Effects of potassium fertilization on enzyme activities associated with sucrose metabolism in the grain development of maize

Field experiments were carried out to compare the dynamic variations of starch accumulation and enzyme activities in the developing grains of high-starch maize (Zea mays L.) Feiyu 3 and low-starch maize (Zea mays L.) Yuyu22 with different levels of basic potassium fertilization. The effects of the fertilization on contents of amylose content and amyloectin were studied, and as well as the relationship between key enzymes activities and the amylase, amyloectin accumulation. The results indicate that the activities of ADPG-PPase and UDPG-PPase in grains of the two maize cultivars are significantly improved under the potassium fertilization when 225 kg/ha potassium fertilizer is applied before the sowing, and the activity of SSS in grains of Feiyu 3 is also improved significantly, while the activities of SSS and GBSS of Yuyu22 are reduced. The treatment of potassium applied before sowing with 225 kg/ha improve the content of sucrose, the ability of sucrose and starch synthesis of ear leaves. The contents of amylopectin and amylose, total starch accumulation rate are significantly increased under the 225 kg/ha application. The total starch contents are increased by 13.6% and 8.2% for Feiyu 3 and Yuyu22 respectively, and the increased total starch content of Feiyu is higher than that of Yuyu22. It is favorable to compose starch by middle and high potassium, which increased the content of soluble sugar in high-starch maize Feiyu 3. But the infection was not significant to low-starch maize (Zea mays L.) Yuyu22. Interactive effects of potassium fertilization application and maize varieties on every target in the study are significant, except soluble sugar.