Effects of Nitrogen Application Time on Caryopsis Development and Grain Quality of Rice Variety Yangdao 6

XIONG Fei,WANG Zhong,GU Yun-jie,CHEN Gang,ZHOU Peng(Jiangsu Provincial Key Laboratory of Crop Genetics and Physiology,Yangzhou University,Yangzhou 225009,China)

caryopsis development;rice quality;amylose;protein body;amyloplasts;nitrogen fertilizer;fertilizer application time

Pot experiments were conducted to study the effects of different nitrogen application time(at the tillering and booting stages under the same nitrogen amounts)on caryopsis development and grain quality of rice variety Yangdao 6.The increased nitrogen fertilizer(urea),especially at the booting stage,could evidently increase head rice rate,milled rice rate and protein content in grains compared with the control,while decrease chalky grain rate and amylose content.The increased nitrogen fertilizer applied at the tillering and booting stages could significantly affect caryopsis development and enhance grain weight,with more obvious when applied at the booting stage.In the course of caryopsis development the increased topdressing of nitrogen fertilizer at the tillering and booting stages could obviously decrease the total starch and amylose contents,but not obviously for amylopectin content.Increased topdressing of nitrogen fertilizer,especially at the booting stage,had significant effect on the development and structures of amyloplasts and protein bodies.That is,it could change the distribution,numbers and shapes of amyloplasts and protein bodies in the endosperm cells especially in grain abdomen.Compared with the control the arrangements of amyloplasts and protein bodies were closer,with more numbers and higher density and less interspaces each other.Furthermore,most amyloplasts showed polyhedron under the increased nitrogen fertilizer.