Effect of agronomic practices on the performance of aerobic rice (Oryza sativa) and associated weeds under Alfisols of eastern dry zone of Karnataka

An experiment was conducted during the rainy season (kharif) of 2011 and 2012 at Bengaluru, Karnataka to evaluate the effect of integrated package of agro-techniques on weeds and aerobic rice (Oryza sativa L.). The experiment was set up in a randomized complete-block design replicated thrice, consisting of 10 treatment combinations of recommended dose of fertilizers (RDF), FYM, FeSO₄ and biofertilizers along with pre-emergence herbicide pyrazosulfuron ethyl at 25 g a.i./ha alone and with integrated weed-management practices. Along with this, site-specific nutrient management for targeted yield of 6.5 and 7.5 t/ha, respectively, + integrated weed management practices were also tried. Treatments receiving integrated weed management practices (pre-emergence herbicide pyrazosulfuron ethyl at 25 g a.i./ha + hand-weeding at 20 days after sowing + first intercultivation 25 days after sowing and subsequent intercultivations at 15 days interval up to panicle-initiation stage) recorded significantly lower weed population, weed dry weight and nutrient uptake by weeds than pre-emergence application of pyrazosulfuron ethyl alone. Application of RDF + FYM + biofertilizers + FeSO₄ + integrated weed management resulted in significantly higher grain and straw yields, water productivity and nutrient uptake (N, P, K, Zn and Fe) by crop than that with RDF + FYM + pyrazosulfuron ethyl at 25 g a.i./ha. Similar trend was also observed for net returns and benefit: cost ratio.