The Effect of an Incandescent Supplement on the Growth of Tomato Plants in Low Light

Young tomato plants were grown at low light flux densities (21W m^-2 for 8 h days) in growth cabinets under three types offluorescent lamps or under a fluorescent/incandescent mixedsource. Whilst net assimilation rates under the fluorescentlamps were in agreement with those calculated from the lampcharacteristics and the photosynthetic action spectrum, therate under the mixed source was about 20 per cent higher thanexpected. Relative growth rates and relative leaf area growthrates were also higher and leaf area ratios lower under thefluorescent/incandescent lamp combination than under the purefluorescent sources. Small differences in stem elongation, leaftemperature and dry weight distribution which were associatedwith the addition of incandescent radiation were not consideredto be responsible for these increases. When the light flux densityfrom the mixed source was reduced by 20 per cent, the plantgrowth parameters were then similar to those in fluorescentlight alone.     

An Analysis of the Growth of Young Tomato Plants in Water Culture at Different Light Integrals and CO2 Concentrations: I. Physiological Aspects

Young tomato plants were grown from germination in water cultureat light-flux densities from 6 to 110 W m^-2 (400–700 nm),daylengths from 8 to 24 h and CO₂ concentrations from 0.4 to2.2 g CO² m^-3 in controlled environment cabinets. The growth rates and net assimilation rates of 14–17-day-oldplants at the highest light integrals were appreciably greaterthan most values previously recorded for tomato, and diminishedwith time. Plants in the lowest light conditions had leaf arearatios five times larger than those in the highest light, attributablemainly to a difference in leaf dry weight/area. Such flexibilityin leaf area ratio has not previously been associated with ‘sun’plants such as the tomato. Relatively normal growth was obtained in continuous light, incontrast to most other reports. This may have been due to theuse of conditions which would minimise water stress. The efficiency of the conversion of incident light energy tochemical energy by the whole plant ranged from 15 per cent inseedlings in low continuous light to about 6 per cent, tendingto be higher in young plants in long days under CO₂ enrichment.The higher values are probably overestimates because of theexclusion of reflected light from the energy receipt values.     

Effects of Temperature and Light on the Carbon Budget of Young Cucumber Plants Studied by Steady-State Feeding with 14CO2

Shishido, Y., Challa, H. and Krupa, J. 1987. Effects of temperatureand light on the carbon budget of young cucumber plants studiedby steady-state feeding with ¹⁴CO°₂J. exp. Bot. 38: 1044–1054. The effect of temperature on the fate of ¹⁴C assimilated insteady-state by the expanding third leaf of cucumber seedlingswas studied at irradiances of either 30 or 75 W m^–2 (PAR)with a daylength of 8 h. The irradiance did not affect the relativedistribution of ¹⁴C assimilated by the source leaf between growth,respiration and export. In the range 15–30°C risesin temperature generally increased the proportion of carbonexported. The average rate of carbon exported during the nightwas about half the rate in the day. About 45% of the exportedcarbon was lost by respiration. The distribution pattern ofcarbon exported during the day differed considerably from thatof carbon exported during the night. The intensity of irradiance did not affect the proportion oflabelled carbon recovered from the roots. Thus the decreasedshoot/root ratio generally observed with increased irradianceis not directly controlled by carbohydrate supply. We found that the distribution patterns of exported ¹⁴C do notnecessarily represent the real carbon distribution, due to differencesin specific activity of imported carbon of individual organs.Consequently distribution patterns of ¹⁴C observed in experimentswith one source leaf have to be considered with caution. Key words: Carbon budget, ¹⁴C, ¹⁴C steady-state feeding, translocation, respiration, assimilate distribution, cucumber, temperature     

Effects of CO(2)-Enrichment and of Aminoacetonitrile on Growth and Photosynthesis of Photoautotrophic Calli of Nicotiana plumbaginifolia

