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Correlation of CO2 compensation point (Γ) with photosynthesis and respiration and CO2-sensitive Γ in rust-affected bean leaves

1980; Academic Press; Volume: 16; Issue: 1 Linguagem: Inglês

10.1016/0048-4059(80)90016-8

1876-7974

V. Raggi,

Plant Pathogens and Resistance

In healthy and rust-affected (100 to 120 pustules per cm2) Pinto 111 bean primary leaves, the CO2 compensation point (at 10, 21 and 60% O2 concentration), respiration and photosynthesis (at 21% O2) were determined daily, from the 2nd until the 10th day after infection, in six independent experiments. The CO2 compensation point of the infected leaves increased almost gradually and highly significantly (regression analysis) especially from the 5th until the 10th day after infection (highly significant at the t-test); photosynthesis decreased highly significantly in the infected leaves (regression analysis) especially from the 6th day onwards (differences highly significant at the t-test); respiration increased significantly (regression analysis) with a higher value from the 6th day onwards after infection (highly significant at the t-test). The increase of the CO2 compensation point was significantly correlated with the increase of respiration and mainly with the decrease in photosynthesis (multiple regression and correlation analysis). The increase of the CO2 compensation point in the infected leaves appears to be the result of increased respiration and mainly of decreased photosynthesis; the contribution of photorespiration appears inconsistent because no significant increase of the CO2 compensation point of diseased leaves (compared with healthy ones) was observed at 10% with respect to 21% O2 concentration.