Terminal Drought Stress Research Articles

Retraction: Combined application of zinc and silicon alleviates terminal drought stress in wheat by triggering morpho-physiological and antioxidants defense mechanisms

Retraction: Combined application of zinc and silicon alleviates terminal drought stress in wheat by triggering morpho-physiological and antioxidants defense mechanisms

Wheat breeding for early heading: Does it improve grain yield under drought stress and well-watered conditions?

Terminal drought stress strongly affects wheat grain yield under Mediterranean conditions. Therefore, developing early-heading bread wheat cultivars in these conditions is an important breeding strategy. In the present research, earliness was transferred from the Australian cultivar, Excalibur, to three Iranian cultivars, Roshan, Kalheydari and Mahdavi, in separate backcross (BC) breeding programs from 2012 to 2018. The earliest and latest heading genotypes of each BC 3 population, were selected as near-isogenic lines (NILs). NILs and their parents were assessed under diverse field conditions including rain-fed, moderate drought stress and well-watered conditions in three locations, Kerman, Sepidan and Semirom, during two growing seasons, 2018–2019 and 2019–2020. Breeding for early heading significantly improved earliness in all genetic backgrounds and increased grain yield by 36.4% and 9.6%, in the rain-fed and moderate drought stress conditions, respectively. Whereas, grain yield was not significantly affected by early heading under well-watered conditions. Results showed that breeding for early heading, a highly heritable trait, is an appropriate method to increase grain yield and reduce water consumption under drought stress and well-watered conditions, respectively. Based on these findings, we recommend transferring early heading to high yield late heading commercial cultivars using backcrossing. • For the first time, near isogenic lines of early heading were developed. • Breeding for early heading increased grain yield by 36.4% in rain-fed conditions. • Early heading increased grain yield by 9.6% in moderate drought stress conditions. • Early heading did not affect grain yield under well-watered conditions in Kerman.

How Does the Environment Affect Wheat Yield and Protein Content Response to Drought? A Meta-Analysis.

Wheat (Triticum aestivum L.) is one of the most significant cereal crops grown in the semi-arid and temperate regions of the world, but few studies comprehensively explore how the environment affects wheat yield and protein content response to drought by means of meta-analysis. Therefore, we collected data about grain yield (GY), grain protein yield (GPY), grain protein content (GPC), and grain nitrogen content (GNC), and conducted a meta-analysis on 48 previously published data sets that originate from 15 countries. Our results showed that drought significantly decreased GY and GPY by 57.32 and 46.04%, but significantly increased GPC and GNC by 9.38 and 9.27%, respectively. The responses of wheat GY and GNC to drought were mainly related to the drought type, while the GPY was mainly related to the precipitation. The yield reduction due to continuous drought stress (CD, 83.60%) was significantly greater than that of terminal drought stress (TD, 26.43%). The relationship between the precipitation and GPY increased in accordance with linear functions, and this negative drought effect was completely eliminated when the precipitation was more than 513 mm. Sandy soils and high nitrogen application level significantly mitigated the negative effects of drought, but was not the main factor affecting the drought response of wheat. Compared with spring wheat, the drought resistance effect of winter wheat was more obvious. Evaluation of these models can improve our quantitative understanding of drought on wheat yield and food security, minimizing the negative impact of drought on crop production.

Study of relationship between morpho-physiological traits and grain yield under terminal drought stress conditions in barley genotypes

Study of relationship between morpho-physiological traits and grain yield under terminal drought stress conditions in barley genotypes

QTL Analysis of Grain Yield-Related Traits for Terminal Heat Stress Tolerance in Wheat Using SSR Markers.

