.

Involvement of Polyamines in Physiological Reactions of Herbicide-treated Wheat Seedlings Subjected to Drought and Waterlogging Stress

Polyamines are plant growth regulators, which take part in plant growth and development, as well as in the physiological responses to diverse biotic and abiotic stresses. Drought and waterlogging are environmental stress factors that disturb normal plant growth. In our study, we determined the content of polyamines spermine, spermidine, and putrescine in young wheat seedlings (Triticum aestivum L., cv. Sadovo-1) pretreated with herbicide Serrate® (Syngenta) and subjected for 7 days to drought or waterlogging. We found that when applied alone the herbicide caused some decrease in polyamine levels but it was not substantial as compared to drought and waterlogging stresses. Obvious reduction of polyamine content was caused by both stress factors when applied alone or in combination with the herbicide. The decrease was more significant in drought-stressed seedlings than in waterlogged. When plants were transferred to normal irrigation regime the polyamine concentrations in drought-stressed plants tended to increase. The waterlogging stress continued to reduce polyamine content even during the recovery period. These data correlate with the growth parameters (fresh weight, height of shoots) indicating the involvement of polyamines in the physiological responses of herbicide-primed wheat seedlings under stress conditions.

Improved strategy of screening tolerant genotypes in drought stress based on a new program in R-language: a practical triticale breeding program

In order to improve the efficiency of breeding programs related to abiotic stresses, a new package in R-based-language, “PBTolindex,” was introduced to distinguish tolerant genotypes to drought stress. Accordingly, a dataset of a practical breeding program on 30 triticale genotypes cultivated under drought stress and normal irrigation conditions in six different environments was evaluated. Correlation plot, scatter plot matrix, 3 D plot, and biplot along with indices’ values and their correlation coefficients were automatically produced as output files for considering the tested genotypes. Additionally, heatmap, a novel data mining method, was successfully applied for the first time in tolerance analysis. Our results indicated that no single suitable tolerance index could be suggested as the best one, and for any other study, different indices should be considered. Furthermore, the outputs of testing triticale genotypes indicated no suitable genotypes for both conditions. However, genotype ELTTCL15 for normal condition and genotypes ET-90-7, ELTTCL21, and ELTTCL18 for stress conditions were recommended by the program. Testing and identifying genotypes by heatmap and principal component analyses showed that the output of our program was accurate. Therefore, using this source-code in future plant breeding projects based on stress indices in any plant species is recommended.

Genotype by Environment Interaction on Tropical Maize Hybrids Under Normal Irrigation and Waterlogging Conditions

Unpredictable rainfall in the tropics often increases the risk of waterlogging or even flooding in agricultural lands, hindering the efforts to fulfill maize demands. Breeding maize for waterlogging tolerance is necessary yet challenging since performing varietal testing on a set of hybrids might be biased toward the presence of genotype and environment interaction (GEI). This study aimed to elucidate the GEI effects on yield and related agronomic traits of tropical maize hybrids under normal irrigation and waterlogging conditions and to assess the adaptability of these hybrids in such conditions using several stability models. Ten hybrids including two commercial checks were evaluated across 14 environments under normal and waterlogging conditions in Indonesia from 2018 to 2020. Waterlogging imposed at the V6 stage for ten consecutive days significantly hampered the plant height and ear height, slightly delayed flowering dates, and reduced yield and yield components. The genotype, location, and genotype by location effects were significant on yield, but the genotype by waterlogging effect was not. Stress tolerance index is highly significantly correlated (p < 0.01) with yield in both normal (r = 0.90) and waterlogging (r = 0.96) conditions. The GGE biplot analysis on yield revealed five sectors, two mega-environments, and five vertex genotypes. This study indicated the possibility of breeding maize hybrids tolerant to waterlogging (G05), as well as high-yielding hybrids under both conditions (G07).

