Effect of light intensity on tuber morphology, starch content and leaf chlorophyll content of calla lily

Objective In order to understand the response of calla lily, Alocasia macrorrhiza L., to different light intensities, verify the accuracy of SPAD chlorophyll meter in chlorophyll measurements of calla lily, and provide a theoretical basis and technical supports for utilizing large land resources under mature rubber plantation and using chlorophyll meter correctly in physiological experiments of calla lily.

Method SPAD value, chlorophyll a, chlorophyll b and total chlorophyll contents of different calla lily leaves under different light intensities were determined using SPAD-502 chlorophyll meter and alcohol-acetone extraction methods.

Result Compared with calla lily grown under natural light, tuber starch content and girth of calla lily under tree-shade decreased by 15.08% and 12.96% respectively, while tuber length increased by 12.11%.SPAD value, chlorophyll a, chlorophyll b and total chlorophyll contents of calla lily under natural light were lower than those of calla lily under tree-shade, while chlorophyll a/b ratio was higher. SPAD value of calla lily under natural light increased gradually from the first-top-leaf to the fifth-top-leaf (except the third-top-leaf). SPAD value of calla lily under tree-shade increased gradually from the first-top-leaf to the second-top-leaf reaching the maximum, and then decreased gradually from the third-top-leaf to the fifth-top-leaf. Light intensity influenced chlorophyll a, chlorophyll b and total chlorophyll contents of different leaves in the same way as it did for SPAD value, but in different degree.

Conclusion Light is conducive to starch synthesis in calla lily tubers. Calla lily can capture more light energy through increasing SPAD value, chlorophyll a, chlorophyll b and total chlorophyll contents of leaves, especially the upper leaves, under limited light conditions. The SPAD value of the fourth-top-leaf is the best estimation for the chlorophyll contents of calla lily under natural light, while the SPAD value of the fifth-top-leaf is the best estimation for the chlorophyll contents under tree-shade.