Abstract
The growth analysis of Italian ryegrass population was executed on the basis of equations (Logistic) of growth regressive curve in seasons of autumn, winter, and spring. Obtained results are as follows. 1) CGR_max and average productivity max (Maximum value for dry matter yield/regrowth period) showed different values in seasons, and when these values were indicated with average values of four years respectively, they were 25.8 and 13.4gm・^<-2>・day^<-1> in spring, 10.5 and 6.7 in autumn, and 7.9 and 5.4 in winter. 2) A close positive correlation (r=0.985) was recognized between CGR_<max> and average productivity max, as shown in the equation (1), despite of different experimental years and seasons. average productivity max≒0.433 CGR_<max> +2.13 (1) 3) Days to CGR_<max> and days to average productivity max showed different values in seasons, and when these values were indicated with average values of four years respectively, they were 28.4 and 39.2 days in spring, 39.8 and 55.3 in autumn, and 65.7 and 90.7 in winter. 4) A close positive correlation (r=0.998) was recognized between days to CGR_<max> and those to average productivity max as shown in the equation (2), despite of different experimental years and seasens. days to average productivity max≒1.367 days to CGR_<max>+0.687 (2) Namely, the period to average productivity max is about 1.4 times as long as that to CGR_<max>.
