The influence of nitrogen supply during growth on the inhibition of gas exchange and visible damage to leaves by NO 2

Abstract

The effects of NO 2 on the appearance and gas exchange of leaves of bush bean ( Phaseolus vulgaris L.) grown with different concentrations and sources of nitrogen were examined. Nitrogen nutrition influenced visible damage to leaves and the inhibition of photosynthesis and respiration by 3·0 ppm NO 2. The rate and time course of NO 2 uptake were also affected by nitrogen supply during plant growth. The characteristics of NO 2 uptake were generally consistent with the operation of a pathway of NO 2 assimilation via nitrate and nitrite reduction.The degree of inhibition caused by NO 2 was not, however, always correlated with the rate of NO 2 uptake. The inhibitory effects of NO 2 on photosynthesis and respiration were correlated with the activities of photosynthesis and respiration per unit leaf protein. This suggests that the effects of NO 2 of leaves may depend on changes iin leaf proteins.