Effect of regulated irrigation on input-output benefits of pear jujube

Jujube is the main cash forest species in the Loess Plateau region. It is now the preferred and dominant cultivated tree species in the region due to its huge economic and ecological benefits. In this region, however, rainfall-fed and overland flooding remain the principal modes of irrigation, leading to low yield and poor fruit quality. This is a par with societal development, where emphasis has from quantity to quality of fruits/vegetables. It is therefore vital to develop water-saving irrigation systems that ensure high quality/yield in water-deficient regions for high economic benefits. In this paper, five irrigation gradients (to maintain soil water content as 70%, 60%, 50%, 40% of field capacity, and non-irrigation) were set up to investigate the influence of regulated irrigation on the quality of pear jujube fruit. The pear jujube trees were irrigated twice during sprouting and leaf-expansion, flowering and fruit setting, and fruit swelling periods, respectively. The fruit quality and input-output benefits of jujube production under the regulated irrigation system were analyzed. The results showed that: (1) fruit swelling, and flowering and fruit setting periods were the critical water demand periods that influenced fruit quality and economic benefits; (2) appropriate irrigation significantly improved not only fruit flavor and nutritional quality, but also increased weight per pear jujube fruit and number of fruit harvest; excessive irrigation also not only increased production cost, but resulted in no improvement in fruit quality and yield; (3) reasonable regulated irrigation during high water demand periods ensured a balance between input (production cost) and output (high yield and quality of fruits). Further analysis showed that proper irrigation significantly improved yield, quality and economic benefits of pear jujube. Under drought conditions, the economic benefits of jujube forest effectively improved by reasonable irrigation system at critical water demand and transfer periods. The study suggested that the reasonable irrigation system in the region for pear jujube was to keep 60% of field capacity.