Drought Resistance Index Research Articles

СЕЛЕКЦИОННЫЕ КРИТЕРИИ ЗАСУХОУСТОЙЧИВОСТИ ТВЕРДОЙ ЯРОВОЙ ПШЕНИЦЫ В УСЛОВИЯХ ЗАПАДНОЙ СИБИРИ

The aim of research is to conduct a comparative assessment of varieties of durum spring wheat for drought resistance in the conditions of Western Siberia. The experiments were laid out after fallow in the conditions of the southern forest-steppe at the stationary site of the laboratory of selection of durum wheat of the Federal State Budgetary Scientific Institution Omsk Scientific Center. In long-term studies (2001–2018) on a large set of varieties (26), when studying the yield, the number of grains in an ear, the weight of 1000 grains, the parameters of drought resistance were determined. In this case, the following indicators for these traits were calculated: average over the years of research, average in dry years, average in favorable years, the degree of reduction under stress compared to conditions without stress, the drought resistance index (DSI according to R.A. Fischer, R. Maurer). Tests on the studied characteristics revealed the following varieties: by yield – Omskiy Izumrud, Aleyskaya, Omskaya Stepnaya, Zhemchuzhina Sibiri, by weight of 1000 grains – Bezenchukskaya Stepnaya, Omskaya Stepnaya, Aleyskaya, Elizavetinskaya, Svetlana, by the number of grains in an ear – Omskiy Izumrud, Saratovskaya Zolotistaya, Zhemchuzhina Sibiri, Omskaya Stepnaya, Bezenchukskaya Stepnaya. According to the general integrated assessment, the best indicators were obtained for the varieties Omskaya Stepnaya, Omskiy Izumrud, Bezenchukskaya Stepnaya, Aleyskaya, Zhemchuzhina Sibiri, Saratovskaya Zolotistaya. The indicators of average values under drought, the degree of reduction under stress conditions, the drought resistance index for grain yield, 1000-grain weight, and the number of grains in an ear are reliable criteria for drought resistance of hard spring wheat. The best differentiating ability is possessed by tests calculated by yield and the number of grains in an ear.

Water use characteristics and drought tolerant ability of different winter wheat cultivars assessed under whole growth circle and at seedling stage

Using drought-resistant cultivars is important to increase crop production in water limited regions. Cultivar performance is influenced by genetic, management and environmental factors, and selection good performance cultivars is often a challenge. Five seasons (2016–2021) of field experiments and three seedling growing durations in a greenhouse, both under three water supply levels (serious water deficit, moderate water deficit and normal water supply), were conducted to assess 10 winter wheat cultivars for their water use characteristics and drought tolerance ability based on seven drought resistance indices and agronomic traits. The performance of the cultivars varied seasonally under field growing conditions. Drought resistance screened by a single index or based on the results from a single season was inconsistent. To avoid seasonal changes in cultivar performance, principal component analyses (PCA) and hierarchical cluster analysis (HCA) were conducted based on the seven indices to classify the ten cultivars into four types of drought responses. The drought resistance classification under field growing conditions at the grain yield level was highly consistent with that obtained under greenhouse growing conditions for biomass at the seedling stage. The results showed that the biomass at the seedling growing stage of the winter wheat cultivars could be used to predict the yield performance and water use characteristics when grown in the field under different water supply conditions. Precisely controlled greenhouse pot experiments could amplify the water use characteristics of different wheat cultivars for assessment. The cultivars with strong stomatal control ability had higher drought resistance and biomass production. Under field growing conditions, lower canopy temperature, deep root growth, a high root/shoot ratio and the maintenance of stomatal conductance under water stress were associated with high drought resistance. These findings provide references for selection methods and indicators for assessing drought-resistant winter wheat cultivars under different growing conditions.

Assessment of spring broad wheat varieties and lines for drought resistance in the conditions of the southern foreststeppe of Western Siberia using drought resistance indices

Assessment of spring broad wheat varieties and lines for drought resistance in the conditions of the southern foreststeppe of Western Siberia using drought resistance indices

Genetic variation, genotype × environment interaction, and correlation among drought tolerance indices in cowpea

