Effects Of Different Nitrogen Application Rates On The Growth And Water Use Efficiency Of Kidney Beans Under Water Control Conditions

The experiment was carried out in the greenhouse test base of Heilongjiang Bayi Land Reclamation University from May to August 2019.The experiment used the kidney bean variety"British Red"as the test material,2 irrigation methods and 5 nitrogen application levels were set,and set 2 irrigation methods:W1:conventional irrigation,W2:controlled irrigation.The soil moisture content of the conventional irrigation was controlled to 80%of the field water holding capacity and the soil water content for controlling the irrigation was controlled to 60%of the field water holding capacity.5 nitrogen application levels(calculated as pure N):N0(0 kg/hm~2),N1(25 kg/hm~2),N2(30 kg/hm~2),N3(35 kg/hm~2),N4(40 kg/hm~2).By measuring dry matter accumulation,chlorophyll content,nitrate reductase activity,plant nutrients,yield and yield composition,water use efficiency and quality of kidney beans,the effects of different nitrogen application rates on kidney bean growth and water use efficiency under water control conditions were determined.This study reveals the law of growth of kidney beans in connection with water and nitrogen and is intended to provide a reference for the study of the water and nitrogen coupling on kidney bean growth indicators and water use efficiency and to provide a theoretical basis for the selection of the optimum water and nitrogen mode of the kidney beans and water-saving,high quality and efficient production.The results of the study are as follows:1.The accumulation of dry matter tends to gradually increase as kidney beans grow and develop.With the exception of the seedling stage,the dry matter accumulation of each kidney bean organ reached the maximum in treatments W1N3 and W2N4,and at the mature stage,treatments W1N3 and W2N4,the dry matter accumulation of the stems increased by 213.42%and 219.49%,respectively,compared to the control.The dry matter accumulation of pods in treatments W1N3 and W2N4 increased by 74.30%and 26.19%compared to treatments W1N0 and W2N0,respectively.During the seedling stage to the flower skin stage,the total amount of chlorophyll a,chlorophyll b and total chlorophyll of kidney beans showed an increasing trend under various water and nitrogen treatments.The nitrate reductase activity of kidney bean seedlings reached the maximum when the nitrogen application rate was 30 kg/hm~2(under N2 treatment),which increased by 177.39%and 41.41%compared to the control.The nitrate reductase activity at the flower and pod stages was in treatments W1N3 and W2N4.To get to the maximum over the control,an increase of 452.82%and 39.51%.2.Under conventional irrigation conditions,the nutrient content of kidney bean plants at various stages and organs showed a tendency to first increase and then decrease with increasing nitrogen application and peaked when nitrogen application was 35 kg/hm~2(treatment W1N3).Under controlled irrigation conditions,the nutrient content of kidney bean plants in various stages and organs showed an increasing trend with increasing nitrogen application rate and reached the maximum when the nitrogen application rate was 40 kg/hm~2(treatment W2N4).During the maturation phase,the total nitrogen,total phosphorus and total potassium levels of the strains from the W1N3 and W2N4 treatments increased by38.24%and 11.17%,11.73%and 32.24%,15.72%and 16%,respectively,13%compared to those of the control.Compared to the control,the total nitrogen,total phosphorus and total potassium contents of the W2N4 grains increased by 10.33%and 20.59%,20.96%and 24.40%,10.09%and 22.17%,respectively.3.Under conventional irrigation,the yield was highest when the nitrogen application rate was 35kg/hm~2(treatment W1N3),and under controlled irrigation the yield was highest when the nitrogen application rate was 40 kg/hm~2(treatment W2N4).Two-year performance was the best for both W1N3and W2N4 treatments.Under the conditions of the W1N3 treatment,the two-year production increased by 30.62%and 30.22%compared to the control.Under the conditions of the W2N4 treatment,the two-year performance was compared with the control.An increase of 72.58%and 53.39%,respectively.4.Under the two irrigation conditions,the water consumption of kidney beans increased in the treatment with the use of nitrogen compared to the treatment without the use of nitrogen.The water consumption of 25 kg/hm~2(N1 treatment)of nitrogen application was the highest,but the water use efficiency was lower.Under conventional irrigation conditions,the nitrogen application rate of 35 kg/hm~2(treatment W1N3)shows the highest water use efficiency,which corresponds to an increase of11.84%compared to the control.Under controlled irrigation conditions,the W2N3 treatment has the highest water use efficiency.Compared to the control,it increased by 27.82%.Compared to treatment with W2N3,the irrigation volume increased by 9.42%and the water use efficiency increased by 1.63%.5.Under conventional irrigation conditions,the protein and crude fat content of kidney beans increased first and then decreased with increasing nitrogen application rate.The nitrogen application rate was 35 kg/hm~2(N3 treatment),the protein content and the crude fat content were the largest,increasing by 18.49%and 53.49%,respectively,compared to the control,followed by the N2 treatment,which compared for control increased by 9.00%and 48.84%,respectively;Under controlled irrigation conditions,the protein content and the crude fat content of each treatment increased with increasing nitrogen use and reached the maximum in treatment W2N4,which increased by 17.08%and 24.02%Compared to the control.