Varying fruit loads modified leaf nutritional status, photosynthetic performance, and bean biochemical composition of coffee trees

Abstract

Changes in the intensity of the sink organs in coffee trees can alter photosynthetic activity and accumulation of nutrients at the foliar level and increase the magnitude of malformed fruits, as well as affecting bean biochemical composition. Therefore, the objective of this study was to evaluate the effect of different intensities of fruits load on photosynthetic performance, nutritional status, yield, and bean biochemical composition of Coffea arabica trees established under full sun field-grown conditions. The evaluations were carried out on three-year-old "Cenicafé 1″ variety trees after their establishment in the field. Nine treatments (fruit load), of 20, 30, 40, 50, 60, 70, 80, 90, and 100 % according to total crop load, were applied at the whole-plant level. Gas exchange, nutrient composition, chlorophylls, and soluble sugars were determined in the leaves. Yield components, sugars, organic acids, and alkaloid concentration were determined in the fruits and beans. With a high fruit load, significant leaf nutrient concentration changes were detected, with deficiencies in nitrogen, potassium, sulphur and copper. Furthermore, significant decreases in the chlorophyll content and stability, as well as in the total soluble sugars at the leaf level, were reported. On the other hand, it is evident that the production per plant was higher, although the number of malformed fruits increased with elevated fruit load. Finally, accumulation of sugars, organic acids, and alkaloids in the bean was modified as a function of the increase in fruit load. These results indicate that, in coffee “Cenicafé 1″ variety trees with high fruit load, the nutrient concentration decreased to critical levels considered to nutritional deficiencies, which modified photosynthetic performance, number of malformed fruits, and bean biochemical composition.