Optimizing irrigation and fertilization at various growth stages to improve mango yield, fruit quality and water-fertilizer use efficiency in xerothermic regions

Mango (Mangifera indica L.) is one of the widely grown fruit crops and brings remarkable economic benefit in the xemthermic regions of southwest China. However, mango yield and quality can not be guaranteed due to the severe seasonal drought, low precipitation and extensive management of water and fertilizer. To investigate the effects of irrigation amount and fertilizer regime on mango yield, fruit quality, water use efficiency (WUE) and partial fertilizer productivity (PFP), an orthogonal experiment [L-9(3)(4)] was conducted on mango under drip fertigation during 2018-2019. The four factors were irrigation amount (IA) and fertilization rate at the flowering (F-I), fruit expansion (F-II) and fruit ripening (F-III) growth stages. There were three irrigation amounts, i.e., full irrigation (FI: 100%ETc), mild deficit irrigation (DIM: 75%ETc) and severe deficit irrigation (DIS: 50%ETc), and three fertilization rates, i.e., 75 (F-75), 50 (F-50) and 25 (F-25) kg ha(-1) using a compound water-soluble fertilizer (N: P2O5:K2O=20%:20%:20%). The results showed the order of factors influencing fruit yield and WUE in terms of their importance was IA, F-II, F-I and F-III, that influencing water, vitamin C and carotenoid contents in fruit was IA, F-III, F-II and F-I, and that influencing soluble solids and total sugar contents was IA, F-III, F-I and F-II. The WUE of DIMFI50FII75FIII25 was highest. FIFI25FII75FIII50 achieved the highest fruit yield, PFP and contents of soluble solid, vitamin C and carotenoid. DIMFI25FII50FIII75 had the highest total sugar content and the lowest titratable acid content. Based on the comprehensive scoring method, DIMFI50FII75FIII25 achieved the optimum score in terms of fruit yield and water-fertilizer use efficiency, while FIFI25EII75EIII50 was optimum for fruit quality. Further, the TOPSIS method indicated DIMFI50FII75FIII25 had the optimal comprehensive benefit. To obtain high yield, quality and water-fertilizer use efficiency, the recommended water and fertilizer scheduling was irrigation with 75% ETc and fertilization with 50, 75 and 25 kg ha(-1) at the flowering, fruit expansion and fruit ripening stages, respectively. The research results provided a scientific reference for identified optimum combination irrigation and fertilizer in the xerothermic environment of southwest China.