盐生植物海莲子的研究进展及前景展望

全面系统地综述了盐生植物海蓬子的生物学特性、经济价值、利用现状及开发前景等。     

温度和盐度对北美海蓬子营养盐吸收速率的影响研究

北美海蓬子(Salicornia hige)是一种耐盐范围广、适应能力强的盐生植物,可以用于净化处理海水养殖废水,不过关于温度和盐度对其营养盐吸收速率的影响研究较少。本研究以北美海蓬子为实验材料,分析了不同温度(20℃、25℃、30℃、35℃)和不同盐度(25、50、75、100)下海蓬子对海水中主要营养盐的吸收速率,以期为海蓬子生态浮床的应用工作提供可靠的数据参考。结果显示:温度和盐度均对海蓬子的吸收速率产生明显影响,在30~35t温度下海蓬子对营养盐的吸收速率最快,以硝态氮为例,吸收速率能够达到2.56 mg·E^-4·g^-1·d^-1;在8~16 g·L^-1海水盐度下,海蓬子对于营养盐的吸收速率最快,以硝态氮为例,吸收速率可以达到1.56 mg·E^-4·g^-1·d^-1。海蓬子能够有效地吸收海水中的氮磷等营养元素,是用于养殖废水处理植物的良好选择,在合适的水体中利用海蓬子处理养殖废水,能够发挥其最大的吸收效率,达到较好的净化效果。     

Effects of a Nitrogen-Fixing Indigenous Bacterium (Klebsiella pneumoniae) on the Growth and Development of the Halophyte Salicornia bigelovii as a New Crop for Saline Environments

Salicornia bigelovii is a novel crop for salty soils, which can contribute to arid‐zone management where irrigation with salty water, including sea water, is now a necessity. Nitrogen fixation by bacteria associated with the roots of S. bigelovii and similar halophytes is an important source of available nitrogen in salt marsh ecosystems. However, the diversity of the rhizosphere of Salicornia is unknown. Five areas around the Bay of La Paz in Baja California Sur, Mexico were sampled to detect nitrogen‐fixing bacteria associated with this halophyte; from these, 18 colonies were isolated. Only one showed high acetylene reduction activity. This bacterium was identified as Klebsiella pneumoniae. The effects of K. pneumoniae were evaluated at the germination and early seedling growth stages of two genotypes of S. bigelovii (‘wild genotype’ and cultivar SOS‐10), as an alternative crop for semiarid and saline environments. This bacterium, in conjunction with Azospirillum halopraeferens, was tested for growth‐promoting ability when inoculated on S. bigelovii genotypes under various saline concentration conditions. During germination and early seedling growth, K. pneumoniae showed high specificity for the wild S. bigelovii genotype, while A. halopraeferens was more specific for the improved S. bigelovii genotype SOS‐10. This is the first report of K. pneumoniae as a nitrogen‐fixing bacterium associated with the oilseed S. bigelovii, a novel halophyte crop. A reliable biological method, based on beneficial bacteria, is suggested to help maintain or improve the fertility of soils sustaining Salicornia fields.     

自然生境下盐角草的离子吸收-运输特征

通过对自然生境下盐角草的离子及部分重金属元素吸收-运输特性的分析,结果表明:①盐角草地上部Cl-, Na , K 含量显著(P≤0.05)大于地下部;②盐角草的离子吸收选择顺序为K ＞Mg2 ＞Cl-＞Na ＞SO42-＞Ca2 ,而运输选择顺序为Na ＞Cl-＞K ＞Mg2 ＞SO42-＞Ca2 ,反映了盐角草对离子(特别是K , Na , Cl-)的优先选择性在吸收和运输方面的不同;③选择性比率SK, Na＞SMg, Na＞SCa, Na,说明稳定体内K /Na 是盐角草耐盐的重要机制;④盐角草的离子吸收和运输存在一个梯度:根系相对于土壤介质,离子的吸收倍数为3.7～129.4;地上部相对于根的运输倍数为1.1～2.8,这种从土壤→根系→地上部离子转运成倍数的累积,既保证营养吸收的需求,又保证了低水势的维持;⑤污灌区盐角草的重金属含量除Cu外,Cd, Pb, As均是地下部含量＞地上部;Cu在地上部的富集系数＞1,As在地下部的富集系数为2.6,反映了盐角草对Cu,As的不同富集能力,因此,盐角草可用于盐渍化土壤重金属污染后的修复.     

Growth promotion of the seawater-irrigated oilseed halophyte Salicornia bigelovii inoculated with mangrove rhizosphere bacteria and halotolerant Azospirillum spp.

