Physiological and Ecological Studies in the Analysis of Plant Environment: XIII. A Comparison of the Effects of Seasonal Variations in Light Energy and Temperature on the Growth of Helianthus annuus and Vicia faba in the Vegetative Phase

The influences of seasonal changes in light radiation and temperatureon the vegetative growth of Helianthus annuus and Vicia fabahave been investigated in the east of Scotland by pot experiments,carried out in the open at weekly intervals between June andSeptember in 1956 and May and October in 1957. To minimize theeffects of ontogenetic drift pots containing plants of a similarmorphological status were selected from batches sown every fewdays. At the beginning and end of each experiment replicatedand paired pots were harvested and the dry weights of the leaves,stems, and roots together with the leaf areas determined. Fromthese data weekly values for net assimilation rate, leaf-arearatio (ratio of leaf area to plant weight), and relative growthrate were calculated. Simultaneously, records were kept of the diurnal changes inair temperature and of light energy by means of an integratingphotometer. Multiple regressions linking light and temperature with netassimilation rate, leaf-area ratio, and relative growth ratewere calculated separately for each year. A significant ‘time-of-season’trend was largely eliminated by including an additional variable,the initial leaf-area ratio. In the individual regressions thevariance accounted for was very high, ranging from 75 to 97per cent. The results demonstrated that for both species the net assimilationrate and relative growth rate were positively dependent on lightand temperature. The leaf-area ratio of both species was negativelyaffected by light, but only for V. faba was there a positiverelationship between the leaf-area ratio and temperature. H.annuus grew faster than V. faba during the major part of theseason, largely because of its higher leaf-area ratio. The results are compared with prior investigations in Englandand elsewhere.     

Physiological and Ecological Studies in the Analysis of Plant Environment: XII. The Role of the Light Factor in Limiting Growth

Previous investigations in southern England on twenty-two herbaceousspecies have demonstrated that for widely spaced plants thediurnal solar radiation limits the net assimilation rate ofall species and restricts the relative growth rate of many.In examining how far these limitations apply to other environmentsit is now shown that in the subtropics and tropics the levelsof net assimilation rate and relative growth rate can greatlyexceed those so far recorded for cool temperate regions, andthese differences are attributed to the higher insolation andtemperatures. From a variety of evidence it is concluded that as the distancebetween plants is reduced 8O the net assimilation rate is progressivelydiminished even in regions of high insolation through the enhancedmutual shading. In consequence levels of light which may besupra-optimal for relatively isolated individuals may yet limitthe dry-matter production of a dense population. There is anoptimal ratio of leaf area to ground surface (leaf-area index)for the maximal exploitation of the incoming radiation in carbonfixation by the population and this optimum will vary with thespecies and the light intensity. Where other environmental factorsare favourable, light may limit dry-matter production everywhere. On an annual basis dry-matter production will be dependent ontwo components—the length of the ‘growing season’and the period over which the leaf-area index remains optimal.In the tropics the highest annual rate of production so farrecorded is 7⁸ tonnes/hect. produced by Saccharum officinarumandin north-east Europe 23.5 tonnes by Fagus sylvatica. Over shortperiods the rate of dry-matter production can attain 3⁸g./m.²/dayand the utilization of solar energy can be as high as 4.2 percent., or 9.5 per cent, for the range 4, 000–7, 000 A. Although information on the productivity of natural communitiesis still ex-ceedingly scanty, an attempt has been made to interpretthe general pattern in terms of the length of the growing season,the level of solar radiation, the magni-tude of the leaf-areaindex of the whole community, and the period over which theleaf canopy remains green. It is postulated that in any regionthe vegetation reaches a dynamic equilibrium when there is themaximum exploitation of the incoming radiation to produce thegreatest production of dry matter.     

Physiological and Ecological Studies in the Analysis of Plant Environment: IX. Adaptive Changes in the Vegetative Growth and Development of Helianthus annuus induced by an Alteration in Light Level

