两个种源木荷幼苗对干旱-复水的生理生态响应

Eco-physiological responses of Schima superba seedlings from two provenances to drought and rewatering

关键词:  干旱-复水, 光合特征, 水力特征, 木荷, 种内差异

Key words:  drought-rewatering, photosynthetic traits, hydraulic traits, Schima superba, intra-specific differences

摘要:

为探讨不同种源树木对干旱-复水的生理生态响应,该研究以广东与福建种源木荷为对象,通过盆栽控水方式模拟干旱及复水条件,研究两个种源木荷的水力及碳生理特征、脯氨酸(Pro)及超氧化物歧化酶(SOD)对干旱-复水的响应。结果表明:(1)对照情况下,广东种源木荷的茎木质部水势(Ψ_xylem)、叶片相对含水量(RWC)、光合速率(A_sat)与气孔导度(G_s)均低于福建种源木荷的。(2)两个种源木荷的水力特征、Pro与SOD对干旱-复水的响应呈一致趋势,其中Ψ_xylem、RWC与Pro均能较快恢复至对照水平,而茎木质部栓塞程度与SOD未恢复至对照水平。(3)福建种源木荷叶片的A_sat对干旱的敏感性较广东种源的高且复水后恢复至对照水平需要更长时间。(4)复水后福建种源木荷非结构性碳水化合物(NSC)的恢复速率高于广东种源木荷。综上认为,福建与广东两个种源木荷均不能通过短期复水(30 d)来修复被栓塞的木质部。尽管广东种源木荷的光合速率能够更快地恢复至对照水平,但其光合速率低于福建种源木荷,并且其NSC的恢复能力较福建种源荷的低。因此,在未来干旱加剧背景下,广东种源木荷的生长及存活可能受到更大威胁。该研究结果有助于了解种源地气候条件对树木抗旱性的影响,为未来森林的经营与管理提供了理论参考。

Abstract:

In the context of global climate change, the research on eco-physiological responses to drought and rewatering among provenances of trees species will help to understand the effect of climate conditions of provenances on drought resistance of trees, further providing theoretical references for cultivation and management of forests in the future. In this study, Schima superba from two provenances in southern China were selected. Potted seedlings were subjected to simulated drought and rewatering conditions. Eco-physiological traits(photosynthesis traits, hydraulic traits, non-structural carbohydrates-NSC, proline concentrations-Pro and superoxide dismutase-SOD activity)of seedlings were examined. The results were as follows:(1)Under well-watered condition, stem xylem water potential(Ψ_xylem), leaf relative water content(RWC), photosynthetic rate(A_sat)and stomatal conductance(G_s)were lower in seedlings from Guangdong provenance compared with Fujian provenance.(2)Responses of hydraulic traits, Pro and SOD to drought and rewatering were consistent between the two provenances. Ψ_xylem, RWC and Pro could recover to control values rapidly, while percent of stem xylem embolism and SOD could not recover to control values in the end.(3)A_sat was more sensitive to drought from Fujian provenance than Guangdong provenance, and it took more time to recover to control in Fujian provenance.(4)The recovery rate of NSC from Fujian provenance was faster than Guangdong provenance. Collectively, seedlings from both provenances could not repair their embolized xylem in the short-term rewatering period(30 days). Although photosynthesis rate in Guangdong provenance could recover to control faster than from Fujian provenance, it was lower than that from Fujian provenance. Furthermore, the recovery rate of NSC was slower in Guangdong provenance than Fujian provenance, indicating that growth and survivals of seedlings from Guangdong provenance may experience greater risk in future characterized with increasing drought stress.