 Inoculation of the oilseed halophyte Salicornia bigelovii Torr. with eight species of halotolerant bacteria, grown in seawater-irrigated pots under environmental conditions native to the plant's habitat, resulted in significant plant growth promotion by the end of the growing season, 8–11 months later. Statistical analysis demonstrated that inoculation with Azospirillum halopraeferens, a mixture of two Azospirillum brasilense strains, a mixture of Vibrio aestuarianus and Vibrio proteolyticus, or a mixture of Bacillus licheniformis and Phyllobacterium sp. significantly increased plant height and dry weight at the end of the season. Some of the bacterial strains also increased the number of side branches and the size of the spikes. The bacteria did not affect the number of seeds or their weight. Inoculation with the mangrove cyanobacterium Microcoleus chthonoplastes had no effect on plant foliage variables. At the end of the growing season, the N and protein content of the plant foliage was significantly reduced by bacterial inoculation; however, the N and protein content of seeds significantly increased. The P content in foliage increased significantly in plants treated with all the bacteria except M. chthonoplastes, whereas the total lipid content of foliage increased significantly only when plants were inoculated with a mixture of A. brasilense strains or with M. chthonoplastes. In three inoculation treatments palmitic acid in seeds significantly increased and linoleic acid significantly decreased. This study demonstrates the feasibility of using bacteria to promote the growth of halotolerant plants cultivated for forage and seed production in proposed seawater-irrigated agriculture. Received: 3 January 2000     

花期海蓬子对盐胁迫的生理响应

研究了花期阶段不同浓度NaCl(0、10‰、20‰、30‰、40‰、50‰和60 ‰)对海蓬子(Salicornia bigelovii)生长、光合色素、光合作用参数、抗氧化和离子含量的影响。结果表明:10‰NaCl盐处理下海蓬子株高、茎生物量、叶绿素(Chl)含量、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、胞间CO₂浓度(Ci)、茎SOD活性和POD活性等指标值均显著高于其它处理,而高盐(40‰NaCl及其以上)胁迫下,上述指标值均表现为下降,同时茎K⁺ 含量也显著下降,而茎Na⁺、Cl^-、Na⁺/K⁺和MDA含量等显著上升。相关分析显示,生物量与Chl a/Chl b呈现显著正相关,与株高、茎Pn、Gs、Ci、Tr、Chl含量、K⁺ 含量、SOD和POD活性呈现极显著正相关,与气孔限制值(Ls)、Car/Chl、MDA含量、Cl^- 含量和Na⁺/K⁺ 等均呈极显著负相关。综上所述,10‰ NaCl处理是花期海蓬子生长和光合生长的最适宜盐度,而无盐和高盐下海蓬子光合抑制主要是来自气孔因素,同时高盐胁迫下还伴随着非气孔限制。     

外源赤霉素对盐胁迫下盐角草种子萌发及幼苗生长的影响

[目的]研究外源赤霉素（GA3）对盐胁迫下盐角草种子发芽及幼苗生长的影响。[方法]通过不同浓度（0、100、300、500、700mmol/L）的NaCl结合10μg/ml GA3处理,研究了外源GA3对盐胁迫下盐角草种子萌发及幼苗生长的影响。[结果]外源GA3提高了盐胁迫条件下盐角草的发芽率、发芽势、发芽指数以及活力指数。在外源GA3处理下,盐角草的根系活力、幼苗根茎长及耐盐性都高于单盐处理。[结论]在一定浓度范围内,外源GA3能缓解盐胁迫对盐角草种子萌发及幼苗生长的抑制作用。     

海水灌溉条件下Salicornia bigelovii的种植密度对个体间养分积累及土壤盐分的影响

对海水灌溉下Salicornia bigelovii的不同种植密度及其个体间的养分积累及土壤盐分的影响进行了调查。结果表明：单位面积地上部的干质量随种植密度增加呈平缓增高,符合最终产量恒定法则;个体间竞争株质量随种植密度增加而降低;随S.bigelovii种植密度的上升,土壤的含盐量和电导率（EC）值明显降低,56株/m2处理区钠的吸收量达261.22 g,在336株/m2处理区钠的吸收量高达489.99 g;随种植密度的增加,个体间的无机盐含量略有下降,但没有显著差异,相反茎、叶中碳和氮含量呈上升趋势。     

海蓬子抗盐性研究进展

对近年来海蓬子（Salicornia bigelovii）抗盐机理的研究进展作了概述,阐明了海蓬子对盐分的反应及盐分对植物的不同伤害;并对盐胁迫对海蓬子生长状况的影响和生理生化变化的研究进展作一综述,对海蓬子的开发前景进行了展望。     

Rehabilitation of abandoned areas from a Mediterranean nature reserve by Salicornia crop: Influence of the salinity and shading

In Reserva Natural de Castro Marim e Vila Real de Santo António (SE of Portugal), most of the salt marshes and saltpans are abandoned contributing to their degradation and, consequently, alteration of some ecological conditions. Rehabilitation of these areas by a Salicornia crop can contribute to their economic and environmental improvement by stimulation of biogeochemical processes and biomass commercialization. However, the development of agro-techniques adjusted to species and variable environmental conditions from Mediterranean are needed in order to improve the Salicornia crop. This study aimed to evaluate: i) potential use of seedlings from greenhouse in the field cultivation; and ii) survival, growth and yield of Salicornia under shading and different salinity conditions of the soils and irrigation waters. Autochthonous Salicornia species (S. ramosissima and S. patula) were tested. Germination tests under controlled conditions and in situ mesocosm assays were carried out. Assays were realized with a low density of seedlings from natural conditions and greenhouse, and soils and waters from estuary both with different salinities. Intermediate and high salinities (25–45?dS/m) affected only S. patula germination. In general, Salicornia growing in soils with low salinity had great fresh biomass accumulation independently of seedling source (from natural conditions and greenhouse) and/or growing season. The shading seems to improve the fresh biomass accumulation and yield. Under Mediterranean conditions, the transplantation of Salicornia from greenhouse to the field was a promising technique, independently of the salinity conditions. This study demonstrated that the abandoned and saline areas can be rehabilitated by a sustainable crop of Salicornia.