Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
Ann Bot. 2010 Jan;105(1):175-84. doi: 10.1093/aob/mcp213.
In the Florida Everglades, the expansion of cattail (Typha domingensis) into areas once dominated by sawgrass (Cladium jamaicense) has been attributed to altered hydrology and phosphorus (P) enrichment. The objective of this study was to quantify the interactive effects of P availability and soil redox potential (Eh) on the growth and nutrient responses of Typha, which may help to explain its expansion.
The study examined the growth and nutrient responses of Typha to the interactive effects of P availability (10, 80 and 500 microg P L(-1)) and Eh level (-150, +150 and +600 mV). Plants were grown hydroponically in a factorial experiment using titanium (Ti(3+)) citrate as a redox buffer.
Relative growth rate, elongation, root-supported tissue/root ratio, leaf length, lateral root length and biomass, as well as tissue nutrient concentrations, were all adversely affected by low Eh conditions. P availability compensated for the negative effect of low Eh for all these variables except that low P stimulated root length and nutrient use efficiency. The most growth-promoting treatment combination was 500 microg P L(-1)/ + 600 mV.
These results, plus previous data on Cladium responses to P/Eh combinations, document that high P availability and low Eh should benefit Typha more than Cladium as the growth and tissue nutrients of the former species responded more to excess P, even under highly reduced conditions. Therefore, the interactive effects of P enrichment and Eh appear to be linked to the expansion of Typha in the Everglades Water Conservation Area 2A, where both low Eh and enhanced phosphate availability have co-occurred during recent decades.
在佛罗里达大沼泽地，由于水文学和磷（P）富营养化的改变，香蒲（Typha domingensis）在曾被锯齿草（Cladium jamaicense）占据的地区扩张。本研究的目的是量化 P 供应和土壤氧化还原电位（Eh）对香蒲生长和养分响应的相互作用，这可能有助于解释其扩张的原因。
本研究通过使用钛（Ti(3+））柠檬酸盐作为氧化还原缓冲剂，在水培条件下，采用因子实验设计，研究了 P 供应（10、80 和 500μg P L(-1））和 Eh 水平（-150、+150 和 +600 mV）对香蒲生长和养分响应的相互作用。
相对生长率、伸长率、根支持组织/根比、叶片长度、侧根长度和生物量以及组织养分浓度均受到低 Eh 条件的不利影响。对于所有这些变量，除了低 P 刺激根长和养分利用效率外，P 供应可补偿低 Eh 的负面影响。最有利于生长的处理组合是 500μg P L(-1）/ + 600 mV。
这些结果以及之前关于锯齿草对 P/Eh 组合的响应数据表明，高 P 供应和低 Eh 应该更有利于香蒲的生长，而不是锯齿草，因为前者的生长和组织养分对过量 P 的响应更大，即使在高度还原的条件下也是如此。因此，P 富化和 Eh 的相互作用似乎与香蒲在佛罗里达大沼泽地 2A 区的扩张有关，在过去几十年中，该地区同时出现了低 Eh 和增强的磷酸盐可用性。
