How irrigation water saving strategy can affect tuber growth and nutritional composition of potato

Apart from some works dealing with potato tuber growth and nutritional composition in response to water supply, no study on the effects of irrigation water saving strategies has been found in the literature. This study aimed to investigate the effects of four irrigation regimes: I0 dry control, I1 irrigation during the whole cycle, I2 irrigation from tuber initiation up to 50% of tuber growth, I3 irrigation from 50% of tuber growth to the end of tuber growth on tubers growth and nutritional composition (dry matter, starch, reducing sugars, protein, ash) of two potato cultivars in two planting dates. Irrigating from tuber initiation up to 50% of tuber growth compared to irrigation throughout the whole cycle, did not substantially modify either the tuber dry weight or the sink/ source ratio, but did improve the nutritional composition of tubers through higher dry matter and starch contents and comparable values of reducing sugars, proteins and ashes; on the contrary, irrigation from 50% of tuber growth to the end of tuber growth, led to similar results to dry control. The two cultivars behaved similarly with respect to the water regime. In conclusion if the water needs of the crop cannot be met during the entire crop cycle, it is more convenient for tuber growth and nutritional composition to schedule irrigation from tuber initiation up to 50% of tuber growth rather than from 50% of tuber growth to the end of tuber growth.