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1.
Rooted cuttings were grown in controlled environment cabinetsat two daily light totals (63 and 125 J cm2 day1)with the light intensity constant throughout the day or in stepsgiving the same daily light total Plants were sampled frequentlyover a period of 83 days by which time they were in full flower.A comparison of the various growth measures derived from theprimary data on leaf area, fresh and dry weight of the plantand its parts, and morphological and floral characteristics,revealed only negligibly small differences between results forconstant and stepped regimes The results for the constant regimeswere compared with other experiments earned out simultaneouslyin order to indicate the reproducibility of growth in independentcabinets having nominally the same conditions 相似文献
2.
Rooted cuttings were grown in controlled-environment cabinetsat daily visible light totals of 31, 63, 125, and 250 J cm28-h day1 and carbon dioxide concentrations of 325 and600 ppm. The experiment was repeated on another occasion withthe inclusion of a further carbon dioxide level of 900 ppm.A 5-h tungsten night break was used in the first week to delayflower initiation The plants in the various treatment combinationswere sampled by frequent small harvests for leaf area and freshand dry weights of leaf, stem, root, and flower, and also forvarious morphological features. Other growth measures were obtainedby manipulation of the primary data, including the fitting ofprogress curves. Plants were respaced at intervals to minimizemutual shading. There was an increase in total dry-matter production with increasinglight and carbon dioxide, with a small positive interactionbetween them. Plants in one experiment had a somewhat higherunit leaf rate and a lower leaf-area ratio, the latter beingdue to a slightly smaller leaf-weight ratio. The effects ofadditional carbon dioxide were largely accounted for by increasedphotosynthesis. Although there were substantial differencesin specific leaf area between treatment combinations withineach experiment, the leaf-weight ratio was little altered inthe period of vegetative growth. The inverse relationship betweenspecific leaf area and unit leaf rate showed a very similartrend for all combinations of light and carbon dioxide concentration.Leaf area was a linear function of absolute leaf water contentfor all treatment combinations within an experiment, but therewas a small significant difference between occasions. Flower development was extremely delayed in the lowest lightlevel and substantially delayed at the next higher level. Thenumber of leaves below the flower decreased with increasinglight level Flower weight increased with increasing light above63 J cm2 8-h day1 and with increasing carbon dioxideconcentration, there being a positive interaction between them The initial weight and leaf area of cuttings differed for thetwo experiments, and although the results on the two occasionswere in the same direction, their magnitudes were different.Some of the discrepancy was eliminated by expressing the variousgrowth measures as functions of plant dry weight, but therewas evidently a difference in the potential for growth of thetwo batches of cuttings. The plants which were initially smallerhad a higher average unit leaf rate which, due to a higher leafwater content, was not offset by a lower leaf area ratio. 相似文献
3.
In earlier work the effects of light intensity over the range31 to 250 J cm2 day1 and carbon dioxide concentrationfrom 325 to 900 ppm with 8-h days at 18.3 °C and 16-h nightsat 15.6 °C were described. The present paper is concernedwith three further experiments with light levels up to 375 Jcm2 day1 (which corresponds to the daily totalin a glasshouse in southern England in early May or August andthe intensity is approximately that of mid-winter sunshine),carbon dioxide concentration up to 1500 ppm, and day temperaturesof 18.3 to 29.4 °C. Final plant weight was increased by light over the range 125375J cm2 day1 and by carbon dioxide over the range325900 ppm, with positive interaction between them; thisinteraction was increased by raising the temperature to 23.9°C and somewhat more at 29.4 °C day temperature. Leaf-arearatio and specific leaf area were reduced by increasing eitherlight or carbon dioxide but there was little effect of temperature.Leaf-weight ratios were uniform within experiments but therewere small consistent differences between one experiment andthe other two which also affected leaf-area ratios. Mean unit leaf rate was scarcely affected by day temperatureover the range investigated. There were the usual increasesdue to increased light and carbon dioxide concentration anda consistent difference in absolute value between one experimentand the other two. These differences in mean unit leaf rateare illustrated in detail in the ontogenetic trend of unit leafrate and plant size. Lower unit leaf rates were to a considerableextent compensated for by increased leaf-area ratios in theusual way. Despite the substantial differences in day temperature the specificwater contents (g water g dry weight1) differed little,showing in the majority of cases higher values in the highertemperature for otherwise similar treatment combinations. Flower development was somewhat delayed at 23.9 °C day temperature,and substantially so at 29.4 °C. Lateral branch length wasincreased at 23.9 °C and excessively so at 29.4 °C.This reveals quite clearly that a temperature optimum for vegetativegrowth may not be the optimum for flowering performance norproduce a desirable plant shape. Despite the marked effects of temperature on rate of flowerdevelopment, the relationship between flower development andthe ratio of flower to total weight was the same for all treatmentcombinations in all three experiments and coincident with thatreported earlier. Gasometric determinations indicated that respiratory loss bythe whole plant was a smaller proportion of net photosyntheticgain at a temperature of 29.4 °C than at 18.3 °C andwas likewise a smaller proportion at 1500 ppm carbon dioxidethan at 325 ppm. If photorespiration of leaves is assumed tobe as great as their dark respiration, the respiratory lossesare in the range of 3150 per cent of the gross gain.Greater rates of photorespiration would increase the proportionaterespiratory loss. 相似文献
4.
