Study On Technique Of Nitrogen Fertilizer Application For Different Types Of Winter Wheat In Huaibei Area

From 2000 to 2002 at Huaibei area in Jiangsu province, two special wheat varieties, Shannong 229 (middle gluten) and Jinan 17(strong gluten), were taken as experimental material to study the effects of different application N amount, ratio of basic to topdressing N and stage of top dressing N on grain yield, population dynamics, absorption and utilization of nitrogen, grain quality, and the technique of the fertilizer application of high yield, high quality and high efficiency was discussed. The main results were as follows:1. In grain yield and its components, there were significant differences (p>0..01) for grain yield in application N amount treatments and ratio of basic to topdressing application, and a significant interaction in grain yield between application N amount and wheat varieties. The relationship between application N amount and proportion of topdressing N during jointing stage and wheat grain yield could be expressed in a quadratic curve. From 0 to 262.5 kg/hm2 of application N amount in Shangnong 229, from 0 to 328.1kg/hm2 of application N amount hi Jinan 17 and from 10:0 to 3:7 of ratio of basic to topdressing N during jointing stage, grain yield could be increase significantly, gram yield could be decrease with the stage of topdressing N delayed. Grain yield was higher in Shangnong 229 with 196.9~262.5kg/hm2 of applied N amount and 6:4~4:6 of ratio of basic to topdressing N, while grain yield was higher in Jinan 17 with 262.5~328.1kg/hm2 and 5:5~4:6. Furthermore, the.ears and grains per spike could be increased and 1000-grain weight could be decreased from 0 to 262.5 kg/hm2 of application N amount in Shangnong 229 and from 0 to 328.1 kg/hm2 in Jinan 17. Per spike and 1000-grain weight could be increased and the ears could be decreased from 10:0 to 3:7 of ratio of basic to topdressing N during jointing stage. And the1000-grain weight could be increased significantly(p>0.05) and the ears and grains per spike could be decreased with the stage of top dressing N delayed.2. In population dynamics aspect, ears/hm2 and maximal LAI and dry matter accumulation could be increased and descending rate of LA after flowering could be decreased from 0 to 393.8.1kg/hm2 of application N amount. Ears/hm2 and descending rate of LA after flowering could be decreased and the relationship between rate of topdressing N during jointing stage and maximum LAI and dry matter accumulation and dry matter accumulation after flowering could be expressed in a quadratic curve from 10:0 to 3:7 of ratio of basic to top dressing N during jointing stage. Higher maximum LAI and dry matter accumulation and dry matter accumulation after flowering and ear percentage of main stems and tillers could be achieved by the method 6:4~4:6 in Shannong 229 and by the method of 5:5~4:6 in Jinan 17. The maximum LAI and dry matter accumulation and dry matter accumulation after flowering and ear percentage of main stems and tillers was lower with the stage of topdressing N delayed.3. Total N accumulation amount could be increase with application N amount and proportion of top dressing N during jointing stage raised significantly(p>0.05), and there was a difference in different types of winter wheat. Accumulation N amount after flowering, its contribution ratio to grain, yield of protein, N-absorption efficiency and N-utilization rate of the same treatment in Jinan 17 were higher than in Shannong 229. N-utilization rate could be decreased with application N amount raised and the stage of topdressing N delayed, but it could be improved significantly(p>0.05) with proportion of top dressing N during jointing stage raised. Higher protein yield and N-utilization rate could be obtained by the method of 262.5 - 328.1 kg/hm2, 5:5~4:6 and the method of topdressing N in jointing and flowering stage(5:2.5:2.5) in Jinan 17, and also obtained by the method of 196.9~ 262.5 kg/hm2 and 6:4-4:6 in Shannong 229.4. From 0 to 393.8kg/hm2 of application N amount and from 10:0 to 3:7 of basic to topdressing and the stage of top...