Abstract

                                Field experiments were carried out at Cotton Research Station, Srivilliputturfrom August to January 2017-18 and 2018 -19 to optimize fertilizerrequirement of prerelease varieties of cotton with two levels of spacingunder irrigated conditions. The experiments were conducted in a splitsplit-plot design with three replications. The treatments consisted of twopre-release cotton varieties (GSHV 177 and CCH 14-1 during 2017-18 andBGDS 1033 and CCH 15-1 during 2018 -19 ) in main plots and two levels ofplant geometry (75 x 30 cm and 75 x 45 cm) in subplots and three doses offertilizers (75 % RDF - 60:30:30 Kg NPK/ha, 100 % RDF - 80:40:40 Kg NPK/ ha and 125% RDF- 100:50:50 Kg NPK/ha) were accommodated in subsubplots.The results revealed that the genotypes GSHV 177 and CCH 15-1performed better by producing taller plants, a higher number of sympodia,bolls per plant, and a number of bolls/m2 with higher seed cotton yield andeconomic benefits. Adoption of normally recommended spacing of 75 x 30cm recorded significantly more bolls production and higher seed cotton yieldthan the wider spacing of 75 x 45 cm during both the years of study. Theeffect of both 125 and 100 per cent RDF on a number of bolls / m2 was onpar. Application of 125 per cent RDF registered comparable seed cottonyield during 2017-18 and significantly higher than 100 per cent RDF during2018-19. Higher total income, net income and benefit-cost ratio were alsoobserved with under 75 x 30 cm spacing and 125 per cent RDF.

Key words : Cotton varieties, economics, fertilizers, seed cotton yield, spacing