| Agricultural sciences |
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| Effects of different transplanting seedling ages and nitrogen managements on plant type of indica hybrid rice. |
| Lü Tengfei1, Zhou Wei1，2, Sun Yongjian1, Zhu Yi1, Yan Fengjun1, Yang Zhiyuan1, Ma Jun1* |
| (1. Key Laboratory of Crop Physiology, Ecology, and Cultivation in Southwest China, Ministry of Agriculture/Rice Research Institute, Sichuan Agricultural University, Chengdu 611130, China; 2. College of Agronomy, Sichuan Agricultural University, Chengdu 611130, China) |
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Abstract Transplanting seedling age is an important factor that may greatly affect the population quality and grain yield formation of rice. Related researches have showed that by extending the transplanting seedling ages, the tillering growth rate would slowed down; the growth duration would get shorted; peak seedling stage would occur in advance; leaf area index (LAI) at full heading stage, the numbers of effective panicle per plant and grains per panicle would decreased, resulting in obvious reduction of grain yield. Due to the special landscape of the hilly area in China, the old transplanting seedling age still exist in those areas. The rice plant type is closely associated with the formation, growth and development of panicle, thus a good individual plant is essentially important for improving the quality of the population. Besides, nitrogen and its management are also important factors affecting the growth and grain yield formation of rice. To investigate the effect of seeding ages and nitrogen managements on some plant type characteristics of hybrid rice, F you 498 was used as test material in this experiment. Split plot was conducted with transplanting seedling ages (35 d, 50 d and 65 d) as main plot and nitrogen application strategy (0% panicle fertilizer, 20% panicle fertilizer, 40% panicle fertilizer and 60% panicle fertilizer) as sub-plot. The aims were to provide the theoretical and practical data for improving the grain yield of old transplanting seedling age in hilly areas. The results showed that the LAI at full heading stage decreased with the extension of seedling age, and the average LAI of 65 d seedling age was significantly lower than 35 d and 50 d, but due to the larger and wider of top 3 leaves of 65 d seedling age, its high effective leaf area ratio was significantly larger than that 35 d and 50 d. With the increase of nitrogen fertilizer application ratio at panicle differentiation stage, the LAI of 50 d and 65 d seedling age at full heading stage increased first and then decreased, and the LAI reached its maximum when the panicle fertilizer ratio was 40%. With the extension of seedling age, the length, width and angle of top 3 leaves increased gradually, and the specific leaf mass of 65 d seedling age was the largest, followed by 35 d and 50 d; the length of the 1st and 2nd leaves from top and the angle of top 3 leaves of 65 d seedling age were significantly higher than those of 35 d and 50 d, and its length of the 3rd leaf from top and the width of top 3 leaves were also higher than 35 d. The length, width, thickness and angle of top 3 leaves were positively correlated with the number of spikelets, filled grains and grain mass per panicle; and either extending the seedling age or decreasing base-tiller fertilizer ratio could reduce the plant height significantly. The effect of transplanting seedling ages on plant type of hybrid rice was closely related with earing fertilizer managements, and extending the transplanting seedling age or increasing the panicle fertilizer ratio could improve fertilizer tolerance and lodging resistance of F you 498, and applying more earing fertilizer under long seedling age could make rice have better population quality and strong photosynthetic capacity, while too large and loosely top leaves would reduce transmittance and photosynthetic efficiency of rice population, and making the yield of long seedling age hard to improve further. It is concluded that long seedling age of rice has large and thick leaves, and applying 40% total nitrogen fertilizer at panicle differentiation stage will be beneficial to expand leaf areas and increase the number of spikelets per panicle. But the oversize of upper leaves can lead to leaf drooping, lower leaves shading, thus will reduce the photosynthetic efficiency of rice groups after flowering, and decrease the setting percentage and 1 000-grain mass, causing production reduction. In addition, the extension of the transplanting seedling age and the reduction of the base-tiller nitrogen fertilizer application ratio can obviously reduce the plant height, improve the ability of resistance to lodging and improve plant type.
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Published: 20 March 2015
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不同秧龄和氮肥运筹对杂交籼稻株型的影响
为探究秧龄和氮肥运筹对杂交稻一些主要株型因子的影响，以四川主推杂交籼稻品种F优498为材料，采用2因子裂区设计，主区为35、50和65 d 3种移栽秧龄，副区为占总施氮量0%、20%、40%和60%的4种穗肥比例运筹.结果表明：随着秧龄的延长，齐穗期水稻叶面积指数（leaf area index，LAI）不断降低，且65 d秧龄的平均LAI显著低于35 d和50 d秧龄，但由于65 d秧龄上3叶的叶片长而宽，其高效叶面积率显著高于35 d和50 d秧龄；随穗肥比例的加大，50 d和65 d秧龄齐穗期水稻LAI则呈先增后降的趋势，穗肥比例40%时叶面积最大；随着秧龄的延长，上3叶的长、宽和夹角整体表现为变大趋势，比叶质量则是65 d>35 d>50 d秧龄，且65 d秧龄的剑叶、倒2叶长及上3叶夹角显著高于35 d和50 d秧龄，倒3叶长和上3叶宽也显著高于35 d秧龄；在65 d秧龄下，随着穗肥比例的加大，剑叶夹角明显增大，倒2叶和倒3叶夹角也呈先增后减的趋势（以40%最大）.上3叶的长度、宽度、厚度及夹角均与总粒数、实粒数和单穗质量呈正相关关系；而且延长秧龄，减少基蘖肥施用比例，株高显著降低.秧龄对水稻株型的影响与穗肥运筹密切相关，延长秧龄和加大穗肥施用比例可以提高F优498的耐肥和抗倒伏能力，而且在长秧龄下重施穗肥还可使其具有较优群体质量和较强光合生产能力，但是上部叶片过大且披散，势必对下层叶片造成遮光，降低水稻群体的光合效率，使长秧龄水稻产量难以进一步提高.
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