Effects Of Water And Nitrogen On The Production And Yield Of Photosynthetic Substances In Winter Wheat With Drip Irrigation

The rational use of nitrogen and water plays a decisive role in improving wheat yield.In this experiment,the optimal combination of water and nitrogen was discussed by adjusting the amount of nitrogen and irrigation amount,which provided a theoretical basis for the high-yield cultivation and water saving and nitrogen saving measures of winter wheat in the region.This article takes the“Xindong 36”as the material,under the drip irrigation condition of the field,0 kg/hm~2,375 kg/hm~2,450 kg/hm~2 and 525 kg/hm~2(pure quantities)were set up for N0,N1,N2,N3,and four nitrogen gradients were 3450 m~3/hm~2,4200 m~3/hm~2,4950m~3/hm~2,5700 m~3/hm~2,named W1,W2,W3,W4.Through the study of dry matter accumulation,leaf area index,photosynthetic physiological characteristics and yield,the effects of water and nitrogen factors on wheat growth were revealed.The main results are as follows:(1)Total stem number,leaf area index and dry matter accumulation were significantly lower than those of nitrogen treatments.Increasing the amount of nitrogen and water can help maintain higher total stem(spike)and leaf area index in the later growth stage,and obtain higher spike number,grain number per spike and yield.Increasing the amount of irrigation under no nitrogen and low nitrogen treatment can increase the leaf area index,dry matter accumulation and yield,and make the rapid accumulation time of dry matter and rapid accumulation rate increase.The total stem number,LAI and dry matter accumulation decreased while the amount of water in the medium nitrogen and high nitrogen treatment was too large.The rapid accumulation time was late and the accumulation rate was small,which was unfavourable to the growth of wheat.Correlation analysis showed that nitrogen,irrigation and water and nitrogen coupling were significantly correlated with panicle number,grain number per spike and yield.The highest yield was 9848.13 kg/hm~2 treated by N2W3,and had no significant difference from N2W2 treatment.(2)Water and nitrogen had significant effects on SPAD value and photosynthetic characteristics of flag leaves.The SPAD value and photosynthetic physiological index of 0-14d flag leaves after flower were higher than that of 14-28 d after the flower.With the gradual decline of leaf function,nitrogen and irrigation could reduce the decreasing trend effectively.No nitrogen and low nitrogen treatment could increase the SPAD value by increasing the irrigation volume,and the SPAD value decreased when the middle and high nitrogen irrigation reached W4.In the later period of growth,the treatment of medium and high nitrogen still maintained high SPAD value and photosynthetic rate,and the plant was greedy and late maturing,and the nutrient could not be transported to the reproductive organs in time,and the 1000 grain weight decreased.(3)The content of total nitrogen in leaves and stems decreased gradually from the jointing stage to the harvest stage,and the total nitrogen content in the leaves was higher than that in the stem.The nitrogen accumulation in the early growth stage was higher than that in the stem,whereas in the later stage,the accumulation of dry matter increased.There was a positive correlation between the irrigation quantity of no nitrogen and low nitrogen treatment and the nitrogen content and nitrogen utilization rate of leaves,stem and nitrogen,and the nitrogen content and nitrogen utilization rate decreased after the irrigation of medium and high nitrogen treatments exceeded a certain threshold.Nitrogen accumulation in leaves treated with N2 and N3 was higher,but N3 treatment was significantly higher than N2 treatment at later growth stage.Therefore,N2 was considered to be the best treatment for nitrogen accumulation in wheat.Nitrogen use efficiency is negatively correlated with nitrogen application rate.Therefore,appropriate nitrogen should be paid attention to in agricultural production so as to improve nitrogen use efficiency and reduce environmental pollution risk.In conclusion,it is considered that the best nitrogen and irrigation treatment for this experiment is N2W2.