TEMPERATURE AND LIGHT INTENSITY EFFECTS ON GROWTH OF DICTYOSPHAERIUM PULCHELLUM

Growth rate and morphological characteristics of Dictyosphaerium pulchcllum were observed from populations maintained at 20 and 25 C under light intensities varying from 100 to 1200 ft-c. Growth rates, expressed as the number of times the population doubled in chlorophyll content per day, were 0.57 (100 ft-c) and 1.71 (1200 ft-c) at 20 C and 0.80 (100 ft-c) and 2.S7 (1200 ft-c) at 25 C. Cell size varied between 3.0 and 7.0 μ among all treatments at 20 C and mean cell size increased with an increase in light intensity. Agitation of asexually reproducing populations resulted in up to 95% of a population occurring in a unicellular form. The percentage of uni-cells was highest in vigorously agitated test tube cultures.     

THE EFFECTS OF LIGHT AND TEMPERATURE ON GROWTH RATES IN BOREAL-SUBARCTIC CRUSTOSE CORALLINES1

A number of boreal-subarctic crustose corallines were kept in natural seawater tanks at temperatures ranging from 0 to 19 C and, using fluorescent lamps at light intensities, ranging from 7 to 750 lux with periods of 8 and 14 hr/day. The resultant growth rates as a function of temperature and light are presented and discussed in relation to the ecology of the plants. All of the Lithothamnieae studied had growth maxima at temperatures from 9 to 15 C. Growth in these species showed little light dependence below 4–6 C, but had a strong light dependence at higher temperatures. The one Lithophyllum species examined gave a flatter growth-temperature curve than the Lithothamnieae and showed little light dependence. The effects of temperature variation, salinity, and current on growth rates were also examined and are discussed. It was found to be especially important in studying growth rates of crustose corallines to allow time for growth stabilization following temperature change. In general, growth was found to exhibit a hysteresis effect, increased rates with the raising of temperatures 5–10 C and decreased rates with lowering temperatures.     

温度对喜马拉雅低额溞生长与生殖的影响

对采自中国云南省高海拔地区-稀有低额溞-喜马拉雅低额溞(Simocephalus himalayensis)在低海拔地区实验室内不同温度梯度下的生长及生殖能力进行了研究.结果表明:高海拔地区生活的低额溞在低海拔地区的相应环境中同样生长繁殖良好,其繁殖率、最大生殖量及种群的增长能力不受海拔高度及不同环境条件的影响.在一定温度条件下(15-31℃,误差为±1℃),喜马拉雅低额溞的发育速率随温度的升高而加快,但在32℃时减慢.在通常培养条件下,喜马拉雅低额溞一般有4个幼龄期(15℃时部分溞体有5个幼龄),16-19个成龄,平均寿命通常为74d(15℃)、54d(20℃)、39d(25℃)和24d(30℃).平均总产仔量在15-25℃最高,分别为449个(15℃)、482个(20℃)和447个(25℃).各温度梯度下的体长增长模型都表明,其体长与龄期之间存在显著的对数关系.每溞平均生殖量以20℃时最高,种群的内禀增长率(rm)和一生的生殖次数都以25℃时最高,净增殖率(R0)以20℃最高.喜马拉雅低额溞最适合的繁殖温度范围在15-25℃.研究还对该种与相应种类在不同温度条件下的生殖量和生物学特性进行了比较.     

Developmental Physiology of Sugar Beet: I. THE INFLUENCE OF LIGHT AND TEMPERATURE ON GROWTH

Sugar beet plants were grown for 12 weeks from emergence ingrowth rooms at temperatures of 10, 17, 24 and 31 °C and20, 50, 80, and 110 cal visible radiation cm^-2d^-1, and the changeswith time in their dry weight, leaf area, leaf numbers, andstorage root sugar determined. The first stage of growth wasdominated by the development of the shoot, but the storage rootgradually assumed increasing importance and eventually grewat a faster rate and to a greater weight than the shoot. Therelative growth rate and final yield of dry matter of the shootwere greatest at 24 °C and of the root between 17 and 24°C. The relative rate of expansion and the final area ofthe leaf surface were also greatest at 24 °C, whilst therates of production and of unfolding of leaves were greatestat about 17 °C. All these attributes were increased withincreased radiation. Net assimilation rate increased almostproportionately with radiation and was not significantly affectedby temperature.The relationships of total leaf area with plantdry weight, root dry weight with shoot dry weight, and totalleaf number with plant dry weight were scarcely affected bychanges in radiation, but were much influenced by temperature.Plants of the same dry weight generally had bigger roots andsmaller areas of leaf surface as temperatures departed from24 °C and had most leaves at 17 °C. Sugar concentrationsin the storage root were greatest at 17 °C, but the totalamount of sugar was about the same at 17 and 24 °C. Theconcentration of sugar in the storage root depended on rootsize.Thus, temperature affected both the rate and pattern ofdevelopment, and radiation affected the rate but not the patternof development.     

