Distribution of Assimilates from Various Source Leaves During the Development of Gladiolus grandiflorus

The distribution pattern of the products of photosynthesis wasstudied in gladiolus plants (Gladiolus grandiflorus cv Eurovision)in four stages of development I, plants having a very younginflorescence still enclosed between the leaves; II, plantswith a young inflorescence just emerged from the leaves, III,plants at full bloom, IV, plants with young fruits. The first,third or sixth foliage leaf was labelled with ¹⁴CO₂, and subsequentdistribution in the plant was determined Results were expressedas a percentage of translocated ¹⁴C accumulated by each partof the plant which gives a measure of its ‘sink strength’,or as ‘relative sink activity’ (RSA) which is independentof the size of the indicated organ. There are two competing sinks in the developing gladiolus—theinflorescence and the new corm. When RSA is the criterton theinflorescence constitutes the main sink irrespective of thesource leaf from the first stage until flowering. With the subsequentwilting of the flowers and fruit set RSA of the inflorescencedeclines rapidly and the new corm becomes the main sink When‘sink strength’ is the criterton it appears thatthe inflorescence acts as a very weak sink when it is youngand becomes increasingly stronger until flowering and then declinessteeply. Sink strength of the corm declines during the developmentof the inflorescence and then increases again steeply with wiltingof the flowers and fruit set. There are small differences betweenthe various source leaves. The young new corm acts as a strongsink for the lower foliage leaf and progressively weaker forupper leaves. Gladiolus grandiflorus, flower development, corm, assimilates distribution, sink strength, relative sink activity     

Patterns of Assimilate Distribution and Source--sink Relationships in the Young Reproductive Tomato Plant (Lycopersicon esculentum Mill.)

Patterns of distribution of ¹⁴C were determined in 47-day-oldtomato plants (Lycopersicon esculentum Mill.) 24 h after theapplication of [¹⁴C]sucrose to individual source leaves fromleaves 1–10 (leaf 1 being the first leaf produced abovethe cotyledons). The first inflorescence of these plants wasbetween the ‘buds visible’ and the ‘firstanthesis’ stages of development. The predominant sink organs in these plants were the root system,the stem, the developing first inflorescence and the shoot ‘apex’(all tissues above node 10). The contribution made by individualsource leaves to the assimilate reaching these organs dependedupon the vertical position of the leaf on the main-stem axisand upon its position with respect to the phyllotactic arrangementof the leaves about this axis. The root system received assimilateprincipally from leaf 5 and higher leaves, and the stem apexfrom the four lowest leaves. The developing first inflorescencereceived assimilates mainly from leaves in the two orthostichiesadjacent to the radial position of the inflorescence on thevertical axis of the plant; these included leaves which weremajor contributors of ¹⁴C to the root system (leaves 6 and 8)and to the shoot apex (leaves 1 and 3). This pattern of distributionof assimilate may explain why root-restriction treatments andremoval of young leaves at the shoot apex can reduce the extentof flower bud abortion in the first inflorescence under conditionsof reduced photoassimilate availability. Lycopersicon esculentum Mill, tomato, assimilate distribution, source-sink relationships     

Dry Matter Partitioning in a Determinate and an Indeterminate Cultivar of Vicia faba L. Under Contrasting Plant Distributions and Densities

Models for root: shoot, vegetative: generative and stem: leafpartitioning are presented to quantify dry matter partitioningof two contrasting genotypes of Vicia faba, an indeterminateand a ‘topless’. A third plant type, a determinateof which two to three inflorescences had been removed, was alsoincluded but behaved similarly to the intact plant. The root:shoot partitioning model predicts linear relationships betweenroot proportion and the product of air vapour pressure deficitand relative growth rate. Data from field experiments were consistentwith model prediction and coefficients estimated were similarfor both genotypes. Partitioning into pods was modelled as proportionalto the number of actively growing pods younger than 1000°Cd. Coefficients estimated were similar in both genotypes butdifferent between densities and years. In the indeterminategenotype, stem: leaf ratio was allometric throughout, whereasleaf growth ceased but stem growth continued in the determinateafter formation of the terminal inflorescence. Relatively moredry matter was allocated to stems than to leaves in high thanin low densities. In conclusion, the main differences in drymatter partitioning between genotypes concern leaf: stem partitioningduring early pod filling and pod partitioning due to pod numberdifferences. Partitioning, root, shoot, leaf, stem, Vicia faba L.     

