| Ebb and flow irrigation,which is a subirrigation method based on capillary force of matrix pores,and its application in vegetable plug seedling is increasing in China.In order to clarify the optimal fertilizer concentration and the characteristics of water retention and dissipation of plug substrate in ebb and flow plug seedling of vegetables,this study has been used the tomato(Solanum lycopersicum L.cv.Zhongza 302),Capsicum annuum L.cv.Zhongjiao No.6),eggplant(Solanum melongena L.cv.jingqie No.1),cucumber(Cucumis sativus L.cv.Zhongnong 18)as the materials to explore the fertilizer supplies and water retention characteristics of vegetable tidal plug seedlings in the whole growth period,which provide practical reference for precise supply of water and fertilizer for ebb and flow plug seedling of vegetables.The main results are as follows:1.Tomato cultivar ’Zhongza 302’ was selected to study the effects of different gradient nutrient solution concentrations on the growth and development of tomato.The nutrient solution was divided into 5 stages of ebb and flow irrigation with gradient concentration The growth and development parameters,nutrient accumulation and utilization rate of tomato plug seedlings were measured and analyzed.It was found-that the seedling emergence rate of 1.0×concentration nutrient solution was the highest in stage I;In addtion,when the nutrient solution concentration was set as 0.25×in stage I,0.25×in stage II,1.0×in stage III,1.5×in stage IV and 1.5×in stage V,plant height,stem diameter,root length,root volume,root surface area,average root diameter,dry and fresh weight and strong seedling index of plug seedlings were the best.The strong seedling index,compared with other treatments,increased by 32% 、36.83%、76.42%、30.77%、55.40%、43.11%、37.16%、27.21%.Further more,the growth rate of dry weight of tomato plug seedlings increased with the growth and development process;Increasing the concentration of nutrient solution promoted the absorption and accumulation of N,P and K in plug seedlings.2.Tomato cultivar ’Zhongza 302’ was selected to investigate the characteristics of water retention and dissipation of tomato seedling substrate under the condition of ebb and flow irrigation.The results showed that,it found that it takes 10-12 minutes to increase the relative water content of tomato plug seedling substrate from 15% to 65%,and 14-17 minutes to increase from 15% to 75%,and the water absorption rate gradually decreases with the extension of time;In summer,the average drop of the relative water content in daytime is about 14.62%,and the average drop at night is about 2.74%,while the average drop of the relative water content in autumn daytime is about 10.90%,and the average drop at night is about 1.81%;There was a significant positive correlation between seedling substrate water dissipation rate and temperature(P<0.01),and a significant negative correlation between seedling substrate water dissipation rate and air relative humidity(P<0.01);The leaf area,SPAD and other indexes of tomato seedlings cultivated by ebb and flow irrigation were significantly higher than those cultivated by top sprinkling irrigation(P<0.05);The water use efficiency of plug seedling,compared with top sprinkler irrigation,by ebb and flow irrigation in summer and autumn increased by 47.41%and 60.12%,respectively.3.Pepper cultivar ’Zhongjiao No.6’ was selected to investigate the characteristics of water retention and dissipation of pepper seedling substrate under the condition of ebb and flow irrigation.The results showed that,it found that it takes 5-7 minutes to increase the relative water content of tomato plug seedling substrate from 15% to 60%,and 8-11 minutes to increase from 15% to 70%,and the water absorption rate gradually decreases with the extension of time;In summer,the average drop of the relative water content in daytime is about 12.22%,and the average drop at night is about 2.36%,while the average drop of the relative water content in autumn daytime is about 10.54%,and the average drop at night is about 2.34%;There was a significant positive correlation between seedling substrate water dissipation rate and temperature(P<0.01),and a significant negative correlation between seedling substrate water dissipation rate and air relative humidity(P<0.01);The water use efficiency of plug seedling,compared with top sprinkler irrigation,by ebb and flow irrigation in summer and autumn increased by 51.46% and 72.90%,respectively.4.Eggplant cultivar ’jingqie No.1’ was selected to investigate the characteristics of water retention and dissipation of eggplant seedling substrate under the condition of ebb and flow irrigation.The results showed that,it found that it takes 11-13 minutes to increase the relative water content of tomato plug seedling substrate from 15% to 65%,and 5-6 minutes to increase from 20% to 65%,and the water absorption rate gradually decreases with the extension of time;In summer,the average drop of the relative water content in daytime is about 11.12%,and the average drop at night is about 1.93%,while the average drop of the relative water content in autumn daytime is about 10.64%,and the average drop at night is about 1.52%;There was a significant positive correlation between seedling substrate water dissipation rate and temperature(P<0.01),and a significant negative correlation between seedling substrate water dissipation rate and air relative humidity(P<0.01);The stem diameter and dry weight of eggplant seedlings cultivated by ebb and flow irrigation were significantly higher than those cultivated by top sprinkling irrigation(P<0.05);The water use efficiency of plug seedling,compared with top sprinkler irrigation,by ebb and flow irrigation in summer and autumn increased by 63.21% and 77.60%,respectively.5.Cucumber cultivar ’Zhongnong 18’ was selected to investigate the characteristics of water retention and dissipation of cucumber seedling substrate under the condition of ebb and flow irrigation.The results showed that,it found that it takes 10-15 minutes to increase the relative water content of tomato plug seedling substrate from 15% to 60%,and 40-45 minutes to increase from 15% to 85%,and the water absorption rate gradually decreases with the extension of time;In summer,the average drop of the relative water content in daytime is about 10.25%,and the average drop at night is about 2.63%,while the average drop of the relative water content in autumn daytime is about 7.93%,and the average drop at night is about 1.85%;There was a significant positive correlation between substrate water dissipation rate of cucumber plug seedling substrate and temperature in summer(P<0.05),while a extremely significant positive correlation with temperature in autumn(P<0.01),both in summer and autumn,there was a extremely significant negative correlation with air relative humidity(P<0.01);The water use efficiency of plug seedling,compared with top sprinkler irrigation,by ebb and flow irrigation in summer and autumn increased by 59.11% and 56.22%,respectively. |
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