中文摘要：

采用大田试验研究旱地小麦休闲期不同时间覆盖（前茬小麦收获后30和60 d）、不同覆盖方式（全覆盖、半覆盖和不覆盖）对植株氮素吸收、利用的影响.结果表明：覆盖后休闲期蓄水效率和播种期0-300 cm土层土壤蓄水量显著增加,各生育阶段氮素积累量、花前营养器官氮素运转量和运转率、花后氮素积累量及籽粒氮素积累量均增加,最终促使产量、氮素吸收效率、氮肥偏生产力和氮收获指数显著提高,且表现为全覆盖效果好于半覆盖.小麦收获后30 d覆盖,下茬小麦播种期0-300 cm土层土壤蓄水量、休闲期蓄水效率、各生育阶段的氮素积累量、成熟期叶片和整株氮素积累量、茎秆＋茎鞘、叶片和营养器官花前氮素运转量、产量均高于麦收后60 d覆盖,其中播种期0-300 cm土层土壤蓄水量与休闲期蓄水效率差异显著.各土层土壤蓄水量与花前营养器官氮素运转量及花后氮素积累量均呈正相关,茎杆＋茎鞘氮素运转量对籽粒产量的直接影响最大,直接通径系数为0.619.休闲期覆盖通过提高播种期土壤蓄水量增加植株对氮素的吸收与利用,提高了产量与品质,其中提早全覆盖效果最好.

英文摘要：

Field experiments were carried out to study the effects of different mulching times（30 or 60 d after previous wheat harvest） and mulching methods（ whole-mulching,half-mulching and nomulching） on wheat plant N absorption and assimilation after deep plowing in fallow period on dryland. The results showed that mulching improved water storage efficiency in fallow period and soil water storage of 0-300 cm at sowing stage significantly. Mulching in fallow period,especially the whole-mulching,increased the N accumulation amount of each growth stage, N translocation amount and rate before anthesis（ NABA）,and N accumulation amount after anthesis（ NAAA） and grain N. Yield,N uptake efficiency（ NUPE）,N partial factor productivity（ NPFP） and N harvest index（ NHI） were all significantly increased under mulching,and whole-mulching had better effects. Mulching at 30 d after previous wheat harvest significantly increased the soil water storage of 0-300 cm at sowing stage and the water storage efficiency in fallow period compared with mulching at 60 d after previous wheat harvest. Compared with mulching at 60 d after previous wheat harvest,mulching at 30 d increased the N accumulation amount of each growth stage,the N accumulation amount in leaf and shoot at maturity,the NABA of stem ＋ sheath,leaf and shoot and the yield. The soil water at the depth of 0-300 cm at sowing stage was positively correlated to N mobilization amount before anthesis and N accumulation amount after anthesis. The N mobilization amount of stem ＋ sheath had a remarkable direct effect on its yield with the direct path coefficient of 0.619. In summary,mulching in fallow period increased the soil moisture at sowing stage to promote N absorption and utilization,increase yield and improve quality,and whole-mulching in advance had better effects.