Lignification and Physiological Factors of Yield in Maize
- C. M. Larroque and
- C. L. Planchon
The digestibility of forage maize (Zea mays L.) may be improved by reducing plant lignification. This study was aimed at determining the variation in plant lignin concentration among inbred lines and their F1 hybrids and its relationship with some physiological traits of canopy photosynthesis. Lignification was characterized by the lignin concentration of the first internode of the plant and by the amount of lignified tissues of the leaf. The effects of a decrease in plant lignification were analyzed for association with various traits influencing biological yield: leaf angle, net photosynthesis under high light, chlorophyll fluorescence index (representative of the photosynthetic functioning under low light). The variation of the various parameters was investigated under controlled and field conditions with water not limited. The large variation in stem lignin concentration was more closely correlated with degree of lignification of the vascular bundles than with their number. A high lignification of stems and leaves induced an erect orientation of the leaves, but had no influence on the net photosynthesis per unit leaf area, which has been associated with the number of vascular bundles in leaves and stems, and with leaf area. Low lignin genotypes displayed the highest fluorescence index, indicating the potential of an increased use of low light in canopies with horizontal leaves. The best compromise between digestibility and crop productivity may be obtained by selecting for genotypes with a high photosynthetic efficiency under low light.
Copyright © 1990.