Effects of Water and Nitrogen Interaction on Fructan Metabolism of Foxtail Millet after Anthesis

Zhang Mengyuan; Guan Yan'an; Chen Erying; Li Feifei; Yang Yanbing; Gao Wenwei; Qin Ling

doi:10.14083/j.issn.1001-4942.2025.01.016

Abstract：In order to reveal the influences of water and nitrogen treatments on metabolism and transloca-tion of fructan in different organs of foxtail millet after anthesis,the test used a strong drought resistant foxtail millet variety of Jigu 22 as material,and potted cultivation was carried out.Three water treatments of normal irrigation(CK,60％to 70％of the maximum field water capacity),seedling drought(W1,30％ to 40％of the maximum field water capacity)and drought during heading to middle of filling stage(W2,30％ to 40％ of the maximum field water capacity),and two nitrogen application treatments of nitrogen application(N150,pure N 150 kg/hm2)and no nitrogen application treatment(N0)were set to study their effects on absolute content of fructan in leaves,stem-sheaths and panicles,as well as activities of sucrose 1-fructosyltransferase(1-SST)and fructan exohydrolase enzyme(FEH)in leaves of foxtail millet.The results showed that the abso-lute content of fructan in stem-sheaths,leaves and panicles of W2 treatment all reached their peak at 14 days after anthesis,among which,the content peak in stem-sheaths and leaves appeared earlier than those of CK and W1 treatments,and the peak absolute content of fructan in W2N0 treatment was significantly higher than those in other treatments.Compared to CK,the occurrence time of the peak in panicles were delayed,and the absolute content of fructan in W2N150 treatment at the peak was higher than that of other treatments.After re-hydration,the absolute content of fructan in W2 treatment did not return to the control level.The 1-SST activi-ty in leaves of each treatment showed an upward trend before reaching its peak,and then followed by a de-crease.The 1-SST activity in leaves of CK and W1 treatments reached its peak at 28 days after anthesis,while in W2 treatment the peak occurred at 14 day after anthesis due to drought stress which was significantly higher than that in CK and W1N0 treatments and decreased after rehydration.The FEH activity of W2 treatment reached its peak at 0 day after anthesis(anthesis period),which was earlier than that of CK and W1 treat-ments and then sharply decreased with the extension of the growth period.The pre-anthesis transport rate and contribution rate of fructan in leaves and stem-sheaths of foxtail millet in W2 treatment were higher than those after anthesis.The post-anthesis transport rate and contribution rate of fructan in leaves and stem-sheaths of both W1 and W2 treatments were higher than those of control,while the post-anthesis transport rate and contri-bution rate in stem-sheaths of W1 treatment were higher than those of W2 treatment,while the opposite was true in leaves.In summary,the synthesis and degradation of fructan was influenced by environment,organs and developmental stages.Drought stress shortened the peak appearance of absolute fructan content in leaves and stem-sheaths,and the combined effect of drought and nitrogen stress increased the peak of absolute fructan content in stem-sheaths and leaves of foxtail millet.Drought stress significantly inhibited the activities of 1-SST and FEH in foxtail millet leaves after the peak of absolute fructan content,which promoted the accumulation of fructan and reduced the losses caused by adversity stress.In addition,foxtail millet should be subjected to ap-propriate drought exercise during seedling stage(W1)was beneficial for improving the post-anthesis transport rate and contribution rate of fructan in foxtail millet.