Screening Of Dominant Grass Species And Grassing Years Of Natural Grass In Korla Pear Orchard

Improving the quality and efficiency is the top priority for the high-quality development of Korla fragrant pear industry,and the orchard grass technology can adjust the soil structure,improve the soil fertility,improve the orchard microbes,improve the fruit quality,especially the natural grass technology,less investment,high orchard ecological diversity,strong adaptability.At present,the technology of grass growing in orchards has been widely used in modern orchard production,but there are few systematic studies on the characteristics and management technology of grass cover in Korla orchard,which affects its application and popularization.Therefore,this study took Korla pear as the test material,investigated the weed community composition,phenology period,mineral nutrient content and germination rate in the pear garden,compared the difference between the internal and external quality of Korla pear fruit and the difference of soil mineral nutrient in the clear cultivated pear garden and the grass pear garden,and analyzed and evaluated the grass cover characteristics of the pear garden systematically by using correlation analysis.The effects of natural grass on soil physical and chemical properties and fruit quality can provide some theoretical basis and technical guidance for soil management in pear orchard.The main results are as follows :(1)Through the investigation of pear orchards,it was found that there were 13 families,30 genera and 34 species of weeds in pear orchards,most of which were annual herbs and a few were perennial herbs.The phenological period of weeds was mostly concentrated in spring and summer.The dominant grass species in pear orchard were Plantago asiatica,Taraxacum mongolicum,Amaranthus retroflexus,Amaranthus retroflexus.The water content of shoot and root of Plantago asiatica was the highest 32.09 g and 5.07 g,and the fresh weight of shoot and root was the highest 40.62 g and 8.64 g.The highest contents of carbon,nitrogen,phosphorus and potassium were 63.59 mg / g(Plantago asiatica),32.72 mg / g(Portulaca oleracea),92.47 mg / g(Amaranthus retroflexus),57.54 mg / g(Plantago asiatica),and had the characteristics of long phenological period and high germination rate.(2)Grass planting can significantly increase the mineral nutrient content of pear orchard soil,but there was no significant difference between 1-2 years of grass planting.In pear orchards,the soil organic matter content in 0-20 cm soil layer increased significantly by 24 %,37.7 % and 61.1 % in 3-5 years.The soil organic matter content of 20-40 cm and 40-60 cm soil layers in 5 years of grass planting increased significantly by 59.96 % and 45.6 %.The content of alkali-hydrolyzable nitrogen in 0-20 cm soil layer increased by 36.19 %,49.52 % and 57.14 %,but the content of available phosphorus in 0-20 cm soil layer decreased.The content of available potassium in different soil layers reached the maximum value of 199.33 mg / kg,193.33 mg / kg and 189.00 mg / kg in the fifth year of grass planting.The total potassium content in the 0-60 cm soil layer,the total nitrogen content in the 0-40 cm soil layer,and the total phosphorus content in the 40-60 cm soil layer of the pear orchard were all improved,and the shallower the soil layer and the longer the planting years,the more obvious the effect.(3)Grass planting in pear orchard can improve the appearance quality of Korla fragrant pear,improve the internal quality of Korla fragrant pear,and change the anthocyanin and chlorophyll content of peel and pulp.After planting grass in pear orchard,the single fruit weight of pear fruit with different grass planting years increased by 11.40 %,4.95 %,20.09 %,12.78 % and 12.06 %,the longitudinal diameter increased by0.14 %,5.62 %,13.59 %,6.09 % and 7.18 %,and the fruit shape index increased by 14.70 %,5.91 %,4.15 %,3.34 % and 7.32 %.Fruit skin hardness increased by 8.99 %,35.20 %,24.18 %,26.99 % and18.89 %.The fruit thickness decreased by 21.87 %,4.68 %,15.62 %,25.00 % and 21.87 % respectively,and the number of fruit points decreased by 21.79 %,16.81 %,8.52 %,13.72 % and 6.90 % respectively.The soluble solids content,Vc content and juice yield increased significantly,and the peel thickness and titratable acid content decreased significantly.The longer the planting years of grass,the more obvious the improvement of fruit quality of Korla fragrant pear.