| During the irrigation of facility agriculture,when water entered the soil,it easily replaced the air in the pores of the soil,resulting in hypoxia stress in the root zone of the crop,which affected the soil environment of the root zone and hindered the normal growth and development of the crop.It is found that aeration drip irrigation could effectively improve soil aeration,and play an important role in improving water and fertilizer utilization efficiency and increasing crop yield.However,the aeration rate and aeration sequence suitable for crop growth had not yet been determined,and the effect of aeration drip irrigation to alleviate crop waterlogging stress was unclear.Therefore,tomato was used as the test crop and ordinary underground drip irrigation as the control in this study.Four kinds of aeration rate(25%,50%,75% and all aeration drip irrigation)and two kinds of aeration sequences(general drip irrigation-aeration drip irrigation and aeration drip irrigation-ordinary drip irrigation)were set up.The changes of tomato growth index,physiological index,yield and quality and soil environment in root zone were analyzed.In addition,during the flowering and fruiting stage and fruit expansion stage,the tomato was flooded and aerated every day with waterlogged and unaerated as the control.By observing the growth and development of tomato in each treatment,the mitigation effect of aeration treatment on crop waterlogging stress was studied.The main conclusions are as follows:(1)Since July 15 th,the plant height,stem thickness and leaf area of each aeration drip irrigation treatment were larger than the control.On August 5th,under the same aeration sequence,tomato plant height and leaf area increased first and then decreased with the increase of aeration,the maximum value appeared in the treatment of 75% aeration.Under the same aeration rate,the tomato plant height and leaf area of the later aeration drip irrigation treatment were significantly greater than that of the previous aeration drip irrigation treatment(P <0.05).Each aeration drip irrigation treatment increased the total root length,total root volume,number of root tips,root vitality,dry weight of aboveground and underground parts of the tomato,and the maximum value was CA3 treatment(75% aeration,later aeration drip irrigation treatment Combination),significantly increased by 3.85 times,8.34 times,2.04 times,10.47 times,5.37 times and 13.5 times(P <0.05).(2)During the fruit expansion and ripening stages,the photosynthetic rate,transpiration rate,potential photochemical efficiency,and chlorophyll index of CA3 treatment were significantly increased than those of the control by 3.26 times,1.11 times,26.07%,and 30.64%(P <0.05),but the maximum photochemical efficiency was not significantly different in different aeration treatments(P> 0.05).Under the same aeration rate,the photosynthetic rate and transpiration rate of the later aeration drip irrigation treatment were significantly greater than the previous aeration drip irrigation treatment(P <0.05),and different aeration timings have little effect on the maximum photochemical efficiency and potential photochemical efficiency(P> 0.05).(3)After aeration drip irrigation treatment,the yield per plant,fruit number,fruit quality,and fruit length and diameter of the crop were all greater than that of the control.The maximum yield per plant and the quality of single fruit appeared in the CA3 treatment,which increased significantly by 84.31% and 66.99%,respectively(P <0.05).However,the maximum number of fruits per tomato plant appeared in A3 C treatment(a combination of 75% aeration and early aeration drip irrigation treatment),which was a significant increase of 58.54%(P <0.05).After aeration drip irrigation,the quality of tomatoes had also been improved,especially CA3 treatment effect was better,its soluble sugar,vitamin C,soluble protein and soluble solids were significantly increased by 129.84%,60.54%,79.87% and 112.89%(P <0.05).(4)Aeration drip irrigation can effectively improve tomato's absorption of soil nutrients,promote the decomposition and consumption of soil organic matter and nitrogen,phosphorus and potassium content.The indexes of soil organic matter,total phosphorus,total potassium,available phosphorus and available potassium under the treatment of CA3 were the smallest,which were reduced by 33.86%,42.86%,14.82%,47.09% and 64.71% respectively(P <0.05).CA1 treatment(50% aeration,post-aeration drip irrigation treatment combination)had the lowest total nitrogen and alkaline nitrogen content.Aeration drip irrigation significantly improved soil microbial diversity and soil enzyme activity.The Chao1 index,ACE index and Shannon index of CA3 treatment were the highest,and the predominant bacterial groups were Proteobacteria and Aspergillus at the phylum and genus levels,respectively.Before harvesting,the soil urease activity,soil phosphatase activity and soil invertase activity of CA3 treatment were significantly increased by 3.02 times,1.71 times and 8.85 times compared with the control(P <0.05).(5)Aeration drip irrigation has obvious mitigating effect on tomato waterlogging stress.During the waterlogging stress period,the photosynthetic rate,potential photochemical efficiency and chlorophyll of the aeration treatment increased by 122%,15.8% and 22.91%(P <0.05).After waterlogging stress,the survival rate,plant height,stem thickness,dry matter quality and yield of aeration-treated tomatoes increased significantly.Compared with the flowering and fruiting stage,the aeration treatment had a more obvious relief effect on the waterlogging stress of the tomato fruit expansion stage,especially the survival rate,which was significantly increased by 3 times compared with the control(P <0.05).Comprehensive consideration of yield and quality factors,75% aeration,and later aeration drip irrigation treatment combination is a suitable aeration drip irrigation method for facilities in Jiaodong area of Shandong Province.Aeration treatment can alleviate the harm of waterlogging stress on tomato plants,and promote the growth and development of tomatoes to a certain extent,especially in the fruit expansion period,the effect of promoting tomato growth is more obvious. |
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