Sex expression as affected by N6-benzylaminopurine in staminate inflorescence of Luffa cylindrica

The effect of N⁶-benzylaminopurine (BA) on the sex expressionof staminate inflorescences of Luffa cylindrica was investigated.Direct application of BA to the staminate inflorescence inducedbisexual and pistillate flowers and finally caused the inflorescenceto develop into a shoot that was similar to the main shoot.Such modification in a staminate inflorescence from the proximalto the distal nodes is usually in the order of staminate flowers,bisexual flowers, pistillate flowers and foliage leaves (shoot).Pinching of the main stem also caused the inflorescence to developinto a shoot in the absence of lateral shoots. BA-induced femalenesswas strengthened when the number of leaves remaining on theplant was increased. On the other hand, application of BA tothe shoot apex of the main stem starting at the 2-leaf stagesuppressed differentiation of the flower bud on the main stem. (Received December 22, 1979; )     

Changes in Dry Matter, Carbohydrate and Seed Yield Resulting from Lodging in Three Temperate Grass Species

The adverse effect of lodging on grass seed yield may be attributed,in part, to assimilate limitation during the seed filling period.This investigation examined plant dry matter assimilate partitioningand seed yield as affected by lodging in three species thatare closely related but phenotypically different: tall fescue(Festuca arundinacea Schreber.), Italian ryegrass (Lolium multiflorumLam.), and perennial ryegrass (L. perenne L.). Studies wereperformed in field plots at Corvallis, Oregon, USA. Seed yieldcomponents (seed number per inflorescence, seed yield per inflorescence,and single seed mass) and leaf, stem (lower, middle, and peduncle)and seed inflorescence dry mass were measured just prior toanthesis to seed maturity. Dry mass and water soluble carbohydrates(WSC) were determined for shoot components. The reduction indry mass and WSC in leaves and stem components following anthesiswas often greater in lodged plants compared to upright plants.The relatively low seed yield depression in lodged tall fescuesuggested a higher compensation potential for partitioning reserveassimilate from leaves and stems to support seed growth anddevelopment. This potential does not appear to be present tothe same degree in Italian ryegrass and to an even lesser extentin perennial ryegrass. These findings suggest that the potentialto compensate for reduced assimilate supply during the periodof high assimilate demand by seeds may be attributed, in part,to the total assimilate reserve accumulated prior to photoassimilatereduction caused by the lodged condition. Copyright 2000 Annalsof Botany Company Tall fescue, Festuca arundinacea Schreber., Italian ryegrass, Lolium multiflorum Lam., perennial ryegrass, L. perenne L., assimilate partitioning, source–sink     

