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

Abstract

This study aimed to illustrate the mechanism of inferior grain plumpness in rice. A field experiment with 0, 90 and 180 kg ha1 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 sucrose in bleeding, daily change of bleeding intensity and the relationship between the bleeding intensity and soluble sucrose 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 solublesucrose 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.