<b>Background and Objective:</b> Late sowing of wheat exposes the anthesis and grain filling stages of the crop to a terminal heat temperature stress Therefore, detecting putative QTL associated with grain yield and its attributes and identifying the most tolerant genotypes to terminal drought and heat stress across environments will be beneficial in wheat breeding programs. <b>Materials and Methods:</b> In the present study, among 49 CIMMYT wheat lines evaluated for yield and stability in eight environments, we selected the highest ten high-yielding (HYL) and the lowest ten low yielding lines (LYL) along with three wheat check cultivars (CC) for screening with eighteen previously published SSR molecular markers associated with drought and heat stress tolerance. <b>Results:</b> Two SSR markers (BARC126 and BARC11) on 7D were associated with delay heading dates under normal and late sowing dates. Likewise, the SSR markers WMC396, GWM537 and XGWM577 which were mapped on 7B, were significantly linked with grain yield-related traits under one/or both sowing dates, most of them showed desirable effects, indicating terminal heat stress tolerance. Different SSR markers viz., BARC11, XGWM132 and GWM537 showed pleiotropic effects. <b>Conclusion:</b> The SSR markers BARC186-5A, XGWM132-6B, WMC396-7B, XGWM577-7B and GWM165-4B were more prominently associated with heat tolerance by showing a desirable performance of grain yield-related traits under late sowing or across environments, some of these desirable alleles were corresponding to previously QTL in various genotypes that could be valuable in breeding for high-yield in wheat.

Contrasting Phaseolus Crop Water Use Patterns and Stomatal Dynamics in Response to Terminal Drought.

Terminal drought stress affects more than half of the areas planted with common bean (Phaseolus vulgaris), the main food legume globally, generating severe yield losses. Phenotyping water deficit responses and water use are central strategies to develop improved terminal drought resilience. The exploration and exploitation of genetic diversity in breeding programs are gaining importance, with a particular interest in related species with great adaptation to biotic and abiotic factors. This is the case with tepary beans (Phaseolus acutifolius), a bean that evolved and was domesticated in arid conditions and is considered well adapted to drought and heat stress. Under greenhouse conditions, using one genotype of tepary beans (resistant to drought) and two of common beans (one resistant and one susceptible to terminal drought), we evaluated phenotypic differences in traits such as water use efficiency (WUE), transpiration efficiency, rate of photosynthesis, photosynthetic efficiency, stomatal density, stomatal index, stomatal size, and the threshold for transpiration decline under well-watered and terminal drought conditions. Our results indicate two different water use strategies in drought-resistant genotypes: one observed in common bean aimed at conserving soil water by closing stomata early, inhibiting stomatal development, and limiting growth; and the other observed in tepary bean, where prolonged stomatal opening and higher carbon fixation, combined with no changes in stomata distribution, lead to higher biomass accumulation. Strategies that contribute to drought adaptation combined with other traits, such as greater mobilization of photoassimilates to the formation of reproductive structures, confer bean drought resistance and are useful targets in breeding programs.

Combining Ability and Heterotic Patterns of Tropical Early-Maturing Maize Inbred Lines under Individual and Combined Heat and Drought Environments.

Information on combining ability and heterotic patterns of multiple stress-tolerant inbred lines are fundamental prerequisites for devising appropriate breeding strategies for the development of climate-resilient maize hybrids. In the present study, we evaluated 150 single cross hybrids derived from the North Carolina Design II (NCD II) along with six commercial checks under terminal drought stress (TDS), heat stress (HS), and combined drought and heat stress (CHDS)conditions. The objectives of the study were to: (i) determine the combining ability of the inbred lines and identify the best testers across the stresses; (ii) classify the inbred lines into heterotic groups (HGs) based on the general combining ability of multiple traits (HGCAMT) and sequencing-based diversity array technology (DArTseq) and (iii) assess the performance and stability of the lines in hybrid combinations. The inbred lines showed significantly (p < 0.01 and p < 0.05) positive and negative general combining ability (GCA) and specific combining ability (SCA) effects for grain yield (GY) and most other measured traits. The inbred line TZEI 135 displayed relatively larger positive GCA effects for GY when mated either as male or female and was identified as the best tester. TZEI 135 × TZEI 182 was identified as the best single-cross tester across environments. Results of the assessment of the relative importance of GCA and SCA effects revealed the predominance of additive gene action over the non-additive. Six HGs of inbreds were identified using the HGCAMT and three, based on the DArTseq marker genetic distance method, were the most efficient. The best hybrids in this study significantly out-yielded the best checks by 21, 46, and 70% under CHDS, HS, and TDS, respectively. These hybrids should be extensively tested in on-farm trials for possible commercialization in sub-Saharan Africa.