Carbon dioxide-enrichment of young tomato plants grown in controlled-environmentcabinets at low light intensity (14 cal cm2 day1,visible radiation) increased their net assimilation rates and,initially, relative growth-rates. Subsequently, the relativegrowth-rate fell to near the rate of non-enriched plants, owingto a fall in leaf-area ratio associated with an increase inleaf dry weight/area. Sowing non-enriched plants a few daysearlier to reach the same total dry weight would not have producedidentical plants. The effects of CO2-enrichment to 1000 vpm could be simulatedby increasing light intensity by approximately one third exceptthat the plants had shorter internodes than those in extra CO2.This was a morphogenetic effect of light since CO2-enrichmentitself produced slightly shorter plants than controls for anequivalent total dry weight. CO2-enrichment did not change the dry-weight distribution inthe plants and had little effect on rate of leaf produoctionor the number of flower primordia. There were no indicationsthat beneficial effects of CO2-enrichment operated other thanthrough increased photosynthesis. 相似文献
5.
Juvenile growth and development rates for Metridia pacifica,one of the dominant larger copepods in the subarctic Pacific,were investigated from March through October of 20012004in the northern Gulf of Alaska. The relationship between prosomelength (PL, µm) and dry weight (DW, µg) was determined:log10 DW = 3.29 x log10 PL 8.75. The stage durationsof copepodites ranged from 3 to 52.5 days but were 815days under optimal condition. Seasonally, growth rates increasedfrom March to October and typically ranged between 0.004 and0.285 day1, averaging 0.114 ± 0.007 day1(mean ± SE). After standardization to 5°C (Q10 of2.7), growth rates averaged 0.083 ± 0.005 day1and were significantly correlated to chlorophyll a, with saturatedgrowth rates of 0.149 day1 for C1C3, 0.102 day1for C4C5 and 0.136 day1 for all stages combined.Measured juvenile growth rates were comparable with specificegg production rates in this species. The comparisons of ourrates in this study with those predicted by the global modelsof copepod growth rates suggested that further refinement ofthese models is required. 相似文献
6.
Non-dormant flower initials are laid down in the axils of successiveleaf initials as they are formed by the apical meristem of Pisumsativum L. In cultivars with a maximum capability of two flowersper raceme, the undeveloped flower meristem divides into twoportions. One forms the first flower and the other either developsinto a small protrusion on one side of the first flower or becomesthe second flower, depending on the prevailing environment.Flower development in conditions favouring single-flowered racemeswas advanced by one plastochron. Variation in the number offlowers per raceme occurs between cultivars and between environments.The number of double flowers formed was favoured by higher lightintensity (120 Js1 m2) and carbon dioxide concentration(330 µ11) and lower temperature (15°C). Incultivars producing more than two flowers per raceme, lowerlight intensity (60 Js1 m2) plus higher temperature(20°C) increased the mean number of flowers per raceme.Soluble sugar levels in all varieties were higher (36.05 mgeq glucose g1 fresh weight) in the low temperature/highlight environment than the high temperature/low light environment(14.80 mg eq glucose g1 fresh weight). The flowering potential and stability of 13 cultivars have beenassessed in controlled environment and in sowing date trialsin the field. A stable variety, which consistently producedtwo flowers per raceme, was identified in controlled environmentand its stability was maintained in field trials. A linear regressionof stability of flower number in the field on stability in controlledenvironment accounted for 89.6 per cent of the variance (P<5per cent), but the flowering potential in a sowing date experimentwas not related to temperature or radiation intensity. 相似文献
7.
