Growth and photosynthetic responses of Scaevola sericea, a Hawaiian coastal shrub, to substrate salinity and salt spray
Growth and photosynthetic responses of Scaevola sericea, a Hawaiian coastal shrub, to substrate salinity and salt spray
复制标题
DOI：
10.1086/297336
复制
发表时间：
1996-03-01
影响因子：
2.3
通讯作者：
Azocar, A
中科院分区：
文献类型：
--
作者：
Goldstein, G;Drake, DR;Azocar, A
研究了绢毛草菇在不同盐度和盐雾条件下的生长规律、水分关系和光合特性。绢毛草菇是热带、亚热带太平洋和印度洋海岸带生态系统中的主要灌木树种。从两个沿海地点的Oakland（夏威夷）的72个插条生长在温室中的6个处理，导致三个水平的基质盐度（0，100和335 mOsm kg（-1））和两个水平的模拟盐雾（0和1200 mg盐m（-2）d（-1））的组合。S.绢毛类受基质盐度的影响很大，而受盐雾的影响很小。单株新茎叶生物量减少约10%。当基质盐度从0增加到335 mOsm kg（-1）时，光合速率下降了65%;在相同的盐度范围内，光合速率仅下降了20%。当基质盐度从0变化到335 mOsm kg（-1）时，叶汁液渗透压增加300 mOsm kg（-1），即使在更高的盐度水平下，也能保持恒定的土壤-叶渗透势梯度，有利于水分吸收。羧化能力，确定的净CO2同化细胞间CO2浓度的关系的初始斜率，保持恒定的植物生长在不同的盐度水平。叶片δ ~（13）C随盐度的增加从-29.2 ‰增加到-26.3 ‰，并与较低的气孔导度有关，但光合速率几乎不变。绢毛草蛉是能够大量的增长和生理反应，这显然是需要保持一个积极的碳平衡，在沿海生境的特点是大的时间和空间变化的基板盐度和盐雾水平。
Growth patterns, water relations, and photosynthetic traits in Scaevola sericea plants grown under different levels of substrate salinity and salt spray were studied. Scaevola sericea is a dominant shrub species in coastal strand ecosystems throughout the tropical and subtropical Pacific and Indian Oceans. Seventy-two cuttings from two coastal sites on the island of Oahu (Hawaii) were grown in a greenhouse under six treatments that resulted from the combination of three levels of substrate salinity (0, 100, and 335 mOsm kg(-1)) and two levels of simulated salt spray (0 and 1200 mg salt m(-2) d(-1)). Several characteristics of S. sericea were strongly affected by substrate salinity but only weakly affected by salt spray. New stem and leaf biomass per plant decreased by ca. 65% as substrate salinity increased from 0 to 335 mOsm kg(-1); photosynthetic rates decreased by only 20% over the same salinity range. Leaf sap osmolarity increased 300 mOsm kg(-1) as substrate salinity changed from 0 to 335 mOsm kg(-1), allowing the maintenance of a constant soil-to-leaf osmotic potential gradient favorable for water uptake even at higher salinity levels. Carboxylation capacity, determined by the initial slope of net CO2 assimilation-intercellular CO2 concentration relationships, remained constant for plants grown under different levels of salinities. The delta(13)C of leaves increased from -29.2 parts per thousand to -26.3 parts per thousand with increasing salinity and was associated with lower stomatal conductances but nearly unchanged photosynthetic rates. Scaevola sericea is capable of substantial growth and physiological responses, which apparently are required to maintain a positive carbon balance in coastal habitats characterized by large temporal and spatial variations in substrate salinity and salt spray levels.