Since light-interception affects the yield of crops, this trait is an important morphological breeding objective for many crops. In this study, the angle of the leaf blade, which is the inclination of the midrib of lamina, was measured using a tiltmeter for tea (Camellia sinensis). Japanese leading clonal cultivar ‘Yabukita’ had a notably high leaf blade angle in Japanese original tea. Modern Japanese tea cultivars had higher leaf blade angles than older ones. Furthermore, the angles were related to the yields of 3 Japanese tea clone populations in cultivars and strains in a preservation field; a germplasm preservation field; and a line selection field. In addition, the leaf blade angle correlated with the visible leaf area (measured vertically from above the plants) and the yields of the strains in line selection. The correlations indicated that the yields increased because light-interception increased the available leaf area. The most important objective in tea breeding is tea quality, and this quality is related to the content of nitrogen and free amino acids. Hence, increased photosynthesis may lead to a loss in quality caused by “nitrogen dilution”. However, the nitrogen absorption and assimilation is facilitated by the energy derived from photosynthesis. Therefore, to enhance yields tea breeders should increase photosynthesis by utilizing light-interception characteristics and increasing the availability of concurrent energy from photosynthesis for nitrogen absorption and assimilation.

View full abstract