THE EFFECTS OF TEMPERATURE ON THE GERMINATION AND RADICLE GROWTH OF PHOTOSENSITIVE LETTUCE SEED

1. The time course of germination of Grand Rapids lettuce seedshas heen followed with different combinations of temperature(3°–35°) and irradiation (red or far-red light).For each set of conditions the following three parameters weredetermined: (i) the time required for half maximum germination,(ii) the rate of germination during the actively germinatingphase, and (iii) the maximum germination attained. In general,as the temperature was lowered, with dark-imbibed seeds, (i)became longer, (ii) became lower, but (iii) became progressivelyhigher. The effect of red light at any temperature was to shorten(i) and increase (ii) and (iii) over the values dark controls.Far-red light exerted an effect opposite to that of red light.Temperatures higher than 25° inhibited (ii) and (iii) underany light conditions. The optimum temperature to the actionof red and far-red light is 25°, at which the stimulatoryeffect of red light and the inhibition of this effect by far-redlight are both maximal. 2. The growth of the radicles of de-coated seeds of Grand Rapidslettuce shows two phases at all temperatures studied. PhaseI is characterized by slow but linear growth which continuesuntil shortly after visible differentiation of the radicle intothe hypocotyl and the root. Phase II is a phase of active growthin which the total length reflects mainly the length of theroot. The optimum temperature for Phase I is 25°-35°,and that, for Phase II is 25°. In neither phase, and atnone of the temperatures studied, is there any effect of redor far-red radiation on the growth of the radicle. The firstvisible sign of radicle elongation in red light induced seeds,however, takes place at exactly the same time as that of germination. 3. Similarities and dissimilarities between the germinationand the growth are pointed out, and it is concluded that thetwo phenomena are different, but proceed at sites closely associatedin the embryo. ¹Present address: Johnson Foundation for Medical Physics, Universityof Pennsylvania, Philadelphia, Pa., U.S.A.     

EFFECTS OF LIGHT INTENSITY AND TEMPERATURE ON CRYPTOMONAS OVATA (CRYPTOPHYCEAE) GROWTH AND NUTRIENT UPTAKE RATES1

Specific growth rate of Cryptomonas ovata var. palustris Pringsheim was measured in batch culture at 14 light-temperature combinations. Both the maximum growth rate (μ_m) and optimum light intensity (I_opt) fit an empirical function that increases exponentially with temperature up to an optimum (T_opt), then declines rapidly as temperature exceeds T_opt. Incorporation of these functions into Steele's growth equation gives a good estimate of specific growth rate over a wide range of temperature and light intensity. Rates of phosphate, ammonium and nitrate uptake were measured separately at 16 combinations of irradiance and temperature and following a spike addition of all starved cells initially took up nutrient at a rapid rate. This transitory surge was followed by a period of steady, substrate-saturated uptake that persisted until external nutrient concentration fell. Substrate-saturated NO₃^?-uptake proceeded at very slow rates in the dark and was stimulated by both increased temperature and irradiance; NH₄⁺-uptake apparently proceeded at a basal rate at 8 and l4 C and was also stimulated by increased temperature and irradiance. Rates of NH₄^?-uptake were much higher than NO₃^?-uptake at all light-temperature combinations. Below 20 C, PO₄^?3-uptake was more rapid in dark than in light, but was light enhanced at 26 C.     

