| Boron is one of the essential trace elements for plant growth and development,playing an important role in the growth and development of plants,and the formation quality.More than half of China’s cultivated soil have varying degrees of boron deficiency,with the improvement of agricultural level,boron consumption in soil has increased,and boron deficiency symptoms have become evident in many crops.The span of boron concentration in soil from deficiency to excess is very small,and boron excess is also a common problem in production.Strawberries are the most widely cultivated small berries in China,strawberry cultivation has become an important industry for the development of urban agriculture and rural revitalization in China.However,in strawberry production,attention is often focused on nitrogen,phosphorus,and potassium fertilizers,while the use of trace element fertilizers,especially boron deficiency,is becoming more prominent,often leading to a decrease in yield and fruit quality.Currently,a large amount of research has been done on the effects of boron fertilizer on plant growth and development,but there is relatively little research on the effect of boron on strawberry growth,development,and fruit quality.In this experiment,’Benihoppe’strawberries were used as the test material,and different concentrations of boric acid(0 mg/L,1.5 mg/L,3 mg/L,4.5 mg/L,6 mg/L)were added to the nutrient solution,and the growth index of strawberry plants was measured by hydroponic strawberry seedings containing different concentrations of boron.Substrate potting watering nutrient solution containing different concentrations of boron,and the yield,mineral element content,fruit quality indexes,sugar content and enzyme activities related to sugar metabolism in strawberries were measured,and the transcriptome of fruits at different development stages was sequenced.The effects of boron on strawberry growth and fruit quality were discussed,in order to provide a theoretical basis for the application of boron fertilizer in strawberry cultivation.The main findings are as follows:1.Compared with boron-deficient treatment,after 30 days of boron treatment with different concentrations of boron,the growth of each growth index in the aboveground and underground parts of strawberry plants increased to varying degrees,which also played a role in promoting biomass accumulation,indicating that boron application could promote the growth of strawberry plants.Overall,when the boron concentration was 3 mg/L,it had a significant effect on the aboveground growth of strawberries,while when the boron concentration was 4.5 mg/L,it had a significant effect on the improvement of root vitality and the accumulation of fresh weight and dry weight of the underground part of strawberry plants,the root vitality increased by 69.17%,and the fresh weight and dry weight of the underground part increased by 128.04%and 48.72%,respectively.2.With the increase of boron concentration,the content of B in different parts of strawberry plants and fruits at different stages of development showed a gradual upward trend,and the B content in the leaves was the highest,followed by the root system,and the content in the fruit was less.The effects of boron application on the contents of N,P,K and Ca in different developmental stage of fruit and different parts of strawberry plants showed different effects,without obvious changes.Boron deficiency promoted the distribution of N to the root system and functional leaves,reduced the absorption of P,and increased the distribution of P to the leaves.When boron is excessive,the root system allocates more N,which promotes P absorption and distribution to young leaves.The K content in strawberry plants was the highest,the K content of each part was functional leaf petioles>young petioles>functional leaves>young leaves>roots,boron had little effect on the K content of strawberry organs,overall boron deficiency inhibited K absorption,boron excess promoted K absorption.The content of N,P and K elements in the strawberry fruits of each treatment showed a gradual downward trend with the development and maturity of the fruits,but the color change stage increased slightly from the ripening stage,and the content of Ca elements in the fruits continued to decrease with the development and maturity of the fruits.The content of N,P and Ca elements in fruits at ripening stage was reduced under the conditions of boron deficiency and boron excess,and the accumulation of K was promoted.3.Boron application could increase the yield and leaf chlorophyll content of strawberries,and with the increase of boron concentration of nutrient solution,the chlorophyll content,yield per plant and average fruit weight in the three periods of strawberry growth showed a trend of first increasing and then decreasing.When the boron concentration was 3 mg/L,compared with T1 treatment,the content of chla+b increased by 31.97%,3.37%and 21.73%,the average weight per fruit increased by 6.83%,and the yield per plant increased by 17.02%.Boron application can increase the soluble sugar content of strawberry fruit,especially sucrose,and reduce the content of titratable acids.When the boron concentrations were 1.5 mg/L and 3 mg/L,the sucrose content was increased by 133.91%and 154.29%,respectively.Compared with boron deficiency treatment.boron application can also increase the content of Vc,total amino acids and total soluble solids in strawberry fruit.When the boron concentrations were 1.5 mg/L and 3 mg/L,the antioxidant capacity of strawberry fruit was higher,and the antioxidant capacity was reduced when the boron concentration was higher.When the boron concentration of 3 mg/L and 4.5 mg/L significantly increased the characteristic aroma of strawberry fruit,4-methoxy2,5-dimethyl-3(2H)furanone,and methyl ester and ethyl esters.It was shown that the appropriate boron concentration could improve the quality of strawberry fruit,and the effect was best when the boron concentration was 3 mg/L.4.With the ripening of strawberry fruits,the content of sucrose,fructose and glucose in each treatment gradually increased,and reached the highest in the S 5 stage,and the highest sucrose content in strawberry ripening fruits.Boron treatment increased the soluble sugar content of strawberry fruits at different developmental stages,and significantly increased the soluble sugar content in the late stage of fruit development,especially the sucrose content.In the later stage of strawberry fruit development,the sugar content showed a trend of first increasing and then decreasing with the increase of boron concentration.Compared with the boron deficiency treatment,when the boron concentration was 3 mg/L,the total sugar content of strawberry fruit in S3,S4,and S5 stages increased by 23.50%,26.90%,and 53.19%,respectively.As the strawberry fruit matures,the activities of SPS and SS-Ⅱgradually increase,while the activities of S-AI and NI gradually decrease.Boron treatment affect the activity of enzymes related to sugar metabolism,When the boron concentration was 3 mg/L can significantly increase the SPS activity of strawberry fruits in S2,S3,S4,and S5 stages,When the boron concentration was 6 mg/L can significantly increase the SPS activity of strawberry fruits in S3 and S5 stages;The activity of SS-Ⅱ in the fruit of each stage was the highest in T3 treatment,while the activity of S-AI in the fruits of each stage was the lowest in T3 treatment.The results showed that the SS-Ⅱ activity was reduced under boron deficiency and high boron conditions,while the activity of S-AI was increased.Adding boron to the nutrient solution resulted in a higher activity of NI in strawberry fruits at all stages compared to boron deficient treatments.Transcriptome analysis showed that boron treatment up-regulated the FaSPS enzyme gene and down-regulated the acidity-β-fructofuran fructosidase gene.This indicates that boron application can promote the accumulation of sugar in strawberry fruits by regulating the expression of sugar metabolism enzyme genes and change the activity of related enzymes. |
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