Abstract

                                Field experiments were conducted in wetlands of Tamil Nadu Agricultural University, Coimbatore during rabi, 2001-02 and summer, 2002 to study the effect of weed control treatments on nutrient uptake by crop and removal by weeds and their impact on yield. Pretilachlor at five levels (0.5, 0.75,1.0,1.5 and 3.0 kg ha-1) were compared with anilofos (0.4 kg ha-1), butachlor (1.25 kg ha-1) and pretilachlor (Rifit) (0.75 kg ha-1) as well as the farmers’ practice of two manual weeding and un weeded control. Nutrient uptake by crop and removal by weeds were recorded at active tillering, panicle initiation and at harvest stage. The results revealed that pretilachlor at 3.0 kg ha-1 resulted in reduced nutrient depletion by weeds and was comparable with pretilachlor at 1.0 kg ha-1. Pretilachlor at 1.0 kg ha-1 recorded maximum nutrient uptake by crop and remained comparable with pretilachlor at 0.75 kg ha-1 and hand weeding twice and thereby grain yield of rice.

Key words : Rice, nutrient uptake, removal by weeds, yield.