Limits to the height growth of Caragana korshinskii resprouts
Limits to the height growth of Caragana korshinskii resprouts
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柠条新芽高度生长的限制
DOI：
10.1093/treephys/tpt006
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发表时间：
2013-03-01
期刊：
影响因子：
4
通讯作者：
Li, Feng-Min
中科院分区：
文献类型：
--
作者：
Fang, Xiang-Wen;Turner, Neil C.;Li, Feng-Min
黎明前叶水势（LWP），LWP之间的09：00和10：30 h（称为最低LWP），茎木质部导水率，叶片氮，叶片气体交换和叶片性状测定在同一天在成年人和1岁至7岁的新芽，去除所有地上部后重新生长。高生长量和地上生物量积累量随扦插年龄的增长而迅速下降，7年生扦插苗与未扦插苗之间差异不显著。黎明前的LWP在芽苗和成虫之间没有显著差异，但最小LWP从1年生芽苗的-2.0MPa逐渐下降到7年生芽苗的-3.0MPa。最小LWP的减少与增加的水力阻力，所示的叶面积特定的水力传导度（K-L）和边材面积特定的水力传导度（K-S）的逐渐减少和相关的增加干原生百分比损失的水力传导度大于2岁的重新发芽。单位面积叶片含氮量（N-面积）也从1年生的3.6 g/m2下降到7年生的1.7 g/m2。随着LWP和N-面积的下降，单位面积叶片光合速率（A（area））从1年生的20 μ mol·m（-2）·s（-1）下降到7年生的11 μ mol·m（-2）·s（-1）。与7年生新芽相比，成苗的K-S值进一步降低，但最小LWP、K-L、N-面积和光合速率分别增加0.3MPa、29%、34%和23%。结果表明，随着年龄的增长，柠条茎导水率逐渐降低，叶片氮素含量逐渐减少，这与柠条光合速率的降低有关。可能改变了光合同化物的分配，减缓了植株的高生长。
Predawn leaf water potential (LWP), the LWP between 09:00 and 10:30 h (termed minimum LWP), stem xylem hydraulic conductivity, foliar nitrogen, leaf gas exchange and leaf traits were measured on the same days in adults and 1-year-old to 7-year-old resprouts that had regrown after removing all the aboveground shoots. Height growth and accumulation of aboveground biomass quickly decreased with resprout age and there was no difference between 7-year-old resprouts and the uncut adults. Predawn LWP showed no significant difference between resprouts and adults, but the minimum LWP decreased gradually from -2.0 MPa in 1-year-old resprouts to -3.0 MPa in 7-year-old resprouts. The decrease in minimum LWP was associated with increased hydraulic resistance, as indicated by the gradual decrease in leaf area-specific hydraulic conductivity (K-L) and sapwood area-specific hydraulic conductivity (K-S) and the associated increase in stem native percentage loss of hydraulic conductivity in older than 2-year-old resprouts. The leaf nitrogen content per unit area (N-area) also decreased steadily from 3.6 g m(-2) in 1-year-old resprouts to 1.7 g m(-2) in 7-year-old resprouts. With the decline in LWP and N-area, the rate of leaf photosynthesis per unit area (A(area)) decreased from 20 mu mol m(-2) s(-1) in 1-year-old resprouts to 11 mu mol m(-2) s(-1) in 7-year-old resprouts. In adults, although K-S decreased further compared with 7-year-old resprouts, the minimum LWP, K-L, N-area and the rate of photosynthesis increased by 0.3 MPa, 29, 34 and 23%, respectively. The results show that a progressive loss of stem hydraulic conductivity and a steady decrease in foliar nitrogen with age were associated with a decrease in the photosynthetic rate of Caragana korshinskii Kom. resprouts, possibly changing the allocation of photosynthetic assimilates and slowing resprout height growth.