Photoautotrophic calli of Nicotiana plumbaginifolia were grown for 3 weeks under two CO₂ concentrations (500 and 20,000 microliters of CO₂ per liter). Calli cultured at high CO₂ exhibited a two-fold higher rate of growth. At CO₂ test levels, these calli were characterized by a lower net photosynthetic capacity than calli cultured at low CO₂. This diminution due to CO₂ adaptation could be ascribed to a 170% stimulation of dark respiration, a 40% decrease in total ribulose-1,5-bisphosphate carboxylase (Rubisco) activity, and also to a feedback inhibition of photosynthesis: high CO₂ grown calli contained about 5.5-fold more sucrose and three-fold less orthophosphate (Pi) than low CO₂ grown calli. Whether the decrease in Rubisco activity is related to the accumulation of sucrose and to the Pi limitation is discussed. Both calli exhibited a Warburg-effect showing the existence of active photorespiration at low CO₂. In calli grown at low CO₂ with 5 millimolar aminoacetonitrile (AAN), an inhibitor of the glycolate pathway, fresh weight decreased by 25% and chlorophyll content by 40%, dark respiration increased by 50% and net CO₂ uptake decreased by about 60% at 340 microliters of CO₂ per liter and 35% at 10,000 microliters of CO₂ per liter. In these calli, glutamine and glutamate contents were half of control calli. In contrast, AAN did not provoke any noticeable effect in calli grown at high CO₂. In photoautotrophic calli, the inhibition of the glycolate pathway by AAN results in severe perturbations in glutamate metabolism and in chlorophyll biosynthesis.     

Long-Term Chilling of Young Tomato Plants under Low Light. III. Leaf Development as Reflected by Photosynthesis Parameters

Young tomato plants were exposed to two weeks of chilling undernon-photoinhibiting or mild photoinhibiting conditions. Thedevelopment of the leaves was studied under chilling and controlconditions by measuring several physiological parameters. Agradual decrease of the efficiency of the photosynthetic apparatuswith maturation and ageing occurred in unchilled plants. Thiswas reflected by gradual changes in CO₂-saturated photosynthesisand protein and rubisco contents. Except for senescing leaves,a correlation close to 1 : 1 was observed between maximum rubiscoactivity and CO₂-saturated photosynthesis. Chlorophyll (Chl)contents and photochemical chlorophyll fluorescence quenchingshowed strong decreases only in the last phase of senescencein the oldest leaves. In plants chilled under non-photoinhibitingconditions (10C, 100–150 µE m^–2 s^–1or 6C, 30–50 µE m^-2 s^–1), a similar patternof ageing was observed, and no indications were found for aninduction of protein or rubisco degradation by chilling. Sincethese plants stopped growing in the cold, they revealed lowertotal photosynthetic capacities than unchilled plants of thesame size. When the chilling conditions were mildly photoinhibitory(6C, 100–150 µE m^–2 s^–1), a much strongerdepression of rubisco activity and photosynthetic capacity wasfound in all leaves, which was partly reversible in the youngones. This decrease in CO₂fixation capacity, in turn, led toa higher susceptibility of the chilled plants to photoinhibitionat 20C. It is concluded that the decrease of both photosyntheticcapacity and growth after long-term chilling in tomato is aconsequence of the preceeding ageing and senescing of the leavesduring chilling, in contrast to chilling-tolerant species withthe ability for acclimation to low temperatures. (Received April 26, 1993; Accepted September 7, 1993)     

外源24-表油菜素内酯对弱光胁迫下番茄幼苗生长及光合作用的影响

以弱光敏感型番茄品种‘基尔斯’为试验材料,采用营养液栽培方式,研究了外源24-表油菜素内酯(24-epi-brassinolide,EBR)对弱光(80μmol.m-2.s-1)胁迫下番茄幼苗生长、气体交换参数、叶绿素荧光参数、叶绿素含量、抗氧化酶活性和MDA含量的影响。结果显示,弱光胁迫显著影响番茄幼苗的生长和相关生理指标。而弱光下叶面喷施EBR 15d后,番茄幼苗的茎粗、地上部鲜重、干重、壮苗指数分别显著升高15.8%、29.3%、79.0%、114.5%,净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)分别显著升高34.1%、46.3%、35.9%,叶绿素荧光参数Fv/Fm、ФPSⅡ、ETR分别升高21.0%、15.4%、16.7%,SOD、POD、CAT和APX活性分别升高16.7%、31.8%、32.7%、51.2%,株高、叶面积、胞间CO2浓度(Ci)、叶绿素总量、MDA含量分别下降9.8%、13.9%、0.9%、13.2%、19.5%。研究表明,适量外源EBR可以通过增强保护酶系统的活性来减轻弱光胁迫造成的膜脂过氧化伤害,有效解除弱光胁迫下番茄幼苗光合作用减弱的非气孔限制因素,维持光合活性,促进幼苗生长。     

Growth and Nitrogen Accumulation in Young Tomato Plants Treated with Gibberellic Acid

