优化栽培模式对水稻根-冠生长特性、水氮利用效率和产量的影响

【目的】探明优化栽培模式对水稻根冠发育以及产量与肥水利用效率的影响。【方法】以甬优1540(三系籼/粳杂交稻)为材料,设置3个处理：0N(空白)栽培模式、当地农户习惯栽培模式(对照)以及优化栽培模式。【结果】优化栽培处理两年的平均产量为11.5 t/hm²,与对照差异不显著;但其氮肥偏生产力、产谷利用率以及水分利用率较对照显著提高。与对照相比,优化栽培处理改善了水稻根系形态与生理特征,降低了根系生物量与根-冠比,提高了深根比与比根长,增加了齐穗期与灌浆中期根系活跃吸收表面积,提高了灌浆中后期根系氧化力与根系伤流液中玉米素(Z)+玉米素核苷(ZR)的浓度。此外,与对照相比,优化栽培处理显著提高了灌浆中后期剑叶净光合速率、叶片中Z+ZR含量以及籽粒中蔗糖-淀粉代谢途径关键酶活性。【结论】优化与集成现有栽培技术,可以改善水稻根系形态与生理特征,提高地上部生理活性,进而实现肥水利用效率的提高。

Effects of Improved Crop Management on Growth Characteristic of Root and Shoot,Water and Nitrogen Use Efficiency,and Grain Yield in Rice

【Objective】This study aims to determine if an improved root system under improved crop management (ICM) could promote shoot growth, physiological processes, and consequently contribute to an increase in grain yield and nitrogen and/or water use efficiency.【Method】An indica/japonica hybrid rice cultivar Yongyou 1540 was field grown. at zero nitrogen level under local farmers’ practice (LFP) and ICM in Hangzhou in 2018 and 2019. 【Results】The grain yield was 11.5 t/hm² under ICM, insignificantly different from that under ICM and LFP. Compared to LFP, ICM significantly increased both nitrogen use efficiency (NUE) and water use efficiency (WUE), and improved several root morphological and physiological traits. For instance, ICM significantly reduced root dry weight and root-shoot ratio, increased root dry weight in 10-20 cm soil layer, specific root length, active absorbing surface area at heading and mid-grain filling period, and root oxidation activity and concentration of Z+ZR in root-bleeding sap at mid- and late-grain filling periods compared to LFP. Furthermore, ICM significantly increased flag leaf photosynthetic rate, concentration of Z+ZR in leaves, activities of enzymes involved in sucrose-to-starch conversion in grains at mid- and late-grain filling periods compared to LFP.【Conclusion】Improved root morphological and physiological traits under ICM promote shoot growth, physiological processes, and consequently, contribute to an increases in water and nitrogen use efficiency.