The juvenile growth rates and development times of subarcticCalanus marshallae and temperate/sub-tropical C. pacificus wereinvestigated during nine cruises (May through October, 200104)in the northern Gulf of Alaska. The artificial cohort methodbased on a length-weight regression was used for growth estimatesand the reciprocal of the molting rate for developmental time.The copepodite stage duration ranged from 3 to 16 days for C.marshallae (C1C4) and 323 days for C. pacificus(C1C5). Seasonally, copepodid growth rates increasedfrom May to October, ranging between 0.055 and 0.291 day1(mean ± SE: 0.176 ± 0.008 day1) for C.marshallae, while growth rates increased from August to Octoberbetween 0.018 and 0.296 day1 (mean ± SE: 0.142± 0.016 day1) for C. pacificus. After standardizationto 5°C (Q10 of 2.7), growth rate averaged 0.118 ±0.007 day1 and 0.075 ± 0.009 day1 for C.marshallae and C. pacificus, respectively. Calanus marshallaegrowth rate is satisfactorily described by a MichaelisMentenmodel using chlorophyll-a concentration (r2 = 0.33) after temperaturecorrection, but the prediction improves with a composite nonlinearmodel combining body weight into the MichaelisMentenfunction (r2 = 0.55). Considering the limited range of dataavailable for C. pacificus, the combination of the data forboth species suggests that C. pacificus has a similar functionalresponse to growth despite the differences in the geographicand temporal distributions with C. marshallae. Measured juvenilegrowth rates of the two Calanus species in this study were comparableto other calanoid species in the same area and showed reasonableagreement to Calanus growth models but less with global copepodgrowth models. 相似文献
8.
The leaf growth, tiller production, light interception, anddry weight increase of a simulated sward of S24 perennial ryegrass(Lolium perenne) were followed during the development of thesward from a collection of two-leaved seedlings to a closedcanopy with an LAI of 23, of which 15 consisted of green leaflaminae. The dry weight of live shoots increased exponentiallyat first, but then entered a long linear phase of increase.This was equivalent to a crop growth rate of 200 Kg ha1day1 and a conversion efficiency of radiant energy (400700nm) of 7.2 per cent. Towards the end of the growth period therate of increase of live shoots declined rapidly to zero anda ceiling yield was reached equivalent to 10 metric tons ha1.Leaf growth continued at a high rate, but was equalled by therate of leaf death, so that the weight of live leaf tissue remainedconstant. By this time the swards had achieved a stable tillerpopulation (about 1 cm1), each tiller bore a constantnumber of live leaves (about three), and the length of eachnewly expanded leaf equalled the length of the old leaf it replaced(about 70 cm). The swards were grown in Perlite so that in theabsence of soil fauna dead leaves accumulated at the base ofthe sward where, after 12 weeks, they accounted for 19 per centof the total weight of dry matter produced. 相似文献
9.
Freezing Avoidance Mechanisms by Supercooling in Some Rhododendron flower Buds with Reference to Water Relations 总被引:3,自引:0,他引:3
Excised florets of some hardy Rhododendron species did not toleratefreezing at 5°C when ice-inoculated due to intracellularfreezing. Florets in intact December buds, however, could besupercooled to about 30°C. When flower buds of R.japonicum were slowly cooled with daily decrements of 5°Cto temperatures ranging from 0 to 20°C, the exothermtemperatures of the florets drastically decreased. This wasaccompanied by a decrease in water content of florets and peduncleand an increase in that of scales. The water in florets andthe peduncle is thought to migrate to scales and other tissuesduring the early stages of freezing; the dehydrated floret hasa lower freezing point which enhances its supercooling abilityand the dehydrated peduncle helps to maintain the supercooledstate of the florets. This hypothesis would explain the dependenceon the cooling rate of supercooling in Rhododendron flower buds.Water migration within flower buds was observed in other hardyRhododendron species with some variation in ice formation siteand the quantity of migrated water. The exotherm temperatureof excised florets was inversely proportional to their watercontent. Dehydration of flower buds by wind at 0°C alsoenhanced their supercooling ability. Mechanisms of freezingavoidance by supercooling in Rhododendron flower buds and therelationship of supercooling to freezing tolerance are discussed.
