旱地小麦休闲期覆盖保水与磷肥对植株氮素吸收、利用的影响

Effects of Mulch in Fallow Period and Phosphorus Fertilizer on Plant Nitrogen Absorption and Utilization in Dryland Wheat

为探索旱地小麦休闲期蓄水保墒及配套磷肥施用技术,在山西闻喜进行了休闲期覆盖或不覆盖条件下低磷（75 kg/hm2）、中磷（112.5 kg/hm2）和高磷（150 kg/hm2）3个水平的田间试验,以明确覆盖对土壤水分、植株氮素吸收利用的影响及磷肥的调控效应.结果表明,休闲期覆盖后,播种期0 100 cm土壤蓄水量显著提高,达39～42mm;增加施磷量,拔节和孕穗期显著提高.覆盖后,播种越冬、拔节—开花各阶段氮素吸收速率提高,各生育时期植株含氮率提高;增加施磷量,播种—孕穗各阶段氮素吸收速率提高,且播种—拔节各阶段氮素吸收速率在高磷条件下显著提高,各生育时期植株氮素积累量显著提高.覆盖后,花前氮素运转量显著提高,叶片、穗轴＋颖壳和整株花前氮素运转对籽粒的贡献率提高,成熟期叶片、穗轴＋颖壳氮素积累量及其所占比例降低;增加施磷量,花前氮素运转量显著提高,叶片氮素运转量对籽粒的贡献率提高,成熟期叶片氮素积累量及其所占比例显著降低.此外,休闲期覆盖配施磷肥条件下,播种孕穗期土壤蓄水量与花前氮素运转量关系密切,尤其播种—返青期土壤蓄水量与穗轴＋颖壳氮素运转量的关系密切,拔节和孕穗期与叶片氮素运转量关系密切.总之,覆盖有利于蓄保休闲期降水,有利于促进植株氮素吸收、积累,有利于花前氮素的运转,尤其促进叶片和穗轴＋颖壳中的氮素向籽粒运转,且配施高磷效果显著,更有利于促进叶片中氮素向籽粒运转.最终,休闲期覆盖配施磷肥150 kg/hm2,氮肥吸收效率、氮肥生产效率、氮素收获指数显著提高.

In order to increase the moisture conservation in fallow period and find the appropriate matching technology of phosphorus application for dryland wheat,a field experiment was carried out in Wenxi,Shanxi province,under the conditions of different mulch（mulch or no mulch）in fallow period and different phosphorus application levels（low（75kg/hm2）,middle（112.5kg/hm2）and high（150kg/hm2））,to study the effects of phosphorus fertilizer and mulch in fallow period on nitrogen absorption and utilization of dryland wheat and soil water.The results showed that after mulching in fallow period,the soil water storage at the depth of 0—100cm at sowing stage significantly increased,reaching 39～42 mm,and soil water storage at elongation stage and booting stage significantly increased with the increase of phosphorus application amount.After mulching,the nitrogen uptake rate at sowing,winter,elongation and anthesis stages was greatly improved,as well as the nitrogen content of plant.Meanwhile,with the increasing amount of phosphorus application,the nitrogen uptake rate at both sowing and booting stage increased greatly.The nitrogen uptake rate also increased at sowing stage and elongation stage under the high level of phosphorus application,and moreover,the nitrogen accumulation amount in plant at different growth stages were also remarkably improved with the increase of phosphorus application amount.After mulching,the translocation amount of nitrogen before anthesis significantly increased and the nitrogen translocation in leaf,rachis＋glume and the whole plant before anthesis showed more significant contribution to wheat grains,while the nitrogen accumulation amount of leaf and rachis＋glume and their proportions at mature stage decreased.In addition,with the increase of phosphorus application amount,the translation amount of nitrogen before anthesis andthe contribution of nitrogen translocation in leaf before anthesis to grains were greatly improved,but the nitrogen accumulation amount of leaf and its proportion at mature stage significantly reduced.Besides,under the condition of mulch in fallow period and phosphorus fertilizer application,the water storage from sowing stage to booting stage and translation amount of nitrogen before anthesis was closely related,and the relationship between water storage from sowing stage to turning green stage and nitrogen translocation before anthesis in rachis＋glume,as well as the relationship between water storage at stages of elongation and booting and nitrogen translocation before anthesis in leaf,were significant.In short,mulch in fallow period was not only beneficial to conserve precipitation in fallow period,but also to promote plant nitrogen absorption and accumulation,to increase nitrogen accumulation translation before anthesis and especially to promote the nitrogen translocation from leaf and rachis＋glume to grains under the high application level of phosphorus.Finally,because of mulch in fallow period and phosphorus application of 150kg/hm2,there was much significant improvement in nitrogen uptake efficiency,nitrogen productive efficiency and nitrogen harvest index.