华北地区夏玉米田马唐治理的生态经济杀除阈期研究

STUDY ON THE ECO-ECONOMIC THRESHOLD PERIOD FOR CONTROLLING DIGIT ARIA SANGVINALIS IN SUMMER MAIZE FIELD IN NORTH CHINA

作者于1992～1994年研究夏玉米田马唐(Digitaria sanguinalis L.)治理的生态经济阈期,借助计算机进行数学模拟,建立夏玉米的相对产量与马唐的相对干扰生长时间、相对出苗时间的函数关系。苗后马唐干扰生长的相对时间即相对天数(Xu)与夏玉米相对产量(Yu)的关系式为: Yu=101.5/{1.0+0.01756EXP[—(—0.0876Xu+0.0004888Xu^2)]}…………(1)苗后马唐出苗的相对时间与玉米相对产量的关系式为: Yd=100.73/{1.0+0.96EXP[—(0.06346Xd-0.00006859Xd^2)]}……………(2) 根据生态经济杀除阈期的定义和(1)、(2)两公式计算可知:夏玉米田马唐防除的生态经济杀除阈期的始期应从夏玉米苗后生育期总天数的11.8％开始,结束于夏玉米苗后生育期总天数的53.9％。例如华北地区夏玉米全生育期总天数一般是95天,夏玉米苗后生育期总天数(T)约为88天,故夏玉米田马唐防除的生态经济杀除阈期约在夏玉米苗后10.6—47.5天之间。

The eco-economic threshold period for controlling Digitaria sanguinalis L. (D. s) in field of summer maize grown in North China region was investigated during 1992 - 1994. The methematic relationship between relative maize yield and relative interference growth time,relative emerging time of D. s were established by mathematic models through computer. The relationship between the relative days (Xu) of interference duration by D. s and the relative yield (Yu) of maize was as follow: Yu = 101.5/{1.0+0. 01756EXP[-(-0. 0876Xu + 0. 0004888Xu2)]} ............ (1) The relationship between the relative time (Xd) of D. s emergence after maize emergence and the relative yield (Yd) of maize was as follow: Yd = 100. 73/{1.0+0. 96EXP[-(0. 06346Xd-0. 00006859Xd2)]} ............... (2) According to the concept of eco-economic threshold period and the calculation of formula (1) and formula (2),the eco-economic threshold period for controlling D. s in the summer maize started at the 11. 8% of the total growth days after the maize emergence,stopped at 53. 9% of the total growth days after the maize emergence. Generally, the total season of the growth and development of maize grown in North China is 95 days with 88 days after crop emergence. Therefore, the eco-economic threshold period for controlling D. s in summer maize was between 10. 6 - 47. 5 days after the summer maize emergence.