Biochemical and physiological response of borage to seed priming and water deficit: antioxidant enzymes, osmolytes, photosynthetic pigments, and fluorescence parameters

Aim of study: To investigate the general response patterns of the borage plant to water fluctuations from a biochemical and physiological perspective. Area of study: East Azerbaijan Province of Iran during the period 2012 and 2013. Material and methods: The study investigated the effects of irrigation (after 60, 90, 120 and 150 mm evaporation) and priming (unprimed, and primed seeds with water, 1% KNO3 and 1% KH2PO4) on the antioxidant enzymes, osmolytes, photosynthetic pigments, and fluorescence parameters of borage using a split-plot experimental design. Main results: The statistical analyses showed no effect of seed priming on all evaluated traits other than than extracellular superoxide dismutase SOD3 activity where it was significantly enhanced by seed pretreatment with 1% KNO3 and 1% KH2PO4. However, irrigations after 120 and 150 mm evaporation increased Cu/Zn-superoxide dismutase (SOD1), SOD2, and SOD3, soluble sugars, and initial fluorescence (F0). The mean contents of Ch a, Ch b, and Ch a+Ch b under mild, moderate and severe water deficit were significantly higher than those under normal irrigation. Severe drought stress gave the highest carotenoids content and quantum yield baseline parameter (F0/Fm) of borage leaves. However, water limitation decreased Chl a/Chl b ratio, maximum primary yield of photosystem II (Fv/F0), and maximum quantum yield of photosystem II (Fv/Fm). Research highlights: Based on these findings, it is postulated that the increase in soluble sugars and SOD activity under stress, and the accumulation of carotenoids under severe water limitation indirectly enhance the tolerance of borage plants to drought stress.

Brassinosteroid Applications Enhance the Tolerance to Abiotic Stresses, Production and Quality of Strawberry Fruits

Brassinosteriods (BRs) have increasingly been used to improve the yields and quality of various crops. In this work we studied the effect of two brassinosteroids, BB16 and EP24, on the growth promotion of Fragaria ananassa plants under normal conditions or exposed to water or saline stress. The influence of both BRs on the plant development and fruit quality was evaluated when cultivated in semi-hydroponic conditions. A marked growth-promoting effect was observed with both compounds when plants were cultivated under normal irrigation conditions and under saline and water stresses. BB16 and EP24 yielded plants with a higher dry weight, root length and surface, a higher number and area of leaves, a higher total weight of fruits per plant, and a higher percentage of fruits of commercial quality. Additionally, a higher content of chlorophyll, number of leaves, and increased dry weight was detected in plants treated with both BRs and exposed to water and saline stresses. Finally, when evaluating the production and quality of fruits obtained under semi-hydroponic conditions, we observed that the pre-harvest treatment with both compounds induced a higher fruit production and better quality of fruits. These results suggest the potential of these compounds to achieve a more sustainable management of strawberry cultivation.

Effect of Water Deficit on Productivity of Some Barley (Hordeum vulgare L.) Genotypes

Two field experiments were laid out during 2019/2020 and 2020/2021 growing seasons at Sakha region, Kafr El-Sheikh Governorate, Egypt to evaluate the productivity and stress tolerance of ten barely genotypes under full irrigation and water stress conditions. Eight traits for barley were measured: days to maturity, plant height, spike length, number of grains/spike, number of spikes/m2, 1000-grain weight, biological yield and grain yield. Also, stress susceptibility index (SSI) was calculated. Results showed that, all the studied traits were decreased under water stress conditions. Mean squares due to seasons, water treatments, genotypes and their interactions were significant or highly significant for most studied traits. From the results, Giza 133 and Line 3 were the earliest genotypes in maturity. Line 4 under normal irrigation and Giza 2000 and Line 5 under stress gave the highest values of grain yield and most of its components. From SSI data, Giza 124, Giza 126, Giza 2000, Line 3 and Line 5 considered as the most tolerant genotypes where it had values less than the unity. so, it can be used in improving barley productivity under water stress condition.

Genetic Analysis of Yield and Fiber Traits in Cotton (Gossypium barbadense L.) under Normal Irrigation and Drought Stress Conditions

Genetic Analysis of Yield and Fiber Traits in Cotton (Gossypium barbadense L.) under Normal Irrigation and Drought Stress Conditions

Direct and Indirect Selection for Grain Yield and Grain Weight in Late Generations of Bread Wheat under Drought Stress and Normal Irrigation Environments.

