Abstract
Drought is one of the most prominent limiting factors that negatively affect crop productivity by manipulating its physiological pathway. One hundred twenty diverse bread wheat genotypes were used in a pot experiment to explore the relationship among their fifteen physio-biochemical traits (PBT) by using multivariate analysis, heatmapping and stress tolerance index (STI) for grain yield as a marker trait to identify high yielding genotype with maximum stress tolerance capability. Increased proline and sugar accumulation were observed from control to moisture deficient environments by 159% and 122%, respectively. Moreover, leaf membrane stability index (LMSI), leaf relative water content (LRWC), relative dry weight (RDW), chlorophyll content, leaf surface area (LSA), Leaf succulence (LS), canopy temperature depression (CTD), relative excised leaf water loss (RELWL) and leaf osmotic potential (LOP) showed significantly decreasing trend in drought stress treatment as compared to well-watered plants by −21%, −21%, −34%, −22%, −38%, −37%, −46%, −18% and −35% respectively. Additionally, principal component analysis and genotype by trait biplot analysis showed that initial 7 principal components (PC1 to PC7) represented 77.27% and 79.02% of total cumulative variation under control and drought stress respectively. Genotypic-Phenotypic correlation revealed that most of the attributes were higher in case of genotypic correlation component (rg) as compared to the phenotypic correlation component (rp) indicating more genetic association between traits. The darker and lighter colour scale produced by heatmap exhibited contrasting nature of genotypes, as positive side with higher values represented drought resistance while values on the negative side with lower values showed susceptible performance of genotypes. Our results concluded that the studied PBT associated with STI for grain yield are the main factors which may contribute in improved productivity of wheat crop and if these traits show appropriate performance under stress condition the crop will show the more productive returns under changing climate.
Highlights
Climate change is a prevalent concern that has imposed several challenging ventures on contemporary agriculture
Proline content was found to be largely affected by drought conditions as it was noted to be increased for each genotype when compared in both of the conditions where it increased in stress conditions
We found a positive significant rg values between leaf membrane stability index (LMSI) and osmo-protectants, i.e. proline and sugars, supported by the highly significant positive correlation with Relative excised leaf water loss (RELWL), canopy temperature depression, chlorophyll content and significant positive correlation with Leaf surface area (LSA), as shown in Table 4 which inferring that a stable cell membrane can maintain effective cellular activities to sustain amount of photosynthetic pigments, making it possible for the leaves to tolerate drought stress
Summary
Climate change is a prevalent concern that has imposed several challenging ventures on contemporary agriculture. Drought is one of the most important abiotic factor that reduces the yield under rainfed environment (Forouzani and Karami, 2011; Liu and Hwang, 2015) It could be more challenging for the cereals cultivating regions of South Asia that comprises arid and semi-arid climates e.g. Pakistan. Around 25% of the Pakistan cultivated land under is rainfed and it is expected that in future yields of the important crops like wheat, corn, rice, pearl millet and mustard will decrease in this region. These yield reductions, especially in staple crops, could be worse for the agriculture-based economies like Pakistan where wheat contains the largest share of the total cultivated farm area, contributing 2.6% in GDP and accounts for 8.9% value-added in agriculture (Mahmood et al, 2019). Identification of traits that are involved in drought stress tolerance could help the breeders to develop drought tolerant genotypes
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