【作者】 刘鹏；

【导师】 胡昌浩； 董树亭；

【作者基本信息】 山东农业大学 ， 作物学， 2003， 博士

【摘要】 本研究于1999~2002年采用大田试验和室内生理、生化分析相结合的技术路线，在搜集、种植大量不同胚乳类型玉米品种并根据产量和品质兼顾的原则筛选出代表性品种的基础上，对糯质型、甜质型、爆裂型和普通型玉米籽粒的品质特性及籽粒发育过程中相关酶活性的动态变化进行系统的比较研究，通过盆栽试验研究了氮、钾对其品质的影响，总结得出了品质特性的差异及其形成机理，并探讨了氮、钾对其品质的调控。研究结果如下：1 不同胚乳类型玉米籽粒品质特性的差异四种类型玉米籽粒中存在的糖有WSP、蔗糖、葡萄糖、果糖、甘露醇和山梨醇，但不存在麦芽糖。籽粒中存在两种WSP，其保留时间分别为5.28min和5.98min。甜质型玉米籽粒可以积累较多的糖，而且籽粒中WSP的含量明显高于其它类型玉米。随着籽粒的发育，糖的组成在类型间产生差异。四种类型玉米籽粒中均存在支链和直链淀粉，在胚中两种淀粉组分均存在，而胚乳中的淀粉糯质型为支链淀粉，其它类型中则含有支链和直链两种淀粉。甜质型玉米积累的总淀粉明显少于其它类型，四种类型玉米总淀粉含量均随籽粒的发育而增加。甜质型和糯质型玉米直链淀粉含量较低，而且随籽粒的发育而下降，爆裂型和普通型玉米籽粒则相反。甜质型籽粒的总氨基酸含量和必需氨基酸含量在籽粒鲜食期低于普通型，但必需氨基酸占总氨基酸的比例较高。爆裂型玉米籽粒的总氨基酸含量和必需氨基酸含量最高，籽粒发育后期必需氨基酸所占的比例最高。籽粒氨基酸品质的首要限制因素为LYS的缺乏，但是次要因素则因类型和生育时期而异。鲜食期，甜质型和糯质型玉米籽粒的蛋白质品质要优于普通型玉米。爆裂型玉米籽粒中可以积累较多的蛋白质，而且必需氨基酸含量和蛋白质的效力比值也优于其它类型玉米。1.2 四种类型玉米籽粒品质差异的主要机理<WP=11>在四种类型玉米籽粒中蔗糖合成酶（合成方向）在蔗糖合成的过程中起主导作用。籽粒发育过程中，蔗糖合成酶（合成方向）的平均活性表现为爆裂型>甜质型>普通型>糯质型。而磷酸蔗糖合成酶的平均活性则表现为：甜质型>爆裂型>糯质型>普通型。甜质型玉米籽粒具有较高的蔗糖合成能力。籽粒中蔗糖的降解主要依靠蔗糖合成酶（降解方向），而蔗糖酶在蔗糖降解过程中起的作用较小。籽粒发育过程中，蔗糖合成酶（降解方向）平均酶活性：甜质型>普通型>糯质型>爆裂型；而蔗糖酶活性则表现为：爆裂型>糯质型>普通型>甜质型。甜质型玉米籽粒蔗糖积累较多的原因主要得益于蔗糖合成能力的增加，而非降解量的减少。玉米籽粒中UDPG－PPase酶活性要高于ADPG－PPase。ADPG－PPase平均酶活性：糯质型>爆裂型>普通型>甜质型。UDPG－PPase平均酶活性：爆裂型> 糯质型>甜质型>普通型。SSS的酶活性低于GBSS。SSS和GBSS的平均酶活性均表现为普通型>爆裂型>甜质型>糯质型。糯质型籽粒直链淀粉含量低的主要原因是较低的GBSS活性。甜质型玉米籽粒淀粉含量降低是由于SSS、GBSS和SDE活性降低综合作用的结果。1.3 氮肥对籽粒品质的影响氮对不同胚乳类型玉米可溶性糖含量的影响不同，对糯质型、甜质型和普通型玉米可以提高籽粒可溶性总糖含量，爆裂型玉米则降低。对各糖组分含量的影响也不同：施用氮素后蔗糖、甘露醇和山梨醇含量四种类型玉米均较对照升高；甜质型玉米施氮后不含山梨醇的时间缩短；甜质型、爆裂型和普通型玉米WSP含量较对照增加；施氮后糯质型、甜质型和普通型玉米的葡萄糖及果糖含量增加，爆裂型玉米降低。氮素对总淀粉含量的影响也因类型而异，施氮提高了糯质型和普通型玉米总淀粉含量，降低了甜质型和爆裂型的含量。施氮后，四种类型玉米直链淀粉含量均提高；而糯质型、普通型支链淀粉含量提高，甜质型和爆裂型则降低。施氮后四种类型玉米籽粒的总氨基酸和必需氨基酸含量均显著增加。氮肥对糯质型、甜质型的氨基酸品质有鲜食期改善，后期降低的双重作用；对爆裂型和普通型玉米则存在单一的负作用。 施氮后四种类型玉米蛋白质的相对含量和绝对含量均增加。氮对蛋白质品质的影响因类型而异，甜质型玉米施氮后籽粒发育前中期蛋白质效力比值高于对照，而后期低于对照；其它三种类型籽粒施用氮素后蛋白质效力比值则均高于对照。氮肥提高了糯质型、甜质型和普通型玉米蔗糖的降解能力，对爆裂型玉米却有降低作用。氮肥提高了糯质型、甜质型和爆裂型ADPG－PPase和UDPG－PPase活性，只降低了普通型玉米籽粒的ADPG－PPase活性。四种类型玉米SSS活性氮素处理均低于对照，而糯质型、普通型的GBSS活性氮素处理高于对照。1.4 钾肥对籽粒品质的影响<WP=12>施钾后，四种类型玉米籽粒的可溶性总糖含量较对照均有显著增加；其中WSP、蔗糖及山梨醇含量钾素处理均显著高于对照；葡萄糖和甘露醇含量，糯质型玉米钾素处理低于对照，其它三种类型则高于对照；果糖含量，糯质型和爆裂型玉米钾素处理低于对照，而甜质型和普通型则高于对照。施钾后，糯质型和普通型玉米的淀粉含量增加，而甜质型、爆裂型玉米降低。施钾降低了糯质型和甜质型直链淀粉含量，而爆裂型和普通型则升高；支链淀粉含更多还原

