Chloride accumulation in different species of grapevine

A range of self-rooted vines, many of which have been used as nematode- and phylloxera-resistant rootstocks, were surveyed for chloride concentration. Petiole analysis showed the following trend for chloride accumulation among Vitis species: V. rupestris < V. berlandieri, V. riparia < V. candicans, V. champini, V. longii < V. cineria, V. cordifolia < V. vinifera.     

Signatures of adaptation to obligate biotrophy in the Hyaloperonospora arabidopsidis genome

Many oomycete and fungal plant pathogens are obligate biotrophs, which extract nutrients only from living plant tissue and cannot grow apart from their hosts. Although these pathogens cause substantial crop losses, little is known about the molecular basis or evolution of obligate biotrophy. Here, we report the genome sequence of the oomycete Hyaloperonospora arabidopsidis (Hpa), an obligate biotroph and natural pathogen of Arabidopsis thaliana. In comparison with genomes of related, hemibiotrophic Phytophthora species, the Hpa genome exhibits dramatic reductions in genes encoding (i) RXLR effectors and other secreted pathogenicity proteins, (ii) enzymes for assimilation of inorganic nitrogen and sulfur, and (iii) proteins associated with zoospore formation and motility. These attributes comprise a genomic signature of evolution toward obligate biotrophy.     

太岳山国有林管理局森林生态系统服务功能间接经济价值评估

论文从物质量与价值量的角度出发,采用影子工程法、机会成本法、市场价值法等方法估算了太岳山国有林管理局森林生态系统服务功能的生态经济价值。结果表明:2004年山西太岳山暖温带森林生态系统的生态服务功能价值为60.90亿元,其中涵养水源价值为24.63亿元,保育土壤价值为4.53亿元,固碳制氧价值为20.66亿元,净化大气环境价值为4.41亿元,生物多样性保护价值为3.77亿元。     

Influence of irradiance on photosynthesis, morphology and growth of mangosteen (Garcinia mangostana L.) seedlings

The influence of shading intensity on growth, morphology and leaf gas exchange of mangosteen (Garcinia mangostana L.) seedlings was investigated over a 2-year period. Diurnal gas exchange studies revealed significantly higher carbon gain for leaves grown in 20 or 50% shade compared to leaves grown in 80% shade. Seedlings grown in 20 or 50% shade accumulated significantly more dry weight than seedlings grown in 80% shade during the 2-year study period. Seedlings grown in decreased shade showed decreased leaf size, increased leaf thickness, lower specific leaf area (SLA) and higher stomatal frequency. Less shaded seedlings also allocated relatively more dry matter to roots than shaded seedlings and exhibited a significant reduction in leaf area relative to total plant dry weight (leaf area ratio). Increased leaf number, enhanced branching and shorter internodes resulted in a more compact appearance of less shaded seedlings. Irrespective of light conditions, mangosteen seedlings exhibited inherently slow growth because of low photosynthetic rates per unit leaf area, low SLA, low leaf area ratios and inefficient root systems.     

Gas exchange characteristics of mangosteen (Garcinia mangostana L.) leaves

We used the plastochron index to study the relationship between plant age, leaf age and development, and net photosynthesis of black cherry (Prunus serotina Ehrh.) seedlings. Leaf area and net photosynthesis were measured on all leaves >/= 75 mm of plants ranging in age from 7 to 20 plastochrons. Effects of plant developmental stage on leaf area and net photosynthesis were evaluated for leaves of differing age (horizontal series), leaves on plants of constant age (vertical series), and leaves of constant age (oblique series). Regression techniques were used to estimate leaf area from leaf blade dimensions. The best equations for predicting leaf area had R(2) values of 0.991-0.992 and used linear or logarithmic functions of both leaf length and width. Suitable, but less precise, equations with R(2) values of 0.946-0.962 were developed from either leaf length or leaf width. Leaf area development in black cherry seedlings was similar to that in other indeterminate species. Leaves of young plants reached full expansion at a lower leaf plastochron age than leaves of older plants. Maximum net photosynthesis per unit leaf area occurred 2-3 plastochrons before full leaf expansion. There was strong ontogenetic drift in net photosynthesis with leaf age; net photosynthesis decreased as plant age increased in leaves of the same plastochron age. Plots of the oblique series were particularly useful in providing information about interaction effects.     

Photosynthesis: Temperate and Tropical Characteristics within a Single Grass Genus

Leaves of two subgenera of Panicum differ in photosynthetic physiology and bundle sheath characteristics. Species of the subgenus Eupanicum, like other tropical grasses, had high phosphoenolpyruvate carboxylase (E.C.4.1.1.31) activity, had specialized chloroplasts within the parenchyma bundle sheath cells, and lacked phatorespiration. The pattern for the temperate subgenus Dichanthelium was opposite.     

Thermal habitat experienced by Atlantic salmon (Salmo salar L.) kelts in coastal Newfoundland waters

Thermal habitat was recorded by data storage tags (DSTs) applied to Atlantic salmon (Salmo salar L.) kelts during their seaward migration in the spring of 1998 at enumeration facilities in Highlands River, Humber River, Western Arm Brook, and Campbellton River, Newfoundland. In total, 139 DSTs were applied and data were downloaded from eleven of the recovered tags. The recovered tags had been applied at Highlands, Campbellton and Western Arm rivers and recovered in the coastal waters of Newfoundland and Québec and at the enumeration facilities at Highlands and Campbellton rivers. Water temperatures experienced by the fish were recorded for periods of 62–118 days at resolutions of 15–30 min. The data from the sea record on the DSTs were analysed for temperature patterns in relation to migration behaviour and diurnal movement of the fish. A variety of patterns were exhibited on the temperature records suggesting that the fish were behaving in various ways at different times. For Campbellton and Highlands fish over the course of some 24 h periods, night‐time temperatures changed little and were among the highest daily temperatures experienced by the fish, whereas daytime temperatures often showed dramatic and frequent shifts in temperature presumably as the fish rapidly and frequently changed depth. For the Western Arm Brook fish, rapid fluctuations in temperature occurred sometimes during the day and night without a consistent diurnal pattern. We also considered large‐scale aspects of the data by examining oceanographic conditions in relation to the temperatures recorded by the tags.