Abstract
Growth analysis was applied on ladino clover swards for 44 days, from October to November at Tohoku University farm, located in temperate climate region. Two experimental swards were set up, the plot (1); the sward clipped the day just beginning the experiment, and the plot (2); the sward clipped at 22 days before beginning the experiment and had higher leaf area and higher plant height than the plot (1). The plot (1) was the control, and the plot (2) was the high LAI plot. On both plots wet and dry weight of leaf, root and stolon, and leaf area were surveyed in each week. Results were as follows : 1. The high LAI plot was suffered from frost and rain injury more severely than the control plot. Leaf area, net assimilation ratio and crop growth rate were decreased by frost and rain damage for about two weeks but recovered later. 2. Leaf area index was 3.5 in the high LAI plot but nil in the control plot at the beginning of the experiment. The both plot increased leaf area and attained 3.3 in the control plot and 5.7 in the high LAI plot after 3-6 weeks. 3. Net assimilation rate was naturally decreased with increasing leaf area index and was higher in the control plot than in the high LAI plot. But LAI-NAR relationship differed in both plots, suggesting the high LAI plot had higher capacity in light interception or higher capacity in photosynthesis per unit leaf area. 4. Crop growth rate was higher in the high LAI plot than in the control plot, since the former had higher LAI and relatively higher NAR as well. These results suggested that the long rest period in grazing or clipping was preferable for dry matter production than the short rest period in autumn.
