| Ginkgo biloba L.is a deciduous tree of the Ginkgo family.Because of its leaf preparations and fruit preparations,the medicinal effects and health care functions are widely concerned.Due to the extensive management of ginkgo fertilization and improper application methods,the quality of the exotesta is unstable and its fruit yield is low.Therefore,taking G.biloba as an object of study,carrying out the research on the fertilization management technology of G.biloba forest for exotesta,which is conducive to the development of the formula of special fertilizer for G.biloba.In this paper,a study was conducted on a ginkgo orchard in Meixi Town,Meizhou,Guangdong.Based on the investigation and analysis of the background conditions of the ginkgo orchard（including the physical and chemical properties of the soil and the yield of ginkgo fruit and its correlation）,three factors of nitrogen（N）,phosphorus（P）,and potassium（K）Level（0 level is no fertilization,1 level is half fertilization level of 2 level,and 3 level is excessive fertilization level）,14 fertilization treatments,to study the effects of different fertilization treatments on G.biloba leaves,ginkgo fruit yield and exotesta quality,The main findings are as follows:1.According to the investigation of Meizhou Ginkgo Base,which found that high SPAD（chlorophyll content）,pure ginkgo single species,and slightly tight soil can promote the amount of ginkgo fruit.There was no significant correlation between soil nutrient content and ginkgo fruit nutrient（P>0.05）,and the amount of fruit was positively correlated with proper soil total nitrogen（TN）and organic matter（OM）content（P<0.01）,which was also positively correlated with available phosphorus（AP）（P<0.05）,SPAD was positively correlated with TN and OM（P<0.01）,and positively correlated with total phosphorus（TP）and AP（P<0.05）.2.Fertilization results showed that the amount of fruit in treatment 3（N2P0K2）was the largest,which was 1899,the highest yield was also treatment 3,reaching 9.57 kg per plant.It can be obtained by the degree of output difference of the N,P,K magnitude groups.The appropriate level of nitrogen fertilizer application is N1,phosphorus fertilizer is P0,and potassium fertilizer is K3.According to the stepwise regression analysis,the equation is obtained.The theoretical maximum yield of ginkgo fruit is 10.017 kg per plant,when the application rate of P is determined to be 0 by the fertilizer effect function model.The treatment with the highest single fruit volume was treatment 11（N1P1K2）,which was 5.92cm3,of which treatment 3,treatment 4（N2P1K2）,treatment 11,and treatment 12（N1P2K1）had a single fruit volume greater than CK（N0P0K0）（P<0.05）.The effect of fertilization on single fruit fresh weight was not significant,ranging from 4.62 to 6.53 g.3.Fertilization has different effects on the SPAD.The SPAD in June is higher than that in September（P<0.05）,fertilization has no significant effect on the leaf water content and leaf area.The leaf area was higher than September（P<0.05）.The highest N content in the leaves in June was treatment 10（N3P2K2）,the highest P content was treatment 8（N2P2K1）,and CK had the highest K,Ca,and Mg contents.The leaves with the highest N and P contents in September were treatment 2,the highest K content was treatment 1,the highest Ca content was treatment 13（N2P1K1）,and the highest Mg content was treatment12.The leaf N,K and Ca contents were different between June and September（P<0.05）.Taking CK as an example,the leaf N,P,K,Ca and Mg leaf change rates were-55.73%,12.16%,10.41%,-24.67%,-60.00%.4.Compared with CK,fertilization has a significant effect on exotesta.The average thickness of exotesta in treatment 10 was the largest,reaching 4.09 mm,which was higher than all treatments（P<0.05）,but dry weight of exotesta was not statistically significant.The yield of exotesta in each treatment was quite different.Among them,treatment 3 has the highest yield,reaching 2.76 kg per plant,which was 2.25 times the lowest yield（treatment15 is organic fertilizer treatment）.The nutrient content of exotesta found that treatment 9（N2P2K3）had the highest average N content of 3.62 g·kg-1.Formula fertilization had no significant effect on the P content of exotesta,The content of K differed little among the treatments,and the highest treatment was CK.The contents of Ca and Mg were low in the exotesta,yet the difference between the treatments is significant.5.Among the flavonoid glycosides,the average content of quercetin and kaempferol in treatment 9 is the highest,90.29μg·g-1and 15.59μg·g-1,respectively.The average content of quercetin is 3.10 times higher than that of CK.Treatment 11（N1P1K2）had the highest isorhamnetin content of 1.72μg·g-1.In summary,treatment 9 had the highest total flavonoid glycoside content of 268.54μg·g-1,which was 5.51 times higher than CK.6.According to the characteristic of exotesta（thickness and its dry weight）and nutrient components（N、P、K、Ca、Mg、flavonoid glycosides）,the entropy weight coefficient and TOPSIS integration method are used to synthesize the exotesta evaluation,the results showed that the comprehensive evaluation index of treatment 9 is the highest,reaching 0.8569.The final ranking in all treatments by evaluation index was treatment 9,treatment 3,treatment 7,treatment 4,treatment 8,treatment 6,treatment 11,treatment 5,treatment 1,treatment 13,treatment 12,treatment 10,CK,treatment 2,treatment 15.7.Under the conditions of fertilization treatment in this article,the correlation of fertilizer elements were conducted.The results showed that excessive N fertilizer was negatively correlated with the yield of ginkgo fruit and the exotesta Mg content（P<0.05）,P fertilizer was negatively correlated with the yield and quality of ginkgo fruit（P<0.05）,but K fertilizer was positively correlated with flavonoid glycoside content（P<0.05）,and negatively correlated with exotesta thickness（P<0.05）.According to the correlation between the nutrient content of leaves and the nutrient content of exotesta,most nutrients are not significantly correlated.Leaf area was positively correlated with single fruit volume and exotesta thickness（P<0.01）,positively correlated with ginkgo fruit yield（P<0.05）.Similarly,SPAD was positively correlated with ginkgo fruit yield and single fruit volume（P<0.01）,leaf water content was positively correlated with the exotesta N content（P<0.05）. |
