Abstract:
A laboratory experiment was carried out to clarify the growth and development of two cigar tobacco varieties under different light intensities. The different light intensities were set as higher light intensity T200 200±12 µmol/(m
2·s) and lower light intensity T100 100±12 µmol/(m
2·s) and the two cigar tobacco varieties were H382 and Guyin 4. The effects of different light intensities on leaf morphology, biomass, and photosynthetic characteristics of H382 and Guyin 4 were analyzed. The results showed a respective increase of 19.8%, 18.1%, and 42.1% under T100 in leaf length, leaf width, and leaf area, compared with high light intensity. While, the leaf length, leaf width, and leaf area of Guyin 4 showed 8.6%, 9.3%, and 15.6% increment under low light intensity in comparison with high light intensity, respectively. The leaf size of H382 was more sensitive to variation in light intensity. Furthermore, the plant growth diminished under low light intensity with a respective biomass reduction of 20.8% and 41.8% in H382 and Guyin 4. The leaf vein density and leaf thickness (LT) were also decreased by 12.4% and 15.7% in H382 and 9.4% and 19.7% in Guyin 4, respectively, under low light intensity. It was noteworthy that the LT and biomass in H382 was less sensitive to low light intensity than that of Guyin 4. The apparent quantum efficiency of H382 increased by 34.4% while the maximum net photosynthetic efficiency and light compensation point decreased by 21.9% and 38.0%, respectively, but Guyin 4 showed no significant change. In conclusion, H382 and Guyin 4 both responded to the light intensity variation, which was expected to control leaf growth by shading and other cultivation measures.