The effects of foliar sprays of gibberellic acid (GA) on thegrowth of tomato plants cv. Potentate were studied in growthrooms and a glasshouse. Four sprays of GA (5 ppm) increasedleaf area and whole plant weight relative to water controlsgrown at constant temperatures (7, 17, 22, and 27 °C) for12 days, the largest plants being obtained with 5 ppm. Experimentsmade at four photoperiods (5, 10, 15, and 20 h) and at two lightintensities (7000 and 10 750 lx) showed that GA increased leafand whole plant weight at 15 h, leaf area at 10 and 15 h andstem height at all photoperiods; area, height, and weight increaseswere obtained at both light intensities, leaf growth being increasedmore by GA at 7000 lx and stem growth more at 10 750 lx. Four foliar sprays of GA (5 ppm) were combined with N supplementsapplied via leaf and/or root to plants in sand culture. Withlow supply to the roots (20 ppm N) GA failed to increase growth,but increased it at higher levels. Total N in leaf and stemwas increased by GA or by NH₄NO₃ (10 sprays 280 ppm N) at alllevels of N supplied to roots, but when applied together theeffect on total leaf N was more than additive except at thehighest level (540 ppm) GA increased the concentration of N(as per cent dry matter) in leaf and stem at all levels of Nsupplied to roots. GA and NH₄NO₃ together resulted in a greateramount and a higher concentration of N in the shoots (and usuallyalso in roots) than did NH₄NO₃ alone. Leaf thickness (as freshweight/unit area) could only be increased appreciably by sprayingwith a complete nutrient solution which reduced leaf area butnot dry weight. Growth increases induced by GA were detectable 43 days afterthe first of four sprays in the glasshouse and after 30 daysin the growth room. The persistence of GA effects was comparedwith those induced by sprays of NH₄NO₃.     

Effects of Waterlogging on the Gibberellin Content and Growth of Tomato Plants

Flooding of tomato roots results in decreased stem growth. Wehave shown that flooding will reduce levels of gibberellins(GA) in the roots, shoots, and bleeding sap of tomato plants.The adventitious roots that appear on the third day of waterloggingmay be responsible for the production of GA that accumulatein the shoot after 3 to 4 days of flooding. The endogenous GAof tomato will stimulate stem growth of tomato plants. Initially,application of gibberellic acid (GA₃) will stimulate the growthof flooded plants to a greater extent than that of nonwaterloggedplants. It is suggested that one of the first effects of floodingis to reduce GA levels and so inhibit stem elongation. At alater stage of waterlogging GA₃ is less effective and otherfactors appear to inhibit shoot growth.     

An Analysis of the Effects of Tobacco Mosaic Virus on Growth and the Changes in the Free Amino Compounds in Young Tomato Plants

Tomato plants at the four-leaf stage were inoculated on thefirst leaf with TMV in a growth room and the effects studiedin systemically-mfected leaves with reference to growth, virusmultiplication and changes in water, nitrogen, nitrate and chlorophyllcontents. Parallel changes in the free amino compounds werealso studied in the growth room (incident radiation 152 mwhcm^-2 day^-1) and in two experiments in a glasshouse (352 and226 mwh cm^-2 day^-1) Dry matter accumulation and leaf expansion in leaves 3, 4 and5 were checked by TMV 5–7 days after inoculation but notin leaf 2. In the period 7–25 days after inoculation therelative growth rates of whole plant and leaves 3 and 6 andnet assimilation rate were not affected by TMV. Stem heightand dry weight were not affected by TMV but ‘root’dry weight was reduced from days 5–15. Virus was presentin the stem and in leaves 2 and 6 by days 3, 5 and 15 respectivelyso that infection per se did not always check growth. Chlorophyllcontent of systemically-infected leaves was reduced 10 daysafter inoculation. Total N and ammonia contents were not affectedby TMV but infected leaves contained less nitrate. At the two lower levels of incident radiation the initial effectof TMV was to reduce the content of total free protein aminoacids and amides, which were minimal 5–7 days after inoculation.In the glasshouse experiment a reduction could be measured only1 day after inoculation or before virus was present in the youngerleaves. With high incident radiation there was no initial reductionbut an increase at day 13 when mottling symptoms were visible.Total non-protein amino acids, of which amino butyric acidwas the major constituent, were increased by TMV in all threeexperiments for up to 13 days after inoculation. It is suggested that inoculation of a leaf with TMV temporarilyinterferes with export of photosynthates and import of root-synthesisedamino acids and that the results reported above can be interpretedin this context. Evidence in support of this is adduced froman experiment in which 13 foliar sprays of gibberellic acid(2·5 ppm) were combined with TMV inoculation and thechanges in free amino compounds followed. It is concluded that analyses of the changes in individual freeamino compounds are unlikely to provide useful information concerningthe sources of virus coat protein.     

