Rice (Oryza sativa), the staple food of more than half of the population of the world, is an important target to provide food security and livelihoods for millions. Direct seeding of rice (DSR) refers to the process of establishing the crop from seeds sown in the field rather than by transplanting seedling from the nursery. Before the advent of Green revolution and adoption of irrigation, rainfed rice was often broadcasted into moist soil and yields were low, variable and highly prone to weed competition. Weed spectrum and degree of infestation in rice field are often determined by rice ecosystems and establishment methods. Research evidences at different places has shown around 20-100% losses due to weeds such as Echinochloa spp., Leptochloa spp., Cyanotis spp., Commelina sp., Digitaria spp. and Alternanthera sp in DSR. Integrated weed management approach based on the critical period of crop weed competition, involving different direct and indirect control measures, has been developed and widely adopted by farmers to overcome weed problem in DSR in a sustainable way. Stale seed bed combined with herbicide (paraquat/glyphosate) and zero till results in better control. About 53% lower density was recorded due to stale seed bed. Brown manuring of Sesbania reduces weed population by 50%. Mulches, crop rotation and rice cultivars like 'Narender 359' and 'Sarjoo 52' were found better for Indo-Gangetic plains. Application of penoxsulam 25 g/ha as broad-spectrum, azimsulfuron + metsulfuron-methyl for Cyperus spp., pendimethalin at 1.25 kg/ha for Echinochloa spp. were found suitable for chemical weed management.Weed-competitive and allelopathic rice varieties, seed priming for increased weed competitiveness, higher seeding density should be considered as a management strategy.
The experiments were conducted during winter season of 2011-12 and 2012-13 to evaluate heat stress response of wheat to paddy straw mulch and foliar nutrition of calcium and potassium in irrigated situation of mollisols of GBPUAT, Pantnagar, Uttarakhand, India. The treatments comprised of paddy straw mulch at 6 t ha -1 (just after sowing) and no mulch as the first factor and 6 foliar nutrition of Calcium Chloride (0.1%) and Potassium Chloride (0.2%) at booting and post-anthesis stage (one week after anthesis) along with two treatments having water spray with same spray volume i.e. 300 l ha -1 applied at booting and post-anthesis stages and no-spray as the second factor. All yield attributing characters were on higher side in mulch treated plots compared to non-mulch however the values were non-significant. Grain yield was significantly higher in mulched plots than non-mulch. Foliar spray of KCl at 0.2% at post-anthesis stage increased the productivity of wheat significantly compared to control and other foliar treatments. All other foliar treatments were at par with control with respect to grain yield of wheat. Climatic condition particularly the rainfall distribution and temperature regime had effect on crop productivity. The betterment of yield due to these treatments was due to better efficiency of PSII accentuated by higher value of Fv Fm-1. The effect of treatments did not influence phenology of crop.
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