Evaluation of a Dynamic Simulation Model for Tomato Crop Growth and Development

A dynamic simulation model for tomato crop growth and development,TOMSIM, is evaluated. Potential crop growth and daily crop grossassimilation rate (P_gc,d) is computed by integration of leafassimilation rates over total crop leaf area throughout theday. Crop growth results fromP_gc,dminus maintenance respirationrate (R_m), multiplied by the conversion efficiency. Dry matterdistribution is simulated, based on the sink strength of theplant organs, which is quantified by their potential growthrate. Within the plant, individual fruit trusses and vegetativeunits (three leaves and stem internodes between two trusses)are distinguished. Sink strength of a truss or a vegetativeunit is described as a function of its developmental stage.In this paper, emphasis is on the interactions between the twosubmodels of, respectively, dry matter production and dry matterdistribution. Sensitivity analysis showed that global radiation,CO₂concentration, specific leaf area (SLA) and the developmentalstage of a vegetative unit at leaf pruning had a large influenceon crop growth rate, whereas temperature, number of fruits pertruss, sink strength of a vegetative unit and plant densitywere less important. Leaf area index (LAI) was very sensitiveto SLA and the developmental stage of a vegetative unit at leafpruning. Temperature did not influence the simulated R_m, asincreased respiration rate per unit of biomass at higher temperatureswas compensated by a decrease in biomass. The model was validatedfor four glasshouse experiments with plant density and fruitpruning treatments, and on data from two commercially growncrops. In general, measured and simulated crop growth ratesfrom 1 month after planting onwards agreed reasonably well,average overestimation being 12%. However, crop growth ratesin the first month after planting were overestimated by 52%on average. Final crop dry mass was overestimated by 0–31%,due to inaccurate simulation of LAI, resulting partly from inaccurateSLA prediction, which is especially important at low plant densityand in a young crop.Copyright 1999 Annals of Botany Company Crop growth, dry matter production, glasshouse, leaf area,Lycopersicon esculentum, partitioning, simulation model, tomato, TOMSIM.     

Role of Foliage Habit in the Competition Between Differently Sized Plants in Carrot Crops

The length of the tallest leaf on a plant varied considerablywithin each of three carrot crops, and in each crop there wasa high positive correlation between shoot height and root weight.Lowering the petiole angle of carrot leaves greatly reducedthe ability of plants to compete against untreated neighbours,but did not affect growth when all plants were treated similarly.Cutting treatments which produced a more uniform shoot heightfor all plants, allowed small plants temporarily to overcomethe dominance of their larger neighbours. Similar cutting treatmentsapplied in a field experiment reduced crop growth and variationin root weight. These findings support the view that shoot heightdifference is an important component of inter-plant competitionin carrot crops and hence is a source of root-weight variation. Daucus carota L., carrot, foliage habit, competition     

The effect of neighbors on the root system of the desert annualEremobium aegyptiacum

Intra-specific competition with a primary focus on root competition between plants living in an area with low resource levels, was studied using the natural monotypic population of a desert annual plantEremobium aegyptiacum (Cruciferae). We tested the effect of neighboring distance on shoot and root biomass, and such root parameters as root length, diameter of root neck, number of first order lateral roots and number of lateral roots per unit of main root length. Our results indicate a strong negative relationship between neighboring plant density and such plant parameters as shoot and root biomass, and root neck diameter. The number of first order lateral roots and the number of lateral roots per unit of main root length were negatively related to the distance between neighboring plants. Contrary to predictions, there was no influence of competition on node distribution: neither root overlap nor root avoidance was observed in pairs of adjacent plants.     

Effect of Temperature During Various Growth Stages on Grain Development and Yield of Pennisetum americanum

In controlled temperature glasshouses plant morphology, gramdevelopment and yield of pearl millet (Pennisetum americanum)were markedly affected by temperature during three stages ofplant growth: vegetative, stem elongation, and grain development.High temperature (to 33/28 °C day/night) during all threegrowth stages lowered grain yields by reducing basal tillering,numbers of grains per inflorescence, and single grain weight.Low temperature (21/16 °C) during the vegetative stage increasedbasal tillering and, as a result, total grain yield per plant.However, low temperature during the stem elongation stage reducedspikelet fertility and influorescence length, and thereby reducedthe potential main shoot grain yield. Low temperature duringgrain development increased the grain filling period and grainyield. The rate of grain filling did not vary over the rangeof 21/16 to 33/28 °C. Although plant morphology and grainyield were markedly affected by pre-anthesis thermal environment,grain development was not. At all temperatures ethanol-solublecarbohydrates stored in the stem were depleted during earlygrain development.     

