Planting geometry and nutrient levels affecting seed cotton yield, productivity indices and economic parameters of Bt cotton (Gossypium hirsutum L.)

Abstract

Aim: Lack of location specific information on nutrition requirement and planting geometry needs of Bt cotton hybrids is creating confusion among farmers. Growing Bt hybrids with traditional knowledge or to try different combinations of nutrition and planting geometries is often non-remunerative. Therefore, studies were initiated to find out the optimum combination of planting geometry and nutritional level for better yield to be advocated among farmers. Methodology: A field experiment comprising of 4 planting geometries (PG1 :67.5 cm x 60 cm, PG2: 67.5 cm x 75 cm, PG3:100 cm x 45 cm and PG4: 100 cm x 60 cm) in main and 3 nutrient levels {NL1 :150:30:50:25 (N: P :K :Zn in kg ha-1), NL2:150:40:20:24 and NL3 :175:60:60:25} in sub plots of split plot design was conducted during 2016 and 2017 at Faridkot. Results: Among planting geometries, PG3 (3303 kg ha-1) recorded the highest seed cotton yield (SCY), while PG4 (2728 kg ha-1) recorded least despite highest bolls per plant. Though nutrition levels varied non-significantly for SCY, yet NL2 exhibited better fertilizer use efficiency (FUE), i.e., 13.64, indicative of its advantages over NL1 (11.93) and NL3 (9.77). Interpretation: Thus, based on the present study a PG of 67.5x75 cm and NL of 150:40:20:24 ( N: P :K :Zn in kg ha-1) is recommended. Productivity indices as well as economic parameters elucidate that nutrition rates could be further reduced by 86 kg ha-1 (i.e., 25:20:40:1 kg of N, P, K and Zn) which amount to 33 $ ha-1 from what farmers (NL3) are applying, without any yield loss. Present findings can reduce fertilizer cost and could save 0.13 million ton of fertilizer in ~1.54 million ha of north India alone.