| In recent years,there have been some problems in the production of winter jujube,such as large amount of chemical fertilizer,less application of organic fertilizer and trace element fertilizer,and some jujube orchards have been yellowed due to lack of nutrients,which leads to the difficulty of ensuring the quality of winter jujube and the decrease of excellent fruit rate.In order to solve the problems of unreasonable fertilization and deficiency yellowing of jujube trees in jujube orchards in Dali County,the fruit quality and soil nutrient content of winter jujube in 242 jujube orchards in 13 towns of Dali County were measured in 2021,and the spatial distribution maps of trace elements and p H were drawn.The canonical correlation analysis method was used to explore the relationship between soil nutrients and fruit quality.A field experiment was carried out in Chaoyi Town,Dali County.The effects of different treatments on fruit yield and quality were investigated by farmers’conventional fertilization treatment（CF）,recommended fertilization treatment（OF）,organic fertilizer replacing 20%chemical fertilizer treatment（T1）and organic fertilizer replacing 40%chemical fertilizer treatment（T2）on the basis of recommended fertilization.The best fertilization scheme was determined.In addition,soil application and trunk injection of iron,manganese and zinc were set up to study the effect of etiolation correction of winter jujube deficiency leaves.The main results are as follows:（1）The soil p H value and trace element content of jujube orchard in Dali County were analyzed and determined,and the spatial distribution map was made.The analysis of soil trace element nutrient content and spatial distribution in jujube orchard showed that the content of available copper in soil was too high,the content of available manganese and zinc in soil was at a high level,and the content of available iron in soil was at a medium to low level.The soil trace element deficiency area and the soil p H high area are basically coincident.The soil of the towns along the Yellow River in the east and the towns near the central wetland park is strongly alkaline,which leads to the low content of available iron,manganese and zinc in the soil,which may be the reason for the frequent occurrence of jujube yellowing symptoms in this area.（2）The analysis between soil nutrients and fruit quality of winter jujube orchard in Dali County showed that soil organic matter,available zinc and iron content could significantly affect the titratable acid content of fruit.The change of vitamin C content in fruit was closely related to the contents of available nitrogen,available phosphorus,potassium,iron,manganese,copper,zinc and organic matter in soil.The changes of soluble solids content in jujube were greatly affected by soil alkali-hydrolyzable nitrogen,available phosphorus,iron,manganese content and electrical conductivity,while fruit soluble sugar was mainly affected by soil available iron,copper,organic matter content and electrical conductivity.In addition,the single fruit weight of winter jujube was mainly affected by the interaction of soil p H,available phosphorus,potassium,iron,manganese and copper content.The fruit shape index was affected by environmental factors such as available nitrogen,available phosphorus,copper,zinc,organic matter content and soil conductivity.（3）The soil nutrient range of Dali high-quality winter jujube orchard:When the soil alkali-hydrolyzable nitrogen content of the jujube orchard was 40.00～100.00 mg kg-1,the effective phosphorus content was 20.0～30.0 mg kg-1,the effective potassium content was150.00～200.00 mg kg-1,the effective iron content was 5.19～10.00 mg kg-1,the effective manganese content was 3.00～20.00 mg kg-1,the effective copper content was 0.20～1.00mg kg-1,and the available zinc content was more than 0.50 mg kg-1.When the organic matter content was 10.00～40.00 g kg-1,the conductivity was 0.12～0.13 d S m-1,and the p H value was 7.70～8.13.（4）The effect of organic fertilizer instead of chemical fertilizer on the yield and quality of winter jujube fruit,and the optimal fertilization scheme was determined.The T2fertilization treatment had the best effect on the yield increase of winter jujube.The single fruit weight was increased by 6.45%and 22.33%respectively compared with the control group,and the fruit was high pile type.The edible rate of winter jujube fruit treated with OF and T2 was about 1.55%higher than that of CF treatment.Compared with CF treatment,the contents of Vc,soluble protein and soluble solids in T2 treatment were significantly increased by 30.18%,15.46%and 6.63%,respectively.With the increase of organic fertilizer substitution ratio,the soluble solids and soluble protein content of winter jujube increased.OF treatment had the best effect on the soluble sugar content of jujube fruit,which was 30.41%higher than that of CF treatment.The fruit hardness of CF treatment was the highest,and the titratable acid content of T2 treatment was the lowest,which was 34.84%lower than that of CF treatment.The contents of boron,iron,manganese,copper and zinc in T2 treatment were the highest,which were 63.64%,36.09%,101.70%,57.52%and 21.92%higher than those in CF treatment,respectively.Compared with OF treatment,the contents of boron,manganese and iron in fruits of T2 treatment were significantly increased,while the contents of available copper and available zinc were not significantly different.Considering the indexes of winter jujube fruit,T2 treatment had the best effect on improving fruit quality and yield.The contents of boron,iron,manganese,copper and zinc in T2 treatment were the highest,which were 63.64%,36.09%,101.70%,57.52%and 21.92%higher than those in CF treatment,respectively.Compared with OF treatment,the contents of boron,manganese and iron in fruits of T2 treatment were significantly increased,while the contents of available copper and available zinc were not significantly different.Considering the indexes of winter jujube fruit,T2 treatment had the best effect on improving fruit quality and yield.（5）In view of the deficiency yellowing phenomenon of winter jujube,soil application and trunk injection can play a role in correcting the yellowing effect,making the yellowing leaves green,leaf area and SPAD value significantly increased.The effect of trunk injection treatment on leaf SPAD value and leaf area was the most obvious,which was 40.27%and25.47%higher than that of yellowing control,respectively.The content of available potassium,calcium,iron,manganese,copper and zinc in the leaves after treatment was significantly increased,while the content of nitrogen,phosphorus and boron in the leaves was lower than that before treatment.Compared with the etiolated control,the content of potassium,calcium,iron,manganese,copper and zinc in the leaves of trunk injection treatment increased by 42.51%,18.82%,39.26%,53.07%,50.73%and 121.57%,respectively.The content of available iron in leaves of soil application and trunk injection after treatment was still 28.82%and 20.82%lower than that of green leaf control group.Soil application treatment had the best effect on the increase of vitamin C content in winter jujube fruit,reaching 492.59 mg 100g-1,which was significantly higher than that of yellowing control.Compared with the chlorotic control,the contents of soluble sugar,soluble protein and soluble solids in the fruit were increased by 80.32%,22.53%and27.96%,respectively,and the titratable acid content in the fruit was the lowest.Both treatments can increase the yield,but the effect of trunk injection is better.The fruit shape index,single fruit weight and hardness of winter jujube fruit treated by trunk injection were the best.Both treatments can reduce the adverse effects caused by yellowing symptoms,promote the growth and development of winter jujube fruits,and significantly increase the mineral nutrient content in fruits,thereby increasing yield and improving quality.The trunk injection treatment had a better effect on reducing yellowing and increasing the content of mineral elements in leaves.According to the spatial distribution of soil trace elements in Dali County and the soil nutrient range of high-quality jujube orchards,the experiment of replacing chemical fertilizer with organic fertilizer was set up to verify that replacing 40%chemical fertilizer with organic fertilizer can improve quality and increase yield.Both trunk injection and soil application of trace element supplements can effectively correct the symptoms of nutrient-deficient yellowing of winter jujube,and trunk injection is more effective. |
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