不同光强处理对设施桃树光合及荧光特性的影响

以二年生“春捷”毛桃为试材，研究了日光温室内遮荫处理桃树在不同光照强度条件下光合特性以及荧光特性的变化。结果表明：随着光照强度的降低，桃树叶片的光补偿点、光饱和点、CO2饱和点（CSP）、CO2补偿点（CCP）、Rubisco活性、表观光合量子效率（AQY）、光呼吸速率、乙醇酸氧化酶（GOX）活性和羧化效率（CE）均呈下降趋势；光合色素含量在不同光强条件下变化较大，两个弱光处理叶绿素a（Chl.a）、叶绿素b（Chl.b）、 类胡萝卜素(carotenoids)的含量均比对照升高。不同光强条件对桃树叶片的荧光参数φPSⅡ、Fo和Fv/Fm的日变化影响显著，弱光照处理的φPSⅡ、Fv/Fm的日变化比较平稳而且维持在一个较高的水平，而对照的上述两个参数的日变化波动较大；三个不同光强处理的Fo的日变化均是在10：00开始上升，在13：00达到最高点而后下降，变化趋势基本一致。     

辽东半岛裙带菜室内常温全人工育苗：双高光控制、温度变化和配子体发育

2010年,作者在辽东半岛成功进行了裙带菜室内常温全人工育苗大规模生产试验,并全程进行了光照强度、温度和配子体发育相关性的研究。研究表明,采用双高光期(≥50μmolphotons/m2·s)调控配子体的生长和发育可达到理想效果。从采苗至度夏前,采用高光照使配子体充分完成营养生长;从度夏结束至幼苗出库前,同样采用高光照,使配子体快速发育形成孢子体并迅速生长。现场观察表明,只要光照强度逾越了诱导发育的阈值,裙带菜配子体在24℃仍然能够正常发育并形成孢子体;幼孢子体能够耐受24～26℃的高温,但是最适生长温度为20～22℃;孢子体越小,耐受高温能力越强。在24～26℃的高温条件下,幼孢子体生长缓慢,较大个体会出现尖端溃烂缺失的现象。在整个育苗过程中,根据温度变化和配子体的显微观察结果因地制宜地对光线进行实时调整。出库前培育的苗帘在幼苗密度、大小和健康方面均达到商业化栽培的要求。     

Effects of enhanced hydraulic supply for foliage on stomatal responses in little-leaf linden (<Emphasis Type="Italic">Tilia cordata</Emphasis> Mill.)

Responses of leaf conductance (g _L) to variation in environmental and plant hydraulic factors were examined on intact and detached shoots of little-leaf linden (Tilia cordata Mill.) with respect to branch position in the crown. Using detached shoots, we manipulated leaf water supply and light availability in order to separate the effects of insufficient hydraulic supply and low irradiance. The intact upper-crown leaves demonstrated 2.0–2.2 times higher (P < 0.001) daily maxima of g _L compared to the lower-crown leaves growing in the shadow of upper branches. Mean soil-to-leaf conductance (G _T) was 1.9 times higher (P < 0.001) for the upper-crown foliage compared to that of the lower crown. The total hydraulic resistance was distributed: soil to distal shoots—41–51%, 25-cm distal shoots—10–15% and leaves—39–44%. In lower branches, g _L was constrained by both low light availability and limited water supply; in upper branches, only by irradiance. Artificial reduction of hydraulic constraints raised bulk leaf water potential (Ψ _L) and made g _L less sensitive to changes in both atmospheric and plant factors. Stomatal responses to leaf-to-air vapour pressure difference (VPD) were significantly modified by leaf water status: high Ψ _L seemingly inverted the g _L versus VPD relationship. Enhanced water supply increased g _L and transpiration rate (E) in the lower-crown foliage, but not in the upper-crown foliage. The results support the idea that leaves in the lower canopy are hydraulically more constrained than those in the upper canopy.     

Effect of variations of PAR on CO2 exchange estimation for Scots pine

A set-up with 161 photosynthetically active radiation (PAR) sensors was used to investigate spatio-temporal variations of irradiance for five horizontal arrays within a Scots pine canopy. The measured PAR was converted to CO₂ exchange using of a shoot-scale photosynthetic response curve and the vertical distribution of the needle area. The net ecosystem exchange was simultaneously measured by the eddy covariance technique. The effect of spatial and temporal averaging of the PAR values and the number of sensors were analysed under different conditions as regards cloudiness and the shading by the foliage. In 1/2 h CO₂ exchange values for the entire canopy, a maximum overestimation of 30% resulted from a spatial averaging over horizontal arrays of 2–5 m and occurred under clear-sky conditions and significant foliage shading. Under partly cloudy conditions, the largest overestimation occurred for a case of little shading and the inaccuracy resulting from 1/2 h temporal averaging exceeded that of spatial averaging.     

