Abstract:

We examined the effects of different combinations of N, P, and K fertilizers on the yield and quality of Ginkgo biloba fruit and sarcotesta, with the aim to provide a theoretical basis for the oriented cultivation of fruit-harvesting Ginkgo biloba and the resource utilization of sarcotesta. Different combinations of N, P, and K fertilizer application were set up, including N fertilizer+P fertilizer (T1), N fertilizer+K fertilizer (T2), P fertilizer+K fertilizer (T3), N fertilizer+P fertilizer+half of K fertilizer (T4), N fertilizer+half of P fertilizer+K fertilizer (T5), half of N fertilizer+P fertilizer+K fertilizer (T6), N fertilizer+P fertilizer+K fertilizer (T7), with no fertilizer application as the control (CK). We measured the characteristics and yield of Ginkgo biloba fruit and sarcotesta, the contents of flavonoids in sarcotesta and the total flavonoids yield of sarcotesta under different treatments. The correlation between fruit and sarcotesta parameters was analyzed. The comprehensive evaluation of different treatments was carried out by the membership function and principal component analysis. Results showed that fertilization significantly increased the size and fresh weight of single fruit, fruit quantity, fruit yield, and dry weight of sarcotesta. The fruit number in T6 (2096 grains·plant^-1) was the higher, while the yields of sarcotesta in both T2 (2.59 kg·plant^-1) and T6 (2.43 kg·plant^-1) were significantly higher than that of other treatments. Furthermore, all fertilizer applications significantly increased the contents of quercetin and total flavonoids in the sarcotesta. The yield of total flavonoids in T2 treatment (658.32 mg·plant^-1) was the highest. The yield of sarcotesta and fruit quantity was significantly correlated with fruit yield (P<0.01). The correlation between total flavonoids yield of sarcotesta and fruit and sarcotesta indices except sarcotesta thickness was also significant (P<0.01). The order of comprehensive effects of fertilization on fruit and sarcotesta was T2>T6>T4>T3>T5>T1>T7>CK. T2 \[the combined application of N fertilizer (0.20 kg N·plant^-1) and K fertilizer(0.24kg K₂O·plant^-1)\] was the optimal fertilization scheme for yield and quality of fruit and sarcotesta, followed by T6 \[the combined application of half of N fertilizer (0.10 kg N·plant^-1), P fertilizer (0.32 kg P₂O₅·plant^-1) and K fertilizer (0.24 kg K₂O·plant^-1)\]. Our results indicated that reducing fertilizer amount did not decrease yield but had better fertilization effects on yield and quality. In practice, fertilizer application scheme should be optimized to improve fertilizer utilization rate.

Key words: fruit-harvesting Ginkgo biloba forest, sarcotesta, flavonoids, fertilizer reduction, yield.