1 Contribution No. 2254 from the Institute of Low TemperatureScience
2 This is a revised form of the master's thesis of the seniorauthor (M.I.) which is cited in the present and previous papers(Sakai 1979a, b, etc.). (Received August 11, 1980; Accepted June 1, 1981) 相似文献
10.
The Growth and Development of the Wheat Apex: The Effects of Photoperiod on Spikelet Production and Sucrose Concentration in the Apex 总被引:2,自引:0,他引:2
Spring wheat (Triticum aestivum cv. Warimba) plants were grownin a controlled environment (20°C) in two photoperiods (8or 16 h). In the first instance, plants were maintained in eachof the photoperiods from germination onwards at the same irradiance(375 µE m2 s1). In the second case, allplants were grown in a long photoperiod until 4 days after double-ridgeinitiation when half the plants were transferred to a shortphotoperiod with double the irradiance (16 h photoperiod at225 or 8 h at 475 µE 2 s1). The rates of growth and development of the apices were promotedby the longer photoperiod in both experiments. Shoot dry weightgain was proportional to the total light energy received perday whereas the dry weight of the shoot apex increased withincreasing photoperiod even when the total daily irradiancewas constant. The principal soluble carbohydrate present in the shoot apexwas sucrose, although low concentrations of glucose and fructosewere found in the apices of long photoperiod plants late indevelopment. Sucrose concentration was invariably greater inthe slow-growing apices of short photoperiod plants, but roseto approach this level in the long photoperiod plants when theterminal spikelet had been initiated. Triticum aestivum, wheat, apex, spikelet initiation, photoperiod, flower initiation 相似文献
11.
Determining the mass density of marine copepods and their eggs with a critical focus on some of the previously used methods 总被引:3,自引:0,他引:3
We collected Calanus finmarchicus copepodites CIV, CV and CVIfemales in a deep fjord on the west coast of Norway during April1996, May 1997 and November 1998. Eggs of C. finmarchicus andCalanus glacialis were collected during May 1989 in the BarentsSea. The sinking speeds of animals and eggs were measured ina homogeneous column with seawater of known density, and Stokeslaw was applied to estimate their mass density. Also the densitycontrast between the organisms and seawater was calculated.The mean mass density of C. finmarchicus ranged from 1.0274to 1.0452 g cm3. During spring copepodite stage CV hada significantly lower mean mass density (1.0345 g cm3)compared to CIV (1.0381 g cm3) and CVI females (1.0408g cm3). Copepods collected during winter had a distinctlylower mass density. The sinking speed of C. glacialis eggs followeda unimodal distribution, with a mean of 25.9 m day1,while sinking speeds of C. finmarchicus eggs were bimodal, thetwo groups of eggs having a mean sinking speed of 23.3 m day1and 35.4 m day1 respectively. Correspondingly the meanmass density was 1.0556 g cm3 for C. glacialis eggs andfor the two groups of C. finmarchicus eggs 1.0639 g cm3and 1.0812 g cm3. Results of earlier work, particularlyusing density gradient methods to determine mass density ofzooplankton, are critically reviewed, and it is suggested thatthis method should not be used to determine the mass densityof small organisms the size of C. finmarchicus. 相似文献
12.