Drought tolerance indices serve as valuable indicators for selecting cowpea genotypes with improved drought tolerance. However, there is a limited understanding of the variability and the impact of genotype (G) × environment (E) interaction (I) on these drought tolerance indices. Therefore, the objective of this study was to assess the extent of genetic variability and the influence of GEI on drought tolerance indices in cowpea. The experiment was conducted over two seasons under controlled conditions in a screen house. The results revealed that seed yield and all drought tolerance indices were significantly influenced by genotype, environment, and GEI. When the data from both years were combined, the yield under non-stress conditions ranged from 10.47 g in G2 to 17.27 g in G7, while under drought stress, it ranged from 2.19 g in G3 to 6.89 g in G1. Through mean rank analysis, principal component (PC) analysis, and clustering, highly tolerant accessions (G1 and G6) and highly susceptible ones (G2, G3, and G8) were identified. This study identified several indices, including geometric mean (GM), yield index (YI), mean productivity (MP), stress tolerance index (STI), modified stress tolerance index for non-stress (MST1), and stress (MST2), GMP, and HM, as effective in selecting high-yielding and drought-tolerant accessions under non-stress and drought conditions. Additionally, the drought resistance index (DRI) and yield stability index (YSI) were found to be reliable indicators under drought stress. Most of the indices exhibited moderate (≥ 30%) to high heritability (≥ 60%) and high genetic advance (≥ 20%), except for MST2, which had low heritability (12.73%).

Влияние засухи на развитие элементов структуры урожайности сортов ярового ячменя

In the researches carried out in 2021–2023 at the Federal Agricultural Research Center of the North-East named N.V. Rudnitsky (Kirov) in the conditions of the vegetation experiment, 10 varieties of spring barley of different origin were evaluated by simulation of drought (breeding varieties of the Federal Agricultural Research Center of the North-East named N.V. Rudnitsky of hybrid and regenerative origin, collection samples). The drought was simulated at the onset of the phase “stem elongation” by stopping irrigation and film sheltering from atmospheric precipitation, eliminating the greenhouse effect. The time of water stress application corresponded to the vegetative interphase of the plants “stem elongation – earing”. The aim of the research was to determine the effect of productivity elements on the yield of spring barley varieties and to determine the elements associated with the variability of the yield of varieties with an increasing drought in the interphase period “stem elongation – earing” and, based on these data, to select drought-resistant varieties. To evaluate the drought resistance of varieties, the Drought Resistance Index (DSI) was used as the ratio of the variety parameters to the average value for all varieties in the presence and absence of stress. The conducted researches have shown that the studied varieties reacted differently to the presence of drought in the interphase period “stem elongation – earing”. It was found that water deficiency significantly reduced the yield of all barley varieties by an average of 73g/m2 and affected the development of most elements of its structure. In the presence of drought, there was no evidence of productivity of barley plants associated with the yield of varieties. Under favorable vegetative conditions (absence of drought), an influence of head length (r = 0.613), head productivity (r = 0.81) and plant productivity (r = 0.84), thousand grain weight (r = 0.56) on the yield of barley varieties was found. The calculation of the correlation between yield DSI and structural elements showed a reliable relationship (r = 0.91) only between the yield DSI and the index “thousand grain weight”, therefore, highly productive genotypes under water stress in the interphase period “stem elongation – earing” should be selected according to the severity of the feature “thousand grain weight”. The varieties Novichok, Tallon, Forward and Bionic can be used as crossing components in appropriate breeding programs.

Physiological response and drought resistance evaluation of Gleditsia sinensis seedlings under drought-rehydration state

G. sinensis is a crucial tree species in China, possessing important economic and ecological value, and having a wide geographical distribution. G. sinensis seedlings is highly vulnerable to the drought-rehydration-drought cycle during their growth, and there is a lack of quantitative and systematic research on the physiological mechanisms of drought resistance and rehydration in G. sinensis. There is also a lack of good drought-resistant families and reliable methods for evaluating drought resistance, which severely hinders the selection and promotion of drought-resistant G. sinensis families and the industry's development. Therefore, this study selection 58 families seedlings of G. sinensis to drought stress and rehydration using an artificial simulated water control method in potted seedlings. The aim was to compare the effects of different levels of drought and rehydration on the growth and physiological indices of seedlings from different families. Identification of drought-resistant families and dependable drought related indices and techniques, the explanation of divergence in drought stress effects on various drought-resistant seedlings and the mechanisms underpinning growth and physiological responses, and the provision of theoretical reference for G. sinensis drought-resistant variety selection and cultivation. The Drought Resistance Index (DRI) served as the primary indicator, supplemented by growth, leaf morphology, and photosynthetic physiological indicators, to thoroughly assess and identify five distinct drought tolerant taxa while also selecting five representative families. Soluble protein (SP), proline (Pro), and malondialdehyde (MDA) contents, as well as the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) in seedlings from the five families, increased as the degree of drought intensified. The highest values were appeared during periods of severe drought, and gradually decreased after subsequent rehydration. Principal component analysis (PCA) revealed MDA and soluble sugars (SS) as the primary predictors of drought and rehydration response in G. sinensis seedlings respectively. Changes in osmoregulatory substance content and increased antioxidant enzyme activity may be crucial for responding to drought tolerance mechanisms. Leaf morphological indicators, seedling height, soil plant analysis development (SPAD) value, photosynthetic indicators, and MDA are dependable parameters for assessing the drought tolerance of G. sinensis seedlings. When assessing the drought-resistance of seedlings using physiological indicators such as photosynthesis, a comprehensive analysis should incorporate multiple indicators and methods. This evaluation approach could serve as a reference for screening exceptional drought-resistant families of G. sinensis.

