GROWTH, RELATIVE WATER CONTENT, TRANSPIRATION AND PHOTOSYNTHETIC PIGMENT CONTENT IN COFFEE TREES (Coffea arabica L.) GROWING AT DIFFERENT SUNLIGHT REGIMES
نویسندگان
چکیده
The effect of different light regimes (100, 85 and 70 % solar exposition) on coffee plants (Coffea arabica L. var. Caturra) was studied. There was an overall effect of solar exposition levels on growth at different crop growth stages, plant height and stem diameter being the most affected variables with higher values in 85 % solar exposition. Relative water content showed daily variations with minimum values at midday for higher exposition level treatments. Transpiration was slightly higher in 100 % level at 11:00 h, and an increased chlorophyll a and b content was observed in 85 % solar exposition, while carotene content was similar in the three levels. The total chlorophyll a+b showed a highest value in the 85 % level of solar exposition. Results indicated some adaptability features of coffee plants to slight shade conditions, because of the constancy observed for chlorophyll a/b ratio among solar radiation exposition levels, and the highest vegetative growth showed in moderated shade (85 % solar
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