Growth and ingestion rates of larval fish populations in the coastal waters of Israel 总被引:1,自引:0,他引:1
Clupeoid larvae were collected on eight cruises between February1984 and February 1985 in the coastal waters of Israel. Fromanalysis of daily growth increments of otoliths, growth ratesof the abundant clupeoids, Engraulis encrasicolus, Sardina pilchardusand Sardinella aurita were found to be 0.55 mm day1,0.67 mm day1 and 0.60 mm day1, respectively, duringthe first month after hatching. Ingestion rates were estimatedusing an equation from the literature relating ingestion andgrowth of larval fish. Ingestion calculated for populationsof fish larvae in pelagic waters ranged from 0 to >23 mgC m2 day1 with maximum rates observed in April.Annual ingestion by larval fish at a pelagic station near Haifawas calculated to be 2.2 g C m2 year1, 1020%of annual primary production estimated from 14C uptake. 相似文献
13.
Palomares-Garcia Ricardo; Bustillos-Guzman J. J.; Lopez-Cortes D. 《Journal of plankton research》2006,28(12):1217-1232
Phytoplankton growth and microzooplankton grazing rates wereevaluated in one station in Bahía Concepción,located in the middle region of the Gulf of California, México.We used high-performance liquid chromatography (HPLC) estimationsof phytoplankton pigment signatures to evaluate the annual variationof taxon-specific grazing and growth rates obtained with thedilution technique. Chlorophyll-a (Chl-a) concentrations variedwidely (0.343.32 µg L1) and showed two maxima,during late spring and autumn, associated with the transitionbetween mixed and stratified conditions. Phytoplankton growthrates varied seasonally with the lowest rates during summer(range: 0.012.55 day1 for Chl-a; 0.003.84day1 for Chl-b; 0.263.29 day1 for fucoxanthin;0.006.27 day1 for peridinin; 0.004.35 day1for zeaxanthin). Microzooplankton grazing was an important lossprocess (range: 0.01.89 day1 for Chl-a; 0.003.12day1 for Chl-b; 0.263.29 day1 for fucoxanthin;0.002.03 day1 for peridinin; 0.003.51 day1for zeaxanthin). Average grazing rates accounted 6889%of estimated average phytoplankton pigment-specific growth rates.The analysis of pigment signatures indicates that diatoms anddinoflagellates were the dominant groups, and contrary to expectationfor typical subtropical lagoons, the specific growth rates inBahía Concepción showed a pronounced seasonalvariability, linked to transitional hydrographic conditions.Our results indicate a close coupling between the communitymicrozooplankton grazing and phytoplankton growth rates, withoutselective feeding behavior. These results suggest that microzooplanktonplay a critical role and may significantly modify the availabilityand efficiency of transfer of energy to higher trophic levels. 相似文献
14.
The thesis that the minimum cell-phosphorus content of planktonalgae is a light- and temperature-independent species constantwas investigated using the marine plankton diatom Thalassiosirarotula. To what extent the maximum cell-phosphorus content isalso a constant, light- and temperature-independent quantityhas been tested in parallel. At 2.5C and 3.03 nE cm2s1 the minimum and maximum cell-phosphorus contents aregreater than the values for 16C and 8.93 nE cm2 s1by a factor of 5.7. The light intensities were kept near thelight saturation for the growth rate for all experimental temperatures(2.5, 6, 12 and 16C). The light dependence of the phosphoruscontent was tested at 12C. For 1.43 nE cm2 s1the minimum phosphorus content was lower by a factor of 2.5than for 64.28 and 80.36 nE cm2 s1 respectively.The maximum P-content for 2.86 nE cm2 s1 was 3.9times higher than for 64.28 nE cm2 s1 T. rotulais, on the basis of the stored P-content, only capable of betweenthree and five cell divisions. The N/P atomic ratios were, dependingupon light and temperature, between 56:1 and 226:1 for the minimumcell-phosphorus content, which implies a pronounced phosphorusdeficiency. 相似文献
15.
