氮肥用量和运筹方式对湘南早稻产量和氮素利用效率的影响

为改进湘南地区早稻氮肥施用方法，明确氮肥施用关键技术，构建高产高效氮肥施用模式，开展了以施氮水平为主区因素、氮肥运筹方式为副区因素的裂区试验，研究了其对湘南早稻产量形成与氮素利用效率的影响。结果表明：（1）增大施氮量和穗粒肥比例能提高水稻茎蘖数和成熟期水稻叶片SPAD值；施氮150-210kg/hm2范围内，早稻产量变化不大，但中氮（180 kg/hm2）水平下提高穗粒肥比例可显著增产。（2）增大施氮量可显著提高稻米整精米率和稻米粗蛋白含量，降低垩白率；提高穗粒肥比例可提高稻米整精米率、直链淀粉含量和粗蛋白含量，降低稻米碱消值。（3）随施氮量增大，水稻氮素积累量显著增大，但氮素偏生产力（NPFP）、氮肥农学效率（ANUE）和氮素回收效率（NRE）显著降低；提高穗粒肥比例可显著提高水稻氮素积累量和中氮水平下NRE、NPFP和ANUE。总体来看，180 kg/hm2施氮量下，提高穗粒肥比例有利于提高湘南早稻产量、米质和氮素利用效率。

Nitrogen Rate and Planning Mode Affect Yield and Nitrogen Utilization Efficiency of Early Rice in Southern Hunan

To improve the nitrogen application methods to early rice in southern Hunan, clarify the key application techniques and construct a high-yield and high-efficiency application mode, a two-factor splitplot experiment with the application rate as main factor and the fertilizer planning mode as secondary factor was conducted and its impact on yield formation and nitrogen utilization efficiency was studied. The results showed that: (1) tiller number and leaf SAPD value at maturity stage of early rice increased with the increase of nitrogen fertilizer rate and ratio of ear and grain nitrogen, the yield had no obvious change when nitrogen rate was from 150 kg/hm2 to 210 kg/hm2, while was significantly increased by increasing the ratio of ear and grain nitrogen with 180 kg/hm2 nitrogen rate; (2) increasing the nitrogen rate could significantly improve the whole head rice rate and rude protein content, and reduce the chalky rice rate, increasing the ear and grain nitrogen ratio could increase the whole head rice rate, amylose content and crude protein content, but reduce the alkalispreading value; (3) with the increase of nitrogen rate, the nitrogen accumulation of early rice significantly increased, but the NPFP, ANUE and NRE significantly decreased, with the increase of the ratio of ear and grain nitrogen, the nitrogen accumulation significantly increased, and the NRE NPFP and ANUE in medium nitrogen level treatment significantly increased. On the whole, when the nitrogen rate is 180 kg/hm2, the increase of the ratio of ear and grain nitrogen is beneficial to improving yield, rice quality and nitrogen utilization efficiency of early rice.