Optimum Seed Rate and Nitrogen Requirement for Broadcast Blackgram (Vigna mungo l.) Grown on Rain-fed Uplands

A field experiment was conducted at the Field Crops Research and Development Institute, Mahailluppllama to identify an optimum seed rate and the respective nitrogen level for broadcast blackgram grown on rainfed uplands during Maha 2009/2010 with the variety MI-1. The study was carried out as a two factor factorial experiment. Six seed rates (25 kg/ha, 37.5 kg/ha, 50 kg/ha, 62.5 kg/ha, 75 kg/ha, 87.5 kg/ha) with two rates of nitrogen (30 kg of N/ha, Zero N) were the two factors tested in the experiment. The results revealed that the plant height, leaf area per plant and canopy diameter did not vary with the seed rate but significantly varied with fertilizer rates. Number of pods per plant, number of seeds per pod and 1000 seed weight did not vary with the seed rate but number of pods per plant and 1000 seed weight varied with the fertilizer level. The maximum yield was recorded at a seed rate of 64 kg/ha. Economic analysis revealed that the optimum seed rate is 62.5 kg/ha. The number of plants/ m2 at which maximum yield was obtained was estimated as 93 plants/m² which is also comparable to this seed rate. As there were no differences observed in yield components except for the number of plants per unit area, the main contributing factor for yield increments with increasing seed rate was the number of plants per unit area. Therefore, it can be concluded that the optimum seed rate for broadcast crop of black gram under rain-fed conditions is 62.5 kg/ha when N is supplied at the rate of 30 kg/ha. <br /><br /><strong>Key words: </strong>Blackgram; Nitrogen requirement; Optimum rate seed <br /><br />DOI: 10.4038/tar.v22i2.2825<br /><br /><em>Tropical Agricultural Research</em> Vol. 22 (2): 165-171 (2011)