In situ growth and development of Neocalanus flemingeri/plumchrusstage C1C4 copepodites were estimated by both the artificial-cohortand the single-stage incubation methods in March, April andMay of 20012005 at 56°C. Results from thesetwo methods were comparable and consistent. In the field, C1C4stage durations ranged from 7 to >100 days, dependent ontemperature and chlorophyll a (Chl a) concentration. Averagestage durations were 12.414.1 days, yielding an averageof 56 days to reach C5, but under optimal conditions stage durationswere closer to 10 days, shortening the time to reach C5 (fromC1) to 46 days. Generally, growth rates decreased with increasingstage, ranging from 0.28 day1 to close to zero but weretypically between 0.20 and 0.05 day1, averaging 0.110± 0.006 day1 (mean ± SE) for single-stageand 0.107 ± 0.005 day1 (mean ± SE) forartificial-cohort methods. Growth was well described by equationsof MichaelisMenten form, with maximum growth rates (Gmax)of 0.170.18 day1 and half saturation Chl a concentrations(Kchl) of 0.450.46 mg m3 for combined C13,while Gmax dropped to 0.080.09 day1 but Kchl remainedat 0.380.93 mg m3 for C4. In this study, in situgrowth of N. flemingeri/plumchrus was frequently food limitedto some degree, particularly during March. A comparison withglobal models of copepod growth rates suggests that these modelsstill require considerable refinement. We suggest that the artificial-cohortmethod is the most practical approach to generating the multispeciesdata required to address these deficiencies. 相似文献
16.
Carbon dioxide efflux from 5- to 20-day-old pea fruits was measuredfor plants grown in controlled environment at 15 °C and600 µmol s1 m2 photon flux density in a16 h photoperiod. The rate of CO2 output per fruit increasedquickly from 0.005 to 0.018 mg CO2 min1 during fruitelongation and subsequently more slowly to 0.030 mg CO2 min1as the fruits inflated. On a d. wt basis the rate was highest,0.175 mg CO2 g1 min1, in the youngest fruits anddeclined curvilinearly with increasing fruit weight to 0.02mg CO2 g1 min1. Separation of maintenance andgrowth components was achieved by starvation methods and bymultiple regression analysis. From the latter method estimatesof the maintenance coefficient declined hyperbolically from150±8.7 mg carbohydrate g1 d. wt day1 inthe very young fruits (0.05 g) to 10.4±0.36 mg carbohydrateg1 d. wt day1 in older fruits (2.0 g). On a nitrogenbasis maintenance costs decreased from 2240 to 310 mg carbohydrateg1 nitrogen day1 while nitrogen concentrationfell from 6.7 to 3 per cent d. wt. A simple linear relationshipbetween maintenance cost per unit d. wt and nitrogen concentrationwas not observed. A growth coefficient of 50±6.7 mg carbohydrate g1growth (equivalent to a conversion efficiency, YG, of 0.95)was estimated for all fruits examined. The overall efficiency, Y, increased from a mean of 0.70 to0.85 during fruit elongation and subsequently declined to 0.80.For a given fruit weight, efficiency increased asymptoticallywith relative growth rate; both asymptote and slope of the relationshipincreased as the fruits grew. Pisum sativum L., garden pea, legume fruit, carbon dioxide efflux, maintenance respiration, growth respiration 相似文献
17.
We tested the hypothesis that the growth rate of Anabaena circinalis,under diurnally stratified conditions, would increase as flotationvelocity increased owing to higher light availability. An insitu experiment compared the growth of diurnally stratifiedpopulations of A. circinalis with flotation velocities of 0.5and 1.0 m h1, with neutrally buoyant populations thatwere exposed to either mixed or persistently stratified conditions.The experiment was conducted in the turbid lower Murray Riverin South Australia (vertical attenuation coefficient = 4.52± 0.36 m1). To represent the mixing patterns,A. circinalis was contained in diffusion chambers that weremoved to different positions in the water column throughoutthe day. Diurnal populations with flotation velocities of 1.0and 0.5 m h1 grew at 0.23 ± 0.01 and 0.15 ±0.01 day1, respectively. Mixed populations grew at 0.19± 0.01 day1, whereas persistently stratified populationsgrew at 0.43 ± 0.01 day1. Results were used toextend a model that predicts growth of A. circinalis when exposedto the different mixing patterns. The model showed that bloomsare unlikely to be formed when the period of diurnal stratificationis <1 week, regardless of flotation velocity. When the diurnallystratified period is >1 week, flotation velocity is importantand a bloom may form depending on values assigned to the growthperiod and maximum mixed depth (Zm). 相似文献
18.
