Effect of reduced fertilization and regulated deficit irrigation coupling on yield and quality of mango in a dry-hot region

Objectives Fertilizer rate and irrigation play important roles in mango yield, quality and production efficiency. We investigated the optimum combination of fertilizer rate and deficit irrigation stage in the dry-hot region of Yunnan Province.

Methods A field experiment was conducted using 7-year-old Guifei mango tree as experimental material. The three deficit irrigation stages were the flowering, fruit expansion and mature stage of mango (DI_FS, DI_ES, DI_MS), the deficit level was 50% of evapotranspiration (50%ET_C), and the full irrigation during whole growth period was used as control (I_F). The three fertilizer rates were high (0.45 kg/plant, F_H), medium (0.36 kg/plant, F_M) and low (0.27 kg/plant, F_L). At matured stage, the mango yield was recorded, and the vitamin C, total soluble solid (TSS), titratable acid (TA) and water content of mango fruit were analyzed. The principal component analysis and the Membership function evaluation method were used for the comprehensive evaluation of the treatment combination effect.

Results Compared with I_F control, DI_FS treatment decreased yield by 23.4%, water use efficiency (WUE) by 13.6%, partial factor productivity of fertilizer (PFP) by 24.0%, mango fruit vitamin C by 6.8% and ratio of TSS to TA by 14.5%, respectively; DI_ES treatment reduced yield, PFP and ratio of TSS to TA by 20.3%, 20.5%, and 39.3%, respectively; DI_MS treatment did not affect yield, but increased WUE, PFP and ratio of TSS to TA by 21.6%, 5.0% and 10.5%. Compared with F_H treatment, F_M treatment increased vitamin C and ratio of TSS to TA by 8.1% and 11.3%, respectively; F_L treatment decreased vitamin C and ratio of TSS to TA by 6.7% and 9.8%. The interaction between irrigation mode and fertilization had significant effects on the WUE and edible rate of mango (P<0.05). The comprehensive scores of top three treatments by Principal component analysis were DI_MSF_M, DI_FSF_M and DI_MSF_H, and the lowest three treatments were DI_ESF_M, DI_ESF_H and DI_ESF_L. The highest subordinate function value was obtained from DI_MSF_M treatment, followed by DI_FSF_M, and DI_ESF_L.

Conclusions Deficit irrigation at flowering and fruit expansion stages, and low fertilizer rate are not conducive to the yield formation and quality of mango, while deficit irrigation at maturity stage will not impact the yield and quality. According to the principal component analysis and the membership function evaluation method , deficit irrigation at fruit mature stage and medium rate of fertilizer are suitable combination for optimum yield and quality of mango, as well as water use efficiency.