Analysis of spatial-temporal patterns and driving mechanisms of land desertification in China

Desertification is a major manifestation of land degradation in China. The monitoring and assessment of land desertification in China and the analysis of its driving mechanisms are crucial to the realization of the aspiration of “net zero land degradation” proposed by the United Nations Convention to Combat Desertification (UNCCD). An improved Mediterranean Desertification and Land Use (MEDALUS) model was applied to assess the multiyear spatial distribution of land desertification sensitivity across China in 2010, 2015, and 2020. A Principal Component Analysis (PCA) was used to evaluate the internal stability of the model. In addition, a Geographical Detector method was used to examine the driving mechanisms of desertification sensitivity in China. The results showed that extremely sensitive desertification areas were primarily concentrated within the Northwest Desert and Desertification Region, northern segment of the Qinghai-Tibet Plateau desert and desertification region, and western sector of the Inner Mongolia-Daxinganling Desert and Desertification Region. In addition, the proportion of land area showing an overall reduction in sensitivity (17.07 %) exceeded that showing an increase (16.56 %). This indicates an overall diminishing trend in sensitivity to land desertification across China. Land use intensity (LUI), drought resistance (DR), erosion protection (EP), and aridity index (AI) are consistently the most important drivers. From 2015 to 2020, the LUI emerged as the principal catalyst behind the transformation of land desertification sensitivity in China. Hence, emphasizing well-planned land use is vital for ensuring harmony between land utilization and ecological capacity. This study establishes a scientific basis for China's land desertification control strategy and serves as a quantitative analysis reference for the driving mechanisms.

Estimation of upland rice samples for the presence of the drought resistance gene qDTY1.1 using a DNA marker

Drought is the main stress factor when growing plants. The effects of drought on rice plants range from reduced dry matter accumulation to poor distribution of metabolites from stems and leaves into grain, resulting in reduced number of full grains per panicle, reduced grain weight and ultimately yield. Rice varietal diversity includes different drought tolerance genes. The purpose of the current research was to estimate upland rice samples and varieties for drought resistance under field conditions and the presence of the qDTY1.1 gene using the DNA marker RM431. PCR analysis was used to estimate 66 rice lines, hybrids and varieties grown in periodically wetted and constantly flooded fields. As a result of marker analysis, there has been identified the presence of the drought resistance gene qDTY1.1 in twenty-two rice varieties and samples such as ‘An-Yun-Ho’, ‘Volgogradsky’, ‘Stalingradsky’, ‘Volgogradsky x Atlant’, ‘Chan-Chun-Man’, etc. The highest value of the drought resistance index (DRI) was found in carriers of the qDTY1.1 allele, they are Manchurian upland varieties ‘An-Yun-Ho’ (79.4 %), ‘Chan-Chun-Man’ (88.5 %) and other samples developed earlier from crossing the variety ‘Chan-Chun-Man’ with productive varieties of Don selection ‘Razdolny’, ‘Boyarin’, ‘Komandor’, ‘Yuzhanin’, ‘Kuboyar’. The identified samples carrying the qDTY1.1 gene exceeded the other forms on average in terms of productivity under drought conditions by 0.20 t/ha, under the control by 0.21 t/ha, and under IZU by 3.9 %. In the long term of improving rice drought tolerance, it is necessary to identify and exploit other QTLs with large and consistent effects and key regulators of plant stress responses.

Water Stress Alters Physiological, Spectral, and Agronomic Indexes of Wheat Genotypes.

