Abstract
Field experiments were conducted at Tamil Nadu Agricultural University, Coimbatore, India, during 1982-83 to study the interaction effects between applied N and insecticides (Carbofuran and Phorate) on growth and yield of rice, to compare the phytotonic effects of these insecticides and to evolve an efficient and economic combination of fertilizer N and soil-applied insecticides for lowland rice. The experiments involved four levels of N (0, 60, 90 and 120 kg ha-1) and three levels of insecticides (no insecticide, Carbofuran at 0. 75 kg ai ha-1 and Phorate at 1.0 kg ai ha-1). The experiment was repeated over three seasons. Carbofuran and Phorate increased the root dry weight, shoot dry weight, LAI, N uptake, recovery percentage of applied N, yield components and grain yield of rice in all three seasons. Nitrogen application also had similar effect on the above characters up to 90 kg N ha-1. The interaction between N and insecticides (Carbofuran and Phorate) was synergistic on growth and yield of rice in all the seasons. Combined application of the insecticides with N reduced the fertilizer requirement of rice by 30 kg ha-1 in all seasons. The highest synergistic effect on grain yield occurred during the summer, with the effect of Carbofuran and Phorate being more or less similar. 60 kg N ha-1 along with Carbofuran at 0.75 kg ai ha-1 or Phorate at 1.0 kg ai ha-1 is an efficient and economic combination of N and insecticides for lowland rice.
