Experimental Study On Alfalfa Growth And Water And Nitrogen Transport Under Drip Irrigation

In view of the low water use efficiency of the arid belt in central Ningxia and the shortage of water resources in Ningxia,this experiment uses a randomized block test design with irrigation quota(W)and nitrogen application rate(N)as experimental factors,each factor setting 3 Levels(W:1800m3/hm2,2400 m3/hm2,3000 m3/hm2;N:270 kg/hm2,420 kg/hm2,570 kg/hm2)Three replicates were set for each treatment,and different water and nitrogen conditions were studied by drip irrigation under the membrane.Aiming at the effects of growth index,yield,quality,soil nitrate nitrogen content and soil water content,a water and nitrogen management scheme suitable for the arid zone in central Ningxia was proposed.The main conclusions are as follows:(1)In the early growth stage,the growth rate of plant diameter and plant height was the fastest,and the growth length of branch length,branch diameter and chlorophyll was the fastest in the growth stage of spring shoots,and the growth rate of each index was the slowest in fruit ripening stage.The growth of ground diameter,plant height,branch length and branch diameter were the highest in treatment W2N2,which were 0.5389mm,20.76cm,16.94cm and 2.3300mn respectively,and the average chlorophyll growth period was 60.64.Treatment of W1N1 The growth of ground diameter,plant height,branch length and branch diameter was the smallest,which was 0.3478mm,11.69cm,13.41cm and 1.6400mm.The average value of chlorophyll growth period W1N1 was only higher than W1N3,which was 58.90.(2)The average value of total sugar content in W3N1 during the growth Period was 48.00%,and the total sugar content in W1N1 was the smallest,which was 40.00%.The mean value of W1N3 in the growth period was the highest,which was 3.46%,and W2N1 was the smallest,2.72%.The average carotenoid content during the growth period was 0.21%for W2N2 and 0.16%for W3N1.The average content of betaine in the growth period was W2N2,which was 0.81%,and the W1N1 content was the smallest,0.55%.Through principal component analysis,the scores of each process are sorted as W2N2>W1N2>W3N2>W2N3>W1N3>W1N1>W3N3>W3N1>W2N1..(3)Lyciura barbarum both fresh weight and dry weight yield were the best in W2N2 treatment,and W1N1 was the lowest.The fresh weight was 7401.48kg/hm2,6375.84 kg/hm2,and the dry weight was 2356.22kg/hm2 and 1506.27 kg/hm2.W2N2 has the lowest fresh-dry ratio of 3.1412,and W1N1 has the fresh-to-dry ratio of 4.23.W2N2 has the highest 100-grain weight of 18.65g,and W1N1 has the smallest 100-grain weight of 17.62g.The fresh water use efficiency range is 1.56-2.99 kg/m3,W3N1 is the smallest,and W2N2 is the largest According to the comprehensive analysis.(4)Different irrigation amount has a great influence on soil water content,and the soil water content increases with the increase of irrigation amount.The maximum value of water content in each treatment mostly appears in 0?60cm,and the fluctuation of 0?60cm is large,60 The fluctuation below-100cm is small.The overall trend of nitrate nitrogen content in soil is gradually decreasing with increasing depth.Different irrigation amounts have a great influence on soil nitrate nitrogen content.Under W3 irrigation level,peaks appear at 60?80cm,and nitrate content in deep soil accumulates.At W1 irrigation level,nitrate nitrogen tends to accumulate in soil.Shallow layer,appropriate increase of irrigation amount will make the nitrate nitrogen migration deeper.The soil water content and nitrate nitrogen varied at different growth stages.The soil moisture content and nitrate nitrogen content increased under different water and nitrogen treatments during the spring shoot growth period.The soil moisture content and nitrate state were treated at the initial stage of flowering and fruit ripening.The nitrogen content decreased to varying degrees.The soil water content and nitrate nitrogen content increased with the increase of nitrogen application rate during the flowering period.Under low water and low nitrogen conditions,water and nitrate nitrogen transport are shallow,low water and high nitrogen will cause shallow concentration to be too high,which is not conducive to water and nutrient absorption;high water and low nitrogen and high water and high nitrogen Nitrate nitrogen is easy to cause nitrate nitrogen to elute and water leakage,so that iitrate nitrogen accumulates in the deep layer,which is not conducive to the water and nutrient absorption of the plant.Based on the comprehensive growth index,yield,quality,soil moisture content and soil nitrate nitrogen content,the optimal water and nitrogen management scheme under the conditions of drip irrigation:W2N2(irrigation quota 2400m3/hm2,nitrogen fertilizer application 420kg/hm2).