| In response to the shortage of agricultural irrigation water resources in the Heilonggang area,the low efficiency of agricultural water and fertilizer utilization,and the continuous expansion of the forage planting area in the context of "grain reform and feed",the Hebei Agricultural University in Julu County,Hebei Province was held from April to October 2019 Comprehensive test station conducts sweet sorghum field water and fertilizer regulation test.By studying the effects of different water and nitrogen conditions on the growth,water consumption characteristics and water and nitrogen utilization of sweet sorghum,a water and nitrogen management model suitable for sweet sorghum planting in this area is proposed,which can improve the water and nitrogen use efficiency of sweet sorghum planting in Heilonggang area and reduce fertilization.The quantity and increasing the yield of sweet sorghum have certain production practical significance.With "Nengsi No.2"sweet sorghum as the test variety,the irrigation water limit is set to 60%±5%of the field water holding rate,and the irrigation upper limit is 90%of the field water holding rate.Fully irrigate to the upper limit of irrigation,and the irrigation quota is 10 According to local fertilization experience,300kg/hm2 is the recommended nitrogen application rate.Set the conditions of two factors,water and nitrogen,the water factors are severe deficit W1(25%I0),moderate water deficit W2(50%I0),mild water deficit W3(75%I0)and full irrigation W4(100%I0),the nitrogen application factors are low nitrogen N1(200 kg/hm2),medium nitrogen(300 kg/hm2),and high nitrogen(400 kg/hm2).There are a total of 12 treatments in the experiment,with three replicates for each treatment.The main conclusions of the research are:(1)The jointing stage-heading stage is the key period of water supplementation for high yield of sweet sorghum,and the seedling stage-joining stage is the key period for sweet sorghum nitrogen accumulation.(2)With the increase of irrigation amount,the dry matter accumulation of sweet sorghum increased significantly and the distribution ratio of dry matter to the stalk was increased.The dry matter accumulation of the stalk W4 treatment was 1.75%,52.16%and 86.54%higher than that of W3,W2 and W1,respectively;With the increase of nitrogen application rate,the dry matter accumulation of sweet sorghum showed an upward trend and then a downward trend,both showed:N2>N3>N1.(3)W3N2 treatment(75%I0 irrigation treatment,300kg/hm2 nitrogen application treatment),fresh weight yield,stalk fresh weight yield and dry matter yield reached 151251.9kg/hm2,120156.2kg/hm2 and 45284kg/hm2,respectively.Using this scheme can achieve the goal of water saving,nitrogen reduction,stable production and high efficiency.(4)With the increase of irrigation amount,the water use efficiency of sweet sorghum increased first and then decreased.The water use efficiency of W3 treatment increased by 4.53%,27.79%and 45.18%compared with W4,W2 and W1 treatments,respectively;with the amount of nitrogen applied in addition to the full irrigation(W4)treatment,the water use efficiency of sweet sorghum also increased first and then decreased.Under full irrigation,the water use efficiency of N3 treatment increased by 3.4%and 16.76%compared with N2 and N1 treatments.W3N2 treatment achieved the maximum water use efficiency of 10.44kg/m3.The nitrogen dry matter production efficiency of sweet sorghum under different nitrogen levels is:N1>N3>N2,the dry matter production efficiency and the apparent nitrogen recovery rate are both:N1>N2>N3,and the W4N1 treatment obtains the highest nitrogen the utilization efficiency is 193.31kg/m3.(5)The regulation of water and nitrogen in Heilonggang area has a significant interaction effect on the growth,dry matter accumulation,yield and water and nitrogen absorption and utilization of sweet sorghum.Under the test conditions,the effect of irrigation and nitrogen application on plant height is as follows:irrigation>nitrogen application,and the effect on stem thickness is:nitrogen application>irrigation;the degree of influence on the accumulation and distribution of dry matter quality,stalk fresh weight and dry weight yield of sweet sorghum is as follows:irrigation>nitrogen application;the degree of influence on water use is expressed as:irrigation>nitrogen application;the degree of influence on nitrogen absorption is expressed as:irrigation>nitrogen application. |
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