LED光源在海水养殖水体中传播特征解析

光是影响水生动物生长和发育的重要环境因子,其在养殖水体中的传播特征仍未明确。本研究选取红光(波峰为645 nm)、绿光(510 nm)、蓝光(445 nm)、UVA(355 nm)以及全光谱(蓝光激发硅酸盐荧光粉辐射的白光波长范围可达400~800 nm)5种LED光源,调整辐射照度为60 W/m2,研究其在不同养殖水质环境中的传播规律,为满足室内工厂化水产养殖对象的光生物学需求,实现养殖光环境标准化调控提供参考。结果显示,5种不同光谱特征的LED光源在深井海水中的透光率随水深增加呈降低趋势,不同光源间变化趋势存在差异。当透光水深为10 cm时,绿光透光率最大,为(46.01±4.03)%,UVA最小,为(26.01±2.53)%;当透光水深为150 cm时,各光色透光率均小于1.5%;5种不同光色的光源在水体中的透光率衰减曲线均符合乘幂函数。水体对LED光的吸收在不同的光谱区域是不同的,具有明显的选择性,水对光谱中红外部分的吸收最为强烈,对可见光谱波段中的红色、黄色和绿色光谱区段的吸收也十分显著;LED光源在养殖水体中衰减严重,水深是影响LED光源在水体中传播的主要因素(P<0.01),其次是总悬浮物(TSS)和化学需氧量(COD),但不同光源在养殖水体中受TSS和COD含量的影响程度不同。光在水体中的衰减由水对光的吸收以及散射作用引起,且光在不同波段的衰减率主要由水生介质的吸收光谱决定。     

Modeled day–night biases in decapod assessment by bottom trawling survey

The activity rhythms of marine species may consistently bias demographic evaluation by bottom trawl survey, depending on the time of day. In this study, we examine occurrence data of selected commercial and non-commercial decapod species at different depths (0–800 m) of the western Mediterranean as produced by the Mediterranean international trawl survey (MEDITS) UE Program by sampling during daytime. In order to show how the activity rhythms and types of displacement (pelagic, nektobenthic and endobenthic) of different species can alter the occurrences determined by bottom trawling, and to quantify relative bias, we modeled potential outcomes of a putative nocturnal MEDITS sampling. MEDITS and published data for studies with 24-h hauls were compared in order to obtain a folding correction factor. We found that the temporal bias of sampling is moderate when trawling is performed on the continental slope and more important when it occurs on the continental shelf. The configuration of daytime and nighttime occurrence data by depth was performed using non-metric multidimensional scaling (nMDS). For the daytime configuration, association with irradiance (PAR) was evaluated by fitting occurrence data with a generalized additive model (GAM). Symmetry in species assemblages was found according to depth (inflection point at 200 m depth) as a significant irradiance-dependence distribution pattern of occurrences that took place on the shelf, above 200 m depth. For the night configuration, the inflection point relaxed due to the active displacements of some species, mixing the assemblages reported in daytime data. Results of the present study indicated that a deep knowledge of the autoecology of decapod species as it relates to activity rhythms (including a precise assessment of displacement typology) is of importance in population distribution and biomass evaluation and also influences locally perceived biodiversity. Accordingly, bottom trawl surveys for population assessment should take into account the timing of sampling as a factor potentially biasing obtained abundances.     

不同光照条件下新疆小拟南芥可塑性反应的生理生化特性

为揭示出小拟南芥可塑性反应的生理生化特点，采用不同光照强度处理新疆小拟南芥，研究其主要生理生化指标，结果表明：在一定的条件下，叶绿素含量随着光照强度的增大而增大。在抗氧化系统中，过氧化氢酶活性与生长光强的变化不一致。膜透性则随着光照强度的增大而增大。新疆小拟南芥组织中抗氧化系统的加强是响应强光的一种措施，显现出极强的可塑性。     

不同土壤水分下金矮生苹果叶片蒸腾速率研究

林木蒸腾作用与光照强度和土壤水分状况之间存在着密切的关系,蒸腾速率一般随光强的增强和土壤水分的改善而增大。因此,林木在苗期时,当土壤水分不足时,应采取措施避免强光照射,以减轻过度蒸腾失水造成生理伤害,提高成活率和促进苗木生长;有利于限制林木蒸腾失水,提高水分利用效率可考虑的土壤水分范围在１０％〈ＳＷＣ〈１５％之间。     

不同光照条件下新疆小拟南芥可塑性反应的生理生化特性

为揭示出小拟南芥可塑性反应的生理生化特点,采用不同光照强度处理新疆小拟南芥,研究其主要生理生化指标,结果表明:在一定的条件下,叶绿素含量随着光照强度的增大而增大。在抗氧化系统中,过氧化氢酶活性与生长光强的变化不一致。膜透性则随着光照强度的增大而增大。新疆小拟南芥组织中抗氧化系统的加强是响应强光的一种措施,显现出极强的可塑性。     

The Influence of Irradiance on Rate of Development and Components of Yield In Barley

A field study was conducted to investigate the effects of variation in levels of daily irradiance on the level of spike-let abortion and the rate of development using two cultivars of spring barky ( Hordeum vulgare L.), Schooner and Weeah. Three different irradiance treatments were imposed from the cessation of spikelet primordia initiation until anthesis: a reduced irradiance treatment (high competition treatment, HCT); an untreated control for medium competition treatment; MCT); and an increased amount of irradiance (low competition treatment. LCT). Variation, in natural daily irradiance (MCT) was imposed by either shading plants with shadecloth (HCT) or by exposing plants to relatively low inter-row irradiance competition effects by obstructing adjoining plant rows with plastic mesh (LCT). The duration of the spikelet growth phase was longer by 5 days (Schooner) and 9 days (Weeah) for HCT when compared to MCT, but there was no difference in its duration between LCT and MCT. Spikelet abortion occurred at 8–16 days before anthesis, but this was dependent on treatment. LCT For both cultivars showed a trend towards higher spikelet numbers per spike, although the increase was not significant over MCT, and HCT was significantly lower in both cultivars. Grain yield and biomass were lower (P < 0.05) for HCT compared to both LCT and MCT.