Abstract
In the previous papers, the relationship between yield and yield components of orchardgrass under individual plant basis was investigated. In the present paper, the relationship between yield components, vertical distribution of leaf area, light extinction coefficient and some morphological characters were analyzed in sward condition. The varieties examined were Pennlate, Latar, Hokkai-1, Potomac, Chinook, Kitamidori, Daprime, S 143, Apanui and Frode. The results obtained were as follows: 1. The dry matter weight was always correlated with leaf area index (LAI), but this correlation was decreased following the growth. Between the dry matter weight and specific leaf weight (SLW), there was negative significant correlation at the early stage of growth, but there was positive significant correlation at the late stage of growth. These results indicated that LAI mainly influenced on the dry matter production at the early stage of growth, but SLW became to have more influence on the dry matter production at the late stage of growth (Fig.1). 2. The dry matter weight always indicated highly significant correlation with the dry weight of a tiller. Between the dry matter weight and the number of tillers, there was positive correlation at the early stage of growth, but there was negative correlation at the late stage of growth (Fig.2). 3. There were the varietal differences among the regression coefficient between LAI and relative light intensity at the ground level at each sampling time (Fig.3). This regression coefficient (light diminution coefficient, K') indicated negative highly significant correlation with the dry matter weight. It was confirmed that the light diminution pattern following the growth should contribute to the dry matter production (Table 2). 4. There were the varietal differences among vertical distribution of leaf area index, light extinction coefficient (K) and leaf area index above the layer indicating the highest leaf area density within the canopy (effective leaf area index, ELAI). These differences had close relations with the dry matter production. ELAI almost corresponded with the LAI absorbing 95% of the incoming light within canopy, and was limited by K. Thus, it became clear that the varietal differences of dry matter production was depending on the differences of ELAI (Fig.5, Fig.6, and Fig.7). 5. K was mainly determined by leaf angle, flag leaf length/3rd leaf length and 2nd leaf length/3rd leaf length. The variety with erect leaf, small flag leaf and small 2nd leaf comparing 3rd leaf, had small K and high dry matter production. Leaf breadth and leaf rigidity index did not have any influence on K and dry matter production (Table 3). 6. Light diminution coefficient (K') indicated highly significant correlation with light extinction coefficient (K).
