10 research outputs found
Morpho-physiological and Molecular Variability in Salt Tolerant and Susceptible Popular Cultivars and their Derivatives at Seedling Stage and Potential Parental Combinations in Breeding for Salt Tolerance in Rice
Get PDFSaltol, a major QTL for salt exclusion, was derived from ‘Pokkali’, a salt-tolerant rice cultivar. Apart from Pokkali, many genotypes with wide variation for salinity tolerance offer ample scope for identifying new genes or QTLs underlying various tolerance mechanisms. Such genes could be aggregated into high-yielding backgrounds to reinforce a breeding programme. To identify potential donors for salt tolerance and prospective parental combinations for developing high-yielding salt-tolerant cultivars, ten genotypes were subjected to salt stress and evaluated for morpho-physiological traits and marker-allele polymorphism in the Saltol-QTL region. Although the salt-susceptible high-yielding varieties clustered together in a 3-D plot, principal component analysis showed marked spatial isolation among the tolerant genotypes. Unlike Pokkali and its derivative FL496, Rahspunjar maintained a higher level of K+ despite high Na+ influx in shoots. The wider genetic distances observed at both phenotypic and genotypic levels suggest the possibility of getting transgressive segregants among the offspring of crosses between Rahspunjar and Gayatri or Swarna Sub1. Similarly, SR 26B, which coped with the stress by diluting the Na+ load by maintaining a higher growth rate, differed from Pokkali or Nona Bokra: these two coped with the stress by regulating the transmission of Na+ from roots to photosynthetically active sites. The F2:3 population derived from Savitri × SR 26B showed wide morpho-physiological diversity for salt tolerance. SR 26B was the most distant genotype from Pokkali in the Saltol QTL region and was salt tolerant despite the absence of Pokkali alleles in this region
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No full textNot AvailableIn rice, a major cereal, drought stress is one of the major constraints for production and yield stability in rainfed ecosystems. In an effort to identify promising rice accessions having tolerance against drought, one hundred and thirty four land races that represent different geographic regions of India and a few from Indonesia and Philippines were examined at the vegetative stage under both field and laboratory conditions. Thirty-day-old seedlings were subjected to moisture stress and the experimental field conditions include a ground water table at a depth of > 90 cm, low soil moisture content (10-12%) and high soil moisture tension (up to -50 kPa) at 30 cm soil depth during the stress period. With an SES (Standard Evaluation System) score of 0-3 in the 0-9 scale, seventy eight accessions were scored as tolerant with twelve having '0' score, eighteen with '1' and forty eight with the score ‘3’. Of the seventy eight genotypes, thirteen had recorded yield over 1.0 t ha-1 while the tolerant (CR 143-2-2) and susceptible controls (IR 20) recorded 2.70 t ha-1 and zero yield respectively. The tolerant genotypes were also evaluated further against poly ethylene glycol-6000 induced osmotic stress at both germination (-6 bar) and seedling stages (-8 bar and -10 bar). From the pooled data, six genotypes i.e. IRGC 12263, IRGC 636, IRGC 45699, IRGC 40275, IRGC 53989 and IRGC 51231 were identified as drought tolerant with good yield potential (0.7-1.95 tha-1) under stress conditions.ICA
