DYNAMICS OF PHOTOSYNTHETIC PIGMENTS IN SWEET POTATO (IPOMOEA BATATAS L.) LEAVES

Abstract

The aim of this study was to evaluate the effect of harvest time and cultivar on the content of photosynthetic pigments in the leaves of sweet potato (Ipomoea batatas L.). Leaves of three sweet potato cultivars, 'Morado', 'Tainung 65', and 'O'Henry' were analyzed. The leaves were harvested in July, August, and September. The contents of chlorophyll a, chlorophyll b, total chlorophyll (a+b), and total carotenoids in the leaves were determined using a spectrophotometric method. The results showed that both harvest time and cultivar had a significant effect on the content of the analyzed pigments (p < 0.05). The highest amounts of chlorophyll (a, b, and a+b) were found in the leaves of the 'Morado' cultivar harvested in July. The lowest amounts of these pigments throughout the entire study period were found in the leaves of 'Tainung 65' compared with the leaves of the other studied cultivars. A decrease in chlorophyll (a, b, and a+b) content was observed in the leaves of all cultivars harvested in September, indicating changes in the photosynthetic system and the processes of leaf senescence. The significantly highest total carotenoid content was found in the 'Tainung 65' leaves harvested in July, while the significantly lowest amount was detected in the 'Morado' leaves harvested in the same month. Throughout the entire study period, the highest content of these pigments was found in the leaves of the 'Tainung 65' cultivar. Based on the obtained results, it can be stated that harvest time and cultivar are important factors influencing pigment accumulation in sweet potato leaves. The obtained data contribute to a better understanding of the photosynthetic system of sweet potato leaves and will be useful in evaluating the biochemical value of this raw material.