The Quantitative Genetics of Flowering Traits in Wide Crosses of Chickpea

Chickpea (Cicer arietinum L.) is one of the most ımportant food legume crops in the world. Chickpea is valued for its nutritive seed composition, which is high in protein content and used increasingly as a substitute for animal protein. Days to fırst flowerıng is an important component of the adaptation and productivity of chickpea in rainfed environments characterized by terminal drought and heat stress. This study aimed to identify the inheritance pattern and identify quantitative trait loci (QTLs) for days to first flowering and flowering color in F2:4 generation nested association mapping (NAM) populations of chickpea obtained using wide crosses between Gokce as the cultivated variety and wild accessions of C. reticulatum and C. echinospermum. A total of ten populations of 113 to 191 individuals each were grown under field conditions near Sanliurfa, Turkey. Two populations were genotyped for 46 single nucleotide polymorphism (SNP) markers, enabling QTL analysis. Flowering time differed between families, with the frequency distributions indicating quantitative inheritance controlled by both genes of major and minor effects. Three significant QTLs for the flowering time were mapped in one mapping family. For flower color, chi-square tests showed that five populations accepted single-gene action, two populations accepted two-gene action, and three populations accepted neither model. Two significant QTLs at three genomic regions were identified across the two genotyped populations. Days to first flowering was positively correlated with flower color for two of the ten populations. The diversity of QTLs identified underscored the potential of crop wild relatives of chickpea as sources of novel alleles for chickpea breeding.

Deeper root system architecture confers better stability to photosynthesis and yield compared to shallow system under terminal drought stress in wheat (Triticum aestivum L.)

Deeper root system architecture confers better stability to photosynthesis and yield compared to shallow system under terminal drought stress in wheat (Triticum aestivum L.)

Canopy temperature depression for drought- and heat stress tolerance in wheat breeding.

An infrared thermometer was first used to assess drought and heat tolerance in plant breeding more than 40 years ago. Soon afterward, this method became widely used throughout the world. However, Russia has not yet applied the described method for evaluating stress tolerance. This paper presents an overview of using infrared thermometry in plant breeding. Taking wheat as an example, it shows major advantages and disadvantages of canopy temperature depression (CTD) values measured by the infrared thermometer. The paper also demonstrates that genotypes with higher CTD values, and therefore with a lower canopy temperature, use more available soil moisture under drought stress to cool the canopy by transpiration. It refers to CTD as an integrative trait that reflects an overall plant water status. Its coefficient of variation lies in the interval of 10 to 43 %. A large number of publications illustrate a close relation between CTD values and yield and indicate a high heritability of the former. Meanwhile, the same works show that yield has a higher heritability. Moreover, some researchers doubt that CTD should be used in applied wheat breeding as there are many factors that influence it. CTD has a high correlation with other traits that reflect plant water status or their adaptation to drought or heat stress. Quantitative trait loci (QTLs) associated with CTD are localized in all chromosomes, except for 3D. These QTLs often explain a small part of phenotypic variance (10–20 %, more likely less than 10 %), which complicates the pyramiding of canopy temperature genes through marker-assisted selection. The paper concludes that the evaluation of CTD appears to be a reliable, relatively simple, labor-saving, objective, and non-invasive method that sets it apart from other methods as well as shows the best results under terminal drought and heat stress conditions

Physiological and Yield Responses of Selected Mungbean Genotypes to Terminal Drought

Extreme drought conditions have been a major limiting factor in legume production worldwide. The development of drought-resilient crops should help mitigate adverse effects of unfavorable environmental conditions such as drought; however, initial characterization is necessary to ensure that the germplasm has the essential genetic variation for drought tolerance. In this study, a field trial was conducted to characterize drought response and potential drought tolerance of 100 mungbean genotypes through the evaluation of several physiological parameters and seed yield. The genotypes were subjected to terminal drought stress before flowering (~ 30 d after planting), reducing soil moisture content (SMC) from 25.0–30.0% to 13.0–15.0% during treatment imposition. Significant differences were observed between mungbean genotypes for total chlorophyll content (Chl), total scavenging activity (SA), electrolyte leakage (EC), and chlorophyll fluorescence (Fv/Fm) during drought. Furthermore, by transforming each physiological parameter into principal components (PCs) via principal component analysis (PCA), five distinct clusters were generated. Based on their physiological response and seed yield, Clusters I and II were identified as potential drought susceptible group, Cluster III was moderately susceptible, and Clusters IV and V were identified as the potential drought-tolerant group. Correlation analysis and PCA also demonstrated the significant relationship among several key traits for drought tolerance such as chlorophyll content, electrolyte leakage, and antioxidant scavenging to chlorophyll fluorescence – suggesting the suitability of fluorescence parameter in mungbean mass screening for drought tolerance. Although weak correlation between physiological parameters to seed yield was present (0.3 &lt;│r│&lt; 0.5), correlations among each physiological parameter were moderately strong (0.5 &lt;│r│&lt; 0.7). The findings suggest that a physiological characterization during initial screening for drought tolerance was an effective approach in identifying possible sources of drought tolerance traits complementary with yield- related traits. The evaluation of chlorophyll fluorescence, scavenging activity, electrolyte leakage, and chlorophyll content was enough to differentiate and characterize the drought response of several mungbean genotypes and will be vital in the development of climate-resilient crops.

