Response of Pea (Pisum sativum L.) to Levels of Phosphorus in Relation to Integrated Weed Management

Pea has higher requirement of P for symbiotic N fixation. However, weeds are the major threat in harnessing the full potential of native and applied P. Management of weeds through integrated means (INM) is imperative to enhance P use efficiency. Three P₂O₅ levels viz. 0, 30 and 60 kg/ha each with six weed management practices viz. weedy check, pendimethalin followed by (tb) hand weeding (HW), stale seedbed (SSB), SSB + pendimethalin tb HW, raised stale seedbed (RSSB), and RSSB + pendimethalin tb HW were evaluated during rabi 2006-07 and 2007-08 on a silty clay loam soil at Palampur. Phalaris minor was the most important weed constituting 60.9 and 64.4% of the total weed flora during 2006-7 and 2007-8, respectively. SSB and RSSB were equal to pendimethalin tb HW in reducing its count upto 120 DAS. Superimposition of pendimethalin tb HW further improved the effectiveness of SSB and RSSB in reducing the count of P. minor. Pendimethalin tb HW with or without SSB/RSSB significantly reduced the count of Vicia sp. and Polygonum sp. over other treatments. In the raised beds, the peas were early in emergence. In the weedy check peas were earlier in maturity. SSB and RSSB were as good as pendimethalin tb HW in influencing pea pod and straw yield. Yields were further increased under SSB/RSSB + pendimethalin tb HW. SSB, RSSB, pendimethalin tb HW, SSB + pendimethalin tb HW and pendimethalin tb HW increased green pea yield by 125, 63, 82, 154 and 173%, respectively over weedy check. All the weed control treatments except RSSB gave higher gross and net returns and B:C ratio. There was significant increase in plant height, plant dry weight, yield attributes, green pod and straw yield of pea and gross and net return, days to emergence, flowering, and maturity with increase in the level of P₂O₅. Under weedy check as well in SSB and RSSB, P₂O₅ application resulted in higher weed dry weight over no P₂O₅ application. But under SSB/RSSB tb pendimethalin tb HW, weed dry weight was more or less similar due to P₂O₅ levels. Crop fertilized with 60 kg P₂O₅/ha under RSSB tb pendimethalin tb HW resulted in highest green pod yield.