Influence Of Light And Temperature On Photosynthesis And Transpiration In Some C3 And C4 Vegetable Plants From Kenya

Abstract

Potted vegetable plants of Amaranthus lividus, Gynandropsis gynandra and Crotalaria brevidens were grown outside under normal tropical conditions and rate of photosynthesis and transpiration were determined simultaneously in attached leaves under a range of leaf temperatures and irradiances. Photosynthetic rates were consistently higher in G. gynandra than in A. lividus and C. brevidens. However, in C. brevidens and G. gynandra the leaf resistances were lower and transpiration rates were higher than those in A. lividus.

The results on optimum temperature requirements for maximum rates of CO2 fixation, coupled with data on CO2 compensation points and leaf anatomy provided clear evidence that G. gynandra and A. lividus are C4 species, while C. brevidens is a C3 species. The differential effects of light intensity and temperature on stomata and mesophyll resistances in C3 and C4 species are discussed in relation to rates of photosynthesis and transpiration.