EFFECT OF TEMPERATURE ON LIGHT-LIMITED GROWTH AND CHEMICAL COMPOSITION OF SKELETONEMA COSTATUM (BACILLARIOPHYCEAE)1

Phytoplankton growth rate in response to irradiance can be approximated by a hyperbola defined by three coefficients: i) initial slope (α); ii) asymptote (μ_m); and, iii) X-axis intercept or compensation irradiance (I_c). To mathematically represent the interaction of temperature and irradiance on growth rate, one must describe the relationship between these constants and temperature. The marine diatom, Skeletonema costatum (Greville) Cleve, was grown in unialgal culture at different levels of irradiance and 2-3 photoperiods at 0, 5, 10, 16 and 22 C. The value of I_c is ca. 1.0 ly·day^?1 or less at all temperatures. The initial slope (div·ly^?1) is a “u-shaped” function of temperature described by the second degree polynomial, α= 0.25–0.02T+0.001T². Within the range 0–10 C, μ_m (div·day^?1) is an exponential function of temperature described by the equation, μ_m= 0.48 exp (0.126T). At each temperature and selected levels of irradiance, cell size and cellular content of C, N and chl a were determined. The C:chl a and N:chl a ratios increased with irradiance because of increases in C and decreases in chl a. At lower temperatures (0, 5, 10 C), the rate of increase of both ratios with irradiance was greater than at the higher temperatures (16, 22 C). Cellular content of N was independent of irradiance and temperature, and the C:N ratio ranged from 5 to 8 with a slight tendency to lower values at low irradiance. Cell volume was not influenced by either temperature or irradiance.     

侧杂食线螨的生长发育与温湿度的关系

侧杂食线螨Polyphagotarsonemus latus(Banks)亦称黄茶螨,严重为害茶叶、茄子、辣椒等作物,造成损失,该螨发育速率与温度成逻辑斯蒂曲线关系。在30℃以下随温度的上升而加快,但在35℃下速度反而减慢。本文用接近致死50%的上下两个温度结合内插法来估计高温致死点,更为简单、精确。本试验测定侧杂食线螨雌螨致死中温为43.60℃,用内插法估计为43.86℃,两者十分接近。湿度对其发育速度的影响不如温度影响显著。     

EFFECT OF TEMPERATURE AND PHOTOPERIOD ON GROWTH AND DORMANCY OF BETULA PAPYRIFERA

The effects of day/night temperatures and photoperiod on the growth and dormancy of paper birch (Betula papyrifera) were studied in seedlings from different geographic origins. The response of Alaskan plants to temperature and photoperiod was distinctly different from other seed sources. Alaskan plants required very long days to prevent cessation of growth while plants from southern seed sources grew on photoperiods as short as 14 hr. Low night temperature (14 C) antagonized the promotive action of long photoperiods in Alaskan plants but had little effect in other seed sources. High day temperatures offset the inhibitory effect of the cool night to a lesser degree in Alaskan plants than in plants from other locations. Dormancy induced by short photoperiods was antagonized (relieved ?) to a lesser degree by high night temperatures in Alaskan birch than in other seed sources. Betula papyrifera var. humilis from Alaska may be an incipient species since its morphological traits are accompanied by adaptive physiological responses to its environment. These responses are as distinct as its morphological characteristics.     

温度和氮磷浓度对平裂藻和栅藻生长及竞争的影响

为了解温度及氮磷浓度对平裂藻和栅藻生长及竞争的影响,分别在18、25和35℃条件下,以BG11培养基为基础,设置了不同的氮磷浓度组,进行了2种藻的单独培养试验和混合培养试验,结果表明:在纯培养条件下,低营养浓度组(磷浓度分别为0.1和0.5 mg/L)平裂藻在3种温度下基本停止生长,高营养盐浓度组(磷浓度分别为1.0和1.5 mg/L)除18℃1.0 mg/L组停止生长外,其余均能正常生长增殖,且细胞最大密度表现为25℃ 18℃ 35℃, 1.5和1.0 mg/L浓度组细胞生长差异不显著。栅藻在纯培养条件下,细胞密度总体表现为随着营养盐浓度升高而增加的趋势,细胞最大密度表现为18℃ 25℃ 35℃。在混合培养试验中,除35℃、1.5 mg/L组平裂藻对栅藻的竞争抑制参数大于栅藻对平裂藻的竞争抑制参数外,其余试验组均表现为栅藻受平裂藻影响较小。在混合培养体系中, 0.1 mg/L组平裂藻仍基本停止生长, 0.5 mg/L组受栅藻的刺激作用,生长优于纯培养体系。1.0和1.5 mg/L组均受栅藻的抑制作用,且浓度越高抑制作用越强。       

THE EFFECT OF GROWTH TEMPERATURE AND CULTURE DENSITY ON THE MOLECULAR SPECIES COMPOSITION OF THE GALACTOLIPIDS IN THE RED MICROALGA PORPHYHDIUM CRUENTUM (RHODOPHYTA)1

The effects of biomass concentration and growth temperature on the molecular species composition of the major galactolipids of the red microalga Porphyridium cruentum Nag. were detmined. At lower biomass concentrations, the Δ17 desaturation of arachidonic acid to eicosapentaenoic acid (20:5) was enhanced in both prokaryotic-type and eukalyotic-type molecular species of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol. We suggest that chloroplastic Δ17 desaturation is correlated with the availability of light. A reduction in the growth temperature led to an increase in the proportion of the eukalyotic molecular species of MGDG, especially for 20:5/ 20:5 MGDG, These results suggest that this molecular species, and perhaps eukaryotic molecular species in general, may play a role in the adaptation of cells to low growth temperatures.     

蔗糖浓度对三裂叶野葛毛状根生长及其次生物质产生的影响

本文研究了蔗糖浓度对发根农杆菌ATCC15834诱导产生的三裂叶野葛毛状根生长及其葛根素和异黄酮类化合物产生的影响以及液体培养基中蔗糖的消耗变化.结果表明毛状根在含5%、4%、3%和2%蔗糖的MS培养基中培养16天后的干重增殖倍数分别为11.7、11.9、10.1和5.9;其中尤以3%的蔗糖浓度最有利于毛状根中异黄酮类化合物及葛根素的积累;培养12天后,毛状根的葛根素含量达到最高,约5.147mg/g DW;而其异黄酮类化合物的含量则在培养16天后达到最高,约27.76mg/g DW.在毛状根液体培养过程中培养基的蔗糖浓度随着毛状根的生长而降低,其消耗速率与毛状根的生长速度及其可溶性总糖含量成正比.毛状根的可溶性总糖含量在培养12天时达到最高,而培养16天后培养基中的蔗糖消耗完毕.