Does wet seeding combined with Sub1 varieties increase yield in submergence prone lowlands of West Africa?

Early season flash flooding and submergence greatly impair rice production in the rainfed lowlands of West Africa. Here, rice establishment is by transplanting into puddled soil. Crops established during the early part of the rainy season are adversely affected by submergence, while delaying transplanting until the flood waters have receded results in the use of old seedlings and terminal drought stress. While the use of submergence tolerant (Sub1) rice varieties can greatly reduce the yield loss caused by 1–2 weeks of early season submergence, changing to wet seeding at the start of the rainy season may confer additional advantages. Elsewhere, wet seeding has been shown to enable more timely (earlier) crop establishment and more rapid early growth, and thus the potential to provide greater resilience to submergence. Therefore, the objective of this study was to assess the performance of two Sub1 varieties developed for West Africa (FARO 66, FARO 67) under transplanted and wet seeded conditions, in comparison with the predominant local variety (WITA 9). On-station experiments were carried-out over three seasons (dry 2018, wet 2019, dry 2019) at Mbé Research Station of the Africa Rice Center, Bouake, Cote d′Ivoire. The fields were submerged for 1–2 weeks at 5–7 weeks after seeding, and the wet season crop was sown at the beginning of the rainy season. Yield of the Sub1 varieties was 1.1–4.5 t ha −1 higher than that of WITA 9, depending on season and establishment method. Wet seeding resulted in much higher yields of WITA 9 than transplanting in the wet season, but yield of the Sub1 varieties was not affected by establishment method in any season. However, tiller survival and biomass production of the wet seeded Sub1 crops were less affected by submergence than the transplanted crops. Wet seeding also reduced labour requirement and cost, and increased profitability. Furthermore, establishment of the wet season crop at the beginning of the rainy season would facilitate intensification to two crops per year. Therefore, the adoption of Sub1 varieties, could enable significant progress towards the goal of self-sufficiency in rice production in West Africa. Combining Sub1 with wet seeding would provide further benefits in terms of increased profitability and resilience to flash flooding. • We compared wet seeded and transplanted local and Sub1 rice submerged for 1–2 weeks • Sub1 varieties sown at start of the wet season out yielded WITA 9 by 2.2–4.5 t ha −1 • Yield of Sub1 varieties was not affected by establishment method • Wet seeding reduced labour and increased profit of Sub1 by 445–660 USD ha −1

Response of chickpea to varying moisture stress conditions in Ethiopia

AbstractChickpea (Cicer arietinum L.) is an economically important crop grown by nearly one million Ethiopian smallholder farmers. The crop is often considered as “stress‐loving,” but moisture stress at flowering and grain filling stages could be detrimental. Yield of chickpea is commonly affected by terminal drought stress in the rainfed production system in Ethiopia. The lack of proper field‐screening methods has hindered the development of drought‐tolerant varieties. This study demonstrates a simple and practical field‐level screening method for drought tolerance traits in the conventional breeding programs. A field experiment was conducted using 28 elite chickpea cultivars during the 2018–2019 main cropping season to study their response to moisture regimes of varying drought intensities. We used yield and its components as proxy parameters of screening to select tolerant cultivars. The study revealed significant variation among the cultivars in their response to different moisture regimes. The kabuli cultivars were found more sensitive compared with the desi types. Yield penalty exceeded 70% under severe drought. Conversely, cultivars tested under mild and severe stress drought showed average yield gain of 22 and 48%, respectively, relative to the irrigated treatment. Overall, over 50% yield gain can be obtained in drought‐affected rainfed production areas in Ethiopia using supplemental irrigation during pod setting to grain filling stages. For post‐rainy‐season crops relying on residual soil moisture, such as chickpea, breeding for shorter duration and resilient cultivars are reliable management approaches to minimize drought‐caused yield losses.

