调亏灌溉条件下水氮互作对滴灌甜菜产量品质的调控机理研究

Xinjiang Province has become the country’s most important sugar-producing area. Nevertheless, compared with advanced countries, sugar beet cultivation in Xinjiang is still hampered by the problems of low sucrose content. Appropriate water and nitrogen supply in root zone is essential to guarantee coordinate development of carbon and nitrogen metabolism of sugar beet. This project intends to use “water deficit and nitrogen interaction effect” as its researching main line, to explore the regulation effects of soil moisture and nitrogen supply on yield and root quality of drip irrigated sugar beet by using field experiment and 15N isotope tracing. The variety BETA356 was chose in the experiment, and is a typical beet grown in Xinjiang. The contents of this project are to: analyze the root-shoot relationship of water deficit and nitrogen interaction on yield and sugar content. identify the effects of water and nitrogen coupling on root-shoot growth and carbon- nitrogen metabolism of beets via drip irrigation. subdivide the nitrogen use efficiency of sugar beet on 15N Tracer. This study may provide a theoretical basis for economically rational irrigation and nitrogen application programmer enabling the high yield and quality cultivation of drip irrigated sugar beet in arid area.

新疆是我国重要的糖料基地，在滴灌甜菜产量日益提高的同时，含糖率的下降已成为制约甜菜品质的瓶颈问题。针对该问题，选取目前新疆种植面积较大的高产高糖甜菜品种BETA356为研究对象，通过小区控制试验和氮同位素管栽试验，明确调亏灌溉条件下施氮量和氮素施用时期对滴灌甜菜根冠结构、根冠功能、碳氮代谢产物及其关键催化酶活性的影响，掌握氮素管理模式下高产优质甜菜氮素吸收转运及分配规律，阐明调亏灌溉条件下水氮互作对滴灌甜菜根冠关系和碳氮代谢的控制机理，探讨与甜菜块根品质有关的敏感性理化指标及其氮素调控途径，为精确制定干旱区滴灌甜菜水氮管理制度，进一步提升甜菜品质提供理论和技术支持。

新疆是我国重要的糖料基地，在滴灌甜菜产量日益提高的同时，含糖率的下降已成为制约甜菜品质的瓶颈问题。甜菜蔗糖含量及块根品质受糖氮代谢的调控，而水分和氮素是影响整个代谢过程的关键指标。项目基于干旱区膜下滴灌技术，明确调亏灌溉条件下施氮量和氮素施用时期对滴灌甜菜根冠结构、根冠功能、碳氮代谢产物及其关键催化酶活性的影响。结果表明，滴灌甜菜块根干重在150 kg•hm-2施氮量下达到最高，该施肥水平下基肥与叶丛期追肥施氮比例为30%：70%的氮肥运筹模式有利于提高生育后期叶片的光合能力，提高块根中的硝酸还原酶和亚硝酸还原酶活性，促进氮肥利用效率提高，增加叶片和块根中的蔗糖磷酸合成酶和蔗糖合成酶合成方向活力，促进光合产物生成蔗糖并向块根转移和贮存，最终提高块根含糖率，因此，该处理甜菜块根产量和含糖量最高。氮素过低不利于块根增长，过多的氮素会提高后期地上部分的同化产物消耗，降低块根中的含糖率。施氮水平和施氮时期对滴灌甜菜生育期干物质积累与转运、氮素吸收运转、氮效率与氮平衡以及产质量影响显著且具互作效应。块根膨大期适量施氮能够平衡甜菜整个生育期内的氮素供应，促进氮素吸收与运转，提高氮素积累与分配。低土壤有效氮条件下，150 kg•hm-2施氮量30%：70%的氮肥运筹模式处理氮收获指数和氮表观利用率最高，分别为70.69%和83.56%；而土壤有效氮较高时，不同供氮水平下各时期施氮比例对甜菜氮利用的影响各异，即150 kg•hm-2施氮量30%：70%的氮肥运筹模式处理具有最高氮表观利用率，同时该处理还增加了土壤无机氮的积累量（19.90%-27.31%），有效降低了土壤表观损失量，研究结果为精确制定干旱区滴灌甜菜水氮管理制度，进一步提升甜菜品质提供基础理论和技术支持。