不同水分处理对日光温室黄瓜叶片光合特性的影响

研究了不同土壤含水量对不同栽培茬口 (冬春茬、秋冬茬 )的日光温室黄瓜叶片的光合速率、气孔阻力、气孔结构特性及叶绿体超微结构的影响。结果表明 :随着土壤含水量的降低 ,单位黄瓜叶片面积气孔密度增加 ,气孔阻力上升 ,光合速率下降 ;叶绿体超微结构观察表明 :土壤含水量的减少明显地降低叶片细胞的叶绿体数目及每个叶绿休内的淀粉粒数。不同茬口的黄瓜其上述特性变化规律相似。     

Reintroduction of a classic vitamin D ultraviolet source

As early as 1930 sunlamps claiming to provide ultraviolet (UV) exposure to make vitamin D were sold to the public in the US and Canada for home use. Today even with dietary supplementation of vitamin D many people do not get enough solar UV exposure to maintain sufficient vitamin D levels. There is growing interest in the availability of sunlamps for this purpose. The original Sperti Sunlamp, with label claiming vitamin D benefit was approved by the American Medical Association in 1940 as a sunlamp. This intermediate pressure mercury lamps ultraviolet B emission lines, at 297, 302, and 313 nm are able to convert 7-dehydrocholesterol in the skin to vitamin pre-D3 initiating the natural process of vitamin D formation. Today's KBD Vitamin D lamp, an updated model of the earlier type source. In order to comply with modern safety guidance, the source is filtered to remove unnecessary UVC radiation and is equipped with a timer to control the dose administered. The 5 min timer provides an exposure, at 20 in. from the user's skin, of one standard erythemal dose (SED). The SED represents a suberythemal dose for even the most sensitive skin type I individual.     

地表覆盖对温室黄瓜生长及生理特性的影响

研究了地表覆盖秸秆、地膜和秸秆加膜对日光温室嫁接和非嫁接黄瓜生长与生理特性的影响.结果表明,地表覆盖可有效促进植株生长,嫁接黄瓜覆盖秸秆加膜、地膜与秸秆的株高和茎粗依次比对照增加91、71、57 cm和0127、0.086、0.111 cm,非嫁接黄瓜增幅较小;地表覆盖可增强光合作用,嫁接黄瓜覆盖秸秆加膜、地膜、秸秆的净光合速率分别比对照增加2.63、2.08与1.36 μmol·m^-2·s^-1,非嫁接黄瓜增幅较小;嫁接黄瓜覆盖秸秆加膜和秸秆的叶绿素含量比对照增加1.8%和3.15%,而覆盖地膜的叶绿素含量降低了3.8%,非嫁接黄瓜的叶绿素含量变幅较小;嫁接黄瓜覆盖秸秆加膜、地膜、秸秆的根系活力比对照提高0.98、0.48和0.8 mg TTC·g^-1FW,同一处理的非嫁接黄瓜根系活力增幅较小;地表覆盖可增加单株干物重,提高早期产量和总产量,嫁接黄瓜覆盖秸秆加膜、地膜与秸秆的单株产量比非嫁接黄瓜分别增加16%、5.3%和3.4%.     

Spectral multichannel monitoring of radiation within a mature mixed forest

A multi-sensor system is described based on fiber optic technology and a diode array spectrometer for near-simultaneous measurement of spectral photon fluence rates (PFR) in the range of 360 nm to 1020 nm with a resolution of 0.8 nm, within a mature Norway spruce ( Picea abies [L.] Karst.) - European beech ( Fagus sylvatica L.) stand. 126 space-integrating spherical sensors, deployed in a regular grid above and within the canopy and on the forest floor, are sequentially connected to the spectrometer by means of fiber optics. About 1 s per sensor is needed to collect spectral data, store them on hard disk and move the channel multiplexer to the next fiber optic position. Data thus obtained serve to determine vertical profiles of wavelength-dependent photon extinction, especially for spectral ratios and wavebands, characterization of phenological stages, analyses of time series, and meteorological influences such as solar altitude and cloud cover. First measurements during leaf fall 2004 show a non-linear relation of the red/far-red ratio (R/FR) with relative photosynthetic PFR (PPFR (rel)). An analysis of relative PFR (PFR (rel)) quantifies the frequency of penumbral sunfleck occurrence and the fraction of incoming radiation on the forest floor. In-canopy measurements of daily means of PPFR (rel) and R/FR indicate that leaf unfolding and leaf fall can be described by a single sensor, independent of its vertical location within the canopy.     

Daily laying time in free-living European starlings: solar noon, a potential synchronizer

Reproduction is generally controlled by important temporal constraints involving complex adaptive mechanisms. Birds, in temperate zones, present marked breeding seasonality as well as marked daily organization of reproductive behavior, especially laying. Intra-specific variability and determinants of this pattern have been investigated mainly in domestic non-passerine birds. The present study analyzed the daily temporal organization of laying in a free-living species, the European starling, Sturnus vulgaris. Breeding in a starling colony was monitored for five consecutive years using a non-invasive method (infrared video camera) to precisely estimate laying times. European starlings present a marked daily laying rhythm, ovipositions occurring only during a morning species-specific temporal window. Inside this laying window, time intervals between successive eggs varied greatly among females. Contrary to many species, the light/dark cycle did not appear to control laying time in European starlings, but daily variations of the ultraviolet composition of the solar spectrum appeared to be a possible Zeitgeber of this behavior.     

