Physiological basis of the difference in net photosynthetic rate of leaves between two maize strains

Abstract

Significant differences in net photosynthetic rate PN of leaves between two maize (Zea mays L.) strains (Shuang 105 and 40x44) grown in the field were observed. At several growth stages, PN of 40x44 was higher than that of Shuang 105 (from 10.3 to 32.5 %). Moreover, the strain 40x44 had a higher plant height, larger leaf area, lower chlorophyll content, and higher photochemical efficiency of photosystem 2 (PS2) (Fv/Fm and δF/Fm') than strain Shuang 105. Shuang 105, which showed lower PN, had lower stomatal conductances gs but slightly higher intercellular CO2 concentrations Ci than those of 40x44. Hence the differences in PN between the two strains did not result from the difference in gs, but probably from that in light reaction system.