EFFECT OF WEED-CONTROL AND NITROGEN ON WEED GROWTH AND YIELD OF GROUNDNUT (ARACHIS-HYPOGAEA)

An experiment was conducted at Bhopal during the rainy (kharif) seasons of 1987 and 1988 on a deep Vertisol, poor in N, medium in P and rich in K status. Hand-weeding twice showed lowest dry matter and nitrogen uptake by weeds and maximum nodulation of groundnut crop compared with the other treatments. This treatment also produced highest pod yield which was at par with the yield obtained by interculturing twice at 25 and 40 days after sowing and pre-emergence application of oxidiazon or fluchloralin each @ 1 kg/ha applied in combination with interculturing at 40 days after sowing. All these treatments were found almost equally effective in controlling the associated weeds. Oxidiazon in combination with interculturing at 40 days after sowing or interculturing twice appeared to be more economical. Higher levels of N (30 and 45 kg/ha) significantly decreased the weed population, dry weight of weeds and its nitrogen uptake and increased the pod yield and root nodulation compared with lower nitrogen levels. The highest net returns/rupee of additional investment on N were obtained up to 30 kg N/ha.