节氮栽培对滴灌小麦根系特征和氮素吸收的调控效应研究

The field and soil column culture experiments will be designed to investigate new methods of educed nitrogen cultivation on root characteristics and nitrogen absorption of drip-irrigated wheat under arid region, the relationship between root morphology and physiology and source-sink characters of drip-irrigated wheat will be studied, aimed to reveal the physiological mechanism of nitrogen resources efficient utilization. According to change nitrogen content, it will regulate root growth and physiological function and optimize its structure and distribution of root system, meanwhile, provide the appropriate nitrogen supply model for improving the yield and nitrogen use efficiency. In order to promote crop seedling growth and provide a scientific basis for production potential development, physiological mechanism of wheat root growth and development under root zone nitrogen regulation will be researched, it aims to raise nitrogen utilization efficiency. Therefore, it has important theoretical and practical significance to detect drip irrigation way of close planting crop based on the continuation of “nitrogen-soil-crop”, by which we would finally realize the target between high-yield and high-quality under lower nitrogen application. After analyzing nitrogen use efficiency, we could draw up the reasonable soil nitrogen supplying capacity adapted to actual production.

为探讨干旱区作物节本增效生产的新途径，以新疆滴灌小麦根系为对象，以“根层减氮+配施有机肥——根系——源库——产量——品质”为研究主线，研究根层节氮栽培对根系形态和生理特性的调节及与植株地上部源库特性的关系，揭示滴灌小麦氮素资源高效利用的生理机理，探寻通过根层减氮，调节根系生长与生理功能，优化根系结构及分布，进而延缓植株衰老，延长经济产量形成期，改进籽粒品质，提出滴灌小麦节本增效的氮素供应模式。开展本项目研究，有助于从理论上认识根层氮素调控滴灌小麦根系生长发育的主要生理机制，进而探求促进根系生长提高氮素利用效率的有效农田调控措施，为促进作物根苗协调生长和生产潜力开发提供科学依据；同时对认识滴灌小麦节氮栽培的生理机制，充分的利用作物自身的适应与调节功能，实现节本增效的生产目的也具有重要意义。

针对新疆麦区干旱气候生态特点，通过研究滴灌条件下春小麦根层减氮和配施有机肥对根系在土壤中的分布特征、生理功能及冠层光合源和籽粒库特性的影响，分析了滴灌春小麦节氮栽培的氮素需求特征和分布特征，阐明了氮素高效利用的生理机制。结果表明，强筋型新春38号与中筋型新春49号均在0~20cm土层的根体积与根长密度最大，在255 kg·hm-2无机肥配施45 kg·hm-2有机肥下，根系形态特征和生理特性表现最佳，冠层结构最优，最大净光合速率分别为24.0μmol·m-2·s-1和22.6μmol·m-2·s-1。在此模式下，两品种茎鞘、叶、穗轴+颖壳、籽粒及植株同化物和氮素积累量和花前花后的贡献最高，籽粒淀粉含量比其它处理分别提高了6.29%～117.04%和3.20%～36.99%，蛋白质含量则提高了7.84～39.54%和5.48%～28.55%。土壤全氮含量、硝态氮含量和铵态氮含量在0~20 cm土层随减氮比例的增大总体呈减小趋势，新春38号15N利用率为20.43%~24.33%，新春49号15N利用率为18.17%~23.07%，配施有机肥处理减小了新春38号和新春49号15N土壤残留量和15N土壤残留率，但对15N总回收率和15N损失率影响差异不显著。新春38号氮素利用效率、氮素农学利用效率、氮素偏生产力分别达到39.55%、7.38 kg·kg -1、25.16 kg·kg -1，新春49号则分别为42.23%、7.45 kg·kg -1、24.73 kg·kg -1。可见，本项目研究有助于从理论上认识节氮栽培对滴灌春小麦不同生育阶段根系和冠层生长的影响，探讨通过根层合理减氮配施有机肥，调节根系生长，有利于同化物和氮素积累与转运，进而稳定小麦产量，改善品质的可能技术途径和氮素供应模式，为新疆滴灌小麦生产合理减氮提供科学依据。