Selecting drought-tolerant and more water-efficient wheat genotypes is a research priority, specifically in regions with irregular rainfall or areas where climate change is expected to result in reduced water availability. The objective of this work was to use high-throughput measurements with morphophysiological traits to characterize wheat genotypes in relation to water stress. Field experiments were conducted from May to September 2018 and 2019, using a sprinkler bar irrigation system to control water availability to eighteen wheat genotypes: BRS 254; BRS 264; CPAC 01019; CPAC 01047; CPAC 07258; CPAC 08318; CPAC 9110; BRS 394 (irrigated biotypes), and Aliança; BR 18_Terena; BRS 404; MGS Brilhante; PF 020037; PF 020062; PF 120337; PF 100368; PF 080492; and TBIO Sintonia (rainfed biotypes). The water regimes varied from 22 to 100% of the crop evapotranspiration replacement. Water stress negatively affected gas exchange, vegetation indices, and grain yield. High throughput variables TCARI, NDVI, OSAVI, SAVI, PRI, NDRE, and GNDVI had higher yield and morphophysiological measurement correlations. The drought resistance index indicated that genotypes Aliança, BRS 254, BRS 404, CPAC 01019, PF 020062, and PF 080492 were more drought tolerant.

Molecular mechanisms of drought resistance using genome-wide association mapping in maize (Zea mays L.)

BackgroundDrought is a critical abiotic stress that influences maize yield and reduces grain yield when it occurs at the flowering or filling stage. To dissect the genetic architecture of grain yield under drought stress (DS), a genome-wide association analysis was conducted in a maize population composed of diverse inbred lines from five locations under well-watered and DS conditions at flowering in 2019 and 2020.ResultsUsing a fixed and random model circulating probability unification model, a total of 147 loci associated with grain yield or the drought resistance index (DRI) were identified, of which 54 loci were associated with a DRI with an average phenotypic variation explanation of 4.03%. Further, 10 of these loci explained more than 10% of the phenotypic variation. By integrating two public transcriptome datasets, 22 differentially expressed genes were considered as candidate genes, including the cloned gene ZmNAC49, which responds to drought by regulating stomatal density. Enrichment and protein interaction network showed that signaling pathways responded to drought resistance, including jasmonic acid and salicylic acid, mitogen-activated protein kinase, and abscisic acid-activated. Additionally, several transcription factors involved in DS were identified, including basic leucine zipper (GRMZM2G370026), NAC (GRMZM2G347043), and ethylene-responsive element binding protein (GRMZM2G169654).ConclusionsIn this study, we nominated several genes as candidate genes for drought resistance by intergrating association maping and transcription analysis. These results provide valuable information for understanding the genetic basis of drought tolerance at the mature stage and for designing drought-tolerant maize breeding.

Drought resistance index screening and evaluation of lettuce under water deficit conditions on the basis of morphological and physiological differences.

Water is one of the important factors affecting the yield of leafy vegetables. Lettuce, as a widely planted vegetable, requires frequent irrigation due to its shallow taproot and high leaf evaporation rate. Therefore, screening drought-resistant genotypes is of great significance for lettuce production. In the present study, significant variations were observed among 13 morphological and physiological traits of 42 lettuce genotypes under normal irrigation and water-deficient conditions. Frequency analysis showed that soluble protein (SP) was evenly distributed across six intervals. Principal component analysis (PCA) was conducted to transform the 13 indexes into four independent comprehensive indicators with a cumulative contribution ratio of 94.83%. The stepwise regression analysis showed that root surface area (RSA), root volume (RV), belowground dry weight (BDW), soluble sugar (SS), SP, and leaf relative water content (RWC) could be used to evaluate and predict the drought resistance of lettuce genotypes. Furthermore, the drought resistance ranks of the genotypes were similar according to the drought resistance comprehensive evaluation value (D value), comprehensive drought resistance coefficient (CDC), and weight drought resistance coefficient (WDC). The cluster analysis enabled the division of the 42 genotypes into five drought resistance groups; among them, variety Yidali151 was divided into group I as a strongly drought-resistant variety, group II included 6 drought-resistant genotypes, group III included 16 moderately drought-resistant genotypes, group IV included 12 drought-sensitive genotypes, and group V included 7 highly drought-sensitive genotypes. Moreover, a representative lettuce variety was selected from each of the five groups to verify its water resistance ability under water deficit conditions. In the drought-resistant variety, it was observed that stomatal density, superoxide anion (O2.-wfi2) production rate, and malondialdehyde (MDA) content exhibited a low increase rate, while catalase (CAT), superoxide dismutase (SOD), and that peroxidase (POD) activity exhibited a higher increase than in the drought-sensitive variety. In summary, the identified genotypes are important because their drought-resistant traits can be used in future drought-resistant lettuce breeding programs and water-efficient cultivation.

