| The experiment was conducted in the fields of Xuanzhuang Village(116°54′E,36°12′N),Daolang Town,Tai’an City,Shandong Province in 2017-2018 and 2018-2019.Shannong 23(A)and Shannong 29(B),two winter wheat varieties with large panicle and multiple panicles,were used as the sub areas.The three levels of no irrigation(J1),medium irrigation(J2)and high irrigation(J3)were set up with the supplementary irrigation level at jointing stage as the sub areas.Among them,the irrigation amount of medium irrigation and high irrigation treatment was calculated according to the irrigation quota formula with 0-20 and 0-40 respectively cm is the planned wet layer depth,with 100% field water capacity as the target soil relative moisture content;with the supplementary irrigation level at anthesis as the sub sub area,two levels of no irrigation(F1)and irrigation(F2)are set,and the irrigation amount of irrigation treatment is calculated according to the irrigation quota formula,with 0-20 cm as the planned wet layer depth,with 100% field water capacity as the target soil relative moisture content.The main results are as follows: 1 Effects of different water supply on nitrogen accumulation,transport and utilization in WheatSupplementary irrigation at jointing stage was beneficial to increase the nitrogen accumulation in the above ground vegetative organs of two winter wheat varieties from jointing stage to anthesis.Compared with the J1 treatment,the N accumulation in the leaves of J2 treatment at anthesis,rachis+glume and stem+sheath increased significantly;compared with the J2 treatment,the N accumulation in the stems+sheath of J3 treatment increased significantly,while the N accumulation in the leaves and rachis+glume did not increase significantly.The results showed that although the total amount of nitrogen uptake increased significantly with the increase of irrigation,the nitrogen accumulation in the main photosynthetic organs such as leaves and ears did not increase significantly.Under the same water supply condition after anthesis,there was a negative correlation between the amount of nitrogen accumulation after anthesis and the amount of nitrogen accumulation above the ground.Compared with F1 treatment,F2 significantly increased the nitrogen accumulation and grain nitrogen accumulation after flowering in both J1 and J2 treatments,but the nitrogen residue in vegetative organs increased in each anthesis.J2F2,J3F1 and J3F2 treatments had the highest nitrogen accumulation in shoot and grain.2 Effects of different water supply on nitrogen assimilation andprotein hydrolysis enzyme activityThe activities of endopeptidase(EP)and carboxypeptidase(CP)increased significantly with the increase of irrigation at jointing stage.After anthesis,compared with J2 treatment,the activity of NR and GS in J3 treatment decreased significantly in the early and middle stage of grain filling.The activities of NR and GS were significantly increased by irrigation at anthesis.With the increase of irrigation at jointing stage,the NR and GS activities of NR and GS activities decreased.Compared with F1 treatment,the activities of two proteolytic enzymes in Flag Leaves of winter wheat were decreased by irrigation at anthesis.Compared with F1 treatment,F2 treatment significantly increased the content of soluble protein and free amino acids in flag leaves after flowering.The results showed that the better water condition from jointing to flowering could improve the activity of nitrogen assimilating enzyme before anthesis,improve the nitrogen nutrition of leaves,and delay the nitrogen hydrolysis of leaves after anthesis.Good soil water supply after anthesis can increase the amount of irrigation at jointing stage,reduce the amount of nitrogen assimilation after anthesis,reduce the adjustment and transportation of nitrogen stored in flag leaf and other photosynthetic organs by grain protein filling,prolong the filling time and reduce the loss of grain yield.3Effects of different water supply on nitrogen nutrition indexandnitrogenfunctionWith the increase of irrigation amount at jointing stage,the nitrogen nutrition index of two winter wheat varieties increased significantly before flowering.The nitrogen nutrition index of the two winter wheat varieties was less than 1 in the anthesis,i.e.they were in the state of nitrogen deficiency;the nitrogen nutrition index of J3 treatment was more than 1,and they were in the state of nitrogen surplus;the nitrogen nutrition index of J2 treatment was closest to 1,and they were in the state of nitrogen supply and demand balance.Compared with the anthesis,the relative nitrogen absorption value of J1 treatment with lower nitrogen nutrition index in the anthesis was higher.The change trend of relative nitrogen yield of each treatment was basically the same as that of relative nitrogen absorption value at maturity.The distribution of nitrogen in different forms was significantly affected by the different depth of planned wetting layer at jointing stage.Compared with the treatment of J1,the content of functional nitrogen and storage capacity of J2 at anthesis increased significantly;compared with the treatment of J2,the content of functional nitrogen of J3 did not increase significantly,but the content of storage nitrogen increased significantly,and the content of transferable storage nitrogen in storage nitrogen increased most significantly.4Effects of different water supply on grain yield,nitrogen and water use efficiencyUnder the same water supply condition after anthesis,the grain yield and water and nitrogen use efficiency of J2 and J3 treatments were significantly higher than that of j1 treatment.The grain yield and nitrogen accumulation of J1F2 and J1F2 were significantly higher than those of J1F1 and J1F1 respectively.Under J3 treatment,there was no significant difference in grain yield and nitrogen accumulation between J1F1 treatment and J1F2 treatment.Compared with J1F1 and J1F2,there was no significant difference in grain yield.With the increase of total irrigation amount,nitrogen use efficiency and water use efficiency increased first and then decreased;the results showed that under the condition of no irrigation and irrigation at anthesis,nitrogen use efficiency reached the highest at 1.08 and 1.04 at anthesis respectively,and water use efficiency reached the highest at 1.02 and 1.00 at anthesis respectively;winter wheat varieties with different spike types reached the highest at 1.02 and 1.00 at anthesis Among the species,the treatment of J1F2 was the highest in nitrogen use efficiency and water use efficiency.To sum up,in jointing and anthesis,the target of supplementary irrigation was to reach 100% of the field water holding capacity in the 0-20 cm plan wet layer depth,and higher grain yield and nitrogen accumulation were obtained in different spike type winter wheat varieties,and higher nitrogen use efficiency and water use efficiency were also obtained. |
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