Pot experiments were carried out in which sunflowers in theearly vegetative phase were first grown for a period under threelevels of light (1·0, 0·5, and 0·24 daylight).Subsequently pots from each light group were subdivided intothree so that in a second period plants could be subjected tothe nine possible combinations of the same three light intensitiesbefore and after transference. During the post-transference period of adaptation to eithera higher or a lower intensity the net assimilation rate is logarithmicallyproportional to the light received and there is no residualeffect of the initial light treatments. Eight days after transferencethe leaf-area ratios (total leaf area/total plant weight) ateach light level become adjusted to a new equilibrium irrespectiveof the large initial differences in the ratio induced by thepre-transference intensities. In both periods there is an inverseand logarithmic relationship between the leaf-area ratio andfalling light intensity; consequently, the greater the degreeof shading in the pre-transference period, the higher are themean ratios in the second period. Since the relative growthrate is the product of the net assimilation rate and the leaf-arearatio, the variations in the leaf-area ratio in the post-transferenceperiod induced by the initial light treatments are reflectedin the relative growth rates. Thus plants transferred from alower to a higher light intensity are leafier and initiallygrow faster than plants maintained at the higher level in bothperiods: the converse conditions lead to a reduction in thegrowth rate. Shading depresses the growth of the roots, but the relativegrowth rate is dependent on the light intensity in both thepre-transference and post-transference periods. With transferencefrom daylight to 0·24 daylight, the roots during theperiod of adjustment may lose weight, while the growth rateis maximal when plants are moved from the lowest to the highestintensity. In two out of the three experiments the relativegrowth rate of the shoot in the post-transference period isof the same order at all light intensities and is largely independentof the light received in the initial period. In terms of leaf weight, decreasing the light intensity decreasesthe relative growth rate and there is no consistent after-effectof the initial light treatments. The rate of expansion in leafarea tends to be highest at the intermediate level of 0·5daylight and over all the post-transference intensities therates are maximal for those plants which received initiallyfull daylight. The ratio of leaf area to leaf weight is inversely and logarithmicallyproportional to the light level. After transference the slopesof the regressions are independent of the initial light treatments,but the mean ratios are inversely correlated with the initialdegree of shading. These adaptive changes to a variation in the light level arediscussed with particular reference to the control of growthexerted by growth-regulating substances. It is concluded thaton the basis of existing knowledge no adequate interpretationis yet possible.     

Physiological and Ecological Studies in the Analysis of Plant Environment: VII. An Analysis of the Differential Effects of Light Intensity on the Net Assimilation Rate, Leaf-Area Ratio, and Relative Growth Rate of Different Species

Since relative growth rate is the product of net assimilationrate and leaf-area ratio (leaf area/plant weight), it followsthat if the effects of shading on both net assimilation rateand leaf-area ratio can be expressed mathematically, then therelationship between light intensity and relative growth ratecan be derived from the product of the two mathematical expressions. For all the ten species investigated in field and pot cultureexperiments, it has been found that during the early vegetativephase both the changes in leaf-area ratio and net assimilationrate, over the range of 0·1 to full daylight, are linearlyrelated to the logarithm of the light intensity. In consequence,the relationship between relative growth rate and the logarithmof light intensity—being the product of the two linearregressions—is curvilinear. For species of shady habitats (Geum urbanum, Solamun dulcamara)neither the levels of assimilation rate nor the ‘compensation-point’values are very different from those of the eight species fromopen situations (e.g. Hordeum vulgare, Pisum sativum, Fagopyrumesculentum). Nevertheless the intensity at which growth rateis maximal varies between species: it is 0•5 for G. urbanum,0•7 for H. annuus, full daylight for F. esculentum, whilefor Trifolium subterraneum the calculated value is 1·8daylight. Such specific differences can be largely accountedfor in terms of the differences in leaf-area ratio at the differentlight levels. On the basis of this analysis of the light factor, a ‘shade’plant is best redefined as a species in which a reduction ofthe light intensity causes a rapid rise in the leaf-area ratiofrom an initial low value in full daylight: for a ‘sun’plant the converse definition holds.     

Physiological and Ecological Studies in the Analysis of Plant Environment: VI. The Constancy for Different Species of a Logarithmic Relationship between Net Assimilation Rate and Light Intensity and its Ecological Significance

In this further study of light as an environmental factor theeffects of shading on the growth of Helianthus annuus, Fagopyrumesculentum, Trifolium subterraneum, Tropaeolum majus, Lycopersicumesculentum, Vicia faba, Pisum sativum, Hordeum vulgare, Solanumdulcamara, and Geum urbanum have been investigated. It has been established that the reductions in the net assimilationcaused by shading are similar for all ten species. The net assimilationrate during the season of active growth is linearly relatedto the logarithm of the light intensity. When similar experimentsare conducted late in the autumn and the relative growth rateis very low, the logarithmic relationship no longer holds. From the data it is possible to obtain precise estimates ofthe compensation point. The mean values of the compensationpoint ranged from 0·06 to 0·09 of daylight foreight species, while for V. faba and H. vulgare somewhat higherfigures were obtained—0·14 and 0·18 of daylight. Flctuations in the net assimilation rate in full daylight showedno correlation with variations in the value of the compensationpoint. From these results it is concluded that species cannot be groupedinto ‘sun’ or ‘shade’ plants, eitheron the basis of differences in the value of the compensationpoint or on the grounds that there are large variations in theeffects of shading on net assimilation rate.     