Estimation of the productivity of rice samples under severe field drought

Drought is one of the most important factors hindering the cultivation of rice, resulting in large yield losses, and limiting productivity growth. The purpose of the current study was to determine the drought resistance of rice varieties and samples of various origins under conditions of periodic irrigation with periods of prolonged soil aridity and high air temperature, to identify drought-resistant plants for the selection of upland varieties. There have been studied 68 varieties and samples of upland rice when grown on irrigated and flooded areas (Proletarsk, Rostov region). There has been established that varieties and samples under drought conditions and sufficient water supply formed different grain productivity, which in 2020–2021 with a lack of water amounted to 63.7 % of the norm, and in 2022 to 30.1 %. There has been found that the correlation of rice productivity under dry conditions with that under full moisture supply was weak negative (r = –0.22±0.12), and with the drought resistance index (DRI) it was high positive (r = 0.95±0.04). The values of quantitative traits under drought conditions have changed significantly in comparison with the control. Such traits as plant height (95.7 %), panicle length (73.1%), panicle density (58.7 %), number of harvested plants per 1 m2 (87.3 %), plant weight (42.3 %), panicle weight (25.1 %), total number of spikelets (54.5 %) and grains per panicle (32.4 %), 1000-grain weight (70.4 %) have decreased. Such traits as number of productive stems per 1 m2 (115.2 %), tilling capacity (126.1 %), the number of empty spikelets per panicle (205.1 %) and the percentage of empty grains (339.1 %) have increased. There have been identified such 9 varieties and samples with DRI from 51.1 to 93.7 % as ‘Kontro’, ‘An-Yun-Ho’, ‘Chan-Chun-Man’, ‘Hong-Mo’, ‘8323’, ‘8338’, ‘8337’, ‘ZULK 8’, ‘ZULK 9’, which formed maximum productivity in dry conditions (3.95–5.51 t/ha).

ANALYSIS OF WINTER WHEAT VARIETIES FOR DROUGHT RESISTANCE IN THE CONDITIONS OF THE STEPPE OF UKRAINE (PART 1 – YEARS WITH SUFFICIENT MOISTURE)

The purpose of our research was the study and analysis of drought resistance of winter wheat varieties selected by the Institute of Climate-oriented Agriculture of the National Academy of Sciences of the Russian Academy of Sciences and the Selection and Genetics Institute of the National Center for Seed Science and Varietal Research of the National Academy of Sciences of the National Academy of Sciences in the conditions of the Southern Steppe of Ukraine. Materials and methods of research. The reaction of 18 varieties of winter wheat to different growing conditions was studied at the Askania State Agricultural Research Station in the village of Tavrychanka, Kherson region (46°33’12”N; 33°49’13”E; 39 m above sea level) during 2015/16–2019/20. Research was conducted under different conditions of irrigation: with irrigation and without irrigation. Analysis of the resistance of winter wheat varieties to stress was carried out using 17 indices of drought resistance. Research results and their discussion. The highest yield under irrigation of 7.87–8.49 t/ha was obtained from winter wheat varieties Burgunka, Koshova, Askaniyska and Shchedrist Odeska, under stress conditions: Burgunka, Koshova, Lyra Odeska and Traditsia Odeska 7.25–7.66 t /Ha. According to the largest number of indices (14), the variety Traditsia Odeska was singled out as the most drought-resistant, the variety Lyra Odeska was distinguished according to nine indices, and Shchedrist Odeska according to seven indices. According to the correlation analysis, two indices were distinguished: the drought resistance index (DI) and the stress resistance index ISR, where yield under stress was characterized by a high correlation (r = 0.851) with the DI index and a medium (r = 0.381) – ISR, on the other hand, a low correlation (r = 0.038–0.226) with yield under irrigation. Conclusions. Two indices were singled out: the drought resistance index (DI) and the ISR stress resistance index, which most fully characterize the resistance of winter wheat varieties to drought. According to the indices of drought resistance and biplot analysis, the most drought-resistant selected varieties are Traditsia Odeska and Lyra Odeska. The Shchedrist Odeska variety stood out as the most resistant to drought.

QTL mapping and analysis for drought tolerance in rice by genome-wide association study.

