Studies On Formative Mechanisms Of Quality Of Different Endosperm Type Maize Grain And Their Regulations

In order to learn the formative mechanisms of quality of different endosperm type maize (waxy, sweet, pop and normal) grain and their regulations, field culture and pot culture were carried out in the corn research garden of Shandong Agriculture University from 1999 to 2002. The results were as follows:1 The different characteristics of quality of four type maize grainThere are WSP, sucrose, glucose, fructose, mannitol and sorbitol in the developments of four endosperm type maize grains, but no maltose were detected. Two types of WSP with different D.P.N. were detected in the grains; their retention times are 5.28 and 5.98 min. The sugar and WSP content are higher in sweet corn grain than other types. With the development of maize grain, the components of sugars in different endosperm type maize grain are different.There are both amylose and amylopectin in different endosperm type maize grains. Both of them were detected in the embryo, but only amylopectin exist in the waxy corn endosperm. Sweet corn accumulated less starch than other type. The content of total starch in different endosperm type maize grain increased with the development of the grain. The contents of amylose in waxy and sweet corn are lower than other types . With the developments of the grain, the contents of amylose in waxy and sweet corn decreased, but in pop and normal corn it increased.The contents of total amino acids and essential amino acids in fresh period of waxy and sweet corn grain is lower than normal corn, but the percent of essential amino acids in total amino acids is higher than normal corn. In Pop corn grain they are highest in four types. In different endosperm type maize grain, the shorting of LYS is the first limiting factor, but the second is different.In fresh period, the quality of protein in waxy and sweet corn grain is excelled than other types. Pop corn grain can accumulated more protein than others, and the protein efficient rate is higher than others.2 The difference of formative mechanisms in different endosperm type maize grainIn process of sucrose synthesis, SS (synthesis) have dominant function in four type maize grains. In the development of grain, the average activities of SS in pop corn> sweet corn>normal corn>waxy corn. The average of SPS activities in sweet corn>pop corn>waxy corn>normal corn. The ability of sucrose synthesis in sweet corn is higher than others.The degradation of sucrose is mainly depending on the SS (degradation) activity, and the effect of invertase is lower than SS. In the development of grain, the average activity of sweet corn grain > normal corn >waxy corn >pop corn, and invertase activity of pop corn > waxy corn >normal corn > sweet corn. The reason of more sugars in sweet corn grain is the increasing of ability of sucrose synthesis but not the decreasing of degradation of sucrose.In different endosperm type maize grain, the activities of UDPG-PPase are higher than ADPG-PPase, SSS are higher than GBSS. The average activities of ADPG-PPase: wax corn >pop corn >normal corn >sweet corn, but the average activities of UDPG-PPase expressed as pop corn >waxy corn >sweet corn >normal corn. Both SSS and GBSS activities of normal corn >pop corn >sweet corn> waxy corn. Low activities of GBSS lead to the low content of amylose in waxy corn, and the intergrated effects of activities decrease of SSS, GBSS and SDE resulted in the lower starch content in sweet corn.3 The effect of nitrogen on the quality of different endosperm type maize grainThe influences of nitrogen to the total soluble sugar content are different in different endosperm type maize grain. Nitrogen can improve the total soluble sugar content in waxy, sweet and normal corn, but decreased it in pop corn. The functions of nitrogen on different sugar components are different. Sucrose, mannitol and sorbitol content increased in four types maize grain after applied nitrogen. The time of no consistence of sorbitol in nitrogen treatment of sweet corn is shorter than control. The WSP content of sweet, pop...