Estimation of vegetation photosynthetic capacity from space‐based measurements of chlorophyll fluorescence for terrestrial biosphere models

Photosynthesis simulations by terrestrial biosphere models are usually based on the Farquhar's model, in which the maximum rate of carboxylation (V_cmax) is a key control parameter of photosynthetic capacity. Even though V_cmax is known to vary substantially in space and time in response to environmental controls, it is typically parameterized in models with tabulated values associated to plant functional types. Remote sensing can be used to produce a spatially continuous and temporally resolved view on photosynthetic efficiency, but traditional vegetation observations based on spectral reflectance lack a direct link to plant photochemical processes. Alternatively, recent space‐borne measurements of sun‐induced chlorophyll fluorescence (SIF) can offer an observational constraint on photosynthesis simulations. Here, we show that top‐of‐canopy SIF measurements from space are sensitive to V_cmax at the ecosystem level, and present an approach to invert V_cmax from SIF data. We use the Soil‐Canopy Observation of Photosynthesis and Energy (SCOPE) balance model to derive empirical relationships between seasonal V_cmax and SIF which are used to solve the inverse problem. We evaluate our V_cmax estimation method at six agricultural flux tower sites in the midwestern US using spaced‐based SIF retrievals. Our V_cmax estimates agree well with literature values for corn and soybean plants (average values of 37 and 101 μmol m^?2 s^?1, respectively) and show plausible seasonal patterns. The effect of the updated seasonally varying V_cmax parameterization on simulated gross primary productivity (GPP) is tested by comparing to simulations with fixed V_cmax values. Validation against flux tower observations demonstrate that simulations of GPP and light use efficiency improve significantly when our time‐resolved V_cmax estimates from SIF are used, with R² for GPP comparisons increasing from 0.85 to 0.93, and for light use efficiency from 0.44 to 0.83. Our results support the use of space‐based SIF data as a proxy for photosynthetic capacity and suggest the potential for global, time‐resolved estimates of V_cmax.     

Climatic relationships of some New Zealand forest tree species

Abstract. A dataset of some 10 000 plots was used to describe the climatic relationships of 33 widespread New Zealand tree species. Estimates of mean annual temperature, temperature seasonality, mean annual solar radiation, and moisture balance were derived from mathematical surfaces fitted to climate station data. Plots were also categorized into five lithological classes and three drainage classes. Generalized additive models were used to examine species/environment relationships. Mean annual temperature and mean annual solar radiation are most strongly correlated with current tree distributions, followed by moisture balance, temperature seasonality, lithology, and drainage. Most broad-leaved tree species other than Nothofagus spp. reach their greatest levels of occurrence in warm, moist environments with high solar radiation. In contrast, Nothofagus spp. generally reach their greatest levels of occurrence in cooler and/or lower insolation environments, and all have lower levels of occurrence on rhyolitic substrates which have resulted from large-scale geomorphic disturbance, mostly over the past few thousand years. Although coniferous species have widely differing climatic optima, many are biased towards lithological classes characterized either by large-scale geomorphic disturbance or harsh edaphic conditions. The relevance of these results to particular synecological questions is briefly discussed. Continuing adjustments in the range of slow-dispersing Nothofagus spp. are strongly suggested, and the climatic suitability of extensive rhyolitic basins in the central North Island, from which these species are largely absent, is confirmed.     

Ambient Temperature is A Strong Selective Factor Influencing Human Development and Immunity

Solar energy, which is essential for the origin and evolution of all life forms on Earth, can be objectively recorded through attributes such as climatic ambient temperature (CAT), ultraviolet radiation (UVR), and sunlight duration (SD). These attributes have specific geographical variations and may cause different adaptation traits. However, the adaptation profile of each attribute and the selective role of solar energy as a whole during human evolution remain elusive. Here, we performed a genome-wide adaptation study with respect to CAT, UVR, and SD using the Human Genome Diversity Project-Centre Etude Polymorphism Humain (HGDP-CEPH) panel data. We singled out CAT as the most important driving force with the highest number of adaptive loci (6 SNPs at the genome-wide 1 × 10⁻⁷ level; 401 at the suggestive 1 × 10⁻⁵ level). Five of the six genome-wide significant adaptation SNPs were successfully replicated in an independent Chinese population (N = 1395). The corresponding 316 CAT adaptation genes were mostly involved in development and immunity. In addition, 265 (84%) genes were related to at least one genome-wide association study (GWAS)-mapped human trait, being significantly enriched in anthropometric loci such as those associated with body mass index (χ²; P < 0.005), immunity, metabolic syndrome, and cancer (χ²; P < 0.05). For these adaptive SNPs, balancing selection was evident in Euro-Asians, whereas obvious positive and/or purifying selection was observed in Africans. Taken together, our study indicates that CAT is the most important attribute of solar energy that has driven genetic adaptation in development and immunity among global human populations. It also supports the non-neutral hypothesis for the origin of disease-predisposition alleles in common diseases.     

Emergy-based indices and ratios to evaluate the sustainable use of resources

By means of a systemic analysis of the relationships among components of an ecosystem's web, the flows of energy and other resources converging to produce the output (biomass, biodiversity, assets, etc.) can be evaluated on a common basis, i.e. the content of solar equivalent energy (emergy). Indices and ratios based on the emergy flows can be calculated and used to evaluate the behaviour of the whole system. In this paper, one of these indices, the emergy yield ratio η (total yield emergy per unit of emergy invested) is evaluated and suggestions made to modify it to account for present and future environmental damages due to the use of a given resource. The meaning of this index, with and without the proposed modification, is stressed illustrating the long-term effects of environmental pollution as well as some key uncertainty factors that are very often not taken into account. Odum, 1993