Physiological and Ecological Studies in the Analysis of Plant Environment: VIII. An Inexpensive Integrating Recorder for the Measurement of Daylight

The design is based on the principle that changes in the currentpassing through a vacuum emission cell, induced by variationsin the light quanta received, control the rate of charge ofa condenser. When the striking voltage of a discharge tube isreached the resultant flow of current energizes an electromagneticrelay which, in turn, is connected with a Post Office counter.In order to eliminate possible errors due to changes in temperature,the compartment containing the discharge tube is kept at a constanthigh temperature (100° F.), while a stabilized mains sourceof electricity is used. A ground-glass diffusing dome is usedand a filter to exclude infra-red and ultra-violet radiation.With a photometric cell of relatively uniform sensitivity inthe visible spectrum the recorder gave a linear response upto the maximum intensity investigated. No change in the calibrationfactor occurred in two summers' continuous use in the open.The electrical components, including the photo-electric cell,cost c. £25, while the construction only demands normalworkshop facilities.     

A Further Analysis of Hybrid Vigour in Zea mays during the Vegetative Phase

Employing the procedures of growth analysis further pot experimentson hybrid vigour in Zea mysa have been conducted in a glasshouse.By serial sampling the changes in plant weight and leaf areahave been followed for six hybrids and their immediate parentsof either dent or flint type. Within 2–3 weeks from sowingthe relative growth-rate (RGR) of the hybrid was significantlygreater in four out of the six triplets and in the remainingtwo the rate for the hybrid exceeded that of one parent. Thesedifferences diminished with time but when observations ceasedat the end of 7 weeks the weight and area of the hybrid wasfrom 1.5 to 1.9 times greater than that of the larger parent.By this time too all but one of the hybrids but none of theparents were in flower. The two components of growth, the leaf-area ratio (LAR) andthe net assimilation rate (NAR) did not differentiate in a consistentmanner between the hybrid and the parents, because of the considerablevariation between emergence and flowering. All the hybrids atsome time up to 28 days had a significantly higher LAR thanthose of one or both parents. Similarly for NAR on no occasionup to 4 weeks did any parent exceed the level of the hybridbut for some hybrids and for some occasions the NAR was significantlyhigher than that of at least one of the parents. Later for bothparameters none of the differences within triplets were significant. A flint and a dent triplet were grown at constant air temperaturesof 10, 15, and 20 °C and illuminated for 14 h at 22 600lx and sampled during the vegetative phase. The results showedthat there were marked differences in the temperature responseswithin and between triplets. The flint hybrid grew faster thanits parents at 15 and 20 °C but not at 10 °C. In contrast,the superiority of the RGR of the dent hybrid was greatest at10 °C. These differences are largely reflected by changesin NAR rather than LAR. The higher NAR of the flint hybrid isfound at 15 and 20 °C, but the superiority of the dent hybridis most evident at 10 °C. The comparative performance within one triplet was examinedfor small and large grains. The patterns of change in the growthcomponents were not influenced by grain size. The interacting effects of genotype, stage of development, andtemperature level are discussed. It is concluded that in thefield the over-riding factor determining hybrid vigour is thehigher RGR in the postemergence phase and that the genetic variationover the six triplets is greater for NAR than LAR.     

Differences in the Interacting Effects of Light and Temperature on Growth of Four Species in the Vegetative Phase

