Effect of fertigation on apple production in different ecological-regions orchards

In order to explore the effects of fertigation on 'Fuji' apple production in different ecological regions of Shaanxi Province, two field experiments (each with three treatments) were conducted simultaneously in Weibei Dry-land and Guanzhong Plain. The treatments consisted of conventional fertilization treatment NPK(C) and fertigation treatment NPK(F) using the same fertilizer rates as the conventional treatment, and half-dose fertigation treatment 1/2NPK(F) using 50% of fertilizer rates of the conventional treatment. The yield, fruit quality, fruit nutrient uptake, fertilizer utilization and economic benefits of apple were then determined and evaluated. The results showed that due to the differences in ecological conditions, soil types and fertility levels of orchards in different ecological regions, the fertigation effects on apple production were obviously distinct. In contrast with NPK(C) treatment, NPK(F) treatment increased apple yield by 13.0%, fruit firmness by 10.6%, sugar acid ratio by 19.1%, and apple fruit uptake of N, P and K nutrients respectively by 36.0%, 75.3% and 44.8% in apple orchards in Weibei dry-land. In addition, partial factor productivity (PFP) increased from 18.2 kg·kg^-1 to 36.3 kg·kg^-1 under NPK(F). However, no significant increases were noted in apple yield, fruit quality and fruit nutrient uptake under 1/2NPK(F) treatment in Weibei Dry-land. In orchards in Guanzhong Plain, apple yield under 1/2NPK(F) treatment increased by 26.2% and apple fruit uptake of N, P and K nutrients increased respectively by 41.8%, 98.9% and 58.9%, compared those under NPK(C) treatment. Meanwhile, PFP increased from 27.2 kg·kg^-1 to 68.7 kg·kg^-1. However, the increment in apple yield under NPK(F) treatment was merely 14.1%, the changes in fruit nutrients uptake were insignificant. As for the economic benefits, in comparison with NPK(C) treatment, NPK(F) treatment enhanced economic benefits by 15 500 Yuan·hm^-2 for orchards in Weibei Dry-land and 36 500 Yuan·hm^-2 for orchards in Guanzhong Plain. Economic benefits under 1/2NPK(F) treatment were increased by 2 100 Yuan·hm^-2 for orchards in Weibei Dry-land and 72 800 Yuan·hm^-2 for orchards in Guanzhong Plain, compared with those under NPK(C) treatment. In conclusion, fertigation management significantly increased yield and fruit quality of apple orchards in different ecological regions in Shaanxi Province. However, the effectiveness of fertigation management differed apparently due to differences in ecological conditions in different regions. Therefore, the use of optimal fertilizer application rates in fertigation management was strongly recommended. The specific conditions of orchards formed the basis of optimal fertilizer application rates for high yields, fruit qualities, fertilizer use efficiencies and economic benefits.