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

Abstract

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.

Analysing the SPAD dynamics of water-stressed vs. well-watered sesame (Sesamum indicum L.) accessions and establishing their relationship with seed yield

“…They stated that differences in genetic components and environmental impact might account for the observed variation in SPAD value between genotypes. The ANOVA in the current study is similar to that in the research study of Pandey et al. (2021b) in sesame, which emphasized that the mean performance of SPAD under both WS and WW conditions exhibited significant differences among the genotypes.…”

“…Sesame is frequently cultivated in arid and semi-arid areas inhabiting “hungry and thirsty” environments ( Ramesh et al, 2019 ), where it is frequently exposed to deficit moisture stress ( Ratnakumar & Ramesh, 2019 ; Pandey et al., 2021a ). In rainfed ecosystems, time and duration of water stress have a significant effect on sesame productivity ( Ravitej et al, 2019 ), although the genotypes might have varied responses in maintaining the leaf chlorophyll content and are directly related to tolerance and higher productivity under WS ( Kadkhodaie et al, 2014 ; Pandey et al., 2021b ).…”

Assessment of drought tolerance of sesame germplasm with agronomic and quality traits

“…We obtained lower mean values for all agronomic traits under WS treatment indicating negative effect of drought on yield and yield attributing traits. Thirty percent reduction was observed in plant height under WS treatment, the decrease for this trait with drought conditions was also obtained by Hassanzadeh et al (2009), Heidari et al (2011), and Pandey et al (2021 in sesame.…”

“…Considering the overall mean values, seed yield decreased by > 50% in WS treatment. A drastic reduction was also reported in sesame (Boureima et al., 2016; Mensah et al., 2006; Pandey et al., 2021) and other important field crops such as chickpea (Nayyar et al., 2006), rice (Vikram et al., 2011), soybean (Guzzo et al., 2021), and peanut (Abadya et al., 2021) under drought conditions. A significant reduction in the seed yield under WS treatment could be due to less number of capsules, branches, and shorter plant height compared to mean of accessions under NS treatment (Table 1).…”

“…(2011), and Pandey et al. (2021) in sesame. Several studies have also reported the detrimental effects of drought on plant height for different crops such as barley (Rollins et al., 2013), maize (Hussain et al., 2019), rice (Patmi & Pitoyo, 2020), and sugarcane (Misra et al., 2020).…”