Effect of planting density and nitrogen levels on productivity and N-use efficiency of rainfed upland cotton (Gossypium hirsutum)

A field experiment was conducted during the rainy season of 1996 and 1997 on a shallow typic ustochrept to evaluate the response to N and plant density requirements for ‘CNH 36’ upland cotton (Gossypium hirsutum. L.). The experiment was conducted in split-plot design with 3 planting densities (D₁, 74,100; D₂, 49, 400; and D₃, 37,050 plants/ha) as main plots and 4 N (0, 50, 75, 100 kg N/ha) levels as subplots. At high plant population (D₁), significant response could be obtained up to 75 kg N/ha and interaction of D X N was significant. The economic optimum dose at D₁, D₂ and D₃ was 84, 88 and 62 kg N/ha respectively. The apparent recovery of applied N was highest with D, (31.3–47.6%), intermediate with D₂ (29.5–31.8%) and least with D₃ (17.8–26.8%). The petiole nitrate-nitrogen was low at higher planting densities.