Effects Of Water And Fertilizer Supply Patterns On Growth,Water Use And Soil Nutrient Balance Of Flue-cured Tobacco

In order to explore the effects of soil and climatic conditions on the suitable water supply and topdressing model for the growth and development of flue-cured tobacco,two-season pot experiments were conducted in May to August(S)and October to December(A)2019 with red soil(R)and purple soil(P).Four water supply modes were designed(-5 k Pa Presure Potential Difference-Crop Initiative Draw Water,p1;-10 k Pa Presure Potential Difference-Crop Initiative Draw Water,p2;60%～80% relative water content simulated drip irrigation,a1;60%～70% relative water content simulated drip irrigation,a2),three potassium topdressing modes(Traditional fertilization of 100% potassium,t1;Traditional fertilization of 75% potassium,t2;Fertigation of 75% potassium,f1).The first season experiment was carried out on two kinds of soil at the same time,with a total of 10 treatments(SRp1t1,SRp1f2,SRp2t1,SRp2f2,SRa1t1,SPp1t1,SPp1f2,SPp2t1,SPp2f2,SPa1t1).In the second season experiment was only carried out on red soil,with a total of 6 treatments(ARp1t1,ARp1f2,ARp2t1,ARp2f2,ARa2t1,ARa2t2).By observing the amount of irrigation,dry matter accumulation,agronomic characters,photosynthesis,nutrient absorption and soil nutrient balance of flue-cured tobacco in each treatment,the effects of different water supply and fertilization patterns on the growth and development,water use,nutrient absorption,soil nutrient distribution and nutrient balance of flue-cured tobacco were studied.The main conclusions and results are as follows:(1)The water supply mode had a greatly effect on the water use efficiency(WUE)of flue-cured tobacco,and its effect was affected by soil and climatic season.Compared with simulated drip irrigation,the water consumption of Presure Potential Difference-Crop Initiative Draw Water(P-CIDW)flue-cured tobacco decreased by 7.5%～83.2%,and WUE increased by 5.1%～30.2%.In the first season experiment,when the water supply mode was-10 k Pa P-CIDW,the water consumption and WUE of red soil were lower than that of purple soil.The second season experiment on red soil was more beneficial to improve the WUE of flue-cured tobacco than the first season experiment.(2)The modes of water supply and topdressing had remarkably effects on the growth and development,dry matter accumulation and nutrient absorption of flue-cured tobacco,and its effect is affected by soil and climatic season.In red soil,simulated drip irrigation was more beneficial to the growth and development,increase the dry weight of each organ and nutrient uptake of flue-cured tobacco than PCIDW in the first season experiment.In the second season experiment,-5 k Pa P-CIDW fertigation with75% potassium was more beneficial to the growth and development,increased root dry weight and root nutrient absorption of flue-cured tobacco than simulated drip irrigation,but it did not significantly reduce the dry weight of leaves and stems.;When the water supply mode is the same as P-CIDW,-5 k Pa is more beneficial to the growth and development of flue-cured tobacco,increase the leaf dry weight and nutrient uptake of flue-cured tobacco,and the fertigaiton with 75% potassium is more beneficial to the growth and development,root dry matter accumulation and nutrient absorption of flue-cured tobacco than the traditional fertilization of 100% potassium.In the first season experiment on purple soil,simulated drip irrigation was more beneficial to the growth and development of flue-cured tobacco leaves and the accumulation of dry matter in leaves and roots than P-CIDW;when the water supply method is P-CIDW,-5 k Pa is more beneficial to increase leaf dry weight and nutrient uptake than-10 k Pa.(3)The modes of water supply and topdressing had significant effects on photosynthetic rate(Pn),stomatal conductance(Gs),intercellular carbon dioxide concentration(Ci)and transpiration rate(Tr)of flue-cured tobacco.At root spreading stage and mature stage,the Pn,Gs,Ci and Tr of flue-cured tobacco under simulated drip irrigation showed topdressing with 100% potassium > topdressing with 75%potassium;under P-CIDW,the Pn,Gs and Tr of fertigation with 75% potassium were higher than traditional fertilization with 100% potassium,the Pn,Gs and Tr of-5 k Pa were all higher than-10 k Pa;compared with simulated drip irrigation,-5 k Pa P-CIDW fertigation with 75% potassium could increase the Pn of flue-cured tobacco.In the fast growing period,the Pn,Gs,Ci and Tr of simulated drip irrigation were higher than that of P-CIDW.(4)The models of water supply and topdressing had significant effects on soil nutrient content,nutrient distribution and nutrient balance,and its effect is affected by soil and climatic season.In the second season experiment,compared with simulated drip irrigation,P-CIDW significantly increased the content of hydrolytic nitrogen in 0～5cm soil layer;under P-CIDW,the contents of available potassium,slowly available potassium and acid-soluble potassium and the variability of nutrients in 0～5cm soil layer of traditional fertilization with 100% potassium treatment were significantly higher than that of fertigation with 75% potassium treatment.The two-season experiments showed that when at the same P-CIDW water supply pressure,compared with the traditional fertilization of 100% potassium,feitigation of 75%potassium was more beneficial to maintain the nutrient balance of soil potassium.In the first season experiment,the nutrient balance of simulated drip irrigation in red soil was much better than that in Pmur CIDW,but there was little difference between them in purple soil.In the second season experiment on red soil,although the nitrogen balance of simulated drip irrigation was significantly better than that of P-CIDW CIDW,the potassium nutrient balance of P-CIDW fertigation treatment was better than that of simulated drip irrigation.