Mobilization of Seedpiece Nitrogen During Plant Growth from Aged Potato (Solanum tuberosum L.) Seed-tubers

A study was conducted to characterize patterns of mobilizationand translocation of seedpiece nitrogen (N) from single-eyeseedcores cut from 5 and 17-month-old potato seed-tubers. Differencesin mobilization efficiency were related to age-induced, morphologicaldifferences in plant development. Seedcores from older seed-tuberssprouted earlier and produced an average of 6.6 shoots per eyecompared to a single shoot from younger seed-tubers. Shoot vigour(d. wt per shoot) from 17-month-old was four-fold lower thanthat from 5-month-old seed-tubers following 25 d of growth.However, total shoot dry matter from older seedcores was two-foldgreater than that from younger seedcores. Differences in vigourper shoot were not explained entirely by differences in shootnumber. Rates and absolute amounts of free amino, soluble protein andtotal-N mobilized from 17-month-old seedcores were greater thanfrom younger seedcores. However, a higher degree of intersproutcompetition from older seedcores translated into a lower amountof mobilized N available to support growth of individual shoots.Furthermore, before seedcore N became limiting, concentrationof foliar N (mg g d. wt^–1) from older seedcores was lowercompared to that from younger seedcores, indicating a lowersink strength for N per unit increase in dry weight of the multipleshoots. Seedpiece N did not appear to limit shoot growth fromyounger seedcores. Age-induced loss of vigour on an individualshoot basis may thus be related to decreased sink strength andincreased competition among multiple shoots for seedcore N. Potatoes (Solanum tuberosum L.), seed-tuber age, nitrogen mobilization, plant growth potential     

Characterization of the effects of inter-tree competition on source–sink balance in Chinese pine trees with the GreenLab model

We investigate the characteristics of individual tree response to competition on source–sink balance through the functional–structural plant model GreenLab. Four Chinese pine (Pinus tabulaeformis Carr.) trees were destructively sampled and were divided into two groups: high-density group and low-density group. First, the effects of density on organ dimensions and on organ relative mass were analysed based on experimental measurements. These were primary indicators of the plant response to competition. Second, the hidden parameters of the GreenLab model, as well as a tree-specific characteristic surface, were estimated using the data of total tree biomass for needle and wood compartments, for each of the four trees in parallel. The quality of the fitting is finally validated using data of individual organ mass at shoot level for the sampled branches. The Mann–Whitney Student’s t test showed that there were significant differences between the shoot attributes of the two groups for shoot diameter, shoot biomass and needle biomass. No significant difference was found for current year shoot lengths of the two groups. The parametric identification of the model allowed estimating and comparing the amount of biomass that was allocated to primary growth and to secondary growth in the two density conditions. It showed that biomass allocated to secondary growth (ring compartment) was the most strongly affected by density, and that the organ demand satisfaction ratio profiles of each of these trees were a relevant, integrated indicator of the tree state.     

Apical Dominance Control in Ipomoea nil: The Influence of the Shoot Apex, Leaves and Stem

The outgrowth of lateral buds is known to be controlled by theupper shoot tissues, which include the apex, the young leavesand the upper stem. An analysis of the influence of these plantparts on axillary bud elongation in Ipomoea nil was carriedout by various treatments on these specific tissues. A restriction of elongation in the main shoot due to eitherdecapitation or shoot inversion resulted in the release of apicaldominance A non-linear type of compensating growth relationshipwas observed between the 13 cm apical growing region of thestem and the lateral buds. It was determined by decapitation,defoliation and AgNO₃ treatments that both the 13 cm stem-growthregion and the young leaves (1–5 cm in length) had a muchgreater inhibitory influence on the outgrowth of specified lateralbuds than did the stem apex (consisting of the terminal 0.5cm of the shoot). The specified lateral buds which were analyzedfor outgrowth were located a number of nodes below the shootapex. The intervening nodes were debudded. Although the importanceof young leaves in the control of apical dominance has beenpreviously recognized, the most significant result from thepresent study with Ipomoea was the strong influence of the 13cm apical growth region of the stem on the out growth of thelateral buds. Apical dominance, Ipomoea nil L., Pharbitis nil, growth region, lateral bud outgrowth, decapitation, defoliation, shoot inversion     

