The N application of earlier-date-emphasized increased SSS activity and the N application of later-date-emphasized increased ADPG and SBE activities.

• 侧重前期施氮有利于提高淀粉合成酶活性，而侧重后期施氮则可提高ADPG焦磷酸化酶和淀粉分枝酶活性。