水莎草对水直播稻产量的影响及其防除技术

EFFECTS OF Cyperus juncellus ON YIELD OF DIRECT SOWING RICE AND CONTROL TECHNIQUE

水莎草是稻田的主要恶性杂草,8月份发生量最大。其密度、与稻苗共生期是造成水直播稻减产的主要因子。产量损失率与稻田后期杂草、前期杂草的相关式分别为:Y_后=0.4539X_1+0.0515X_2-9.5820;Y_前=0.3485X_1+0.0672X_2-10.6441。不同时期水莎草造成的损失差异很大,因此防治指标是动态的,不同时期有不同的防治指标。

Cyperus juncellus is an important perennial weed in thd rice fields.The emer- gence peak of Cyperus juncellus occurred through whole August.The main factors causing yield loss of direct sowing rice were different densities and different periods of interference duration of Cyperus juncellus.The relative pattern between thd yield loss of rice and Cyperus juncellus in the late growth period of rice was:y=0.4539X_1+0.0515X_2—9.5820;in the early growth period of rice was:y=0.3486X_1+0.0672X_2—10.6441,where Y is rate of yield loss of rice,X_1 is days of interference duration,X_2 is density of Cyperus juncellus.There is great dif- ference in thd yield loss of rice caused by Cyperus juncellus in different periods,therefore, economic threshold is changeable with thd time.