Central Die-back of Monoclonal Stands of Reynoutria japonica in an Early Stage of Primary Succession on Mount Fuji

Reynoutria japonica is a common perennial pioneer species onJapanese volcanoes. In a volcanic desert (1500m above sea level)on Mount Fuji (3776m), central Japan, this species forms circularstands (patches). As a patch develops, shoot density decreasesin its centre (‘central die-back’). The centraldie-back has been considered a key process in the early stagesof primary succession, though its mechanism has been unknown. The pattern of patch development, population dynamics of aerialshoots, and growth patterns of below-ground organs were analysedin order to investigate the mechanism of die-back, and the followingtraits are clarified: (1) central die-back areas occur in mostsmall patches (approx. 1m²) without later successional species;(2) shoot characteristics are dependent both on their positionwithin a patch and on patch size; (3) despite the large differencesin shoot density, neither time course of shoot growth nor theirmortality differs between the centre and periphery of patches;and (4) rhizomes ofR. japonicagrow outwards with regular sympodialbranching. From these results, it is concluded that neither interspecificnor intraspecific competition is likely to be a primary causeof the die-back phenomenon, but that central die-back is broughtabout intrinsically by the growth pattern of the rhizome systems.We also discuss the importance of the central die-back in facilitatingestablishment of later successional species in the early stagesof primary succession. Clonal plant; central die-back; competition; facilitation; Japanese knotweed; Mount Fuji; primary succession;Reynoutria japonica ; rhizome growth; volcanic desert     

The Hexagonal Branching Pattern of Rhizomes of Alpinia speciosa L. (Zingiberaceae)

Alpinia speciosa L. (Zingiberaceae) is a striking example ofa plant in which an organized architectural structure fulfilsa basic functional requirement - the economical explorationand exploitation of the substrate. This rhizomatous plant spreadslaterally in a predictable manner by vegetative growth to forma clone of separated ramets. A morphological study establishes‘rules of growth’ governing the success and failureof lateral branches (sympodial units), their lengths, and theirrelative angles. The basic branching pattern of this rhizome system approximatesto that of a hexagonal grid - the most economical structuralshape that uniformly ‘samples’ a plane surface.It is shown that the significant deviation of branching anglefound in Alpinia from that required to develop an exact hexagonalnetwork will virtually eliminate aerial shoot ‘clashes’in which the placing of one aerial shoot coincides with thatof another aerial shoot, whilst at the same time enhancing thebenefits of the hexagonal system. The broader implications ofthe organised architecture of plants are emphasised. rhizome, branching pattern, architecture, productivity     

Interactions of the Growth Retardants Daminozide and Piproctanyl Bromide, and Gibberellins A1, A3, A4+7, A5 and A13 in Stem Extension and Inflorescence Development in Chrysanthemum morifolium Ramat

