Tropical Grasslands (2006) Volume 40, 231236
Radiation use and stomatal behaviour of three tropical forage legumes
WANG LI1,2, YANG YUNFEI1, LIU JINXIANG3 AND MA FANG2
1 Institute of Grassland Science, Northeast
Normal University, Key Laboratory of Vegetation
Ecology, Ministry of Education, Changchun
Three promising tropical forage legumes, Cratylia argentea, Flemingia macrophylla and Desmodium velutinum were evaluated in a tropical monsoon environment in Hainan Province, China. D. velutinum had higher net photosynthetic rate (PN) and water use efficiency (WUE) than the other two species, and photosynthetic performance was consistent with their stomatal conductance (gs). Responses in gs to increasing photosynthetically active radiation (PAR) showed two phases. Light was the main trigger for opening stomata at low light intensity (0–400 μmol quanta/m2/s), as was a reduction in intercellular CO2 (Ci). Indirect actions contributed more to stomatal behaviour than the direct effect of light at intermediate to intense light intensity (400–2000 μmol quanta/m2/s), with water status being the major factor that controlled stomatal behaviour. D. velutinum was more affected by vapour pressure deficit (VPD) feedback regulation in intense light, and less by Ci at low light intensity than were the other two species.