Rate of Azolla (Azolla pinnata B.Br.) on Weed Control in Pre-Germinated Direct-Seeded Rice

Abstract

A study on weed control in pre-geminated direct-seeded rice was done by applying with fresh azolla at 40, 80, 160, 320 and 640 kg/rai compared with herbicide, hand weeding and untreated treatment. Azolla was broadcasted immediately into puddled soil after seeding of rice. rate of superphosphate fertilizer at 9 kg/rai was done by split applications 3 times during its growth cycle, at seeding and every 7 days after seeding. The water was flooded at 3 days after seeding (DAS). The experiment was conducted at Pathum Thani Rice Research Center, during March-june, 1997. The resultsshowed that azolla covered over the paddy water suface after 15 to 20 days. Azolla amounting 40 to 640 kg/rai reduced total dry weight of weed 20 to 80% at 30 DAS, but had no effects on growth of rice. Azolla amounting 320 and 640 kg/rai increased in number of plants, number of panicles and grain yield over untreated treatments.