Production potential and nitrogen-use efficiency of interspecific and intra-hirsutum cotton hybrids under graded levels of nitrogen and weed-control methods

A field study was conducted during the winter season of 1997 and 1998 at Tamil Nadu Agricultural University, Coimbatore. Two hybrids (inter-specific ‘TCHB 213’ and intra-hirsutum ‘Surya’) were evaluated for their production potential under 3 N levels (90, 120, and 150 kg/ha) and 4 weed-control methods (Pendimethalin 1.0 kg + 1 hand-weeding, glyphosate 1.0 kg + 1 hand-weeding, hand-weeding twice and unweeded control). The hybrids were grown following the recommended spacing of 90 cm x 60 cm for ‘Surya’ and 120 cm x 60 cm for ‘TCHB 213’. Among the hybrids, ‘TCHB 213’ gave better yield attributes and yield on per plant basis. But ‘Surya’ gave significantly more yield than ‘TCHB 213’ on unit area basis. The response to applied N was increasing at increasing rate up to the highest level (150 kg/ha) of N. But the N-use efficiency decreased with increase in N level. Among the weed-control treatments, hand-weeding twice recorded significantly higher seed-cotton yield and N-use efficiency which was closely followed by glyphosate + hand-weeding.