带形蜈蚣藻盘丝体孢子的形成及温度和光照强度对其放散的影响

在实验室条件下, 首次发现了带形蜈蚣藻(Grateloupia turuturu)盘状体产生的丝状体能够形成孢子, 暂命名为“盘丝体孢子”。研究详细观察了该盘丝体孢子的形成过程, 并探讨了不同温度6、12、16、20、24和30℃及不同光照强度10、30、45、60、90和120 μmol/(m2·s)对盘丝体孢子放散的影响。结果表明: (1) 带形蜈蚣藻雌配子体的囊果释放果孢子, 果孢子发育形成盘状体, 盘状体经过诱导再生出单列细胞的丝状体, 丝状体形成多室孢子囊, 并放散出大量盘丝体孢子; (2) 温度和光照强度均对丝状体中盘丝体孢子的放散产生显著影响。在温度为16℃、光照强度为60 μmol/(m2·s)时盘丝体孢子放散量有最大值; (3) 在温度低于12℃或高于24℃时, 盘丝体孢子的放散受到影响, 数量明显减少; (4) 在光照强度低于30 μmol/(m2·s)或高于90 μmol/(m2·s)时, 盘丝体孢子的放散明显受到抑制。研究结果补充了带形蜈蚣藻无性繁殖过程, 为其种质保存、人工育苗及养殖提供更为丰富的理论依据, 为探讨带形蜈蚣藻的起源与演化提供新思路。     

Growth and Development in the Young Tomato: I. THE EFFECT OF TEMPERATURE AND LIGHT INTENSITY ON GROWTH OF THE SHOOT APEX AND LEAF PRIMORDIA

Tomato seedlings were grown at constant temperatures of 25°and 15° C. in a 12-hour day at light intensities of 1,600,800, and 400 f.c. The rate of increase in size of the shootapex and the rates of formation and growth of leaf primordiaduring the vegetative phase were followed by dissecting samplesfrom the time of cotyledon emergence onwards. The rate of enlargement of the shoot apex increased with lightintensity, but apical enlargement was delayed at the highertemperature, the delay being longer the lower the light intensity.The rates of leaf formation and leaf growth increased with bothtemperature and light intensity. Temperature had a larger effecton leaf growth than on leaf formation. More leaves were formedbefore flowering at 25° C. than at 15° C., the increasein leaf number being greater the lower the light intensity. It is suggested that the delay in the enlargement of the apexat high temperature can be explained in terms of competitionfor assimilate, the competitive potential of the expanding leafprimordia exceeding that of the apex at higher temperatures.     

STUDIES ON LUMINOUS BACTERIA : II. THE INFLUENCE OF TEMPERATURE ON THE INTENSITY OF THE LIGHT OF LUMINOUS BACTERIA.

1. A method has been described whereby the intensity of the light of luminous bacteria may be measured in a quantitative manner. 2. It is pointed out that the temperature coefficients for light intensity do not follow the van''t Hoff rule, but are higher and vary with each 10° temperature interval. 3. From a comparison with other data it is found that the process is not a simple one, but that the observed curve is the resultant of several reactions which proceed simultaneously. 4. The discrepancies in the temperature coefficients in the neighborhood of the "optimum temperature" may be due to a process of coagulation of the colloidal particles of the enzyme. This coagulation will tend to cause a deviation of the curve away from that normal for chemical reactions.     

Devlopmental Physiology of Sugar-Beet: II. EFFECTS OF TEMPERATURE AND NITROGEN SUPPLY ON THE GROWTH, SOLUBLE CARBOHYDRATE CONTENT AND NITROGEN CONTENT OF LEAVES AND ROOTS

