Effect of weed control and phosphorus sources on productivity of wheat (Triticum aestivum)

A field experiment was conducted to study the effect of herbicides and phosphorus sources on productivity of wheat (Triticum aestivum L.). The weed flora at site were Chenopodium murale, C. album, Anagallis arvensis, Convolvulus arvensis, Melilotus indica, Spergulla arvensis, Malva parviflora, Fumaria parviflora, Rumex obtusifolius and Coronopus didymus among broadleaf weeds and Phalaris minor in grassy weed. The experiment consisted of eight herbicide (weedy check, 2,4-D at 500 g ha-1, triasulfuron at 15 g ha-1, carfentrazone at 20 g ha-1, isoproturon at 750 g ha-1, 2,4-D + isoproturon at 500 + 750 g ha-1, triasulfuron + isoproturon at 15 + 750 g ha-1, carfentrazone + isoproturon at 20 + 750 g ha-1) and three phosphorus sources (DAP, SSP and PROM) making twenty four treatment combinations. These treatments were evaluated in randomized block design with four replications. Amongst the weed control treatments tank mixture of carfentrazone + isoproturon (20 + 750 g ha-1) resulted in complete elimination of all the broadleaf weeds except Convolvulus arvensis. Isoproturon and its tank mixture with other reduced weed density and dry matter of Phalaris minor significantly than weedy check and rest of the treatments. Tank mix application of herbicides tended to reduce weed dry matter significantly in comparison to singly applied herbicides, however, carfentrazone + isoproturon resulted in minimum weed dry matter (11.29 kg ha-1) and highest weed control efficiency (97.33%). Consequently, it produced significantly higher grain (5816 kg ha-1) and straw (8904 kg ha-1) yields and net returns ( 65267 ha-1) compared to other treatments. This mixture recorded significantly lower N, P and K uptake by weeds with concomitant 84.9, 119.5 and 73.3 % higher uptake of these nutrient elements by wheat crop over weedy check.