Starch Granule Size Distribution in Grains of Strong and Weak Gluten Wheat Cultivars

Granule size and structure of starch affect starch quality fatally in wheat(Triticum aestivum L.).The quantity and volume of starch granule and starch components in grain vary in different types of wheat.Many researches have unveiled the dis-tribution of starch granule size in wheat grain,but rarely mentioned the relationship between grain quality and starch granule characteristics.In the present experiment,the purpose was focused on starch granule size distribution and the relationship between starch granule size and grain quality properties.Four winter wheat cultivars(Defeng 3 and De 99-3 as strong gluten type,Binyu 535 and Lumai 21 as weak gluten type)were planted at Tai'an and Dezhou experimental sites in Shandong Province,respectively,with randomized block design in 2004-2005 growing season.The starch granule in matured grain was 0.37-52.60 μm in diameter,containing smaller B-type(diameter 9.8 μm)and larger A-type(diameter 9.8 μm)granules.The distribution frequency showed typical two-peak curve in starch granule volume and surface area,and single peak curve in number of starch granule.The number of B-type granule accounted for over 99% of the total starch granule.The percentages of volume and surface area of B-type starch granules were higher than those of A-type granule in the strong gluten wheat cultivars,but on the contrary in the weak gluten cul-tivars.The contents of amylose and starch were negatively correlated with the volume of 2.0-9.8 μm(r =-0.483*,-0.679**)and 9.8 μm(r =-0.465*,-0.667**)starch granules,respectively,but positively correlated to 9.8-18.8 μm starch granule(r = 0.648**,0.673**).The content of protein was positively correlated with the volume of 2.0-9.8 μm(r = 0.528**)and 9.8 μm(r = 0.514*)starch granules,respectively,but negatively correlated with that of 9.8-18.8 μm(r =-0.548**)starch granule.The con-tents of starch and protein had no correlation with volume percentage of starch granule with other size ranges.