| With the development of peach industry,replant problem are becoming more seriously.It has been an urgent need for the industrialization development to uncover the formation mechanism of the peach replant problem.In this study,replated live soil and its sterilized soil were mixed with different ratios in volume to explore the effect of soil biota on the growth of peach seedlings.The repla nted soil extract was filtered through different size sieves(1 mm,20 μm,5 μm and 0.22 μm)to prepare the inoculums containing different soil biota and only soil substances.The inoculums were irrigated into potted peach seedlings to explore the effects of different biological communities and autotoxins on peach seedlings growth.This work aimed to identify the main causal agents causing peach replant problem,and to provide theoretical basis for the precise prevention and control of peach continuous cropping obstacles.The main results are as follows:(1)Replanted soil organisms inhibited the growth of peach seedlings.The peach seedlings growth was not inhibited when cultivated with sterilized replanted soil.However,the addition of different proportions of replanted live soil to the sterilized replanted soil,the growth of peach seedlings were significantly inhibited.With the increase of the proportion of replanted live soil,the inhibition on the growth and physiology of peach seedlings was more evident.Compared with the sterilized replanted soil,the phenotypic growth data of peach seedlings treated with 100%replanted live soil were significantly decreased,the net plant height growth,average leaf area,aboveground fresh weight,underground fresh weight and total fresh weight were significantly decreased by 53.29%,52.04%,59.18%,63.53% and 55.87%,respectively.And lead to peach seedling root architecture degradation,chlorophyll content and fluorescence value significantly reduced,further damage the antioxidant enzyme activity system,MDA and reactive oxygen species significantly accumulated.(2)The inhibitory effects of different pore size of soil extracts on the growth of peach seedlings varied significantly.Compared with the sterile water control,the growth of peach seedlings was significantly inhibited by the treatment with the soil extracts of 1 mm,20 μm and 5 μm pore size,while the 0.22 μm soil extracts had no obvious inhibition on the peach seedlings growth.Among them,soil extracts with 1mm and 20 μm had the greatest inhibiton on peach seedlings.In contrast,soil extracts with 5 μm significantly alleviated the inhibition of peach seedling growth,while the chlorophyll content,chlorophyll fluorescence properties and antioxidant activity abilities were increased.The chlorophyll fluorescence value,reactive oxygen species level,membrane lipid peroxidation level,POD and CAT contents of peach seedlings treated with 5 μm soil extract were comparable to 0.22 μm treatment.In view of the soil microbial community composition of different pore size treatments,it was speculated that fungal community may be the main causal agents for the peach replant problem,which induced the accumulation of reactive oxygen species,impairment of the antioxidant system and inhibition of the photosynthesis of peach seedlings. |
