Influence of sorghum cultivars and weed management practices on nutrient uptake by crop and weeds in semi-arid tropical India

Field experiments were conducted at Directorate of Sorghum Research, Rajendra Nagar, Hyderabad, India during the rainy seasons of 2009 and 2010 to assess the effect of grain sorghum cultivars and weed management practices on nutrient uptake in grain sorghum and associated weeds. Treatments were unweeded control (weedy check), atrazine 0.50 kg ha−1 as pre-emergence + 1 hoe weeding at 30 days after sowing (DAS) and atrazine 0.50 kg ha−1 as pre-emergence + 2 hoe weeding at 30 and 45 DAS in main plots and 11 grain sorghum cultivars including six hybrids (CSH 16, CSH 23, CSH 14, SPH 1596, SPH 1606 and SPH 1616) and five open pollinated varieties (CSV 15, CSV 17, CSV 20, CSV 23 and SPV 462) in sub plots replicated thrice in a split plot design. Sorghum cultivars varied significantly for NPK uptake by sorghum and also the nutrients depletion by the weeds. Uncontrolled weeds removed 38.71–43.45 kg N, 8.91–9.97 kg P and 38.57–43.38 kg K ha−1 from the soil. The NPK uptake by sorghum increased significantly under weeding once or twice compared to that of unweeded control due to effective control of weeds. The lowest N depletion (11.65 and 15.47 kg ha−1) by weeds was recorded with ‘CSV 20’, P (2.65 and 3.72 kg ha−1) with ‘CSH 16’ and K (11.07 and 17.58 kg ha−1) with ‘SPV 462’ due to variations in the weed suppressing ability of the cultivars. Use of nutrient-use efficient and weed suppressive cultivars like ‘CSH 16’, ‘CSV 20’ and ‘SPV 462’ in integration with appropriate weed management practices are necessary to increase the nutrient-use efficiency and productivity of sorghum. As the weeds contain large amount of nutrients, the manually removed weeds may be used in composting as well as in mulching to conserve the soil moisture in dryland situations. © Indian Society for Plant Physiology 2014.