干旱胁迫对平邑甜茶不同生长时期氮素吸收利用的影响

为研究干旱胁迫对苹果砧木平邑甜茶不同生长时期N素吸收利用效率的影响，以1年生盆栽平邑甜茶为材料，设置干旱胁迫和对照2组处理，其中干旱胁迫是在施肥前对平邑甜茶提前2周控水，保持盆土45%～55%田间最大持水量；对照正常供水，保持盆土75%～85%田间最大持水量。以¹⁵N标记的尿素为N源，分别于4月10日、5月10日、7月10日和9月10日4个生长时期施1.0 g ¹⁵N标记的尿素，分析干旱胁迫对平邑甜茶4个生长时期的植株N含量、各器官肥料N的百分率(N_dff)、¹⁵N分配率、利用率以及N素转运代谢相关基因表达量的影响。结果表明：1)与对照相比，4个生长时期中，干旱胁迫均降低平邑甜茶植株N含量、各器官对N的吸收转运能力以及N素利用率，其中在7月生长期降低的最显著，植株N含量降低27.0%、根、茎、叶的N_dff值分别降低23%、35%、40%、N素利用率降低42%。2)干旱胁迫下平邑甜茶各器官氮素分配由地上部分向地下部分转移，优先供应植株生长中心。3)干旱胁迫下平邑甜茶根系对N素吸收...

Effects of Drought Stress on Nitrogen Uptake and Utilization of Malus hupehensis at Different Growth Stages

The effects of drought stress on nitrogen absorption and utilization efficiency of Malus hupeheusis (a kind of rootstock of for apple production) at different growth stages were studied.One-year-old potted M.hupeheusis was used as materials.Two treatments of drought stress were set up by controlling the water capacity two weeks in advance before fertilization and maintaining the maximum water capacity of 45%-55% of basin soil.The normal water supply (control) was carried out by maintaining the maximum water capacity of 75%-85% of basin soil.The ¹⁵N labeled urea was used as nitrogen source and 1.0 g ¹⁵N labeled urea was applied at four growth stages on April 10,May 10,July 10 and September 10,respectively.The effects of drought stress on nitrogen content,Ndff (Nitrogen derived from fertilizer) value of each organ,¹⁵N distribution rate,utilization rate and gene expression level of nitrogen transport and metabolism in M.hupeheusis seedlings during four growth stages were analyzed.The main results showed that 1) compared with the control,drought stress reduced the nitrogen content of the plant,N absorption and transport capacity of various organs and N use efficiency decreased in the four growth stages,and the decrease was most significant in July.Nitrogen content of plant decreased by 27.0%,Ndff values of root,stem and leaf decreased by 23%,35% and 40%,respectively,and nitrogen use efficiency decreased by 42%.2) Under drought stress,nitrogen distribution in various organs transferred from aboveground part to underground part,and the plant growth center was preferred.3) Under drought stress,the nitrogen uptake ability of the roots reduced: firstly,the expression level of nitrogen transporter gene DUR was down-regulated,which decreased the absorption; secondly,the expression levels of nitrogen assimilation metabolism-related genes NR,GDH2,GS,NADH-GOGAT and FD-GOGAT were down-regulated,which resulted in inhibition of nitrogen assimilation.