不同追氮模式对河南沿黄稻区粳稻根系生长和产量的影响

为明确不同追氮模式对河南沿黄稻区粳稻产量的影响,以常规粳稻品种郑稻19和郑稻20为材料,于水稻拔节后设置4种追氮模式,基蘖肥∶促花肥∶保花肥∶粒肥分别为6∶4∶0∶0（T1）、6∶0∶4∶0（T2）、6∶2∶2∶0（T3）、6∶0∶2∶2（T4）,以施用等量基蘖肥不追施氮肥（T0）作为对照,研究中后期不同追氮模式对水稻根系形态和生理特征的影响及其与产量的关系。结果表明,郑稻19和郑稻20的穗数、结实率和千粒重在不同追氮模式间无显著差异,而T3处理的穗粒数和产量显著高于其他处理,均表现为T3>T1>T2>T4>T0。同时,2个水稻品种齐穗期、齐穗后至成熟期的根系体积、根干重、总吸收表面积、活跃吸收表面积和地上部干重均是T3处理最高,且根系氧化力、吲哚乙酸含量和玉米素+玉米素核苷含量也是T3处理最高。说明水稻拔节后分次适时（促花肥和保花肥）追氮能够促进中后期根系生长,维持根系较高的生理活性,延缓根系退化衰老,有利于水稻高产,而一次追肥或延迟追肥对水稻生长促进作用减弱。

Effects of Nitrogen Topdressing Models on Root Growth and Grain Yield of Japonica Rice in the Region along Yellow River of Henan Province

A field experiment was conducted to reveal the effects of nitrogen topdressing models on root morphology and physiological characteristics and grain yield of japonica rice varieties Zhengdao 19 and Zhengdao 20 in the region along the Yellow River. Four nitrogen fertilizer topdressing models were set after jointing stage of rice. The ratio of base fertilizer and tillering fertilizer, flower promoting fertilizer, flower preserving fertilizer and grain fertilizer were applied in the ratio of 6:4:0:0 (T1), 6:0:4:0 (T2), 6:2:2:0 (T3), 6:0:2:2 (T4) and applying the same amount of base fertilizer and tillering fertilizer, and no nitrogen application (T0) after jointing as a control. The results showed that Zhengdao 19 and Zhengdao 20 had no significant changes in number of panicles, seed-setting rate and 1000-grain weight, while spikelets per panicle and grain yield of T3 treatment were significantly higher than those of other treatments, and showed T3 > T1 > T2 > T4 > T0. At the same time, the root volume, root dry weight, total root absorption surface area per plant, root active absorption surface area per plant, and shoot dry matter of the two rice varieties at the full heading stage and after full heading stage to maturity stage under T3 treatment were the highest, and the root oxidation activity, indole acetic acid content, and zeatin + zeatin nucleoside content were the highest under T3 treatment. It showed that the appropriate nitrogen topdressing (flower-promoting fertilizer, flower-preserving fertilizer) after jointing stage of rice could promote root growth at the middle and late stages, maintained high physiological activity of the root system, delayed root degeneration and senescence and was beneficial to high yield of rice.