MORPHOGENETIC CHARACTERIZATION OF WHEAT GERMPLASM FOR DROUGHT TOLERANCE

Abstract

Drought is the main environmental problem that causes high negative effect on cereals crops particularly wheat. It is a great challenge for crop breeders to produce cultivars having good potential of survival in drought stress environment. In the present research one hundred and three Wheat genotypes were evaluated for drought stress. On the basis of morphological traits, genotype 010718 ranked first on the basis of days to maturity (DM), 010771 showed highest number of tillers per plant (NTP), 010817 has highest spike length (SL), 010814 has highest peduncle length (PL), 010813 has greatest number of spikelets per spike (NSPS), 010874 has highest 1000 grain weight (GW), 010874 have highest harvest index (HI) and 010822 showed optimum plant height (PH). These genotypes could be used for further breeding programs to improve wheat production under drought stress conditions of Pakistan. The same genotypes were also evaluated for physiological tests including relative water content normal (RWCN), relative water content stress (RWCS), water loss rate normal (WLRN), water loss rate stress (WLRS) and water use efficiency (WUE) under both normal and drought stress regimes. The analysis of variance (ANOVA) results concluded that highly significant differences were found among the genotypes in both normal and drought stress. 010824 recorded the highest RWC in normal while 010809 recorded the highest relative water content (RWC) in drought stress conditions. 010808 and 010808 was ranked first on the basis of water loss rate normal (WLRN) and water loss rate stress (WLRS) while 010831 was ranked first in water use efficiency (WUE) test. These genotypes may be suggested for further cultivation in irrigated and rainfed areas of Pakistan. In the present study thirteen root traits were evaluated for drought tolerance. All root traits showed significant differences among the genotypes at (P≤0.01). 010842, 011862, 010853, 010829 and 011881 ranked first on the basis of root traits and considered to be best for drought stress areas of Pakistan. All the genotypes were screened with 105 SSR markers. Most of the markers showed high level of polymorphism. Total of 279 polymorphic alleles generated. The alleles per locus ranged from 1-3 and an average of 2.63 per locus. Polymorphic information content (PIC) values of the markers was calculated in the range of 0.00–0.59. The association analysis revealed that one hundred and three genotypes having different genetic background were classified into fifteen distinct groups. Total of 08 MTAs were recorded for root traits in GLM and MLM models. The genetic information obtained in the present study in the form of MTAs/QTLs could be utilized for breeding programs to improve drought stress tolerance.