The Influence Of Anti-hail Nets With Different Color On Apple Tree Growth And Fruit Quality

Hail is an agricultural meteorological disaster that can cause serious damage to the apple industry.Anti-hail nets can greatly avoid the damage caused by hail disasters to the apple industry,but the establishment of an anti-hail nets will have a certain impact on the microenvironment of the orchard,thus affecting the growth and development of fruit trees and the quality and yield of fruit.At present,there are many kinds of colorful anti-hail nets used in orchards in agricultural production.It has not been reported which kind of anti-hail nets is the best for the growth and development of fruit trees and fruit quality in China.In this paper,a systematic study of the impact of apple orchard covered with white,blue,black,green four colors hail nets with 70% transmittance each on the orchard microenvironment was conducted and the growth and development of fruit trees and fruit yield and quality were measured,to prevent the orchard from the hail damage and provide certain theoretical and application basis to improve the yield and quality of the orchard.This study was carried out in 2020 and 2021 to assess the impact of different colors of the anti-hail nets from three aspects.Firstly,the orchard environment includes light intensity,light quality,relative air temperature,relative air humidity,and soil temperature.Secondly,the growth and development status of fruit trees includes shoot growth,leaf growth index,photosynthetic efficiency,element content,and other convenient evaluation aspects;Thirdly,the effects on fruit yield and fruit quality include fruit external and internal quality.The results of the experiment in 2020 are compared with those in 2021,and the stable results in two years are the final results.To conclude,the optimal treatment is obtained by principal component analysis and comprehensive evaluation.The results show that:(1)The light intensity of the orchard did not change significantly in four different color nets,but the overall performance was that the shading effect of black,green,blue,and white anti-hail nets decreased in turn.In addition,the coverage of the blue anti-hail nets could significantly increase the proportion of blue light,and the coverage of the green anti-hail nets could significantly increase the proportion of green light.The coverage of blue,black,and green anti-hail nets all could reduce the ratio of red light and far-red light.Finally,different treatments could affect the diurnal variation of soil temperature,but there was no significant change in relative air humidity and temperature.(2)Compared with the white anti-hail nets,the blue nets could help the fruit tree significantly increase the length and roughness of new shoots,the leaf area,the leaf fresh and dry weight,leaf relative water content,but reduced the leaf thickness;the black nets could significantly increase the length and roughness of new shoots,the leaf area,leaf thickness;the effect of the green nets was not stable and presented that the length and diameter of new shoots could increase significantly in the first year,but had an obvious recession in the second year.Different color nets did not affect the leaf shape index of apple trees in this article.(3)There was no significant effect on the overall level of chlorophyll content by covering different colors of anti-hail nets,but compared with the white nets,covering black and green anti-hail nets could significantly reduce the value of chlorophyll a/chlorophyll b,while the value of chlorophyll a/chlorophyll b under the blue nets was slightly higher.(4)The diurnal changes of photosynthesis on sunny days and cloudy days were compared.The blue anti-hail nets could ensure that plants have good photosynthetic intensity whether on sunny or cloudy days.The white nets could maintain a high photosynthetic rate on cloudy days.(5)Different color nets had no significant effect on the external quality of fruit but had a great impact on the internal quality.Peel ductility under blue、black、green anti-hail nets had improved significantly,but the fruit firmness,peel firmness,flesh crispness,the contents of soluble solids and titratable acid showed a downward trend.(6)Compared with the white anti-hail nets,the blue nets could steadily improve the single fruit weight and yield per plant of apple,and the black net had the second effect.The green nets were not conducive to the increase in apple yield.(7)Using principal component analysis for a comprehensive evaluation,the results showed that the best-covering effect was blue anti-hail nets,followed by black anti-hail nets,white anti-hail nets,and finally the green one.