Effects Of Water Supply Pressure And Negative Pressure Seepage Material On Water Use Efficiency Of Three Crops

The face of serious shortages of water resources and the existence of inequality,while some areas are still the status quo of the traditional irrigation mode of flood irrigation,not only a large amount of waste of water resources,but also exacerbated the tense situation of water resources.Negative pressure irrigation is a kind of water-saving technology that embeds the water seepage device into the soil and does not require external power to drive it.It is a water-saving technology that automatically replenishes the crops with the matrix potential.It has the potential to increase the yield and water use efficiency of crops and has a good development prospect.In the whole negative pressure irrigation system,the water seepage device is the core part,and it is also a key factor in the accurate supply of water and affecting the irrigation rate.At present,the negative pressure water infiltration devices used in the tests are mostly clay inorganic materials,which have problems such as fragility,poor toughness,and high cost,and need further improvement,but they are more difficult.In order to alleviate this problem,a kind of organic polymeric material polyvinyl-formal(PVFM)with high hydrophilicity,good toughness,stable chemical properties,and easily adjustable pore size has been studied.Currently,the material is used in negative pressure irrigation.Few,only Congping and Ding Yahui analyzed the feasibility of verifying the feasibility of the water sterilizer with different proportions and specifications in the indoor soil column.However,PVFM was rarely used in crop cultivation.Therefore,in this paper,two kinds of material infiltrating devices are applied to the crops with short growth period.The potting experiments are used to compare and analyze the seepage performance of the two materials and their effects on crops in various aspects.In addition,the negative pressure irrigation is currently used in flue-cured tobacco test is less,and the appropriate water supply pressure of flue-cured tobacco in different regions will be different,so through the negative pressure water supply to explore the appropriate supply pressure of Yunnan flue-cured tobacco,the test of this paper includes: 1.Effects of water supply pressure and emitter material on the growth,water use efficient and nutrient uptake of garland Chrysanthemum(Chrysanthemum coronarium L.)under negative pressure irrigation.2.Effects of water supply pressure and emitter material on the growth,quality and water use efficient of green vegetable(Brassica chinensis L.)undernegative pressure irrigation.3.Effects of water supply pressures on water use efficiency and quality of flue-cured tobacco.After comprehensive analysis of the above tests and data,the following results are obtained:(1)Negative pressure irrigation of Chrysanthemum potted plants,there was a good correspondence between the water supply pressure and soil water content.The water consumption module and the growth trend of each stage of Chrysanthemum with different negative pressure water supply were basically consistent with that of CK,and the water consumption peaked at the third week,and they all grew most vigorously at 40 days.In the range of-4kPa to-12 kPa,with the decrease of water supply pressure,the water supply,water consumption,plant nitrogen content decreased gradually,and the phosphorus and potassium contents of the plants increased gradually.The N,P,and K nutrient uptake of the plant increased first and then decreased.At the same time,negative pressure irrigation can increase the proportion of phosphorus and potassium absorption.When the water supply was at-8kPa,the average plant height,yield and WUE of chrysanthemum were the highest.Under NPI,the correlation between dry matter and root-shoot ratio was significant,showing that with the increase of dry matter,the root-shoot ratio increased first,and tended to be stable after the dry matter was 0.94 g.Under the same water pressure,the soil water content,plant height,yield,nutrient uptake and WUE of PVFM emitter were superior to those of ceramic cup emitter.Adopting the continuous negative pressure water supply and PVFM emitter for chrysanthemum,the best water supply model for potted chrysanthemum was to set the water supply pressure at-4kPa in the early growth stage and at-8kPa in the middle and late stages.(2)A water supply test was conducted on Shanghai green vegetable(Brassica chinensis L.)using negative pressure irrigation.The fluctuation of soil water content at different water supply pressures was small.With the decrease of water supply pressure,the soil moisture content decreased,and the soil water content change trends of different stages of Brassica chinensis L.were consistent,and reached the maximum at 28 days.Negative pressure water pressure has a significant effect on the agronomic traits of Brassica chinensis L.Plant height,effective leaf number,leaf area,stem diameter and root-shoot ratio were positively correlated with water supply pressure.Negative pressure irrigation water pressure also has a significant impact on water consumption,production and WUE.The water use efficiency of ceramic cup with-15~-5kPa increased by 121.3%~192.4% compared with conventional irrigation.The water use efficiency of PVFM was 102.8%~193.5% higher than that of conventional irrigation,achieving the purpose of high water-saving efficiency.Negative pressure irrigationwater pressure has a significant effect on nitrogen,phosphorus and nutrient absorption,vitamin C and nitrate in Shanghai green vegetable.With the decrease of water supply pressure,the absorption of nitrogen and phosphorus gradually decreased,the absorption of potassium did not change significantly,and the vitamin C content gradually decreased,while nitrate and SPAD gradually increased.With the same water supply pressure,the soil water content,agronomic traits,yield,water use efficiency,and quality were all higher in PVFM.Under the conditions of this experiment,the pressure of water supply was set to-5kPa,and the use of PVFM emitter can increase the yield of Brassica chinensis L,significantly increased the water use efficiency,and promoted the formation of quality.(3)Set the water supply pressure to treat the flue-cured tobacco in the range of-5kPa to-15 kPa.It was found that the agronomic traits of flue-cured tobacco grew well under the-5kPa and-10 kPa treatments,and the proportion of total biomass of flue-cured tobacco accounts for the whole plant showed leaf > stem > root.And-15 kPa treatment was not conducive to the growth and development of flue-cured tobacco.In the range of-5kPa to-15 kPa,with the decreased of water supply pressure,the water consumption decreased gradually.Under negative pressure irrigation,water use efficiency could be significantly improved and water consumption reduced.With the decrease of water supply pressure,the absorption of N,P and K decreased,and the content of nicotine increased first and then decreased.The total sugar and reducing sugar first decreased and then increased.There was no significant difference between water-soluble chlorine and potassium oxide.Integrating different water supply pressures on the agronomic traits,biomass and distribution of tobacco,water use efficiency,nutrient uptake,and chemical composition,under the conditions of this test,set the negative pressure water supply pressure at-5kPa,which was conducive to the growth and yield of flue-cured tobacco.