P. K. Singh

Bayes Estimator of Inverse Gaussian Parameters Under General Entropy Loss Function Using Lindley's Approximation

In this article, we obtained Bayes estimators of parameters of Inverse Gaussian distributions under asymmetric loss function using Lindleys Approximation (L-Approximation). The proposed estimators have been compared with the corresponding estimators obtained under symmetric loss function and MLE for their risks. This comparison is illustrated using Monte-Carlo study of 2,000 simulated sample from the Inverse Gaussian distribution.

Characterization of yellow rust resistance genes by using gene postulation and assessment of adult plant resistance in some Indian wheat genotypes

The yellow rust caused by Puccinia striiformis f.sp. tritici is an important constraint to wheat production worldwide. Host resistance is the most economicalway to manage yellow rust. Race-specific resistance is short-lived and overcome by the evolution of new races of the pathogens. However, non-race-specific, or quantitative resistance, controlled by many genes and effective at the adult plant stage, is generally considered to be more durable and long-lasting. Such type of resistance should be of primary interest to wheat breeders around the world. With this background, old wheat genotypes/cultivars were evaluated against different pathotypes of Puccinia striiformis for resistance at both the seedling and adult plant stages. By applying the gene matching technique, three yellow rust resistance genes viz., Yr2, Yr9 and Yr18 were postulated. Adult plant resistancewas assessed through host response and epidemiological parameters i. e. final rust severity, relative area under rust progress curve, coefficient of infection and infection rate. Promising adult plant resistance was observed on the cultivars DBW 17, DBW 71, PDW 314, HS 507, VL 804, VL 829, VL 907, HPW 251, HPW 349, HD 2967, HD 2985, HD 3043, HD 3086, PBW 660, C 306, HI 1563, WH 1021, WH 1080 and Raj 4083 consistently during rabi seasons of 2013–15. All these promising yellow rust resistant cultivars at adult plant stage were susceptible at seedling stage to one or more pathotype(s) of yellow rust, which indicated the presence of adult plant resistance. At seedling stage, adult plant resistance gene Yr18 was characterized in eight cultivars, namely, HS 277, VL 804, VL 829, HD 2733, NI 5439, NIAW 34, PBW 175 and C 306 where, it occurred in combination with other genes in the seven cultivars. All these wheat cultivars exhibited effective adult plant resistance.