Bio inoculants for enhancing the productivity and nutrient uptake of winter irrigated cotton (Gossypium hirsutum) under graded levels of nitrogen and phosphatic fertilizers

摘要

Field experiments were conducted during winter (August February) seasons of 2003-04 and 2004-05 under irrigated condition at Coimbatore to study the usefulness of bio-inoculants in reducing the inorganic nitrogen and phosphatic fertilizers for cotton. Four graded levels of N and P ( 0,50,75 and 100 % recommended dose (RDNP) and four bio inoculants viz., Azospirillum from, Haryana, Tamil Nadu and Surat were combined with Phosphorus Solubilizing Bacteria (PSB) + Pink Pigmented Facultative Methylotrophs (PPFM) along with uninoculated control. Cotton 'LRA 5166' responded significantly to graded levels of N and P and bio-inoculants. Application of 75% RDNP along with Azospirillum (HAU) + PSB + PPFM yielded 2.91 tonne/ha seed cotton with higher net return (Rs 40,553) and net B:C ratio value of 1.94 while, application of 100% RDNP without bio-inoculants yielded only 2.54 tonne/ha. Judicious combination of bio-inoculants along with moderate use of chemical fertilizers is recommended for cotton.