Artificial Intervention Of Natural Grass Growing Technology In Dryland Apple Orchard And Effect Of Potassium Application In Different Periods Before Mining

Improving quality and efficiency is one of the main tasks of the current high-quality development of apple industry.Orchard grassing can improve orchard ecology,promote soil fertility,and improve fruit quality,which has been widely used in modern orchard production.Especially,natural grassing technology has begun to be applied in dryland apple orchards due to the use of local natural vegetation,strong adaptability,high ecological diversity of orchards,and low investment.However,the lack of systematic research on the characteristics of dryland apple orchard vegetation and management technology has affected its application and promotion.Therefore,taking Luochuan apple orchard as the representative,this paper systematically studied the characteristics of grass cover,cutting mode and the influence of grass on soil physical and chemical properties and fruit quality in dryland orchard,and put forward the natural grass technology scheme of artificial drought in dryland orchard.At the same time,the effects of potassium fertilizer application at different stages before harvest on fruit quality of Fuji apple were studied to provide technical support for high quality production of dryland apple.The main research results are as follows :(1)The occurrence characteristics and community composition of herbaceous plants in dryland apple orchard were investigated.Margalef richness index and Simpson index were calculated by using the population density and coverage of herbaceous species.At the same time,excellent herbaceous species suitable for natural grass in dryland apple orchard were screened according to the relative height and root length of herbaceous plants.The results showed that there were 32 species of herbaceous plants belonging to 15 families in dryland apple orchards.The dominant grass species varied with seasons.Zoysia,Chenopodiaceae and cruciferous herbaceous plants had obvious growth advantages in spring than other herbaceous plants.However,after entering summer,cruciferous herbaceous plants were gradually replaced by Zoysia,Gramineae and Compositae herbaceous plants.Until November,the growth advantages of Zoysia,Setaria viridis,Pennisetum viridis,Digitaria sanguinalis and Echinochloa crusgalli were still obvious.According to the niche index,August and September were the months with high annual herb richness index.The screening results showed that Pennisetum,Pennisetum,Digitaria sanguinalis,Echinochloa crusgalli,Zoysia japonica,Taraxacum mongolicum,Ixeris sonchifolia and Huoxuedan could be used as excellent herb species for natural grass in dryland apple orchard.At the same time,the effects of different cutting heights on the grass cover were analyzed in the simulation of cutting management technology in the apple orchard with natural grass in dryland.It was found that the effect of stubble 1-2 cm after cutting treatment was better,which was not easy to damage the root system of grass species,and could effectively control the growth rate of grass species without affecting the normal growth of grass species.(2)In the experiment,three natural grass-growing orchards and one clear-tillage orchard were set.By measuring the soil,leaf and fruit indexes of the perennial natural grass-growing orchard,it was proved that the grass-growing treatment improved the soil environment and fruit quality of the orchard,and promoted the growth and development of the tree.Grass treatment can balance ground temperature and effectively reduce soil temperature difference.Although the grasses in July and August with drought and low rainfall reduced the soil water content in the soil layer,the soil water content in the orchard surface was reduced and the water infiltration was promoted in September and October with rainy days.Grass treatment significantly reduced soil bulk density,increased soil porosity,and increased the contents of total carbon and inorganic carbon in soil,but natural grass treatment had no significant effect on the contents of available nitrogen,phosphorus and potassium.At the same time,natural grass treatment promoted leaf growth and significantly increased leaf thickness,weight and leaf area.The effect of grass treatment on soluble solids content was not obvious,which may be related to the continuous rainy weather before harvest in the experimental year.However,grass treatment reduced the titratable acid content,significantly increased the solid-acid ratio of fruit,increased the coloring area and anthocyanin content,enhanced the peel hardness and peel ductility,and increased the content of nitrogen,phosphorus and potassium in fruit compared with clean tillage orchard.Based on the comprehensive measurement results,it was indicated that the natural grass-growing technology under artificial intervention was worth popularizing in dryland apple orchards.(3)In order to explore the effect of potassium fertilizer application on fruit quality of Fuji apple in different periods before harvest,the experiment of potassium fertilizer application in soil during apple expansion was carried out on July 15,August 1,August 15,August 31 and September 15.The experimental results showed that the effect of potassium fertilizer application was the best in the two periods from July 15 to August 15,and the effect on improving fruit quality was obvious.According to the yield of 1 kg potassium fertilizer per 100 kg,the contents of soluble solids and anthocyanin increased,the content of titratable acid decreased,and the flesh brittleness and peel ductility increased.At the same time,the contents of N,P and K in the fruit were effectively improved after potassium fertilizer application.