Effect of anti-hail nets on the growth and leaf diseases of Donghong kiwifruit during growing period

Abstract: 【Objective】China has the largest planting area and output in the world for kiwifruit which is vulnerable to extreme climate. Hail is considered as one of the most serious natural disasters,which is characterized by the rapid and sudden onset, strong unpredictability and significantly destructive power. In recent years, frequent hail disasters have seriously threatened the safe production of kiwifruit. Antihail nets have become one of the effective measures for disaster prevention and protecting against reduction in production. Therefore, analyzing the effect of anti-hail nets in kiwifruit orchards is of great significance to prevent from hail disasters, develop new materials and optimize structural design, guide the fine management and elevate fruit quality and efficiency of kiwifruit industry.【Methods】6- year- oldDonghong kiwifruit vines were used as test materials at Shapo village, Panlong town, Shuicheng District, Liupanshui City from 2020 to 2021. On the same plot, white anti-hail nets were covered and openair culture was used as the control. GSP-6 automatic temperature recorder was used to measure the orchard temperature, and the AS823 illuminance meter to determine the orchard light intensity. The bud break stage, flowering stage, maturity stage and leaf fall stage of kiwifruit were analysed. Additionally, the mean internode distance, bud germination rate on mother canes and the main flower number, single flower rate, orchard yield, fruit quality and leaf disease on bearing canes were measured on different length of bearing canes for 40-80 cm, 80-120 cm and above 120 cm. The temperature, bud break stage, flowering stage, maturity stage, leaf fall stage, mean internode distance, bud germination rate, main flower number, single flower rate and leaf disease were compared between inside and outside of antihail nets.【Results】Compared with the control, the temperature of the kiwifruit orchard in the anti-hail nets was always higher than the control from February to April, up to 0.8 ℃, and was lower than the control from June to September, up to 2.1 ℃. The germination stage was delayed 3-5 days, the flowering stage was delayed 4-5 days, the maturity stage was delayed 7-8 days, and the defoliation stage was delayed 18-23 days. In 2020, the number of main flowers on bearing canes significantly decreased by 23.96% , 26.98% and 31.24% , and the single flower rate on bearing canes significantly increased by 95.39%, 103.31% and 105.76%. In 2021, the number of main flowers on different length bearing canes significantly decreased by 24.52%, 22.43% and 28.37%, and the single flower rate on bearing canes significantly increased by 99.49%, 92.64% and 95.16%. Brown leaf spot disease rate, diseased leaf rate and disease index were 17.55%, 21.95% and 4.13%, and 17.33%, 21.15% and 7.04%, respectively, being lower than the control for two years. The rate of diseased plants, diseased leaf rate and disease index of gray spot were 6.73%, 20.73% and 6.02%, and 9.04%, 25.66% and 8.63%, respectively, being lower than the control. The rate of diseased plants, diseased leaf and disease index of black spot were 6.11%, 7.96% and 2.24%, respectively, being lower than that of the control. There were no significant effects on mean internode distance and germination rate.【Conclusion】Anti-hail nets can reduce the number of main flowers, promote the centralized opening of flowers and improve the single flower rate, reduce the incidence of leaf disease, but not affect the yield and quality of kiwifruit, and has a promoting effect on kiwifruit production. Anti-Hail nets is one of the effective measures to solve the contradiction between hailstorm disaster and airspace control, and it is expected to be popularized and applied in the production of high efficiency cash crops like high-quality fruits and vegetables.