Callus tissue was induced from floral parts of African violetcultured on MS medium containing NAA (2 mg I1) and BAP(0.2 mg I1). When maintained on this medium in the presenceof light, the callus produced many shoots and roots. Large numbersof adventitious shoot buds were formed apparently in the absenceof callusing when ovary, sepal, and petal tissue was culturedon MS medium supplemented with BAP (1 mg I1) and NAA(1 mg I1). In contrast, culturing the same floral partson MS medium augmented with kinetin (1 mg I1) and NAA(0.5 mg I1) and NAA (0.5 mg 1-1) led to the profuse developmentof roots. Organs seemed to be initiated from the epidermis ofcultured floral parts and did not appear to be related to particularcells or loci. Transfer of shoots to MS medium deviod of growthsubstances resulted in the formation of plantlets, which ata height of 3 cm could be transferred to soil and grown to maturitywithout variation in morophology or cytology. 相似文献
19.
The growth of the cultivar Golden Princess Anne (G.P.A.) wasstudied in controlled announcement cabinets in a range of lightconditions (125375 J cm2 8-h day1) andcarbon dioxide concentrations (3251500 ppm) in all combinationsPlants obtained in January and grown from January to April showedgreater final total dry weight and flower dry weight at bothhigher light intensity and higher carbon dioxide concentrationwith a strong positive interaction between them, whereas plantsobtained in September and grown from September to December didnot respond much to increased carbon dioxide concentration andthere was only a small positive interaction with light intensity.The plants grown from January to April had larger final leafareas, larger mean leaf-area ratios due mainly to larger specificleaf areas, and higher mean specific leaf-water contents comparedwith SeptemberDecember plants. Despite the differencein specific leaf-water content, leaf area was almost the samelinear function of absolute leaf-water content at both timesof year. The other vegetative parts also had higher specificwater contents throughout the JanuaryApril experimentand the lateral branches were longer when compared with thecorresponding values for SeptemberDecember Flower developmentwas slightly faster in SeptemberDecember and the plantsbore on average one flowering branch less compared with JanuaryAprilplants. Plants in the lower light and carbon dioxide conditions hadlower unit leaf rates, but for plants of similar total dry weightthe effects of this on dry-matter increment were partially offsetby larger leaf areas at both times of year. The JanuaryAprilplants had greater leaf areas than SeptemberDecemberplants of similar unit leaf rate and total dry weight. The cultivar Bright Golden Anne (B.G.A ) showed effects whichwere in the same direction but smaller in magnitude, tendingto diminish the differences between the times of year For example,the positive interaction in total plant dry weight was smallerin JanuaryApril compared with G P A , but larger in SeptemberDecember.Leaf area, leaf-area ratio, specific leaf area, specific watercontent of leaf, stem, and root, and lateral branch length,were all larger for B G A in corresponding treatment-combinationsin two JanuaryApril experiments than in a SeptemberDecemberone, although the difference between the times of year was smallerthan for G.P.A except for leaf area which was relatively butnot absolutely smaller Dry-matter increment and leaf area showedan inverse relationship for plants of the same total dry weight,as in G P A. In JanuaryApril B G.A plants of similarunit leaf rate and total dry weight also had greater leaf areasthan in SeptemberDecember but the differences were notso large as for G.P.A Total dry-matter production was slightlygreater for B.G.A. in JanuaryApril and considerably greaterin SeptemberDecember compared with G P A , and at bothtimes of year B.G.A. was more leafy, with higher specific watercontents for the vegetative parts. It was not possible to determine the cause of the differencesin growth obtained at the two times of year. It could have arisenbefore the cuttings were removed from the stock plants, duringpropagation, or during the course of the experiments in thegrowth cabinets. 相似文献
20.
To a certain extent the flowering of Lemna paucicostata 6746is evoked in continuous light by application of abscisic acid(ABA) and CCC. Moreover, the action of the combined substancesappears in two separate concentration ranges. In the range ofABA 2?109 M/CCC 107106 M floweringis initiated without inhibition of vegetative growth and proceedsonly in the presence of high intensity light and sucrose. Acombination of ABA 2?105 M/CCC 103M simultaneouslycauses a strong inhibition of frond multiplication. Here theeffect can be observed also under low intensity light conditionsand without sucrose in the medium. A range with flower inhibitingactivity lies between the two flower promoting concentrationranges. (Received November 16, 1972; ) 相似文献