Rice drought resistance is a complicated quantitative feature involving a range of biological and agronomic variables, but little is known about the underlying genetics and regulatory mechanisms that regulate drought tolerance. This study used 120 recombinant inbred lines (RILs), derived from a cross between drought tolerant Lvhan 1 and susceptible Aixian 1. The RILs were subjected to drought stress at the first ear stage, and phenotypic data of 16 agronomic and physiological traits under varying conditions were investigated. Genome-wide association study (GWAS) on the drought resistance index of traits was carried out. A total of 9 quantitative trait loci (QTLs) associated with drought-related traits were identified on chromosomes 2, 6, 7, 8, 9, and 10, which includes QTLs for plant height (PH) qPH10.1, effective panicles number (EPN) qEPN6.1, panicle length (PL) qPL9.1, thousand-grain weight (TGW) qTGW2.1, qTGW6.1, qTGW8.1, leaf length (LL) qLL7.1, leaf width (LW) qLW7.1, and leaf area (LA) qLA7.1. The fraction of phenotypic variation explained by individual QTL varied from 10.6% to 13.9%. Except for days to flowering (DTF), the mean values of all traits under normal water management conditions were considerably higher than those under drought conditions. Except for the DTF, the drought resistance index of all rice traits was less than 1, indicating that drought treatment reduced the EPN, FGPP, SSR, PH, and LA, which affected the growth and development of rice. The drought resistance index of DTF was 1.02, indicating that drought prolonged the heading time of rice and diminish the yield parameters. Along with identifying QTLs, the results also predicted ten candidate genes, which are directly or indirectly involved in various metabolic functioning related to drought stress. The identification of these genomic sites or QTLs that effectively respond to water scarcity will aid in the quest of understanding the drought tolerance mechanisms. This study will facilitate the marker-assisted rice breeding and handy in the breeding of drought-tolerant rice varieties.

Evaluation of water-stress tolerance in soybean using NDVI, gas exchange and morphological traits

A field experiment was conducted during 2017 and 2018 under drought stress (DS) and non-stress conditions (IR) to identify drought tolerant soybean accessions as well as agronomic and physiological traits contributing to drought stress tolerance. Sixty-four soybean accessions including released varieties, genetic stocks and five check varieties were sown in an augmented design. The traits contributing to total biomass viz., plant height, number of pods, number of branches, shoot-root dry weight at vegetative stage, and NDVI at vegetative as well as pod filling stage were associated with water-stress tolerance in soybean. Physiological traits viz., relative leaf water content (RWC), normalized vegetative index (NDVI) and chlorophyll index were higher in non-stressed crop. Similarly, higher activities ofthe gas exchange traits viz., photosynthetic rate (Pn), stomata conductance (Gs), intercellular CO2 concentration (Ci) and transpiration rate (Tr) were observed under non stress condition. On the basis of minimumyield reduction under stress and drought tolerance indices the soybean accessions RSC 10-46, TAMS 98-21, EC 241780, MACS 1281, HARDEE, MAUS 612, DS 9814, MACS 1460 and KDS 753 were observed as water stresstolerant while, EC 241695, LEE 54, MACS 1370, CAT 3466, PK 1029, VLS 75, AGS 228 and AMS 1002 were observed as water stress sensitive. These findings were confirmed by the cumulative rank due to drought tolerance indices such as stress susceptibility index (SSI), stress tolerance index (STI), tolerance (TOL), yield index (YI), drought resistance index (DRI), yield stability index (YSI), stress susceptibility percentage (SSPI), drought tolerance efficiency (DTE) and modified stress tolerance index (MSTI) as well as cluster analysis using drought tolerance indices, hence, could be useful in soybean improvement for water-stress tolerance.

Identifying Drought Tolerant Finger Millet Landraces for the Hills of Nepal

Finger millet is in the fourth rank among the major cereals in Nepal after rice, maize and wheat. Since it is cultivated in rainfed conditions, drought is one of the vital production constraints for this crop. With the objective of enhancing the utilization of native landraces conserved ex situ in genebank, 300 finger millet accessions were evaluated under drought stress and normal conditions at Khumaltar (1,360 masl), Lalitpur, Nepal during 2017 and 2018. In both the years, genotypes were significantly different for the yield and other agronomic characters. Eight different drought tolerant indices namely drought resistance index, geometric mean productivity, harmonic mean, mean productivity, stress susceptibility index, tolerance, yield index and yield stability index for each genotype were calculated using grain yield data recorded from the stress (Yds) and non-stress (Yns) experiment. Majority of the landraces were grouped under moderately susceptible group in both the years followed by moderately tolerant and susceptible group based on all the drought tolerant indices (DTIs). Five landraces, namely NGRC4849, NGRC6487, NGRC04852, NGRC03491 and NGRC6490 with average grain yield of 4670, 3624, 3426, 3191 and 3132 kg/ha, respectively, were identified as stable drought tolerant landraces compared to the released varieties. These landraces could be the potential sources of drought tolerance for finger millet improvement program for the mid-hills of Nepal.

