Photosynthesis Characteristics of Ten Varieties of Coix lacryma-jobi L. in Wenshan Prefecture, Yunnan Province

Ten varietiesY9-7, Y12-2 (white), Y3-1, Y3-4, Y6-1, Y12-2 (black), Y7-1, YLO, YGL-12, YWS-2 of Coix lacryma-jobi L. cultivated in Wenshan Prefecture, Yunnan Province were used as materials, and their photosynthetic characteristics and chlorophyll mass fractions were determined to study the photosynthetic differences among different C. lacryma-jobi varieties and to provide theoretical support for the selection. The results show that: the net photosynthetic rate of Y12-2 (black) was higher than those of the other nine varieties, of which that of Y3-1 was the lowest. The net photosynthetic rates, transpiration rates and stomatal conductance of all varieties presented single peak curve; the net photosynthetic rate reached the maximum at 11:00 a.m. and gradually decreased at the afternoon; the stomatal conductance and transpiration rate reached the maximum at 3:00 p.m., while the intercellular CO2 concentration reached the maximum at 9:00 a.m., which displayed high-low-higher-lower trend. The chlorophyll a and b contents of Y12-2 black were the highest, the chlorophyll a content of Y7-1 was the lowest and the chlorophyll b content of Y3-1 was the lowest.