WILD RICE BIOLOGICAL CHARACTERISTICS AND INTEGRATED CONTROL

摘要

Wild rice is a kind of dangerous weed in paddy field in many countries, which seriously inhibited rice growth and caused rice yield loss more than 50%. The dormancy, germination, reproduction, blooming, seeding, biological characteristics of wild rice varieties Oryza rufipogon, O. barthii, O. punctata, and O. longistaminata were observed for two years at Mubalali Farm in Tanzania. Germination rate of O. rufipogon seeds in 0-4cm depth of soil was more than 98% and under 4cm depth of soil very low. Compared with rice, wild rice had the characteristics such as rate of high seed reproduction, short growth period, quick ear coming, blooming, maturing and seed falling. O. longistaminata seeds had more than one-year dormant period with very low germination rate. O. longistaminata reproduced vegetatively on roots and stems mainly and its root system can reach more than 40cm depth when high soil moisture exists. Integrated control methods for wild rice are water flood crop and dry land crop rotation, germination induction, combined with chemical control. Encouraged germination of annual wild rice seeds, killing of wild rice seedling at 3-4 leaf stage by Gramaxone, integrated with direct seeding under non-tillage gave 96% control of O. rufipogon and other two species. The perennial wild rice O. longistaminata with buds induced at 5-6 leaf stags was controlled with Glyphosate, and combined with zero-tillage cowing, which had than 90% control result.