Determination of drought resistance of soybean breeding material

The purpose and objectives of the study. To determine the resistance of soybean genotypes to drought according to drought resistance indices based on the analysis of yield in years contrasting in terms of hydrometeorological conditions.
 Materials and research methods. The material for determining the influence of year conditions on the level of average yield of soybeans and drought resistance were varieties and breeding numbers of the competitive variety test (CVT). Experiments were carried out in four repetitions with a plot area of 25 m2. Drought intensity (D) was determined by the formula proposed by Fischer R.A. and Maurer R. Differentiation of breeding numbers and varieties of CVT soybeans was carried out according to yield in 2016 and 2018 according to indices of drought susceptibility (DSI), drought tolerance (TOL), average yield (MP), yield stability (YSI), yield (YI), stress tolerance (STI), geometric mean yield (GMP). Processing of research results was carried out according to B.O. Dospehov [27] using STATISTICA 10 and Excel programs.
 The discussion of the results. During the research period (2008–2021), the highest yield of soybeans in CVT was obtained in 2016 – 2.57 t/ha, and the lowest in 2018 – 0.50 t/ha. A comparison of soybean yield in CVT in 2016 and 2018 showed that the average yield loss due to drought was 2.07 t/ha, or 81%. At the minimum yield, losses were equal to 1.78 t/ha, or 84.8%. At the maximum – 2.19 t/ha and 75.5%, respectively. Therefore, the minimum yield difference was greater than the maximum yield difference. The level of drought intensity (D) in the dry year of 2018 was equal to 0.81.
 According to yield indicators, a number of indices were calculated and analyzed, which characterize the resistance of samples to drought. The value of the drought susceptibility index (DSI) ranged from 0.87 to 1.09, with an average value of 1.00. The drought tolerance index (TOL) was 1.61–2.41 with an average value of 2.11. The average yield (MP) was in the range of 2.34–3.15 t/ha and had an average value of 2.85 t/ha. The yield stability index (YSI) value varied from 0.12 to 0.30 with an average value of 0.19. The yield index under stress conditions (YI) was 64.6–143.3%, with an average value of 98.9%. The stress yield index (YI) ranged from 64.6% to 143.3%, with an average value of 98.9%. The geometric mean (or proportional mean) yield (GMP) of the studied samples ranged from 0.92 t/ha to 1.38 t/ha, with a median value of 1.11 t/ha.
 According to each index, the researched soybean samples were differentiated and drought-resistant breeding material was selected.
 Conclusions. According to most indices: stress susceptibility (DSI), drought tolerance (TOL), crop stability (YSI), productivity (YI), stress tolerance (STI) and geometric mean yield (GMP) number CVT 23-18 (3836 / 76-130 selection). According to five indices: stress susceptibility (DSI), yield stability (YSI), yield (YI), stress tolerance (STI) and geometric mean yield (GMP) number CVT 16-18 (Volgohradka / Mriya) stood out. Number CVT 49-18 (Kharkivska 56 / Ilsoy) stood out according to the indicators of four indices: average yield (MR), yield (YI), stress tolerance (STI) and geometric mean yield (GMP). According to three indices, it is identified as drought-resistant number CVT 22-18 (selection №14) – according to indices of stress susceptibility (DSI), drought tolerance (TOL) and yield stability (YSI); numbers CVT 36-18 (Kharkivska zernokormova / Yug 30) and CVT 24-18 (Kharkivska 62 / Hodson) – according to indices of yield (YI), stress tolerance (STI) and geometric mean yield (GMP). Selection number CVT 28-18 (4305-04) stood out according to stress tolerance index (TOL) and average yield level (MR). Number 29-18 (Narrow-leaved / mutant 82-205) stood out according to the stress tolerance index (TOL) and the level of average yield (MR). Numbers CVT 50-18 (selection from Pasteter Schwarus) and CVT 37-18 (Success / Dream) were distinguished by indices of susceptibility to stress (DSI) and yield stability (YSI). According to the level of average yield (MR), number CVT 20-18 (Kharkivska 35 / Kyivska 27) and Podyaka variety stood out. The Roksolana variety stood out according to the stress tolerance index (TOL). Selected genotypes of soybeans with a high level of resistance to abiotic stress are recommended for use in crop breeding for high drought resistance.

