V.G. Dubey

Genetic Variability, Heritability and Diversity for Yield Contributing Traits in Reference Varieties of Wheat

Genetic variability study in 129 wheat varieties (80 bread and 49 durum wheat) revealed high magnitude of variability and high degree of heritability for majority of yield associated traits. Difference between the PCV and GCV was high for harvest index followed by number of grains per spike and grain yield/plant indicating the influence of environment on their expression. High magnitude of genotypic coefficient of variation (≥ 17.0%) was observed for spike length, plant height, grain yield/plant and flag leaf length, which indicates high degree of genetic variability and offers great scope for selection of these characters. High to moderate heritability coupled with high to moderate genetic advance as percentage of mean was exhibited for 7 traits viz., days to flowering, days to maturity, plant height, number of tillers/plant, biomass/plant, flag leaf length and 1000 grain weight, which indicated the predominance of additive gene action in the expression of these characters and very high possibility of improvement through selection for all these characters. Bread wheat varieties viz., CPAN 3004, GW 322, HI 617, HI 1500, DWR 39, DWR 195, GW 89, UP 2113, NP 700 and NP 771 and durum wheat varieties viz., A-28, HI 8381, MPO 215, HD 4530, HD 4672, NIDW 295, Raj 1555 and UAS 415 were found to be superior for grain yield and other traits along with being divergent from other lines, which can be utilized as donors for developing superior genotypes with high grain yield.

Validation of race non-specific, adult plant leaf rust resistance genes Lr34 and Lr67 in some common wheat (Triticum aestivum L.) cultivars

Twelve common wheat cultivars with Lr34 postulated based on leaf tip necrosis and other observations were studied for adult plant resistance to leaf rust (Puccinia triticina) pathotype 77-5 (121R63-1), and validation of Lr34 and Lr67 through allelic tests. Line 897 and Frontana, known Lr34 carriers, served as checks. Resistance was governed by one dominant gene each in C 306, Kalyansona, Line 897, NI 5439 and WH 147; and by two dominant genes each in Frontana, GW 173, HD 2189, HI 1077, HP 1744, K 9107, PBW 175, PBW 373, and UP 2338. Allelic tests showed presence of Lr34 in Frontana, GW 173, HD 2189, HP 1744 and Line 897; and of Lr67 in C 306, NI 5439 and K 9107. Comparison is drawn with reports based on molecular markers. Our findings should be useful in multiple disease resistance breeding as Lr34 and Lr67 are associated with resistance to multiple wheat pathogens.

Genetic diversity for adult plant resistance to leaf rust in bread wheat (Triticum aestivum L.)

There is an increasing worldwide interest in adult plant resistance (APR) since most examples of durable resistance to leaf rust in wheat are this kind. Twelve bread wheat genotypes were studied for inheritance of APR to leaf rust using pathotype 77-5 (121R63-1), the most prevalent and widely virulent one on bread wheat germplasm in India. Resistance was controlled by a pair of dominant and recessive genes each in CPAN 1676 and CSP 44 and by two independent dominant genes each in CPAN 1796, Frontana, HD 2009, HD 2135, HUW 37, HW 517, Nainari 60, Pavon 76,VL 404 and WG 138. Segregation patterns observed in their intercrosses showed the presence of at least four genes, including a recessive one, among these genotypes in addition to known APR genes Lr34, Lr46, Lr48, Lr49 and Lr68. The present findings are expected to contribute toward enriching diversity for leaf rust resistance in bread wheat improvement programmes.