氮素和钾素对小麦籽粒淀粉合成关键酶活性的影响

Effects of Nitrogen and Potassium on Key Regulatory Enzyme Activities for Grain Starch in Winter Wheat

【目的】阐明氮、钾施肥对小麦淀粉合成关键酶活性的影响。【方法】在大田栽培条件下,以两个品质类型不同的冬小麦品种‘宁麦9号’(弱筋)和‘扬麦10号’(中筋)为材料,研究氮、钾施肥对小麦籽粒中淀粉合成相关酶活性和淀粉含量的影响及其与开花期旗叶氮、钾营养的关系。【结果】与不施氮、钾肥的对照处理相比,氮、钾施肥明显提高了花后籽粒中的蔗糖含量及蔗糖合成酶(SS)、可溶性淀粉合成酶(SSS)和束缚态淀粉合成酶(GBSS)的活性,提高了淀粉产量,但降低了总淀粉和支链淀粉含量,两小麦品种的表现基本一致,其中氮肥的作用大于钾肥,施氮降低了直链淀粉含量,施钾提高了直链淀粉含量,宁麦9号高于扬麦10号。【结论】相关分析表明,氮钾肥料配合提高开花期旗叶氮、钾营养并维持适宜的氮/钾比,是氮、钾施肥提高籽粒SSS和GBSS活性,进而促进小麦籽粒淀粉合成、改善籽粒品质的主要生理因素。施钾提高两小麦品种GBSS活性是直链淀粉含量提高的酶学基础。较高的SS、SSS和GBSS活性是弱筋品种宁麦9号较高淀粉含量的酶学保障。

[Objective] The objective is to evaluate the effects of nitrogen and potassium fertilization on wheat key regulatory enzymes for grain starch. [Method] Under the condition treated with two fertilization levels of nitrogen （0 and 225 kg N-haa） and potassium （0 and 150 kg K20 ha^-1） in the field, two winter wheat （Triticum aestivum L.） cultivars differing in gluten content, ＇Ningmai 9＇ （low） and ＇Yangmai 10＇ （medium）, were planted in the field to investigate the activities of enzymes for starch formation and starch content of grain and the relationship with fertilization levels. [Result]The results showed that the changing patterns in the sucrose content, the activities of enzymes for starch formation and starch content of grain were similar in two cultivars, but the enzyme activities and the contents of sucrose and starch were higher in ＇Ningrnai 9＇ than in ＇Yangmai 10＇. Compared with non-nitrogen and non-potassium fertilization （NOK0） treatment, N and K fertilization increased sucrose content, the activities of SS, SSS and GBSS and starch yield in grains, but decreased the content of total starch and amylopectin in grain. Grain amylose contents were decreased by nitrogen fertilization, while increased by potassium in two wheat cultivars. Compared with potassium fertilization, the role of nitrogen on sucrose content and relative enzyme activities was greater. [ Conclusion ] Correlated analysis indicates that the activity of SSS and GBSS in grain, which was increased by appropriate flag leaf N/K ratio at anthesis with N and K supply, is the key physiological basis for starch formation. Grain GBSS activity, which increased by potassium fertilization, is the enzymology basis for K enhancing grain amylose contents. Higher enzyme activity of SS, SSS and GBSS is the enzymology base of higher starch contents for weak gluten cultivar ＇Ningmai 9＇ than for medium gluten cultivar ＇Yangmai 10＇.