Two cycles of pedigree selection for grain yield/plant (GY/P) and grain weight (GW) (100-grain weight) were imposed under drought stress and normal irrigation to study the direct and indirect selection of GY/P and GW in bread wheat. The selection started in the F6-generation (Cycle0-C0) of bread wheat (Triticum aestivum L.) traced back to the cross (Giza 164/Sids 4) of two Egyptian cultivars. The narrow sense heritability was higher under drought than under normal irrigation and increased by selection. Under drought, the observed direct gain after two cycles of selection for GW was 21.51% (p ≤ 0.01), and accompanied with an indirect gain in GY/P of 15.52%. The observed direct gain for GY/P was 17.98% and the indirect gain in GW was 13.81%. Under normal irrigation, the observed direct gain for GW was 12.86% and the indirect gain for GY/P was 16.04%. The direct gain in GY/P was 16.04% and the indirect gain in GW was 11.95%. The genotypic correlations were different in both environments before and after selection. Single trait selection was effective in improving the selection criterion, and selection greatly affected gene associations.

Evaluate the effect of salicylic acid and ascorbic acid on agronomic and antioxidant activities of Sunflower in water deficit conditions

To evaluate the effect of salicylic acid and ascorbic acid foliar application on a number of agronomic and antioxidant activities of sunflower, an experiment was conducted at research farm of Mahabad city, locted in the south of West Azerbaijan Province, Iran during 2016-2018 cropping seasons. The experiment was laid out as a split-plot design based on a completely randomized block design with three replications. Irrigation regimes (irrigation after 60 mm and irrigation after 120 mm evaporation from class A pan respectively) were established as main plots and the foliar applications of ascorbic acid (control, 50 and 100 ppm) and salicylic acid (control, 100 and 200 ppm) were the sub-plots. In the present study, the highest amount of proline content and activity of antioxidant enzymes was recorded under water deficit conditions and foliar application of 100 ppm salicylic acid. Applying salicylic acid increased grain yield under both normal irrigation and water deficit conditions. Also, the highest proline content and activity of antioxidant enzymes were under the treatment of water deficit and application of 50 ppm ascorbic acid. The results showed no significant difference between the combined foliar application of salicylic acid and ascorbic acid in terms of grain yield and oil percentage with their separate application. Therefore, simultaneous use of these two substances under normal irrigation and water deficit conditions was not economical and not recommended.

Optimization of drip irrigation and fertilization regimes to enhance winter wheat grain yield by improving post-anthesis dry matter accumulation and translocation in northwest China

The excessive irrigation and fertilization are common in wheat (Triticum aestivum L.) production in northwest China, which not only results in resources waste and environmental pollution, but also not necessarily guarantee high wheat yield due to the plant overgrowth. It is thus crucial to explore a suitable irrigation and fertilization strategy that benefits high-yield wheat cultivation by regulating post-anthesis dry matter accumulation and translocation. A consecutive four-season field experiment (2014–2018) was undertaken on drip-fertigated winter wheat with three irrigation levels based on the soil moisture content of moistening layers (W1: normal irrigation, W2: mild deficit irrigation, W3: severe deficit irrigation) and three fertilization (N-P2O5-K2O) rates (F1: 175–117–150 kg ha−1, F2: 125–84–108 kg ha−1, F3: 75–50–65 kg ha−1). The results showed that the logistic growth equation could well describe the accumulation process of aboveground dry matter with R2 ranging 0.989 − 0.999 (P < 0.01). Water stress advanced the thermal time required from sowing to the maximum aboveground dry matter rate, while the maximum aboveground dry matter rate and average accumulated rate of aboveground dry matter increased with the increase of irrigation and fertilization regimes. Dry matter translocation showed a negative relationship with fertilization rate. However, both the post-anthesis dry matter accumulation and its contribution to total dry matter at maturity (CDMA) increased with the increasing fertilization rate. With the increase of water and fertilizer supply, dry matter translocation efficiency decreased, but CDMA showed the opposite trend. The post-anthesis dry matter accumulation was positively related to winter wheat grain yield. When the grain yield reached above 7.5 Mg ha−1 in northwest China, the post-anthesis accumulated dry matter should be more than 4.7 Mg ha−1. It was concluded that the mild deficit irrigation along with N-P2O5-K2O fertilization of 125–84–108 kg ha−1 enhanced the productivity of winter wheat by increasing the post-anthesis dry matter translocation and accumulation.

