FLOODING TREATMENT RESTRAINS VOLUNTEER RICE GERMINATION AND SEEDLING GROWTH

Volunteer rice is a global problem in rice production, especially conservation tillage. Here volunteer rice from four rice cultivars viz. Xiangyaxiangzhan, Meixiangzhan, Changnongjing 1 and Yliangyou 11 73 was treated with different flooding treatments. Two weeks of water flooding were applied at four depths: 2.0-2.5 cm (F1), 3.0-3.5 cm (F2), 4.5-5 cm (F3) and 6.0-6.5 cm (F4). A control was set by maintaining the soil wet as normal farmer practice of this region. It was found volunteer rice germination was more reduced with increased submergence levels, while treatments F3 and F4 both decreased the germination index and germination energy greatly for all rice varieties. Flooding treatments also reduced the seedling rate and inhibited the growth of volunteer seedling. Treatments F3 and F4 decreased seedling rates of Changnongjing 1 and F2 generation of Yliangyou 11 73 to zero, while the flooding treatment induced the malonaldehyde accumulation and altered the activities of peroxidase, superoxide and catalase in seedlings for all rice varieties. Hence, we suggest 2 -week flooding at soil depth 6 cm after the harvest of early-season rice in South China in order to prevent the harvest loss in late-season rice caused by volunteer rice.