No abstract

The magnitude of genetic inheritance and expected genetic advance are important for the prediction of response to selection in diverse environments and provide the basis for planning and evaluating breeding programs. This work investigated the inheritance of traits related to drought in wheat under natural drought conditions. Cross combinations were made to produce F 1 and F 2 hybrid populations, which were evaluated in a randomized completed block design with three replications at University of Agriculture, Faisalabad, Pakistan. Six wheat varieties/lines and six derived F 2 hybrids were studied to ascertain heritability and genetic advance for plant height, days taken to maturity, number of tillers per plant, spike length, number of grains per spike, 1000-grain weight, and grain yield per plant. Data were collected and subjected to statistical genetic analyses. Heritability estimates and expected genetic advance for plant height, days taken to maturity, number of tillers per plant, 1000-grain weight and grain yield per plant were high for the entire cross combinations while the estimates for spike length and number of grains per spike were relatively low. Our results suggest that improvement for these characters should be faster because of higher heritabilities and greater phenotypic variation. Prospects of genetic improvement for all the characters studied are evident. The most promising cross combinations were WL60 × LU26S and WL61 × LU26S. These traits, therefore, deserve better attention in future breeding programs for evolving better wheat for stress environments.

Several wheat genotypes were screened against heat stress. Seven wheat (Triticum aestivum L.) cultivars obtained after screening against heat classified as tolerant, moderately tolerant, and susceptible to heat stress, were mated in a complete diallel mating system to study the inheritance pattern of relative cell injury percentage (cell injury %) and some yield contributing parameters under normal and heat stress conditions. Significant genotypic differences were found (P < 0.01) for all the studied traits under both regimes. The scaling test disclosed partial adequacy for traits such as days to heading and days to maturity, but for flag leaf area and relative cell injury %, it showed full sufficiency under both environments. The model for grain yield per plant and biomass per plant were fully adequate under normal conditions, but partially adequate under stress. The harvest index showed partial adequacy under normal conditions, but was fully adequate under stress. The additive component of genotypic variation (D) was significant for all studied traits and more significant than the H 1 and H 2 dominance components. Values of the gene proportion with positive and negative effects in the parents (H 2 /4H 1 ) demonstrated an unequal distribution of dominant genes in the parents for almost all the traits except for flag leaf area, grain yield per plant, and harvest index which showed an equal distribution of dominant genes under stress conditions. High heritability estimates were found for days to heading, days to maturity, flag leaf area, grain yield, and relative cell injury percentage under both regimes. Moderately high estimates were found for biomass per plant and harvest index.

To cite this paper: Hussain, M., M.A. Khan, M. Hussain, N. Javed and I. Khaliq, 2015. Application of phenotypic and molecular markers to combine genes for durable resistance against rust virulences and high yield potential in wheat. AbstractIn order to combine genes for enhancing rust resistance and high yield potential in wheat, parent lines were selected for hybridization on the basis of slow rusting history and phenotypic characters for durable resistance. The hybridized germplasm was advanced in filial generations from F 1 to F 5 . Total 750 head rows were planted in F 6 from selected heads among F 5 generation. From 750 single head rows planted in Kaghan, 345 lines were selected on the basis of agronomic traits and rust resistance; two hundred and twenty lines were selected for high yield and rust resistance performance and evaluated for the presence of durable rust resistant genes with molecular markers. It was confirmed that the lines showing durable rust resistance possessed Lr34/Yr18, Lr46/Yr29 and Sr2/Yr30 genes in combination or individuals from these lines. The results indicated that the most prominent lines i.e., V-11211, V-11212, V-11218, V-11227, V-11262, V-11288, V-11296, V-11304, V-11308, V-11319, V-11338, V-11353, V-11365 and V-11396 showed the combination of three designated slow rusting genes. These lines were high yielding with better resistance than all existing approved wheat varieties of the country. None of these lines had complete resistance, but were of slow rusting type and were suitable for commercial cultivation. These results will be useful for wheat breeders and pathologists of the country in planning of future hybridization program.