Effects of Far-red Light on the Hormonal Control of Side Shoot Growth in the Tomato

Side shoot growth in young tomato plants was almost completelysuppressed by a 5 min period of far-red light immediately followinga 16 h photoperiod from fluorescent tubes, whereas plants givenan identical photoperiod but lacking the far-red treatment branchedprofusely. The influence of far-red light on the degree of sideshoot suppression and the correlated changes in the levels ofauxins, gibberellins, cytokinins and abscisic acid is presentedand discussed in relation to current hypotheses of correlativeinhibition. It is suggested that far-red light causes increasedauxin synthesis in the apex and young leaves, which in turninduces the formation of abscisic acid in or near the axillarybuds, and it is this hormone which inhibits bud outgrowth. Therole of cytokinins and gibberellins remains uncertain but theyprobably act in a sequential manner, the gibberellins promotingbud growth following cytokinin-mediated release from apicaldominance.     

Effects of Some Growth Regulators on Young Iron Deficient Maize Plants

Young maize plants, grown hydroponically, were supplied with 1/10 the optimal amount of iron (0.75 mg dm^–3). Foliar treatments with solutions, containing N⁶-benzyladenine (BA), indole-3-acetic acid (IAA) or (2-chloroethyl)-trimethylammoniumchloride (CCC) were conducted after chlorosis had been well manifested. Changes in growth, chlorophyll content, rate of photosynthesis, catalase and peroxidase activities in leaves, and the contents of Fe, Cu, Zn, Mn, and P in leaves were recorded. Growth regulators improved (CCC, IAA) or aggravated (BA) the physiological state of chlorotic plants. Their effect might be explained by changes in Fe transport towards the leaves, by increased efficiency of Fe utilization, and by effects on plant metabolism not involving Fe.     

不同光质LED弱光对樱桃番茄植株形态和光合性能的影响

基于新型LED光源研究了不同光质弱光对樱桃番茄植株形态和光合性能的影响.结果显示:(1)红蓝光(RB)的基础上添加不同的光色处理,对植株的形态没有显著影响,但对植株生物量有显著影响,能调节生物量的分配.除红蓝黄绿紫复合光处理(Z)外,其他复合光处理的单株总生物量都大于RB处理,添加绿光、黄光、紫光和黄紫光有利于植株地上部的生长,而添加绿光和紫光却抑制植株地下部的生长.(2)除红蓝黄紫复合光(RBYP)和红蓝紫复合光(RBP)处理外,所有处理的光合色素含量都比RB处理高,并以Z处理光合色素含量最高.(3)叶片的光补偿点和表观量子效率以及净光合速率受光质的调控.RBYP处理的最大净光合速率和表观量子效率显著大于其他处理,光补偿点在红蓝绿复合光(RBG)和红蓝黄复合光(RBY)下较大,而在白光(CK)和Z处理下较小.(4)各处理光系统Ⅱ的光能分配存在差异,RB处理光化学淬灭系数较其他处理小,而Z和RBP的非光化学淬灭系数较小,各处理间最大光化学效率及电子传递速率无显著差异.研究发现,复合光质的光色间对植株生长发育的影响是相互协同、相互制约的关系;红蓝黄紫复合光处理植株光合潜能较大,能够在一定程度上缓解红蓝弱光胁迫,促进植株幼苗生长;在红蓝光基础上添加其他光色有利于植株光合色素的积累并促进光合,同时可提高植株光化学效率.     

Environmental Effects on the Diurnal Accumulation of 45Ca by Young Fruit and Leaves of Tomato Plants

Diurnal uptake and distribution of ⁴⁵Ca in young fruiting tomatoplants were assessed 12 or 24 h after ⁴⁵Ca was applied to thenutrient solution at the beginning of either the light (12 h)or the dark (12 h) period. During the experiment, the salinityof the nutrient solution (measured as electrical conductivity,EC) was either 2·5 or 17 mS cm^–1 and the relativehumidity (measured as vapour pressure deficit, VPD) was either0·2 or 0·6 kPa The uptake of ⁴⁵Ca by a tomato plant over 12 h was higher inthe light than in the dark but the difference was less at lowhumidity. More ⁴⁵Ca was transported from the roots to the shootin the light than in the dark. More than half of the ⁴⁵Ca inthe shoot was accumulated by the stem; the proportion of ⁴⁵Cain the stem was greater in the dark and was further enhancedby high humidity to more than 80% of the ⁴⁵Ca in the shoot.The accumulation of ⁴⁵Ca by the fruit truss in the dark wasgreater than in the light in all experimental conditions. Underlow humidity the accumulation of ⁴⁵Ca by young leaves was similarin both light and dark. In high humidity there was considerablyless accumulation of ⁴⁵Ca by the young leaves in the dark The uptake of ⁴⁵Ca continued over 24 h but the transport of⁴⁵Ca to individual organs in the second 12 h period was affectedby both light and humidity. Some of the ⁴⁵Ca accumulated byyoung leaves and fruit in the second period appears to havebeen derived from ⁴⁵Ca released from the xylem wall along thetransport pathway in the stem The roles of root pressure and transpiration in the diurnalaccumulation of calcium in young fruit and leaves are discussed Calcium, diurnal translocation, tomato, young fruit and leaves     

