Competitiveness of bulrush (Bolboschoenus planiculmis) with rice cultivars, Hashemi and Khazar

Interference interaction of two rice cultivars (Hashemi and Khazar) with Bolboschoenus planiculmis in planting ratios of 4:0, 3:1, 2:2, 1:3 and 0:4, rice seedling : weed tuber were investigated in a replacement series studies. The results showed higher height for Hashemi cultivar than Khazar and B. planiculmis and less tiller number and total dry weight for both rice cultivars comparing to B. planiculmis. Stem multiplication and dry matter production of B. planiculmis decreased more in competition with Hashemi than that with Khazar. Total production of rice tillers and weed stems per pot increased with raising the ratio of weed at the planting proportion. Multiplication of one tuber of weed comparing to three plant of rice was four times more and produced equal dry weight.Relative yield, rice aggressivity index and relative crowding coefficient showed more competitive ability for weed against both rice varieties. As the ratio of rice at the planting proportion raised, biological yield, grain yield, panicle number, and total, filled and unfilled seed number increased. At the competition condition, lower biological yield and panicle length, while higher harvest index, panicle number and 100-seeds weight for Hashemi than khazar. In general, this experiment indicated greater competitiveness for B. planiculmis than the rice cultivars,and Hashemi cultivar showed more interference interactions on the weed than Khazar.