Evaluation of differnt sowing methods for enhancing productivity and water use efficiency of wheat under limited water condition

Drought is a serious threat for food security worldwide. Wheat is most popular staple crop of world severely affected by drought at water sensitive crop growth stages. Selection of appropriate sowing method is very important for improving water use efficiency. A field trial was conducted in winter season of 2018-19 to investigate the impact of different sowing methods on water use efficiency of spring wheat exposed to water deficit at anthesis. Wheat was sown with three different sowing methods viz. broadcast sowing, drill sowing and augmented furrow sowing and two different irrigation regimes i.e. normal irrigation and water deficit at anthesis stage. All agronomic practices were kept uniform throughout the experiment. Different sowing methods and irrigation regimes significantly affected grain and straw yield of wheat. Among different sowing methods, wheat crop sown with augmented furrow method produced maximum plant height (111 cm), no. of tillers per m2 (427), 1000 grain weight (37.93 g), grain yield (4.73 t ha-1) and straw yield (4.24 t ha-1). Maximum irrigation water use efficiency (17.72 kg ha-1 mm-1) and benefit cost ratio (1.34) was recorded in augmented furrow method of sowing of wheat exposed to water deficit at anthesis stage.

Genetic Analysis of Water Stress Tolerance Attributes in F1 Maize Diallel Crosses

A half diallel set of crosses involving 10 inbred lines of maize along with commercial hybrid ARCGH 128 were evaluated at two different irrigation treatment during two season 2019 and 2020 using RCBD design with three replications at two locations (Minia and Assuit governorates), to determine combining ability and gene action for grain yield and its components. the most superior crosses for the economic traits were detected in L1 X L2 for leaf proline content, ear weight and number of rows/ear, L1 X L8 for number of ear /plot and number of rows/ear, L4 X L9 for Days to tasseling and Days to silking, L3 X L8 for Leaf angle, leaf rolling, number of kernels/ear, number of rows/ear and number of kernels/row and L3 X L10 for days to tasseling, days to silking,leaf rolling, relative water content (RWC %), kernel fresh weight, number of rows/ear and yield. Highly significant and larger in magnitude values of dominance (H1 and H2) components were found to be at the significant level at (5%) for all studied characters which confirmed their importance in the expression of these characters. However (D) dominance component was reached to the significant level only for the normal irrigation treatment for the leaf angel at both locations, all irrigation treatment for leaf proline content at both locations, normal irrigation treatment for number of kernel/row at Assuit location and all irrigation treatment for 100 kernel weight and number of ear/plot at both locations. The (F) component was significant and positive for all irrigation treatment for leaf proline content at both location, normal irrigation treatment for number of kernel/row at Assuit location, all irrigation treatments for 100 kernel weight at both location, stress irrigation treatment for number of ear/plot at Minia location. Significant differences of environmental variance (E) components were recorded for all irrigation treatment for leaf rolling at Assuit location, all irrigation treatment for ear weight at Minia location and all irrigation treatment for number of rows/ear and number of ear/plot at both locations. Dominance component of variance (H1 and H2) were significant and/or highly significant for all studied traits and (H1) was greater than (H2) in F1 indicating that positive and negative alleles at loci of these trait were not in proportional equal for parents. The estimator (h2) were refers to the dominance effect overall heterozygous loci was significant for all studied traits except days to tasseling for normal irrigation treatment at both locations, stress irrigation treatment for leaf angel at Minia location, all irrigation treatment for leaf rolling at both locations, normal irrigation treatment for ear weight/kg/plot at both locations and for stress irrigation treatment for number of rows/ear at Minia location. Average degree of dominance (H1/D) 0.5 was more than unity for all traits, these finding indicated the involved of an over dominance expression for all characters. However the over dominance observed in such character may not be an index of true over dominance could be based due to linkage epistasis or both together. Since the ratio of dominance (KD) recessive (KR) alleles was more than one for all the studied characters, these indicates a preponderance of dominant gene in the parents for the characters. The value of K (h2/H2, which stands for the number of groups of genes that exhibit dominance for each character) was <1 for all the studied characters for normal irrigation treatment at Assuit location and all irrigation treatment at Minia location and all irrigation treatment at Minia location for number of rows/ear and 100 kernel weight/gm. This suggested that just one group of genes showed dominance governed all of them while this parameter could be underestimated, when the dominance effects of all genes was not concerned with equivalent, size and distribution, where the distribution of genes was correlated, or complementary gene interactions occur. Heritability values in bored sense (h2b) were relatively low for all characters. However, heritability in narrow sense (h2n) was high scored values more 50% except leaf rolling for stress irrigation treatment at Minia location (0.48%) these results confirmed that the environmental effects constitute a major portion of the total phenotypic variation in these characters.

