Influence Of Alternate Partial Root-zone Subsurface Drip Irrigation On Tomato Growth

Subsurface drip irrigation is to bury the emitter outlet under the soil,which has remarkable water-saving effect.Alternate partial root-zone irrigation as an efficient form of water-saving irrigation technology has been widely known.At present,there are many researches on subsurface drip irrigation,but the researches on alternate partial root-zone subsurface drip irrigation are very limited.The depth of underground drip irrigation outlet is a hot topic,and it is necessary to design different depth according to the characteristics of different plant roots.In this experiment,tomato was taken as the research object to study the effect of appropriate emitter burial depth on tomato growth under subsurface drip irrigation in alternate root zone.In experiment plot,conventional sufficient deep,conventional deficit deep,alternate deficit deep,alternate deficit middle,alternate deficit shallow.The main results of the experiment are as follows:(1)Under the same irrigation amount,compared with conventional deficit deep drip irrigation,all the three treatments of alternate partial root-zone subsurface drip irrigation had a promotion effect on the root system,and the promotion effect was stronger when the emitter buried depth was 12.5cm.The aboveground part showed a decrease in plant height and a significant increase in total biomass with different degrees of stem thickening.The chlorophyll content of leaves increased and the photosynthetic rate increased.The SOD activity and Pro content of leaves increased,and reached the maximum at alternate deficit middle,which improved the ability of plants to resist water and nutrient stress.During an alternate cycle,with the extension of irrigation time,the emitter burial depth decreased,and the ABA content increased gradually,while the ZR,IAA and GA3 contents decreased with the irrigation time,and the hormone content reached the maximum at alternate deficit middle.The uptake of N,P and K in the vegetative organs of tomato plant was significantly increased,and reached the maximum at alternate deficit middle.The yield and water use efficiency of tomato fruit were greatly improved,and the ratio of sugar to acid was increased,and the fruit quality was improved.(2)Under the condition of reduced irrigation amount,compared with conventional full irrigation,the buried depth of alternate partial root-zone subsurface drip irrigation of 12.5cm had no significant effect on root growth;The plant height of the aboveground part was greatly reduced,while the stem diameter and biomass were not significantly different.There was no significant difference in leaf chlorophyll content,and the photosynthetic rate and transpiration rate decreased,but the photosynthetic rate did not decrease significantly.The activities of protective enzymes in leaves increased significantly,and the content of ABA increased,while the contents of ZR,IAA and GA3 decreased in one irrigation cycle.There was no significant difference in nitrogen,phosphorus and potassium uptake in vegetative organs.There was no significant difference in tomato fruit yield,water use efficiency was significantly improved,vitamin C content and sugar to acid ratio of tomato fruits were increased,and the taste and flavor of tomato fruits were improved.(3)To sum up,considering the effects of emitter burial depth on tomato plant growth and development,physiological response,fruit yield and quality,irrigation efficiency and other aspects,alternate partial root-zone subsurface drip irrigation controlled with emitter burial depth of 12.5cm is a more suitable subsurface drip irrigation method for tomato growth.