| As an excellent fresh jujube variety,Ziziphus jujuba cv.Dongzao is popular among farmers and consumers because of its unique flavor,rich nutrition and high economic benefits.Dongzao is widely introduced and planted in China,and it is also one of the main fruit trees in Tianjin,mainly distributed in Dagang District,Jinghai District and other areas.However,with the rapid development of the Dongzao planting industry,problems such as extensive management and excessive application of chemical fertilizers have emerged,resulting a decline in fruit yield and quality.Therefore,to study the reasons for the low yield of Dongzao,to determine the period of nutrient deficiency,the type of deficiency and the degree of nutrient deficiency,to explore the nutrient metabolism mechanism of Dongzao,both in theory and practical application have important significance.This study determined the basic nutrient status(soil p H,salt content,soil organic content,total nitrogen content,total phosphorus content and total potassium content),as well as the content of alkaline nitrogen,available phosphorus,available potassium,exchangeable calcium,exchangeable magnesium,available iron,available manganese,available boron in soil and the content of nitrogen,phosphorus,potassium,calcium,magnesium,iron,manganese,boron in leaves in various phenological periods(germination stage,initial bloom stage,full-bloom stage,fruit development stage,fruit expanding stage,fruit ripening stage and Deciduous stage),which provides a theoretical basis for rational fertilization and yield improvement by studying the variation of various nutrient elements and their correlation with yield.In this study,the effects of girdling on Dongzao fruits quality were studied by measuring the fruit weight,fruit shape index,fruit firmness,fruit firmness,fruit soluble sugar content,fruit vitamin C content and fruit soluble protein content of fruits on girdling jujube trees and non-girdling jujube trees.The results show that:(1)The content of soil organic,total nitrogen,total phosphorus and total potassium in the soil of high yield orchards were significantly higher than that of low yield orchards.The average soil organic content in high-yield orchards was ‘medium’ level,and low-yield orchards was ‘lack’ level;The average total nitrogen content in the soil of different Dongzao orchards with different yields was ‘medium’ level;The average total phosphorus content in high-yield orchards was ‘lack’ level,and low-yield orchards was ‘very lack’ level;The average total potassium content in high-yield orchards was ‘rich’ level,and low-yield orchards was ‘medium’ level.The average soil p H and salt content in high-yield orchards were significantly lower than those in low-yield orchards,and the average salinization of low-yield orchards was higher.Correlation analysis showed that soil organic content,total nitrogen,total phosphorus and total potassium content were positively correlated with yield,and soil p H and salt content were negatively correlated with yield,but they did not reach significant levels.In the production management of Dongzao orchards,it is recommended to apply organic fertilizer to improve soil fertility and timely supplement phosphate fertilizer.(2)From germination stage to deciduous stage,the content of alkaline nitrogen,available potassium,available iron and available manganese in soil of Dongzao orchards increased,and the content of available phosphorus,exchangeable calcium,exchangeable magnesium and available boron decreased.The average annual content of alkaline nitrogen,available phosphorus,available potassium,exchangeable magnesium,available iron,available manganese and available boron in the soil of high-yield orchards was higher than low-yield orchards,while the average annual content of exchangeable calcium in the soil of low-yield orchards was higher than high-yield orchards.Correlation analysis showed that the available phosphorus content and available boron content in soil of initial bloom stage,the alkaline nitrogen content in soil of full-bloom stage,and the available phosphorus content and exchangeable calcium content in soil of fruit expanding stage were extremely significantly positively correlated with yield;The available phosphorus content in soil of germination stage,the available boron content in soil of full-bloom stage,the alkaline nitrogen content in soil of fruit development stage,and the available phosphorus content in soil of Deciduous stage were significantly positively correlated with yield,while the rest did not reach the significant levels.The correlation between soil nutrient content and yield was highest in initial bloom stage,followed by full-bloom stage and fruit expanding stage.In short,the lack of multiple nutrients in low-yield orchards requires timely replenishment.Among them,the application of phosphorus should be applied during the germination stage,and nitrogen,phosphorus,and boron should be applied during the flowering period.Nitrogen and calcium should be applied during fruit development and expanding stage,and phosphorus should be applied during the deciduous stage.The key period of fertilization is about the flowering period.(3)From germination stage to deciduous stage,the content of nitrogen,phosphorus and boron in leaves of Dongzao orchards decreased,the content of potassium,calcium,magnesium,iron and manganese increased.The average annual content of nitrogen,phosphorus,potassium,calcium,iron and boron in the leaves of high-yield orchards was higher than low-yield orchards,while the average annual content of magnesium and manganese in the leaves of low-yield orchards was higher than high-yield orchards.Correlation analysis showed that the potassium content in leaves of initial bloom stage and the boron content in leaves of fruit development stage were extremely significantly positively correlated with yield;The calcium content in leaves of full-bloom stage and the potassium content in leaves of fruit development stage were significantly positively correlated with yield,while the rest did not reach the significant levels.The correlation between soil nutrient content and yield was highest in full-bloom stage,followed by initial bloom stage and fruit development stage.Therefore,in the production management of Dongzao orchards,the nutrition can be supplemented by the method of leaf spraying,and the key period is the flowering period and the fruit development stage.(4)The average fruit weight,average fruit firmness,average fruit soluble solid content,average fruit soluble sugar content,average fruit sugar/acid ratio and average fruit vitamin C content of the Dongzao fruits after jujube trees girdling were significantly higher than those of the non-girdling jujube trees.The average fruit soluble protein content of Dongzao fruits of non-girdling jujube trees was significantly higher than that of girdling jujube trees.Jujube trees girdling had no significant effect on fruit shape index and fruit titratable acid content of Dongzao fruits.In the production management of Dongzao orchards,girdling is an effective measure to improve the yield and fruit quality,but it will also cause some damage to the tree.Therefore,it is recommended to combine other supporting technologies in production to ensure yield and quality while reducing damage to the tree. |
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