Identifying Traits Associated With Terminal Drought Tolerance in Sesame (Sesamum indicum L.) Genotypes.

Sesame is predominantly cultivated in rainfed and low fertile lands and is frequently exposed to terminal drought. Sesamum species inhabiting dryland ecosystems adaptively diverge from those inhabiting rainfed habitats, and drought-specific traits have a genetic basis. In sesame, traits associated with drought conditions have not been explored to date, yet studies of these traits are needed given that drought is predicted to become more frequent and severe in many parts of the world because of climate change. Here, 76 accessions from the available Indian core set were used to quantify variation in several traits under irrigated (WW) and terminal drought stress (WS) conditions as well as their association with seed yield over two consecutive years. The range of trait variation among the studied genotypes under WW and WS was significant. Furthermore, the traits associated with seed yield under WW and WS differed. The per se performance of the accessions indicated that the expression of most traits was reduced under WS. The correlation analysis revealed that the number of branches, leaf area (LA), leaves dry weight (LDW), number of capsules plant–1, and harvest index (HI) were positively correlated with seed yield under WW and WS, and total dry matter (TDM), plant stem weight, and canopy temperature (CT) were negatively correlated with seed yield under WW and WS, indicating that smaller and cooler canopy genotypes had higher yields. The genotypes IC-131936, IC-204045, IC-204861, IC-205363, IC-205311, and IC-73576 with the highest seed yields were characterized by low canopy temperature, high relative water content, and high harvest index under WS. Phenotypic and molecular diversity analysis was conducted on genotypes along with checks. Phenotypic diversity was assessed using multivariate analysis, whereas molecular diversity was estimated using simple sequence repeat (SSR) loci to facilitate the use of sesame in breeding and genetic mapping. SSRs showed low allelic variation, as indicated by a low average number of alleles (2.31) per locus, gene diversity (0.25), and polymorphism information content (0.22). Cluster analysis (CA) [neighbor-joining (NJ) tree] revealed three major genotypic groups and structure analysis showed 4 populations. The diverse genotypes identified with promising morpho-physiological traits can be used in breeding programs to develop new varieties.

ارزیابی ژنوتیپ‌های گندم نان تحت شرایط تنش خشکی در مرحله گیاهچه‌ای با استفاده از شاخص‌های خشکی