Plants were grown at temperatures of 15 and 25 ?C with two ratesof nitrogen supply. The changes in dry weight, leaf area, cellnumber, mean cell volume, soluble carbohydrate, and total nitrogenconcentration of the cotyledons, the first and second pair oftrue leaves, and the storage root were measured. Changes incell number and cell volume of the first pair of true leavesand storage root of plants were also measured at 11, 18, 25,and 32 ?C. Leaf growth before unfolding was chiefly by increase in cellnumber and after unfolding by increase in mean cell volume,while the growth of the storage root was almost entirely byincrease in cell number. The rates of cell division and cellexpansion were fastest at 25 ?C, but the initially high ratesof cell division in the terminal bud and in individual leavesdecreased rapidly and greater rates were maintained at the sub-optimaltemperatures, i.e. 15 and 18 ?C. After an initial period ofslow growth, the first-formed leaves grew faster and becamelarger at 15 than at 25 ?C. Leaves were produced, unfolded,grew faster, and became larger with increase in the externalconcentration of nitrogen, because cells divided and expandedfaster, so that nitrogen increased the number and size of cells. Sugar concentration was greater at 15 than at 25 ?C in leavesbut not in the storage root. Sugar concentration in the petiolesof the first and second pair of true leaves increased to 1.2and 2.0 per cent fresh weight respectively. Decreased nitrogensupply temporarily increased the sugar concentration of cotyledonpetioles and the seedling hypocotyl, but later decreased itin the leaves and storage root. Nitrogen concentration was greaterin the leaves and storage root at 15 than at 25 ?C with thelarger nitrogen supply. Nitrogen concentrations were similarin young leaves of all treatments but as the size of leavesincreased nitrogen concentrations decreased most rapidly at25 ?C with the smaller nitrogen supply. It is suggested that when increased leaf production and storage-rootgrowth occurs at temperatures below the growth optimum (25 ?C),they may be due to an effect of increased carbohydrate supplyon cell division and sugar storage.     

温、光、盐对硅藻STR01生长、总脂、脂肪酸的影响

为了优化新分离STR01的生态培养条件, 采用单因子试验和正交试验研究了不同温度、光照强度、盐度和温、光、盐三因素三水平对该藻的生长、总脂和脂肪酸组成影响。结果表明: 温、光、盐对STR01的生长、总脂和脂肪酸组成影响显著(P<0.05)。生长的适宜温度为15—35℃, 最适25—30℃(K值达0.679—0.682), 总脂含量积累的最适温度是25℃(总脂可达17.23%), 温度20℃时有利于该藻PUFA的积累, 可达34.23%。STR01生长的适宜光照强度为40—120 μmol/(m2·s), 最适光强为60 μmol/(m2·s), 光照强度40 μmol/(m2·s)有利于该藻的PUFA积累, 可达34.29%。STR01生长的适宜盐度为10—35, 最适盐度25, 盐度25时PUFA含量较高(43.42%)。正交试验结果表明温度对STR01的平均相对生长速率和总脂含量影响显著, 生长的最优组合: 温度30℃、光照强度60 μmol/(m2·s)、盐度25, 该组合下的生长速率达0.756; 总脂含量积累的最优组合: 温度30℃、光照强度60 μmol/(m2·s)、盐度20, 该组合下的总脂含量为20.00%。PUFA的最优组合: 温度25℃、光照强度60 μmol/(m2·s)、盐度20, 该组合下PUFA的含量为35.37%。综上所述: 该藻生长迅速, 总脂含量较高, PUFA丰富, 是一种可开发利用的耐高温浮游硅藻。     

EFFECTS OF TEMPERATURE AND IRRADIANCE ON THE GROWTH OF TWO FRESHWATER PHOTOSYNTHET1C CRYPTOPHYTES1

Effects of light and temperature on growth of two freshwater photosynthetic cryptophytes of different cell size were studied in batch cultures. For the smaller Cryptomonas 979/67, Steele's model and equation of Platt et al. described the relationship between growth rate and photon flux density (PFD), whereas a hyperbolic tangent function gave a better fit for the larger Cryptomonas 979/62. Maximum growth rates given by the three models were consistent with each other, but the hyperbolic tangent function gave slightly lower estimates. Maximum growth rates in relation to temperature were well described for both species by the model of Logan et al. The optimum temperature for growth for Cryptomonas 979/67 was ca. 24.5° C and 19.0° C for Cryptomonas 979/62. The lethal temperatures were 30.4° C and 23.1° C for 979/67 and 979/62, respectively. The estimated maximum growth rates were 1.38 div.·day^?1 for Cryptomonas 979/67 and 0.87 div.·day ^?1 for Cryptomonas 979/62. There were interspecific differences in photoadaptation strategies, as Cryptomonas 979/67 required relatively high PFDs to show net growth, whereas Cryptomonas 979/62 grew at lower irradiances. Cryptomonas 979/67 showed photoinhibition soon after the saturation point, but Cryptomonas 979/62 tolerated a much wider range of irradiance. From their growth responses to light, Cryptomonas 979/ 67 appears to be a stenotopic and Cryptomonas 979/ 62 a eurytopic strain.