水稻不同部位伤流强度的差异及其与籽粒充实的关系

为明确水稻弱势籽粒充实的作用机理，以豫粳6号(粳稻)和两优培九(籼稻)为试验材料，于幼穗分化期设置不同的氮素穗肥处理(即0、90、180 kg hm^-2纯氮)试验，研究了基部节间和穗颈节间伤流强度、伤流液中可溶性糖的灌浆期动态变化，灌浆盛期伤流强度日变化规律及穗颈节间伤流强度和伤流液中可溶性糖与籽粒充实度的关系。结果表明，水稻基部节间和穗颈节间伤流强度灌浆期变化不同，基部节间伤流强度于花后5 d达最大值，之后呈下降趋势；穗颈节间伤流强度于花后5 d、17 d各出现一个峰值，花后11 d达低谷，平均穗颈节间伤流强度表现为无氮肥处理最高，高氮肥处理最低。穗颈节间伤流强度日变化以白天较低，夜晚较高且随着施氮量的增加而降低。籽粒灌浆期，花后10、15、25和35 d粳稻穗颈节间伤流强度与其弱势粒充实度呈显著或极显著正相关关系，而籼稻相关性不显著；穗颈节间伤流液中可溶性糖含量与强弱势粒充实度均极显著正相关。基部节间伤流与籽粒充实度的关系不显著。说明穗颈节间伤流与弱势粒充实关系密切，可以此作为衡量弱势粒充实程度的指标之一。因此，以氮素调控为手段提高穗颈节间伤流强度来提高弱势粒充实度是可行的。

Difference of Bleeding Intensity in Different Parts of Rice Plant and Its Relationship with Grain Plumpness

This study aimed to illustrate the mechanism of inferior grain plumpness in rice. A field experiment with 0, 90 and 180 kg ha^-1 N spike fertilizer application in the stage of rice young ear differentiation was carried out in 2005 and 2006 on the farm of Henan Agricultural University, Henan province, China. Two varieties (indica and japonica rice) were used to study the periodical changes of basal and neck internode bleeding intensity, soluble sugars in bleeding, daily change of bleeding intensity and the relationship between the bleeding intensity and soluble sugars of neck internode with grain plumpness in the grain filling stage. The results showed that the changes of bleeding intensity between the basal and neck internodes were obviously different. The bleeding intensity in the basal internode reached the maximum value in the fifth day after anthesis and presented the drop tendency afterwards. The bleeding intensity of the neck internode appeared two peak values in the fifth and seventeenth days after anthesis. There was a valley value in the eleventh day after anthesis on average. The average bleeding intensity in the neck internode was higher under zero N lever than high N level. The daily change of bleeding intensity in the neck internode was low in the daytime and high at night, which reduced with rising N fertilizer application. Correlation analysis showed that there existed significantly positive correlation or highly signification between inferior grain plumpness and the bleeding intensity of neck internode in the 10, 15, 25, and 35 days after anthesis for the japonica, but not for the indica rice. The relationship between soluble sugars in the bleeding of neck internode and inferior grain plumpness showed highly significantly positive correlation, while that of the basal internode was not notable. It indicated that the relationship between bleeding in the neck internode and the inferior grain plumpness is close. The bleeding intensity of neck internode can be used as a index for measuring inferior grain plumpness. Therefore, increasing the bleeding intensity of neck internode by regulating N application can improve the inferior grain plumpness.