Introduction The existence of drought stress at the beginning of the growing season is one of the most important threatening factors in wheat production of Iran. The coleoptile length is the most important morphological trait in determining sowing depth, emergence power and seedling establishment. The coleoptile length has been used as an effective indicator for selecting the drought tolerant genotypes in wheat breeding programs. Various indices have been developed to evaluate crop response to various stresses, including tolerance index (TOL), productivity mean (MP), geometric mean productivity (GMP), harmonic mean (HM), stress tolerance index (STI), stress sensitivity index (SSI), yield index (YI), yield stability index (YSI) and relative stress index (RSI). The efficiency of each indices depends on the breeding objectives and the target environment. Materials and methods In order to evaluate some of the landrace wheat genotypes under drought stress conditions at the seedling stage, an experiment with 35 pure lines under three moisture conditions (control, drought stress with PEG6000 10% and 15%) was conducted in a completely randomized design (CRD) with three replications at Gorgan university of agricultural sciences and natural resources.. The coleoptile length was measured after eight days. The indices of MP, GMP, HM, STI, SSI, YI, TOL, RSI and YSI were calculated based on the coleoptile length values under control (Yp) and stress (Ys) conditions. Data analysis was performed using iPASTIC: an online toolkit to estimate plant abiotic stress indices. Results and discussion In control and 10%-drought stress conditions, genotypes 11 and 2 had the highest of coleoptile length. While, in 15%-drought stress conditions, genotypes 3 and 6 had the highest of coleoptile length, respectively. Also in control and 15%-drought conditions genotypes 30 and 35 and in 10%-drought stress conditions genotypes 15 and 21 had the lowest of coleoptile length. Based on MP, GMP, HM, STI and YI indices, genotypes 2 and 11 were identified as tolerant genotypes, while genotypes 15, 21 and 30 were susceptible genotypes, under 10% drought stress conditions. Under 15%-drought stress conditions, MP, GMP, HM, STI and YI indices identified genotypes 21 and 34 as the most susceptible genotypes, whereas genotypes 30 and 35 were the most susceptible genotypes. Under three moisture conditions, the coleoptile length had the highest coefficient of correlation (positive and significant) with MP, GMP, HM and STI indices. Using three-dimensional plots, the genotypes were divided into four groups A, B, C, and D. The most appropriate indices being the ability to distinguish group A, from other groups. Group A selects genotypes that have high yield in both control and stress conditions. The result showed genotypes 3, 6, 11, 16, 19, 20 and 24 were classified as group A in both drought stress conditions. The Iranian commercial cultivars (genotypes 30, 34 and 35) placed in Group D, which indicates insufficient attention to drought stress at the seedling stage, while tolerance to terminal drought stress is one of the most important goals in wheat breeding programs of Iran. Principal component analysis (PCA) showed that the first two PCAs explained 99.78% of the variation in 10%-drought stress and 99.80% in 15%-drought stress conditions. MP, GMP, HM and STI had the sharp angles with together that it indicates high correlation among mentioned indices. Multivariate biplos showed that drought tolerant genotypes were adjacent to vectors related to the best drought tolerance indices. Conclusions Correlation coefficients of drought tolerance indices showed that MP, GMP, HM and STI were the most suitable indices for selecting of drought tolerant genotypes. Based on stress tolerance indices and 3D plots, genotypes 3, 6, 11 and 24 (originated from Turkey, Afghanistan, Iran and Afghanistan, respectively) were identified as drought tolerant genotypes at the seedling stage, while genotypes 14, 15, 21, 30 and 35 were identified as the most susceptible genotypes. The landrace genotypes identified in this study could be used in breeding programs of bread wheat under drought stress at the seedling stage.

Accumulation and remobilization of assimilates in different genotypes of durum wheat under terminal drought stress

Accumulation and remobilization of assimilates in different genotypes of durum wheat under terminal drought stress

Combined application of zinc and silicon alleviates terminal drought stress in wheat by triggering morpho-physiological and antioxidants defense mechanisms.

Wheat is an important global staple food crop; however, its productivity is severely hampered by changing climate. Erratic rain patterns cause terminal drought stress, which affect reproductive development and crop yield. This study investigates the potential and zinc (Zn) and silicon (Si) to ameliorate terminal drought stress in wheat and associated mechanisms. Two different drought stress levels, i.e., control [80% water holding capacity (WHC) was maintained] and terminal drought stress (40% WHC maintained from BBCH growth stage 49 to 83) combined with five foliar-applied Zn-Si combinations (i.e., control, water spray, 4 mM Zn, 40 mM Si, 4 mM Zn + 40 mM Si applied 7 days after the initiation of drought stress). Results revealed that application of Zn and Si improved chlorophyll and relative water contents under well-watered conditions and terminal drought stress. Foliar application of Si and Zn had significant effect on antioxidant defense mechanism, proline and soluble protein, which showed that application of Si and Zn ameliorated the effects of terminal drought stress mainly by regulating antioxidant defense mechanism, and production of proline and soluble proteins. Combined application of Zn and Si resulted in the highest improvement in growth and antioxidant defense. The application of Zn and Si improved yield and related traits, both under well-watered conditions and terminal drought stress. The highest yield and related traits were recorded for combined application of Zn and Si. For grain and biological yield differences among sole and combined Zn-Si application were statistically non-significant (p>0.05). In conclusion, combined application of Zn-Si ameliorated the adverse effects of terminal drought stress by improving yield through regulating antioxidant mechanism and production of proline and soluble proteins. Results provide valuable insights for further cross talk between Zn-Si regulatory pathways to enhance grain biofortification.