A comparative study, employing the concepts of growth analysis,has been made of the varying responses in the early vegetativephase of Gossypium hirsutum, Helianthus annuus, Phaseolus vulgaris,and Zea mays to combinations of light intensity (1.08, 2.16,3.24, 4.32, and 5.4 x 10⁴ lx—photoperiod 14 h) and constantdiurnal air temperatures (10, 15, 20, 25, 30, and 35 °C).Depending on the combination of treatments, the temperatureof the internal tissues departed from air temperature by 6.9to 1.4 °C: so only the internal temperatures are cited here. For each species there are complex interactions between theeffects of light and temperature on the net assimilation rate,the leaf-area ratio, and the relative growth-rates of plantweight and leaf area. The magnitude of the changes induced bythe two factors vary both with the growth component and thespecies. The temperature responses are maximal up to 20–5°C while at the highest temperatures they may be negative.The temperature coefficients for leaf-area ratio are consistentlyless than those of the other three components: here betweenspecies the coefficients over 10–20 °C vary by a factorof 9.6, 5.4, and 5.1 for the rates of gain in plant weight andleaf area and the net assimilation rate, while the orderingwithin each growth component is species dependent. Under conditions of optimal temperature the relative growth-rateand net assimilation rate progressively increase, accordingto the species, up to either 4.32 or 5.4x 10⁴ lx. The leaf-arearatio is always largest at the lowest intensity. The level oflight at which the rate of gain in leaf area reaches a maximumranges from 2.16x 10⁴ lx for Phaseolus to between 4.32 and 5.40x10⁴ lx for Gossypium. The highest relative growth-rate and net assimilation rate ofHelianthus exceed those of Zea substantially. Indeed the maximalassimilation rate for Helianthus of 2.10 g dm^–2 week^–1is the highest ever recorded under field or controlled conditions.Possible reasons for this reversal of the photosynthetic potentialsof the two species observed by previous workers are discussed.     

Interacting Effects of Light and Day and Night Temperatures on the Growth of Four Species in the Vegetative Phase

A comparative examination has been made under controlled conditionsof the interacting effects on growth in the vegetative phasewhich takes place when the diurnal temperature is either maintainedconstant at 20 and 25 ?C or reduced at night by 5 and 10 ?Cand the plants subjected daily to either 2.16 or 4.32 ? 10⁴lx for 14 h. For each species (Gossypium hirsutum, Hclianthusannuus, Phaseolus vulgaris and Zea mays) the changes in netassimilation rate, the leaf area ratio and the relative growthrates in plant weight and leaf area were recorded. Contrary to some previous findings, none of these componentsof growth are favoured by cool nights. Rather such reductionsin temperature retard the growth processes to a varying degreeaccording to the species and the component. In general, significantreductions are more evident for the two relative growth rateswhen a drop from 20 to 10 ?C is combined with the lower levelof illumination. The implications of these results are considered in relationto a prior study where for similar light conditions the samespecies plants were subjected to constant temperatures rangingfrom 10 to 25 ?C.     

Different Growth and Physiological Responses to Cadmium of the Three Miscanthus Species

Miscanthus has been proposed as a promising crop for phytoremediation due to its high biomass yield and remarkable adaptability to different environments. However, little is known about the resistance of Miscanthus spp. to cadmium (Cd). To determine any differences in resistance of Miscanthus to Cd, we examined plant growth, net photosynthetic rate (Pn), activities of anti-oxidant and C₄ photosynthetic enzymes, concentrations of Cd in leaves and roots, and observed the chloroplast structure in three Miscanthus species treated with 0, 10, 50, 100 or 200 μM Cd in solutions. Miscanthus sinensis showed more sensitivity to Cd, including sharp decreases in growth, Pn, PEPC activity and damage to chloroplast structure, and the highest H₂O₂ and Cd concentrations in leaves and roots after Cd treatments. Miscanthus sacchariflorus showed higher resistance to Cd and better growth, had the highest Pn and phosphoenolpyruvate carboxylase (PEPC) activities and integrative chloroplast structure and the lowest hydrogen peroxide (H₂O₂) and leaf and root Cd concentrations. The results could play an important role in understanding the mechanisms of Cd tolerance in plants and in application of phytoremediation.     

不同音乐环境对小鼠生长发育的影响

目的探讨音乐对小鼠生长发育的影响。方法采用30只ICR小鼠,在50 dB与60 dB的古筝与葫芦丝音乐环境中,饲养27 d,每3天测定体重一次,每9天测定饲料各种营养消化率一次。结果雌鼠体重在不同音乐环境中都有显著提高（P〈0.05）,且50 dB组高于60 dB组（P〈0.05）。雄鼠体重在古筝音乐环境中有显著提高（P〈0.05）;而在葫芦丝音乐环境中有显著降低。在不同音乐环境中,鼠的各种营养物质消化率无显著差异（P〉0.05）。结论不同的音乐环境对小鼠的体重有显著影响,而对小鼠的各种营养物质的消化率无显著影响。     

Studies on the Growth in Culture of Plant Cells: XI. THE INFLUENCE OF SHAKING RATE ON THE GROWTH OF SUSPENSION CULTUEES

