抗盐、耐海水蔬菜的生物技术培育与海水无土栽培应用

本研究是以植物起源于海洋的系统进化理论和植物细胞的全能性理论为依据的。 对芹菜(Apium graveolensL．)、油菜(B. rapa, chinese group)、叶用甜菜(Beta vulgaris(L.)Koch, Cicla group)、甘蓝(B. oleraceae, acephala group)、豆瓣菜(A'asturtiumofficinale R．Br*.）、番杏（Tetragonla expansa Ait.)、菠菜(Spinacia oleracea　L．)等蔬菜种类进行大规模种质资源筛选和鉴定， 从芹菜、油菜、叶用甜菜等植物中筛选出20多种能够耐受l%NaCI或1/3海水盐度的蔬菜品系。在耐盐蔬菜品种资源筛选的基础上，为了证明用生物技术提高盐敏感蔬菜耐盐性的可行性，本研究以植物体外培养细胞体系为操作平台，对盐敏感的蔬菜一一豆瓣菜进行了生物技术改造。一方面，筛选豆瓣菜的耐盐细胞变异体并使得耐盐细胞再生植株，获得了耐1/3海水的豆瓣菜变异体;另一方面，通过将盐生植物山菠菜(Atriplex hortensisL)的耐盐相关基因，甜菜碱醛脱氢酶(BADH)基因转入豆瓣菜，使得BADH基因在豆瓣菜中过量表达和积累甜菜碱，提高了豆瓣菜的渗透调节能力，从而提高了豆瓣菜的耐盐性。同时，本研究还将所获得的多种抗盐、耐海水蔬菜材料以海水无土栽培的方式进行生产和应用， 取得了很好的效果。 本文的结果证明了在陆地淡水栽培的蔬菜和野生蔬菜资源中，存在着部分耐盐性较强的蔬菜种质;通过生物技术改造能够提高盐敏感蔬菜的耐盐性，并获得抗盐、耐海水的蔬菜新品系。对这些抗盐、耐海水蔬菜材料进行1/3海水无土栽培应用的成功结果表明，某些陆地蔬菜具有重新适应海洋生境的潜能。

Carbon dioxide dynamics and controls in a deep-water wetland on the Qinghai-Tibetan Plateau

To initially characterize the dynamics and environmental controls of CO2, ecosystem CO2 fluxes were measured for different vegetation zones in a deep-water wetland on the Qinghai-Tibetan Plateau during the growing season of 2002. Four zones of vegetation along a gradient from shallow to deep water were dominated, respectively by the emergent species Carex allivescens V. Krez., Scirpus distigmaticus L., Hippuris vulgaris L., and the submerged species Potamogeton pectinatus L. Gross primary production (GPP), ecosystem respiration (Re), and net ecosystem production (NEP) were markedly different among the vegetation zones, with lower Re and GPP in deeper water. NEP was highest in the Scirpus-dominated zone with moderate water depth, but lowest in the Potamogeton-zone that occupied approximately 75% of the total wetland area. Diurnal variation in CO2 flux was highly correlated with variation in light intensity and soil temperature. The relationship between CO2 flux and these environmental variables varied among the vegetation zones. Seasonal CO2 fluxes, including GPP, Re, and NEP, were strongly correlated with aboveground biomass, which was in turn determined by water depth. In the early growing season, temperature sensitivity (Q(10)) for Re varied from 6.0 to 8.9 depending on vegetation zone. Q(10) decreased in the late growing season. Estimated NEP for the whole deep-water wetland over the growing season was 24 g C m(-2). Our results suggest that water depth is the major environmental control of seasonal variation in CO2 flux, whereas photosynthetic photon flux density (PPFD) controls diurnal dynamics.

Effect of iron on growth and lipid accumulation in Chlorella vulgaris

The economic feasibility of algal mass culture for biodiesel production is enhanced by the increase in biomass productivity and storage lipids. Effect of iron on growth and lipid accumulation in marine microalgae Chlorella vulgaris were investigated. In experiment I, supplementing the growth media with chelated FeCl3 in the late growth phase increased the final cell density but did not induce lipid accumulation in cells. In experiment II, cells in the late-exponential growth phase were collected by centrifugation and re-inoculated into new media supplemented with five levels of Fe3+ concentration. Total lipid content in cultures supplemented with 1.2 x 10(-5) mol L-1 FeCl3 was up to 56.6% biomass by dry weight and was 3-7-fold that in other media supplemented with lower iron concentration. Moreover, a simple and rapid method determining the lipid accumulation in C. vulgaris with spectrofluorimetry was developed. (c) 2007 Elsevier Ltd. All rights reserved.