メヒシバの発生消長を気温と土壌水分によって表現する動的モデルの策定

概要

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As the first step to develop a prediction method for the seasonal variation in emergence of weeds, a dynamic model that can represent the seedling emergence patterns of D. adscendens for various rotary tilling dates was designed by computing the daily air temperature and soil moisture content. The model is based on the following equations. (1) Y=1/(1+99999 exp(-λ・1nX)) ・・・・・・・・・・・・・・・(1) X =ΣX_i ・・・・・・・・・・(2)x =a(TM-T_0)・b(WS-W_0)・・・・・・・・・・・・(3) If TM<T_0 or WS<W_0 then x = 0 Where Y is the accumulated rate of emergence (0<Y<1) ; X is the daily accumulated values of the emergence equivalent(x); i is the i th day after rotary tilling; TM is the daily mean air temperature(℃) ' WS is the daily soil moisture content (water%/dry soil)' To, W a b and λ are parameters (Fig. 1). The value of the parameters was determined by the Simplex Method based on data of field experiments in which ten different tilling dates were selected for three consecutive years. The results obtained were as follows: T_0=13.20℃ , W_0=37.63%, a=0.984, b=0.917 and λ=1.613 (Table 1). In general, a good agreement was obtained between the predictions and the observations in the seedling emergence patterns of D. adscendens for different rotary tilling dates (Fig.2-5)
日本雑草学会の論文
1989-10-30