Starch Granule Size Distribution in Grains of Maize with Different Starch Contents

【Objective】The purpose of this research was to reveal the size-distribution characteristics of starch granules in maize endosperm and to study the relation of starch granule size to grain starch content,protein content and test weight.【Method】In the present experiment,four maize cultivars(Nongda 108 and Zhengdan 958 as common maize,Feiyu 3 and Zhengdan 18 as high starch maize) were used,and maize grains at mature stage were analyzed to study the changes of number,volume and surface area distribution of starch granules in maize endosperm.【Result】The starch granule in matured grain was 0.37-31.5 μm in diameter.Taking 2 μm and 15 μm as limit,the starch particles were divided into three types: small starch granule group(SSG,2μm),middle starch granule group(MSG,2-15 μm) and large starch granule group(LSG,15 μm).The distribution frequency showed two-peak curve in starch granule volume,and three-peak curve in starch granule surface area.Maize endosperm had a typical single peak curve in number of starch granule,and the SSG granule accounted for over 95% of the total starch granule.The percent age of volume of SSG and MSG were higher than that of LSG in the high starch maize,but in the common maize,the percent ages of volume,number and surface area of LSG were higher than those in high starch maize.Correlation analysis indicated that the starch content was positively correlated with the volume of 0.8-2 μm(r=0.777,P0.05),2-10 μm(r=0.735,P0.05) and 10-15 μm starch granules,but negatively correlated with other size ranges.The content of protein and test weight had no correlation with volume of starch granule with other size ranges.【Conclusion】Maize has a typical single peak curve in number of starch granule,two-peak curve in starch granule volume,and three-peak curve in starch granule surface area.The percent ages of volume of SSG and MSG in the high starch maize were higher than that of common maize significantly.