| To explore the influence of water and nitrogen interaction on silage maize growth,water consumption,yield and water and nitrogen use efficiency in typical semi-arid and semi humid area of Heilonggang basin,and to provide theoretical basis and technical support for determining the water and fertilizer management system of silage maize in this region.The field experiment was carried out in the comprehensive experimental station of Hebei Agricultural University in Julu County,Hebei Province from April to August,2019,with a total rainfall of 294.64mm.In the field experiment,"silage Xunqing 818"was used.Two factors of irrigation amount and nitrogen rate were designed.Four irrigation levels were set:0.25I(W1),0.50I(W2),0.75I(W3)and 1.00I(W4)(I was the irrigation amount of high water treatment).The irrigation amount of W4 was controlled by the upper and lower limits of soil moisture content,and the lower limit of irrigation at seedling stage was 55%±2%,The lower limit of irrigation is 60%±2%of field water capacity,and the upper limit is 95%of field water capacity.Three nitrogen application levels were set as follows:N1:120 kg/hm2,N2:240 kg/hm2,N3:360 kg/hm2,a total of 12 treatments,each treatment set 3 repeats,a total of 36 plots,each treatment plot was randomly arranged.The main results are as follows:1)The main influencing factors were stem height and leaf area.There was significant or extremely significant interaction between irrigation and nitrogen application at jointing stage.The plant height,stem diameter and leaf area index of silage maize were significantly increased by increasing irrigation and nitrogen application.2)The total water consumption of W4N3 treatment was 492.67 mm,which was significantly increased by 6.15%-41.11%compared with the other treatments.Under the W4 and W3 irrigation levels,the water consumption of silage maize could be significantly reduced by reducing nitrogen application,and the crop water consumption could be reduced by 2.26 m3/hm2 and 1.26 m3/hm2 by reducing 1 kg/hm2 of nitrogen fertilizer.3)The results showed that the fresh weight yield and dry weight yield of Silage Maize ranged from 59.65 t/hm2 to 107.49 t/hm2,and the dry weight yield ranged from 12.75 t/hm2to 29.56 t/hm2;the maximum dry and fresh weight yield of W4N3 treatment was only 3.43%and 1.61%higher than that of W4N2 treatment,and the difference was not significant.With the increase of irrigation and nitrogen application,the dry matter percentage of silage maize ear first increased and then stabilized;W3N3 treatment accounted for the largest proportion of ear,but only increased by 2.02%compared with W3N2 treatment,there was no significant difference.4)Irrigation,nitrogen application and their interaction had significant effects on WUE of silage maize.The WUE of W4N2 treatment was the largest in the whole growth period of silage maize,and there was no significant difference between W3N2 and W4N2 treatments.The highest proportion of nitrogen uptake was in the ear of W3N2,which was 66.43%of that of W3N2 treatment.Moderate water deficit and appropriate nitrogen application could obtain a higher proportion of nitrogen uptake by ear,and also reduce the amount of irrigation and nitrogen application.The NUE of W3N2 treatment was 113.52 kg/kg,which had no significant difference with W4N3 treatment,but reduced 49.17 mm irrigation amount and 120 kg/hm2 nitrogen application rate.Nitrogen application rate and irrigation amount had significant effects on partial Nitrogen productivity(PFPN)and nitrogen recovery rate(NRE)of silage maize,under the same nitrogen application level,irrigation amount was directly proportional to PFPN and NRE,while nitrogen application was inversely proportional to PFPN and NRE.5)Water saving,nitrogen reducing,bumper crop and high efficiency could be achieved by using mild water deficit treatment W3(irrigation amount 141.57 mm)and medium nitrogen level N2(240 kg/hm2 nitrogen application rate). |
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