The influence of shaking rates (expressed as revolutions permin) on orbital shaking platforms (1 in (2.54 cm) diam. rotarymotion) on the growth of cell suspension cultures of Acer pseudoplatanusL. and Atropa belladonna cultivar lutea Döll are described.By following cell growth and respiration and the levels of oxygenand carbon dioxide in the media during the progress of incubationit is concluded that the reduction of growth at sub-optimalshaking rates is not due to oxygen deficiency or toxic accumulationof carbon dioxide. The growth of the Atropa cell suspensionin ‘closed systems’ has been studied by the developmentof modified culture vessels and evidence obtained that the reducedgrowth in the systems is due to the formation by the culturesof an unidentified volatile growth inhibitor and not to eitheroxygen depletion or toxic accumulation of either carbon dioxideor ethylene. It is suggested that the reduced growth in ‘opensystems’ cultures at sub-optimal shaking speeds is eitherdue to retention of this volatile inhibitor or to restrictionof nutrient uptake by the existence of a stationary liquid-phaseboundary to the cells.     

The Three Cortical Membranes of the Gregarines (Parasitic Protozoa). III. Comparative Studies of the Membrane Proteins Among Different Sporozoan Species During Their Vegetative Phase1

ABSTRACT. The cortical membrane proteins of three gregarine and one coccidian species were compared using sodium dodecyl sulfate/polyacrylamide-gel electrophoresis. About 30 proteins were identified in the ghosts of Gregarina blaberae and G. garnhami and 20 in G. rhyparobiae ghosts and Sarcocystis tenella pellicles. No protein with the electrophoretic mobility of muscular actin was present in the ghosts of the sporozoan species under study. Each species possessed a characteristic electrophoretic pattern; no protein was present simultaneously in the four sporozoan species and only one protein band with a similar electrophoretic mobility was found in the three gregarine species (52 Kd protein). Two G. garnhami subpopulations living in Locusta migratoria and Schistocerca gregaria exhibited the same ghost protein pattern. Thus, large differences were observed between species and not within species, and the protein electrophoretic analysis appears to be a powerful tool for taxonomic investigations in gregarines. Gregarina blaberae and G. garnhami glycoconjugates were compared after periodate/Schiff staining of the polyacrylamide gel slabs. Several glycoconjugates were reported to belong to the cytoplasmic fraction; and, in view of cytochemical and ultrastructural data, a contribution of these glycocomponents to the secretion of a mucus is discussed.     

The Effect of Shading During Vegetative and Reproductive Growth on the Photosynthetic Capacity of Leaves in a Grass Sward

The decline in photosynthetic capacity of successive newly expandedleaves, which occurs as a vegetative grass sward increases inleaf area, was prevented in a field sward of S24 perennial ryegrass(Lolium perenne L.) by protecting tillers from shading by theirneighbours. This adds support for the view that the declineis caused by the shading of leaves during their expansion. However, in a flowering sward where there is no such decline,the photosynthetic capacity of leaves was not reduced by shadingthem with a plastic mesh during expansion, although it was bypegging down tillers so that they developed at the bottom ofthe sward. Lolium perenne, perennial rye-grass, photosynthetic capacity, growth, shading     

Interrelationships between the Nature of the Light Source, Ambient Air Temperature, and the Vegetative Growth of Different Species within Growth Cabinets

The interacting effects within growth cabinets of the natureof the light source and the temperature of the ambient air on14 parameters of vegetative growth have been examined for Gotsypiumhirsutum, Helianthus annuus, Phaseolus vulgaris, and Zea mays.The comparisons were between fluorescent lighting and mixtureswith tungsten lamps (17 and 26 per cent of the total wattage),adjusted to give 32 400 lx and covering six equally spaced andconstant air temperatures from 10 to 35 °C. The relationships are highly complex. Species differ in theirresponses to the three light sources. Moreover, for some parameters,but only for some species, there are highly significant interactionsbetween the nature of the light source and the temperature level.Part of this complexity is due to the varying growth potentialof species at low and high temperatures but important contributingfactors are the differences between the temperatures of theambient air and the plant parts. Such disparities may be positiveor negative and are greater for leaf as against root temperature.The divergencies are larger during the day and largest for leaftemperature. With the higher proportion of tungsten lamps theleaf day temperature ranges from 7.1 °C above an ambienttemperature of 10 °C to 2.5 °C above 35 °C ambient.For fluorescent lighting the leaves are 2.8 °C above ambientat 10 °C and 2.5 °C below at 35 °C. When variations in the response are examined against the meaninternal day temperature of the plant, for some parameters,but not others, differences between light sources are no longerevident. Here again the reactions of species differ. It is concluded firstly that if only ambient air temperaturesare recorded errors will arise in the interpretation of theinduced biological responses, and secondly that departures fromthe ambient air temperatures will be dependent on the designof the cabinet and the lighting system.