Effects Of Different Irrigation Methods On The Growth And Yield Of Celery In Greenhouse

Appropriate irrigation method is one of the important measures to promote water-saving irrigation.Studying the water-saving response mechanism of economic crops in water-deficient areas,and establishing an irrigation system with efficient water use based on this,has important theoretical and practical value for promoting the sustainable use of local water resources,sustainable agricultural development,and ensuring ecological security.In this experiment,celery is used as the test crop,and a total of five treatments are set up(border irrigation treatment T1,T2:the upper limit of irrigation is 80%θ_Fc（soil field water holding rate）,90%θ_Fcand drip irrigation treatment T3,T4:the upper limit of irrigation is respectively80%θ_Fc,90%θ_Fc,the control treatment CK adopts the local traditional irrigation method.This experiment design starts from the slow seedling water and irrigates every three weeks.The starting point of the irrigation is that the water reaches the irrigation water limit),and the effects of different irrigation methods on the growth and physiological changes of greenhouse celery,soil water dynamic changes,yield and water use efficiency are analyzed,and the irrigation mode that is beneficial to the growth of greenhouse celery is determined,and provided a basis for formulating the irrigation system of celery.The main findings are as follows:（1）The variation of soil moisture in greenhouse celery under different irrigation methods.During the growth period of celery,the soil moisture fluctuates in a zigzag shape with irrigation and plant evapotranspiration,and has a tendency to increase with the increase of irrigation water.Under the same irrigation method,the average soil moisture content is positively correlated with the irrigation water during each growth period.As the growth period advances,the fluctuation of soil moisture content becomes smaller and smaller.Compared with border irrigation,drip irrigation has a smaller coefficient of variation of water content and tends to stabilize water distribution.The soil moisture in the outer leaf growth period shows a trend of first increasing and then decreasing with the increase of soil depth.The soil moisture content of 40-60cm soil layer of border irrigation is 2.66-16.39%higher than that of drip irrigation.The drip irrigation in the vertical stage has more advantages in the performance of water in the 0-40cm soil layer.The maximum water content in the growth period of the heart leaf is located in the 40-60 cm soil layer,and the border irrigation treatments are all higher than the drip irrigation treatments.（2）The change law of greenhouse celery growth index under different irrigation methods.During the growth period of celery,the plant height and leaf stalk width shows a slow increase first and then a rapid growth trend with the advancement of the growth period,and the T2 treatment increases the fastest.Under the same irrigation method,the treatment with more irrigation volume has a larger increase,and the drip irrigation treatment with a slightly lower irrigation volume under different irrigation methods has a larger increase than the border irrigation treatment T1.The order of plant height uniformity of each treatment is:T4>T3>CK>T2>T1,there is a significant difference between border irrigation and drip irrigation.During the growth period,the number of celery leaves shows a slow increase first,then a rapid increase,and finally a gentle change trend as the growth period progressed,and the differences in the leaves of the celery phase reached a significant level.During the growth period of celery,the effect of drip irrigation on the number of leaves do not reach a significant difference,while border irrigation reaches a significant difference.The change trend of celery leaf water potential during the growth period of each treatment is greatly affected by soil moisture.With the increase of irrigation amount,the leaf water potential shows an upward trend.Drip irrigation maintains a moderate leaf water potential under a small irrigation volume.With the increase of irrigation amount under the same irrigation method,the fresh weight and dry weight of celery above ground increases gradually.Under border irrigation treatment,the total fresh weight and total dry weight of T2 treatment are significantly higher than that of T1 treatment,but there is no significant difference from T1 treatment.Under the drip irrigation treatment,the fresh and dry weight of high water treatment T4 is significantly greater than that of low water treatment T3,and reaches a significant level.The drip irrigation treatment T4 irrigation volume is 13.41%smaller than T1 treatment,but the fresh and dry weight are 2.47%and 17.08%larger than T1 respectively.（3）The changes of physiological characteristics of greenhouse celery under different irrigation methods.The net photosynthetic rate（Pn）,transpiration rate（Tr）and stomatal conductance（Gs）of celery leaves in different treatments all shows a trend of first increasing,then decreasing and then increasing with the advancement of the growth period.The peaks all appears on the 49th day.With the increase of irrigation volume,Pn,Tr and Gs gradually increased.The intercellular carbon dioxide concentration（Ci）shows the opposite change law.Compared with border irrigation,drip irrigation is more conducive to reducing the fluctuation of photosynthetic characteristics of celery leaves.The diurnal variation curves of Pn,Tr,Gs,and Ci of celery leaves in different treatments all shows a single-peak curve,and the peaks of Pn,Tr,Gs and the lowest values of Ci appears between 12:00 and 14:00.The daily average values of Pn,Tr and Gs of CK treatment are the maximum values of each treatment,and T3treatment are the minimum values,and the difference between the two reaches a significant level.Ci shows the opposite law.The changes of chlorophyll content（SPAD value）of T1,T2,T3 and T4 are basically the same.The chlorophyll SPAD value of celery is similar in the early stage,and there is no significant difference.Within 35 to 70 days of colonization,the differences between treatments are obvious.（4）Different irrigation methods have different effects on the yield of celery.The yield of each treatment is arranged in order of T2>CK>T4>T1>T3.From the perspective of irrigation volume,the border irrigation treatments T1,T2 and drip irrigation treatments T3,T4 are all in the order of T2>CK>T4>T1>T3.The yield during high water treatment is high.During the whole growth period of celery,the total water consumption of CK treatment is the largest,which is 1.47-24.63%higher than border irrigation treatments T1 and T2,and 30.63-49.17%higher than drip irrigation treatments T3 and T4.All treatments shows that the crop’s water consumption intensity is the highest in the core stage,and the growth period with the largest water consumption is the heart leaf growth period.（5）The overall water use efficiency of each treatment is T4>T1>T3>T2>CK,and the difference reaches a significant level.Irrigation water use efficiency and water use efficiency under different irrigation methods show different differences,the overall performance is T3>T4>T1>T2>CK.The irrigation water use efficiency of drip irrigation is 18.28～49.74%higher than that of border irrigation,reaching a significant difference.（6）Comprehensive analysis of celery by principal component analysis method,the comprehensive score ranking is T2﹥CK﹥T4﹥T1﹥T3.According to the ranking of the comprehensive principal components,it can be concluded that the best treatment is the T2treatment,that is,the border irrigation T2 treatment with the upper limit of irrigation of 90%θFc.