糯玉米胚乳发育过程中淀粉粒粒度分布的变化

摘要

为明确糯玉米淀粉粒粒度分布形成过程及特征,为糯玉米淀粉品质改良及调控糯玉米淀粉粒粒度提供理论依据,采用激光衍射粒度分析仪测定糯玉米胚乳发育过程中淀粉粒粒径以及体积、表面积和数目分布的变化。结果表明,授粉后10~20 d,糯玉米胚乳淀粉粒粒径下限逐渐减小,粒径上限和平均粒径显著增大；授粉后20 d一直到成熟期,粒径各项指标无显著变化。随着胚乳发育,糯玉米胚乳淀粉粒体积和表面积分布均呈现“单峰-双峰-三峰”的动态变化,数目分布始终表现为单峰曲线。以成熟期淀粉粒体积分布三峰曲线的谷值为界线,将糯玉米淀粉粒分为小型(7.422μm)。胚乳发育前期,小型淀粉粒所占体积和表面积百分比呈降低趋势,数目百分比呈增加趋势,中型淀粉粒所占体积、表面积和数目百分比整体上呈降低趋势,而大型淀粉粒则呈增加趋势；淀粉粒的体积、表面积和数目分布均以小型淀粉粒所占比例最高,其次为中型淀粉粒,大型淀粉粒所占比例最低。胚乳发育中后期,不同粒径淀粉粒分布情况均趋于稳定,体积分布以大型淀粉粒为主,而表面积和数目分布以小型淀粉粒为主。因此,胚乳发育前期是糯玉米淀粉粒形成的关键时期,此时期调控淀粉粒粒度分布,可有效改良糯玉米淀粉品质。%In this study, the diameter, volume, surface area and number distribution of starch granule during waxy corn endosperm development were determined using laser diffraction particle size analyzer. The results showed that the minimum of starch granule decreased, the maximum and mean of starch granule increased from 10 DAP ( days after pollination) to 20 DAP. The minimum, maximum and mean of starch granule didn’ t have a significant change af-terwards. With endosperm development, starch granule vol-ume and surface area distribution showed a similar dynam-ics of “single peak-double peak-three peak” curves, how-ever, the number distribution exhibited a single peak curve all along. According to the concave point of three peak curve of starch granule volume distribution at maturity, starch granules were classified into three types:small (7. 422 μm). At the earlier period of endosperm development, the volume and sur-face area percent of small starch granule decreased whereas the number percent increased, the volume percent, surface area percent and number percent of middle starch granule droped, and those of large starch granule increased. Small granule starch was the most abundant and accounted for the biggest surface area and volume, followed by middle granule and large granule starch. At the middle and late period of endosperm development, large starch granule was predominant in volume distribution and small starch granule was predominant in surface area and number distribution. Therefore, the key phase of starch granule formation was the earlier period of endosperm development when starch granule size distribution could be controlled to improve starch quality of waxy corn.