Evaluation of drought resistance and index screening of foxtail millet cultivars

Abstract Screening for identification indicators and establishing a drought-resistance evaluation system can provide a basis for the selection and layout of drought-resistant foxtail millet cultivars. Twenty-one main foxtail millet cultivars in China were evaluated for drought resistance by measuring their main agronomic traits and photosynthetic indicators under the condition of drought stress and normal irrigation. Identifying the drought resistance is difficult when using a single index. The order of drought resistance of tested foxtail millet cultivars based on drought resistance comprehensive evaluation values (D value) and drought resistance index (DRI value) differed to an extent; therefore, a comprehensive evaluation method combining D and DRI values was appropriate and accurate. Gray correlation analysis showed that the grain weight per ear, yield, ear weight, and ear length could be used as indicators for drought-resistance evaluation of foxtail millet cultivars at the mature stage. According to the clustering analysis based on D and DRI values, the tested cultivars were divided into three grades of drought resistance and six foxtail millet cultivars with strong drought resistance were identified. The photosynthetic indicators showed that the net photosynthetic and transpiration rates and D and DRI values had correlation coefficients greater than 0.320.

Comparative Analysis of Primary Photosynthetic Reactions Assessed by OJIP Kinetics in Three Brassica Crops after Drought and Recovery

Plant drought tolerance depends on adaptations of the photosynthetic apparatus to changing environments triggered by water deficit. The seedlings of three Brassica crops differing in drought sensitivity, Brassica oleracea L. var. capitata—white cabbage, Brassica oleracea L. var. acephala—kale, and Brassica rapa L. var. pekinensis—Chinese cabbage, were exposed to drought by withholding water. Detailed insight into the photosynthetic machinery was carried out when the seedling reached a relative water content of about 45% and after re-watering by analyzing the OJIP kinetics. The key objective of this study was to find reliable parameters for distinguishing drought−tolerant and drought-sensitive varieties before permanent structural and functional changes in the photosynthetic apparatus occur. According to our findings, an increase in the total performance index (PItotal) and structure–function index (SFI), positive L and K bands, total driving forces (ΔDF), and drought resistance index (DRI) suggest drought tolerance. At the same time, susceptible varieties can be distinguished based on negative L and K bands, PItotal, SFI, and the density of reaction centers (RC/CS0). Kale proved to be the most tolerant, Chinese cabbage was moderately susceptible, and white cabbage showed high sensitivity to the investigated drought stress. The genetic variation revealed among the selected Brassica crops could be used in breeding programs and high-precision crop management.

The perspective soft spring wheat variety Semenovna is the result of international cooperation

The research is aimed at studying economically valuable traits and genetic control of resistance to leaf-stem diseases, photoperiodic reaction and short stemming of soft spring wheat variety Semenovna, created by scientists of the Omsk Agrarian Scientific Center (Russia) and the North Kazakhstan Agricultural Experimental Station (Kazakhstan). Using methods of state variety testing, molecular genetics and in vitro methods, morphological features of a new variety, features of its development have been described, the yield level at different ecological test points for three years (2015-2017) has been analyzed. The studies conducted at two ecological points made it possible to select a medium-sized promising line of soft spring wheat (Lutescens 354/04-6), which was transferred to the State Registration Service of the Republic of Kazakhstan and after two years of testing was included into the State Register of the Republic of Kazakhstan under the name Semenovna (patent No. 1023). In terms of grain quality, it was at the level of valuable wheat, exceeded the standard in protein content by 1-2 % and raw gluten by 3-4 %. The new medium-ripe Semenovna variety combines increased yield (2.73-4.40 t/ha) with resistance to drought (resistance index Ir = 0.57), brown and stem rust (IU = 0.00-0.23). The genotype of the variety contains wheat-rye translocation 1RS.1BL (with a cluster of Lr26/Sr31/Pm8/Yr9 genes). The medium-stem variety carries the Rht8b allele in its genotype (174 bp) and is photosensitive to the length of the day (allele 414 bp). The parameters of ecological plasticity of the new variety are determined: linear regression coefficient (bi = 1.08), stability index (σd2 = 0.27).