紫玉米脆质果皮性状及形成机理研究

The essential problems affecting the palatability of fresh edible maize especially sweet corn were thick pericarp, excessive peeling and weak tenderness. There was no ideal solution to overcome these problems at home and abroad at present. According to many years research on fresh edible maize, the research group of specialty corn institute found some purple corn inbred lines such as STK1545 and STK1716 had brittle pericarp. These purple corn tasted without residue peeling and had good palatability. In our daily life, some vegetables and fruits also had brittle pericarp characters. Such as the residue peeling of some pears tasted better than apples, even though the peicarp of pears thicker than apples. The study was attempted to take brittle pericarp characters as breakthrough and planed to explore a new method through brittling maize pericarp to improve the palatability of fresh edible maize. Purple corn, waxy corn and sweet corn with different brittle pericarp and different pericarp thickness were used as the experiment material in this study. The pericarp characters, cytology and biochemistry of pericarp were studied to verify the formation mechanism of brittle pericarp. The objective of this study was also to analysis the correlation between the brittle of stalk, cob and leaf with pericarp brittleness, build the identifying method of purple corn with brittle pericarp. This research could lay theoretical foundation for the study of the genetic regularity of brittle pericarp and breeding of fresh edible maize with brittle pericarp. It also could provide technical parameters for improving the palatability of fresh edible maize especially sweet corn, extending shelf life and harvest life, improving the processing quality of fresh edible maize. The study also had significant value for future studies and use of brittle pericarp gene in improving the palatability of fresh edible maize especially sweet corn.

果皮厚、皮渣多、柔嫩性差是影响鲜食玉米特别是甜玉米适口性的首要问题，国内外一直没有找到理想的解决办法。本课题组前期研究发现沈农紫糯玉米STK1545和STK1716果皮具有脆性特质。鲜食时果皮脆嫩、口感无渣、适口性好。根据在其他一些瓜果中存在的脆质果皮现象，例如梨子，尽管有的果皮厚于苹果，但皮渣感明显优于苹果。因此试图以果皮脆度为突破口，通过果皮脆化来解决鲜食玉米的适口性问题。本研究拟采用不同脆性、不同果皮厚度的紫糯玉米、糯玉米、甜玉米为试材，从果皮性状、果皮细胞学及生物化学基础入手，研究果皮脆性的形成机理；探究茎秆、穗轴、叶片等器官脆性、强度与果皮脆性的相关性，构建果皮脆性的表型鉴定技术体系，为鲜食玉米果皮脆质遗传和脆皮鲜食玉米新品种选育研究奠定基础。该研究对改善鲜食玉米特别是甜玉米的适口性，延长货架期和采收期，提高加工品质，以及对后续的脆质基因挖掘利用研究具有重要价值。

本项目以果皮脆性、厚度和柔嫩性不同的糯玉米自交系为材料，对鲜样和熟样的果皮厚度、拉力和硬度指标进行研究。探究果皮性状、果皮生物化学基础对脆度的影响，果皮脆性与茎秆、穗轴强度的相关性。主要结果如下：1.糯玉米自交系果皮脆度与适口性主要品质的相关分析，结果表明脆性与糯性、果皮薄厚关系并不明显。2．果皮厚度、拉力和硬度，无论鲜样还是熟样，不同品系间均存在明显差异；果皮厚度、拉力和硬度值，熟样均比鲜样降低。自交系间果皮拉力、硬度的极差值，鲜、熟样之间差异很大，且熟样使品系间的差值幅度拉大，变异系数增加；果皮厚度，鲜样与熟样之间呈高度正相关；果皮硬度、拉力，鲜样与熟样之间呈高度正相关；果皮拉力、硬度与厚度之间均无相关关系。研究发现：熟样可使样品间的果皮厚度、拉力和硬度值差异放大，即熟样能更容易进行品种间比较。因此在糯玉米品种选育中，除了果皮薄厚以外，还要考虑到果皮的韧性和硬度。3．果皮脆性与果皮拉力值相关程度较高，鲜样和熟样的相关系数分别为0.94、0.83，均达到显著水平。利用果皮拉力来评价果皮脆性性状，具有较高的价值。果皮厚度、果皮硬度与果皮脆性的相关系数，鲜样、熟样分别为0.34、0.15和0.38、0.37，即相关性很低，且均未达到显著水平。4．果皮电导率、电阻率对果皮硬度、拉力的影响均不明显。5．果皮拉力、硬度与细胞壁纤维素、半纤维素含量相关系数均较低。果皮细胞壁木质素含量与鲜、熟样果皮拉力的相关系数分别为-0.63（P<0.05）、-0.88（P<0.01），细胞壁木质素含量对果皮拉力影响较明显。木质素含量越大，果皮拉力就越小。该研究对改善鲜食玉米特别是甜玉米的适口性，延长货架期和采收期，提高加工品质，以及对后续的脆质基因挖掘利用研究具有重要价值。通过项目开展，发表科研论文3篇，申请国家发明专利1项，审定鲜食玉米新品种2个，获辽宁省科技进步奖三等奖1项，大北农科技创意奖1项。