Manzoor A. Ganai

Effect of water regimes and weed management practices on nutrient uptake by rice and weeds under the system of rice intensification

A field experiment was conducted in kharif 2012 and 2013 at MRCFC, SKUAST, Khudwani (Kashmir) on a silty clay loam soil to evaluate the impact of water regimes and weed management practices on nutrient uptake in rice and weeds under SRI. The soil at experimental site was neutral in reaction, medium in available P, K and organic carbon and low in available N. The treatments comprised of 3 irrigations schedules [alternate wetting and drying (AWD), continuous saturated condition and continuous flooding] and 7 weed management practices viz., 4 herbicidal treatments [pyrazosulfuron ethyl @ 20 g a.i. ha−1 (3 DAT); cyhalofop butyl @ 80 g a.i. ha−1 (15 DAT); pyrazosulfuron ethyl 20 g a.i. followed by cyhalofop butyl 80 g a.i. ha−1 (3 and 15 DAT), and butachlor @ 1.5 kg a.i. ha−1 (3 DAT)]; cono weeding, weedy check and weed-free control. The results revealed that saturated water regime treatment had highest uptake of macronutrients by grain and straw, while highest uptake of macro-nutrients by weeds was in AWD and lowest in continuous flooding. Among weed control measures, the lowest macronutrients uptake by crop was associated with post-emergence application of cyhalofop-butyl and highest amount of NPK depletion by weeds was observed in unweeded control. Minimum NPK uptake by weeds was noticed in sequential application of pyrazosulfuron-ethyl @ 20 g a.i. ha−1 and cyhalofop-butyl @ 60 g a.i. ha−1 treatment.

Management of nitrogen through leaf colour chart (LCC) in rice under irrigated conditions of Kashmir

A field experiment was conducted at Research Farm, SKUAST-Kashmir, Shalimar, Srinagar (India) to study the management of N through leaf colour chart (LCC) in two rice genotypes cv. ‘Jhelum’ and ‘SR-2’ during kharif 2012 and 2013. The soil of experimental field was silty clay loam with organic C 0.92%, pH 6.6, EC 0.22 dS m−1, available N 308.96 kg ha−1, P 33.38 kg ha−1 and K 169.26 kg ha−1. Genotype ‘SR-2’ gave significantly more yield than ‘Jhelum’ whereas LCC ≤ 5 @ 30 kg N ha−1 i.e. 150 kg N ha−1 applied in 5 splits gave significantly higher grain yield but was at par with 120 kg N ha−1 applied in 6 splits [LCC ≤ 5 @ 20 kg N ha−1] as compared to the recommended dose of 120 kg N ha−1. Chlorophyll content increased significantly with increase in N through LCC. The mean chlorophyll content varied from 0.22 to 0.39 and 0.22 to 0.40 g m−2 during 2012 and 2013, respectively. The correlation coefficient between SPAD and LCC, and SPAD and N were positively correlated at all growth stages of rice. Use of LCC also saved 10 to 40 kg N ha–1 over fixed-time N applications. The application of N through LCC ≤ 5 @ 30 kg N ha−1 gave higher gross returns, net returns and benefit cost ratio in both the rice genotypes.