低温弱光对以色列番茄幼苗生长及生理指标的影响

用以色列引进品种F-044和安徽省地区主栽品种皖红3号番茄为材料,研究在不同低温(10℃/5℃)弱光(60μm ol.m-2.s-1)处理下及恢复过程中,番茄幼苗生长及生理指标的变化。结果表明:各处理指标变化趋势相同;10℃低温弱光处理后,番茄幼苗生长势、叶片叶绿素含量及超氧物歧化酶(SOD)、过氧化氢酶(CAT)活性下降,而过氧化物酶(POD)活性、丙二酶(MDA)含量,根冠比上升。各指标在恢复期内均能恢复到对照水平;5℃低温弱光胁迫后,F-044仅地上部分干物质积累受胁迫影响,根冠比上升了14.97%,而皖红3号因地下干物质积累减少显著,根冠比则下降了27.74%;各处理下F-044的各项指标变化、恢复情况均显著好于皖红3号,低温弱光耐性强于皖红3号。     

CO2-Enrichment and photosynthetic photon flux affect the growth of in vitro-cultured apple plantlets

Micro-cuttings (shoots with two small leaves) of cultivar M9 apple were cultured in-vitro for 40 d under CO₂-enriched and non-enriched (i.e., ambient air) conditions, and at a PPF of 40 or 100 μmol m^-2 s^-1 Afterward, shoot length, number of leaves, leaf area, chlorophyll content, shoot and root fresh weights, and % survival were recorded. Those plant-lets grown under CO₂- and PPF-enriched treatments were healthy and vigorous, and showed higher values for their growth parameters. In contrast, those grown without supplemental CO₂ or PPF often showed hyperhydricity. We also demonstrated that CO₂ enrichment and a relatively high PPF during in-vitro culture promoted normal photosynthesis and growth after ex-vitro transplantation.     

Long-Term Chilling of Young Tomato Plants under Low Light. IV. Differential Responses of Chlorophyll Fluorescence Quenching Coefficients in Lycopersicon Species of Different Chilling Sensitivity

Temperature dependences of chlorophyll fluorescence quenchingcoefficients were studied in the cultivated tomato (Lycopersiconesculentum) and three lines of the chilling-tolerant L.peruvianumfrom different altitudes, i.e. LA 1373 (20 m a.s.l.), LA 2157(1,650 m a.s.l.) and LA 385 (2,400 m a.s.l.). At actinic lightintensity near light saturation of photosynthesis (370 µEm^–2 s^7minus;1), photochemical quenching (qP) increasedwith increasing temperature between 5 and 30°C. The temperature,at which qP reached the numerical value 0.5 [T (qP=0.5)] decreasedby 2.5–4.5°C after a chilling treatment of 14 daysat 10°C in L. peruvianum, indicating acclimation of thephotosynthetic dark reactions in this species. The final T (qP=0.5)attained after chilling could be arranged in the order L.esculentum>LA1373>LA 2157>LA 385. The fast relaxing non-photochemicalquenching (qN) component (qf, consisting mainly of energy-dependentquenching, qE) exhibited minima near the optimum temperaturefor photosynthesis. These minima shifted to lower temperaturesupon chilling in L. peruvianum. Photoinhibitory quenching (ql)was unaffected by chilling in the high altitude lines, but-increasedstrongly in LA 1373 and L. esculentum. Under low actinic light(40 µE m^–2 s^–1), temperature dependences ofqP and qN were nearly identical in L. esculentum and LA 385and revealed abrupt changes at approx. 8°C. It is concludedthat qP and ql, measured after defined chilling treatments,are valuable screening parameters for chilling tolerance inearly growth stages of Lycopersicon plants. (Received November 2, 1993; Accepted February 28, 1994)