Genetic Characterization of Leaf Tip Necrosis and its Effect on Quantitative traits in Wheat (Triticum aestivum L.)

The study aimed to estimate the phenotypic variability for LTN as well as yield traits, genotypic variability for Lr34, Lr46 and Lr67 and to investigate the association between genotypic and phenotypic variability for LTN and yield traits. Two hundred fifty wheat genotypes were screened for the presence of Leaf Tip Necrosis (LTN), a phenotypic marker of wheat resistance to leaf rust infection following Randomized Block Design. Of which 77 genotypes showed variable expression of LTN. Twelve yield traits were analyzed that showed highly significant differences. All these 77 genotypes were validated for the presence of three genes using respective markers viz., csLV34 for Lr34; Xwmc44 for Lr46, and Xcfd71 for Lr67. Out of 77 genotypes, 19 genotypes showed the presence of a single gene (7 with Lr34, 5 with Lr46, and 7 with Lr67), 13 genotypes had all the 3 genes, 14 with a combination of 2 genes and 31 had not shown the presence of any gene. Wheat genotypes within the individual presence of three genes increased the LTN area but their combination, reduced the thousand grain weight, LTNA, and the plot yield. All three genes individually or in combination increased the leaf area. Lr67 alone and in combination with Lr46 reduced the plot yield of wheat genotypes. Interestingly, LTNA had no significant correlation with any of the traits analyzed in this study. Leaf area showed a negative correlation with days to heading, glaucousness index, and thousand grain weight (TGW). NDVI-3 (at dough stage) showed a positive correlation with plot yield and TGW but had a negative association with the leaf area. High heritability coupled with high genetic advance was observed for leaf area (99.70%, 29.52%), LTNA (99.35%), 1000- grain weight (95.37%), grains per spike (93.65%, 17%), and days to headings (88.04%).