Basic production analysis of forages using a factor of light interception property of canopy

This numerical study of crop growth rate (CGR) was conducted to investigate the forage productivity per unit of leaf area using mean leaf area weighted with relative light intensity (MLA) in a forage canopy. The results obtained were as follows. (i) The MLA was a kind of combination of light extinction coefficient (K) and leaf area index (LAI) of a canopy. The MLA with large K showed a lower value than that with small K for all LAI and the difference increased with the increase in LAI, suggesting that MLA was small when the shading effect was high due probably to the large area of leaves inclining horizontally. (ii) The application of MLA to CGR led to modified net assimilation rate (mNAR) and modified LAI (mLAI), where CGR = (mNAR)· (mLAI). Higher values in mNAR than in NAR suggested that the combination of K and LAI was more important than LAI only in assessing the contribution of canopy leaves to forage productivity, especially when the canopy was large in shading effect and low in the efficiency of light interception.