Studies On PhysicoChemical Characteristic Involved Of Grain Filling In Different Types Maize

In our study four maize types with different kernel textures, normal corn, waxy corn, pop corn and sweet corn as well as three maize types with different yield productivity (high, middle and low)were used. In order to study the mechanism of grain yield formation and its quality, the proliferation of endosperm cell, the changes of grain hormone, and the developments of enzymes related to the accumulation of carbohydrate and the physiological characteristics of leaf were analyzed by both field culture and lab measurement in Shandong Agriculture University from 2005 to 2008. The main results were as follows:1 Characteristics of endosperm cell proliferation and yield development with different maize typesThe number of endosperm cell between four different maize types were significantly different, normal corn>sweet corn>waxy corn>pop corn, with an especially larger difference represented in the middle and low position of the panicle. The number of endosperm cell of different position in panicle were also significantly different, that was low>middle>top.Here was significantly positive relationship between the proliferation of endosperm cell and grain filling characteristics. The correlation coefficients between the number of endosperm cells per kernel and the grain filling rate of normal corn, waxy corn, sweet corn, pop corn was 0.9592, 0.8336, 0.8251 and 0.5865, respectively. It showed that the number of endosperm cells was a key factor to the yield.2 Correlation between the content of endogenous hormone and the grain weight of different maize typesThere was difference of the endogenous hormone related to the grain development of different maize types. In the normal corn, there was significantly positive between IAA, ZR and the content of soluble sugar and protein, while there was significantly negative between ABA and grain filling rate. The function of GA3 compared to ABA was reverse, with a significantly positive with grain filling. As for the waxy corn, IAA and ZR could enhance the proliferation rate of starch effectively; ABA was negatively related to the soluble sugar content and sucrose content. For the sweet corn, there was significantly reverse correlation between the content of IAA and ZR and the content of sucrose and soluble sugar, which may because IAA and ZR could enhance the amylase activity.3 The relation between the activity of amylase and starch accumulation of different maize typesDuring the grain development of different maize types, the starch proliferation and the activity of SS, SSS, GBSS, SBE, AGPase and UGPase presented a single-peak curve. The activity of AGPase among various maize types showed that: sweet corn>waxy corn>pop corn>normal corn; the activity of UGPase was: sweet corn>waxy corn>normal corn>pop corn. As for the activity of SS, it was waxy corn> pop corn>normal corn> sweet corn. For SSS activity, it was sweet corn>pop corn>waxy corn>normal corn. The activity of GBSS was pop corn>normal corn>waxy corn>sweet corn, while the activity of SBE was pop corn>sweet corn>waxy corn>normal corn. The activity of AGPase, UGPase and SSS were significantly higher for the sweet grain than other maize types, but its activity of SS, GBSS and SBE were significantly lower compared to other maize types. The accumulation rates of amylose and amylopectin correlated well with the activities of GBSS and SBE, respectively. SS had been supposed to be the"rate-limiting"factor in starch biosynthesis. GBSS had an important effect on amylose accumulation especially. SSS and SBE were involved in the amylopectin biosynthesis.The content of sucrose and soluble sugar among different maize types was sweet corn>waxy corn>normal corn>pop corn, which was vital to starch content and utilization of the different maize types.There was significantly difference of the starch content among different maize types. The amylose content represented that normal corn>pop corn> sweet corn>waxy corn, while the amylopectin content was for waxy corn>pop corn>normal corn> sweet corn. The total starch content showed that: waxy corn>normal corn>pop corn>sweet corn.4 The differences of physiological characteristics of grain sink with different yield cornThere was significantly difference in grain endosperm cell number of different yield types, which was positively related with yield, it showed a tendency of high yield type>mediate yield type>low yield type. The content of IAA and ZR showed a similar trend ency with the endosperm cell number between various yield types, however, the average content of ABA and GA3 represented that low yield>mediate yield>high yield type. As the top value of amylase activity was concerned, the SS, SSS, AGPase, UDPase and SBE all represented the same trend of low yield> mediate yield>high yield, showing a significantly positive relationship with starch proliferation. The grain amylose content represented high yield>mediate yield>low yield, but the content of both amylopectin and starch showed a completely reverse trend between the three yield types.5. The differences of photosynthesis characteristics with different maize typesThere was remarkably difference of photosynthesis between different leaf positions of different maize types. The Pn of both top and middle leaf position represented that normal corn>waxy corn, sweet corn>pop corn, with no significantly difference between waxy corn and sweet corn. The difference of the low leaf position bettwen different genotypes was not significant.The photosynthesis indexes just as Gs, Ti, CHL and SLW were significantly different among different maize types, which were also significantly positive related with Pn.