【Abstract】 In order to learn the formative mechanisms of quality of different endosperm type maize (waxy, sweet, pop and normal) grain and their regulations, field culture and pot culture were carried out in the corn research garden of Shandong Agriculture University from 1999 to 2002. The results were as follows:1 The different characteristics of quality of four type maize grainThere are WSP, sucrose, glucose, fructose, mannitol and sorbitol in the developments of four endosperm type maize grains, but no maltose were detected. Two types of WSP with different D.P.N. were detected in the grains; their retention times are 5.28 and 5.98 min. The sugar and WSP content are higher in sweet corn grain than other types. With the development of maize grain, the components of sugars in different endosperm type maize grain are different.There are both amylose and amylopectin in different endosperm type maize grains. Both of them were detected in the embryo, but only amylopectin exist in the waxy corn endosperm. Sweet corn accumulated less starch than other type. The content of total starch in different endosperm type maize grain increased with the development of the grain. The contents of amylose in waxy and sweet corn are lower than other types . With the developments of the grain, the contents of amylose in waxy and sweet corn decreased, but in pop and normal corn it increased.The contents of total amino acids and essential amino acids in fresh period of waxy and sweet corn grain is lower than normal corn, but the percent of essential amino acids in total amino acids is higher than normal corn. In Pop corn grain they are highest in four types. In different endosperm type maize grain, the shorting of LYS is the first limiting factor, but the second is different.In fresh period, the quality of protein in waxy and sweet corn grain is excelled than other types. Pop corn grain can accumulated more protein than others, and the protein efficient rate is higher than others.<WP=14>2 The difference of formative mechanisms in different endosperm type maize grainIn process of sucrose synthesis, SS (synthesis) have dominant function in four type maize grains. In the development of grain, the average activities of SS in pop corn> sweet corn>normal corn>waxy corn. The average of SPS activities in sweet corn>pop corn>waxy corn>normal corn. The ability of sucrose synthesis in sweet corn is higher than others.The degradation of sucrose is mainly depending on the SS (degradation) activity, and the effect of invertase is lower than SS. In the development of grain, the average activity of sweet corn grain > normal corn >waxy corn >pop corn, and invertase activity of pop corn > waxy corn >normal corn > sweet corn. The reason of more sugars in sweet corn grain is the increasing of ability of sucrose synthesis but not the decreasing of degradation of sucrose.In different endosperm type maize grain, the activities of UDPG-PPase are higher than ADPG-PPase, SSS are higher than GBSS. The average activities of ADPG-PPase: wax corn >pop corn >normal corn >sweet corn, but the average activities of UDPG-PPase expressed as pop corn >waxy corn >sweet corn >normal corn. Both SSS and GBSS activities of normal corn >pop corn >sweet corn> waxy corn. Low activities of GBSS lead to the low content of amylose in waxy corn, and the intergrated effects of activities decrease of SSS, GBSS and SDE resulted in the lower starch content in sweet corn.3 The effect of nitrogen on the quality of different endosperm type maize grainThe influences of nitrogen to the total soluble sugar content are different in different endosperm type maize grain. Nitrogen can improve the total soluble sugar content in waxy, sweet and normal corn, but decreased it in pop corn. The functions of nitrogen on different sugar components are different. Sucrose, mannitol and sorbitol content increased in four types maize grain after applied nitrogen. The time of no consistence of sorbitol in nitrogen treatment of sweet corn is shorter than control. The WSP content of sweet, pop更多还原