Promising versions of a commercial pearl millet hybrid for terminal drought tolerance identified through MAS

Extreme climatic conditions like drought are a major threat to global food production. Terminal drought stress causes severe yield losses in pearl millet. Development of climate-resilient varieties/hybrids can minimize the yield losses to the farmers caused due to climatic extremes. In the present study, marker-assisted selection (MAS) was employed with an aim to develop improved version of HHB 226 by introgression of QTLs for terminal drought stress tolerance into the male parent of the hybrid (HBL 11). HBL 11 (recurrent parent) was crossed with PRLT 2 (donor) to develop F1 and backcrossed four times to raise BC4F1 and further selfed twice to raise BC4F3. Four polymorphic SSR markers were used to track the QTL introgressed lines in each subsequent generation until BC4F2. The recurrent parent genome recovery was assessed using 25 polymorphic SSRs. Morpho-physiological analysis of BC4F3 generation at field-level under terminal drought stress conditions showed that the QTL introgressed lines showed higher, grain yield, 1000-seed weight, relative water content (%), and lower electrolyte leakage (%) than the recurrent parent. Line number 63 performed best with all the four foreground markers, 97.20% recurrent parent genome recovery, 7.27 g 1000-seed weight, 73.27% relative water content, 65.06% electrolyte leakage, 0.58 (fv/fm) chlorophyll fluorescence, and 53.25 g grain yield per plant. Finally, the Improved version of HHB 226 was developed by using the Improved HBL 11 developed through MAS. Besides this, HBL 11 is the male parent of other commercial hybrids like HHB 223 and HHB 197 as well making Improved HBL 11 an asset to improve these pearl millet hybrids.

Evaluation crop indices of canola spring genotypes in terminal drought stress conditions and foliar application of Potassium silicate

Introduction Drought is a restriction in crop production in arid and semiarid regions. It is forecast that climate change may cause droughts shortly. After oxygen, silicon (Si) is the second most common element in the soil. In reducing both biotic stress (e.g., plant diseases and pest damage) and abiotic stresses such as salinity, drought, aluminum toxicity, heavy metal toxicity, nutrient imbalance, lodging, radiation, high temperature, wounding, and freezing. Materials and Methods In order to study the effects of terminal drought stress and foliar application of potassium silicate on yield and canola spring genotypes components, a factorial split-plot test was conducted in Karaj, Iran in a full randomized block configuration with three replications for two years of cultivation (2016-2018). The irrigation was performed at two levels in this study, including routine irrigation (control) and interruption of irrigation from the pod formation stage. Potassium silicate foliar application at two levels comprised of 0 and 4 g liter-1 in factorial status in main plots and five Brassica napus L. genotypes including OG × AL, RGS × SLM, DALGAN, RGS003 and RGS × Okapi in subplots. SAS Ver 9.1 statistical analysis was used for variance analysis. Results Combined variance analysis showed that the impact of the year on some characteristics seed number in silique, silique length and seed yield was significant. Also, the effect of irrigation was significant on seed yield. The effect of genotype on plant height was significant indicating that the genotypes had different reactions. The interaction effect of irrigation × genotype on Harvest index was significant. The interaction effect of Irrigation × Potassium Silicate × Genotype on branch number, silique number, silique length, seed number in silique, seed weight, biological yield, seed yield, oil content and oil yield was significant. The mean comparison of irrigation and Potassium silicate interaction demonstrated that the most grain yield was observed in normal irrigation and the least value related to cut off irrigation at pod formation stage. The results indicated that, irrigation, foliar application of Potassium silicate and their interaction had significant effect on growth and agronomic traits and increased them. Conclusions Finally, our study showed the beneficial effects of Potassium Silicate in improving the drought tolerance of canola plants, especially at the end of the season. This can provide a basis for attempting new strategies to reduce the damage from drought and create a functional link between the role of silicon, physiological response and tolerance to drought stress in canola plants. According to the results, in the case of application of Potassium Silicate and normal irrigation, the promising genotype of OG×AL, with the highest seed and oil yield, is recommended as standard. Also, in the case of application of Potassium Silicate and late-season drought stress (restricted irrigation from the pod formation stages), RGS × SLM and DALGAN with the highest seed yield, is recommended.

Development of advance pearl millet lines tolerant to terminal drought stress using marker-assisted selection

Development of advance pearl millet lines tolerant to terminal drought stress using marker-assisted selection