Abstract:In order to explore the accurate management mode of water and fertilizer supplies for young apple tree in semi-arid area field, the bucket cultivation experiment, including four levels of irrigation as 75%~85% (W 1), 65%~75% (W 2), 55%~65% (W 3) and 45%~55% (W 4) of field capacity, and three levels of fertilization (N-P 2O 5 -K 2O) as 30-30-10 g/plant (F 1), 20-20-10 g/plant (F 2) and 10-10-10 g/plant (F 3), was conducted to study the effects of water and fertilizer coupling on yield, fruit quality and water and fertilizer use efficiency of three-year old young apple tree. The results showed that controlled water and fertilizer can effectively regulate the plant and leaf area growth during bud flowering to new growth period; the highest and lowest yields were obtained by F 1W 1 and F 3W 4 treatments, respectively (compared with F 3W 4, yield of F 1W 1 was increased by 139.1%), and the determination coefficient between yield and dry mass was 0.908 5. Increasing irrigation depth could improve apple color index but it would reduce the shape index, deficit irrigation and increased fertilizer application rates both could improve apple firmness. Increased fertilizer application rates could improve the vitamin C content of apple under mild deficit irrigation treatment (F 2); irrigation depth had no significant effect on soluble solids content and soluble sugar content, but increased fertilizer application rates could improve both of them; increased irrigation depth could reduce titratable acid and improve the sugar acid ratio, but fertilization rate had no significant effect on them. High irrigation depth and low fertilization rate could get high partial factor productivity (PFP), but the maximum water use efficiency (WUE) could not be got by F 1W 1 treatment. The maximum WUE was appeared in F 2W 2 treatment with yield decreased by 7.5%, water consumption decreased by 16.7% and WUE increased by 11.2% compared with F 1W 1 treatment. Thus, F 2W 2 treatment was the best water and fertilizer application combination for the young apple tree and it reached the best water and fertilizer coupling mode.