Evaluation of Maize Grain Yield and Yield Stability Under Drought Stress by Ammi Analysis

Genotype-by-environment (G×E) interaction reduces the correlation between genotypic and phenotypic parameters and complicates progress of selection. Among several models proposed for evaluation of the G×E interaction, the Additive main effects and multiplicative interaction (AMMI) and GGE-biplot are the most informative models. The objective of this study was to estimate the G×E interaction in 55 maize genotypes to identify maize genotypes of stability and/or adaptability across two irrigation treatments at two locations using the AMMI and GGE-biplot models. A randomized complete block design was used in each environment with three replications. The AMMI analysis of variance indicated that the genotype (G), environment (E) and G×E interaction for Feddan Yielg data showed highly significant due to treatments, genotypes and environments this pointed out that all sources of variance are important in analysis, however genotypes contributed with (48.36%) in treatments variances, the environment contributed with (44.0%) in treatments variance also interaction principal component axis (IPCA) accounted for (53.52% and 39.44%) respectively, were found to be highly significant, the (IPCA1 and IPCA2) together with had a total (92.96%) variances of the interaction. GGE biplot analysis environments showed that the genotype (10, 20, 32 and 36) was found promising in normal irrigation treatment at Assuit location in descending order. The genotypes (22, 27 and 44) was promising in normal irrigation treatment at Minia location in descending order. The genotypes (14, 17, 25, 45 and 49) are suitable to stress irrigation treatment at Minia location. The genotypes (6 and 50) are suitable to drought irrigation treatment at Assuit location. The polygon reflects that G11, G33, G34, G53, and G56 are poor grain yielding and not suitable to either of the environments and relationships between genotypes and environments showed that the environments with a small angle between them are highly positively correlated, and they provide similar information on genotypes. Present investigations showed that N1 and N2 for grain yield. The two environments S1 and S2 are similar; they had small angle between them and they provide similar information on genotypes. In contrast, either N1 or S1 and N2 or S2 were dissimilar, since the angle was obtuse, and they provide different information on genotypes.

Prediction of Chlorophyll Content in Multi-Temporal Winter Wheat Based on Multispectral and Machine Learning.

