Comparing the photosynthetic activity of maize, winter wheat, potato and some significant weed

Abstract

Special adaptations and policies will be necessary to take advantage of the opportunities and minimize the negative impacts of climate change on agriculture. Those farmers producing C4 crops, such as maize, sorghum and millet, will see very little benefit from higher C02, and at the same time their crops will face increased competition from C3 weeds. Many researchers studied the influencing factors of the photosynthesis system of the crops from different aspects. However, most of the literature reports on measurements made in the laboratories, field measurings are rare. Also there is little information available about the photosynthetic activity of the weeds. The aim of our work was to compare the photosynthetic activity of maize, winter wheat, the potato and some significant weed, on different light levels. The effects of increased light intensity were tested by Vidal et al. (1996) on soybean. Their results show, that in consequence of the tripling the light intensity from 400 pE m" V to 1200 pE m'V, the photosynthesis intensity was doubled. Sharma et al. (1998) studied the effect of UV-B radiation on net photosynthesis and chlorophyll fluorescence in wheat seedlings. They found that the UV-B radiation caused significant decrease in net photosynthesis, which was much greater than could be explained by limitation of stomatal conductance. Shangguan et al. (2000) investigated the nitrogen nutrition and water stress effects on leaf photosynthetic gas exchange in winter wheat. The photosynthetic gas exchange parameters were remarkably improved by water and nitrogen supply. The effect of nitrogen nutrition on photosynthetic characteristics was not identical under different water status. In light acclimated pea leaves studied Park et al. (1996) the photosynthesis under three light intensity, 50 (low light), 250 (medium light), and 650 (high light) pmol photons m'V1. The results show that in the low light adapted leaves light -stress induced because of increasing the photon exposure. Under high light intensity the photoinactivation of PS II was greatly increased. Bindraban (1999) wrote that in his observations the photosynthesis in the lower leaves of wheat depended mainly on the light intensity. The effect of nitrogen supply was low. Photosynthesis and its tolerance to photoinhibition, high temperature and drought stress of flag leaves were investigated in wheat by Xinghong et al. (2006). Their results suggest that high resistance to photo-oxidative damage of the flag leaves be the physiological basis for the high yield.