Estimating canopy light interception and absorption using leaf mass per unit leaf area in Solanum melongena

Knowledge of canopy light interception and absorption is fundamental For un derstanding many aspects of crop growth and productivity, and for crop mode lling. Light interception is commonly measured with expensive equipment or estimated with elaborate models: simpler and more economical ways of estima tion would be advantageous. Since leaf mass per unit lear area (M-A) is clo sely related to long-term light interception by leaves, the latter can be e stimated by measuring M-A. In this study, partitioning of leaf area into on e of six classes of M-A was used to estimate canopy light interception and absorption in aubergine (Solanum melongena L.) grown with different amounts of nitrogen fertilizer and with or without artificial shade. Although plan ts grown with ample fertilizer had a greater leaf area index (LAI) than tho se grown with less nitrogen, the increase in leaf area occurred in the lowe r and intermediate Mg classes, while the leaf area in the two highest M-A c lasses was similar. Artificially shaded plants had more leaf area in the lo wer M-A classes and less in the higher classes compared to unshaded plants, showing acclimation to low light conditions. The amount of light intercept ed daily by leaves in each M-A class was estimated using the previously det ermined light : M-A relationship. Canopy light interception was calculated as the sum of intercepted light for all M-A classes, and canopy light absor ption was estimated from light interception data assuming a constant absorp tion coefficient (82%). To validate the results. the estimated values were compared to those calculated from independent measurements of light absorpt ion carried out in the same field. Results indicate that it is possible to estimate canopy light interception and absorption from the partitioning of leaf area into M-A classes. (C) 2001 Annals of Botany Company.