To obtain the canopy chlorophyll content of winter wheat in a rapid and non-destructive high-throughput manner, the study was conducted on winter wheat in Xinjiang Manas Experimental Base in 2021, and the multispectral images of two water treatments' normal irrigation (NI) and drought stress (DS) in three key fertility stages (heading, flowering, and filling) of winter wheat were obtained by DJI P4M unmanned aerial vehicle (UAV). The flag leaf chlorophyll content (CC) data of different genotypes in the field were obtained by SPAD-502 Plus chlorophyll meter. Firstly, the CC distribution of different genotypes was studied, then, 13 vegetation indices, combined with the Random Forest algorithm and correlation evaluation of CC, and 14 vegetation indices were used for vegetation index preference. Finally, preferential vegetation indices and nine machine learning algorithms, Ridge regression with cross-validation (RidgeCV), Ridge, Adaboost Regression, Bagging_Regressor, K_Neighbor, Gradient_Boosting_Regressor, Random Forest, Support Vector Machine (SVM), and Least absolute shrinkage and selection operator (Lasso), were preferentially selected to construct the CC estimation models under two water treatments at three different fertility stages, which were evaluated by correlation coefficient (r), root means square error (RMSE) and the normalized root mean square error (NRMSE) to select the optimal estimation model. The results showed that the CC values under normal irrigation were higher than those underwater limitation treatment at different fertility stages; several vegetation indices and CC values showed a highly significant correlation, with the highest correlation reaching.51; in the prediction model construction of CC values, different models under normal irrigation and water limitation treatment had high estimation accuracy, among which the model with the highest prediction accuracy under normal irrigation was at the heading stage. The highest precision of the model prediction under normal irrigation was in the RidgeCV model (r = 0.63, RMSE = 3.28, NRMSE = 16.2%) and the highest precision of the model prediction under water limitation treatment was in the SVM model (r = 0.63, RMSE = 3.47, NRMSE = 19.2%).

​​Assessment of Multiple Tolerance Indices for Moisture Stress in Fenugreek (Trigonella foenum-graecum L.)

Background: Drought and moisture stress is the most limiting factor affecting growth and productivity of crop plants. The genotypes may differ in their ability to withstand drought or moisture stress. Therefore, the research was carried out to identify suitable genotypes in moisture stress environments. Methods: The forty eight genotypes of fenugreek were planted in randomized block design with three replications under two environmental conditions namely, (i) normal irrigation (E1) and (ii) staggered irrigation (E2) during rabi 2016-2017. Eight stress tolerance indices viz., stress tolerance (TOL), stress susceptibility index (SSI), stress tolerance index (STI), mean production (MP), geometric mean production (GMP), yield index (YI), stress susceptibility percentage index (SSPI) and modified stress tolerance index (MSTI) were calculated based on seed yield under moisture stress (Ys) and non-stress condition (Yp). The correlation coefficient and mean rank of stress indices were calculated to identify the moisture stress tolerant genotypes. Result: The seed yield under non-stress condition (Yp) had significant positive association with TOL, SSI, STI, MP, GMP, SSPI and K1STI. The seed yield under stress condition (Ys) had significant positive association with STI, MP, GMP, YI and K2STI, while significant negative association with TOL, SSI and SSPI. The results showed that MP, GMP and STI indices were more effective in identifying high yielding genotypes in both stress and non-stress conditions while TOL, SSI, YI and SSPI under moisture stress condition. Based upon the mean seed yield and stress tolerance indices, the genotypes UM-124, UM-60, UM-55, UM-28 and UM-4 were found tolerant to staggered irrigation conditions. Hence, these genotypes may be used further in breeding programmes for moisture stress tolerance.

Changes in Carbon and Nitrogen Metabolites before, at, and after Anthesis for Wheat Cultivars in Response to Reduced Soil Water and Zinc Foliar Application.

Water deficit stress is one of the major constraints for commercial agriculture, as it disturbs the metabolic processes in plant. Identification of carbon and nitrogen receptors that act on drought resistance helps in breeding for drought resistance varieties. Zn fertilizer can regulate multiple antioxidant defense systems at the transcriptional level in response to drought. Two field experiments were conducted in 2018–2019 and 2019–2020 seasons to explore the effectiveness of foliar application of zinc oxide on soluble sugar, soluble proteins, and free amino acids under normal irrigation and drought-stressed environments. Three Egyptian wheat cultivars (Triticum aestivum L.) were used. The experimental design was split-plot in RCBD with three replications, applying zinc oxide levels to the whole plot and the split plots. Leaf samples were taken for analysis before anthesis, at anthesis, and after anthesis. Application of Zn increased soluble sugars. However, the free amino acids were higher under irrigation, reached the maximum at anthesis, and decreased sharply after 2 weeks from anthesis. The ranking of cultivars for the three metabolites differed according to plant stage, reflecting the response to Zn and years. Correlations between metabolites according to Zn were positive. The findings suggest the potential of foliar application of Zn to alleviate drought stress.