Authors:D. Garg, S. Sareen, S. Dalal, R. Tiwari and R. Singh
Terminal heat referred to as increase in temperature during grain filling, is one of the important stress factors for wheat production and is responsible for decline in wheat production in many environments worldwide. In order to meet the challenges of high temperature ahead of global warming, concerted efforts are needed to evaluate wheat genotypes for heat tolerance and develop genotypes suitable for such stressed environments. Twenty-seven advanced wheat genotypes developed for stress and normal environments by different research centres were evaluated during 2009–10 and 2010–11 under timely sown (normal) and late sown (heat stress) environments. Analysis of variance revealed that the genotypes differed significantly in grain filling duration (GFD), grain growth rate (GGR) and thousand-grain weight (TGW). Out of 27 genotypes, 16 were found to be tolerant for thousand-grain weight under late planting (heat stress) during 2009-10 but only 12 were tolerant during 2010–11. Many of the genotypes registered more reduction in thousand-grain weight during 2010–11 as compared to 2009–10; the temperatures during 2009–10 were higher. The differences in grain filling duration under two conditions during both seasons as well as difference in temperatures during first half of grain filling explain the reduction pattern in the genotypes. GFD had significant negative correlation with temperatures during post heading period and the difference in GFD under two environments had positive correlation with these temperatures. The reduction in GFD had regression of 33.3% on reduction in GGR and reduction in GGR had regression of 41.6% on reduction in TGW genotypes AKW 1071, DBW 17, HS 277, K 7903, K 9107, NW 1014 and RAJ 3765 had less sensitivity to stress environments during both years.
Authors:S. Singh, R. Malik, R. Garg, R. Devraj and P. Sheoran
Apart from the issue of sustainability and resource drain, the yield plateau in the rice-wheat cropping system of south-east Asia is the major area of concern. Realizing that genetic gain is a remote possibility, efforts are directed to management options for yield improvement. Adequate crop nutrition in general and nitrogen (N) in particular figure at the top among various management issues. A survey was conducted covering the rice-wheat belt of Haryana state, India representing Trans-Gangetic plains to know about on-farm practices related to N management in wheat crop and how far it deviates from the blanket recommendations given by State Agricultural Universities. The survey revealed that about 42.7 per cent farmers used either recommended dose of N (150 kg/ha) or less and others used higher dose of N. Positive correlation between the size of the farm and extent of N used was established. Whenever the farmers tended to use higher dose of N, they also tended to partition it in more number of splits (up to 3 splits, excluding basal application) staggering upto 54 days after sowing (DAS) as against the recommended practice of two splits (including basal application) within 35 DAS. The study confirmed deviation from the recommended practices of N management but major revelation came about reverse gap holding that the practice of N management in wheat crop being followed by the farmers is better in terms of grain yield. The NPhysical optimum and NEconomic optimum exceeded the current use (165.7 kg/ha) and recommended levels. This study suggests a fit case for the upward revision of recommended dose of N in wheat crop involving no element of risk as arising from aggravated problem of insect pest and disease complex. Nearly half of the farmers use either recommended dose of N or less than that and it is here, where opportunity lies in augmenting the wheat productivity by enhancing the existing level of N use.