氮硫互作对冬小麦旗叶衰老、产量和氮素利用效率的影响

试验采用裂裂区设计,小麦品种(烟农19和汶农6号)为主区,施氮(N)量为裂区,设0(N0)、120(N120)、240(N240)kg hm-2三个施N水平,施硫(S)量为裂裂区,设0(S0)、20(S20)、40(S40)、60(S60)kg hm-2四个施S水平。结果表明,汶农6号开花后旗叶超氧化物歧化酶(SOD)活性、旗叶净光合速率、产量和氮素利用效率均高于烟农19。在一定施氮水平下适量施硫显著提高烟农19和汶农6号小麦开花后旗叶SOD活性和可溶性蛋白质含量,提高旗叶净光合速率和开花后干物质积累量,增加植株地上部氮素积累量和籽粒产量;当施氮水平为120 kg hm-2施硫量超过40 kg hm-2和施氮240 kg hm-2施硫量超过20 kg hm-2时,汶农6号植株地上部氮素积累量仍继续增加,但旗叶抗氧化能力和光合同化能力均无明显提高,籽粒产量不再增加,烟农19号旗叶SOD活性、可溶性蛋白质含量和光合速率均降低,植株地上部氮素积累量和籽粒产量均减少。在同一施氮水平下,两小麦品种氮素利用效率总体表现为随施硫量增加而降低的趋势。在土壤有效硫为38.9~42.1 mg kg-1的条件下,适量施用氮肥和硫肥有利于延缓小麦花后旗叶衰老,提高光合同化能力,增加籽粒产量,但不同品种小麦对氮肥和硫肥施用量的响应不同,氮素利用效率较高的品种在较高的氮硫供给水平下仍有较好的光合同化和产量表现,而氮素利用效率相对低的品种对高氮高硫的适应性较差,后期易早衰,影响产量和氮素利用效率。

Interactive Effects of Nitrogen and Sulfur on Flag Leaf Senescence, Yield and Nitrogen Use Efficiency of Winter Wheat

Abstract[Objective]Nitrogen(N)and sulfur(S)are nutrient elements essential to winter wheat in growth and development. The purpose of this article was to determine the effects of nitrogen and sulfur and their interaction on flag leaf senescence,photosynthetic rate after anthesis,accumulation and distribution of dry matter,grain yield and nitrogen use efficiency(NUE)of winter wheat.[Method]A field experiment, designed to have two cultivars(Yannong 19 and Wennong 6)of wheat,three levels of N application rate, that is 0(N0),120(N120)and 240 kg N hm-2(N240)and four levels of S application rate,that is 0 (S0),20(S20),40(S40)and 60 kg S hm-2(S60),was carried out.[Result]Results show that Wennong 6 was higher than Yannong 19 in all the four following indices,that is,superoxide dismutase (SOD)activity in flag leaf,photosynthetic rate(Pn)in flag leaf,yield,and NUE. Application of an appropriate rate of S in addition to the application of a certain amount of nitrogen significantly increased the activity of SOD,the concentration of soluble protein,Pn and dry matter accumulation in flag leaf after anthesis,and hence nitrogen accumulation in the shoot and grain yield in both cultivars of wheat. In the plots applied with 120 kg hm-2 of N and over 40 kg hm-2 of S or with 240 kg hm-2 of N and over 20 kg hm-2 of S, nitrogen accumulation in the shoot kept on rising,but no more positive effects on antioxidant ability and photosynthetic assimilation capacity of the flag leaf and grain yield were observed in Wennong 6,while SOD activity,soluble protein concentration and Pn in the flag leaf,nitrogen accumulation in the shoot and grain yield all declined in Yannong19.[Conclusion]In the plots the same in N application rate,NUE of the two cultivars generally decreased with increasing sulfur rate. In the plots where soil available sulfur in the 0~20 cm soil layer was in the range of 38.9~42.1 mg kg-1,application of an appropriate amount of N and S could delay senescence of the flag leaves was delayed,thus increasing photosynthetic assimilation capacity of the flag leaf and grain yield in both wheat varieties,but the two varieties differed in response to application of relatively high rates of N and S. The one,higher in NUE,still performed quite well in photosynthetic assimilation and yield,while the one,lower in NUE,was not so good in adaptability to a high application rate of N or S and tended to start senescence earlier at the late stage,thus affecting its yield and NUE.