The Effect Of Mixed Intercropping Garlic And Other Crops On The Alleviation Of Peach Replant Problem

Peach is an economically important fruit tree,ranking the fourth largest fruit tree in China.During the renewal process of old peach orchards,peach replant problems such as low survival rate,weak growth and poor resistance are often occurred in newly planted seedlings.The causes of peach replant problem are too complicated,and it is difficult to precisely prevent and control,and no effective solutions are available at present.Intercropping,relay and mixed intercropping are the general agronomic managements to alleviate continuous cropping obstacles in facility-cultivated vegetables and staple crops,but no relevant reports on peach.In this study,peach seedlings cultivated in pots filled with replanted peach soil were intercropped with other crops such as Brassica juncea,Allium schoenoprasum,Allium tuberosum,Allium cepa,Medicago sativa or Allium sativum.The effect and possible mechanism of different intercrops on the alleviation of replanted soilmediated inhibition of peach seedlings growth were explored.The main conclusions were as follows:1.Except Brassica juncea,the mixed intercropping with other crops for 90 days promoted the growth of peach seedlings to a certain extent,increased the above-and belowground biomass of peach seedlings,and improved the growth of leaves and roots.Among the intercrops,compared with the control,the plant height,fresh weight of aboveground part,dry weight of aboveground part and total root length of Allium sativum were increased by 22.7%,61.0%,48.8% and 52.9%,respectively,followed by Medicago sativa,Allium cepa,Allium tuberosum,Allium schoenoprasum.The mixed intercropping improved the net photosynthetic rate,surface area and chlorophyll content of peach seedling leaves.The Allium sativum treatment showed the highest leaf area and chlorophyll content,while the Allium tuberosum treatment had the highest net photosynthetic rate.The leaf area,net photosynthetic rate and total chlorophyll content of peach seedlings with mixed intercropping Allium sativum were increased by 80.5%,14.4% and 94.0%,respectively,compared with the control.2.The activity of soil urease,catalase and invertase were improved in different degrees by mixed intercropping treatment,among which the effect of Allium sativum was the most evident,the activities of soil urease,catalase and invertase increased by 43.9%,22.1% and24.8%,respectively,compared with the control.The soil physicochemical properties were changed after different mixed intercropping treatments,which did not cause significant difference in soil fertility,but altered the composition of soil microbial community.3.Mixed intercropping with Brassica juncea or Allium sativum altered soil bacterial and fungal community structure,increasing the abundance of the beneficial bacteria Streptomyces and the fungus Clitopilus,decreasing the abundance of the harmful bacteria Gaiella,and reduced the abundance of plant pathogenic fungi whose function was predicted.The mixed intercropping of Brassica juncea also improved the functions of 20 soil bacteria in four categories of cell transformation,genetic information processing,environmental information processing and metabolism related to plant growth.In summary,the effect of mixed intercropping with Allium sativum showed the best effect on the alleviation of peach replant problem,mainly by improving the soil urease,catalase and invertase activities,increasing the abundance of the beneficial bacteria Streptomyces and the fungus Clitopilus,decreasing the abundance of the harmful bacteria Gaiella,reducing function prediction for the abundance of plant pathogenic fungi to improve peach seedling growth.