Interactions between the growth retardants daminozide (a substitutedsuccinamic acid) or piproctanyl bromide (a quaternary ammonium,piperidinium compound), and a subsequent application of a singledose (40 µg) of either gibberellin A₁, A₃, A₄₊₇ or A₁₂,showed that, in Chrysanthemum morifolium Ramat. cv. Bright GoldenAnne, a strong interdependence exists between elongation ofthe lateral shoot and the rate of development of its terminalinflorescence. A₁, A₃, and A₄₊₇ were highly active in overcoming the restrictionson both internode extension and the rate of flower-bud developmentimposed by either retardant, suggesting that these two retardanteffects are caused by a deficiency of active gibberellins (GN).In the absence of retardant, A₁, A₃, and A₄₊₇ markedly increasedstem elongation, and flowering occurred earlier than in plantsreceiving neither retardant nor GN. A₁₃ the only 20-carbon GNtested, was much less active, while A₅ had a relatively greatereffect on the time of flowering than on shoot elongation. Thus,it is not necessarily the rate of stem extension which determinesthe rate of inflorescence development. The response to different amounts of A₁, A₃ or A₁₃ (1, 5, 10,20, or 50 µg per shoot) neither suggest that different‘threshold’ levels of a particular GN are requiredto induce increases in either stem elongation or in the rateat which inflorescences develop, nor did a change in the dosegiven lead to any consistent differential effect on these twoprocesses. Chrysanthemum morifolium Ramat., stem extension, inflorescence development, growth retardants, gibberellins     

Correlative Inhibition in the Shoot of Agropyron repens ( L.) Beauv

Correlative inhibition was investigated in plants of Agropyronrepens at two temperatures. Reciprocal inhibition ocrurred betweenthe main shoot apex and the outgrowing axillary shoots, withthe balance of inhibition varying with temperature. Apical dominancewas stronger at 10 °C than at 20 °C , but even at 10°C release of apical dominance by decapitation had onlyminor effects on the timing of outgrowth, growth pattern andrate of dry weight aocumulation of the axillary shoots. Dominanceof the main shoot apex by the axillary shoots was stronger at20 °C than at 10 °C. Removal of axillary buds preventeddecline in size and activity of the main shoot apex ard resultedin increased rates of primordium initiation, leaf emergenceand dry weight accumulation in the main shoot. It is suggestedthat a system of reciprocal dominance provides a mechanism formaintaining the characteristic habit of the grass plant andlimits growth in height of vegetative shoots. Agropyron repens (L.) Beauv, couch grass, correlative inhibition, apical dominance, shoot, apex     

Phenotypic Diversity and Patterns of Variation in West and Central African Plantains (Musa Spp., AAB group Musaceae)

Plantains (Musa spp., AAB group) are an important food crop and an integral component of the farming systems in the lowland humid forest zone of West and Central Africa. A group of 24 plantain cultivars, representing the major variability in West Africa, was evaluated for nine quantitative characters. The association between growth and yield parameters in this African plantain germplasm was examined to determine if the pattern of quantitative variation in inflorescence and vegetative traits agreed with taxonomic groupings based on inflorescence type and plant size. Phenotypic correlations between these traits were calculated. Giant cultivars were taller, their pseudostem thicker, and they flowered much later than medium-sized cultivars. Giant cultivars produced more foliage, resulting in heavier bunches with more hands and fruits. Groupings that resulted following principal component analysis (PCA) supported conventional taxonomic groupings of plantains. PC A was based mainly on time to flowering, pseudostem height, and number of fruits. The last two traits, in combination with the number of hermaphrodite flowers and the persistence of the male bud, sufficed to group plantain cultivars.     

Biomass Accumulation and Main Stem Elongation of Durum Wheat Grown under Mediterranean Conditions

Detecting and exploiting genetic variation in biomass accumulationis of great importance for increasing wheat yield when the harvestindex is close to its upper limit. This study was undertakento analyse the pattern of biomass accumulation and main stemelongation in 25 durum wheat (Triticum turgidum L. ‘Durum’)genotypes. Field experiments were conducted over 2 years intwo environments contrasting in the amount of available water,in northeastern Spain. Plants were sampled at the main stagesof Zadoks' scale, and dry weight per plant, crop dry weight(CDW) and main stem length were measured at each stage. Measurementsfor growth traits and thermal time from sowing fitted betterto an asymmetric logistic peak curve than to the Richards logisticmodel. Four biological variables were computed from the curve.Differences among curves describing changes in biomass werefound to be greater between irrigated and rainfed sites thanbetween years. Drought stress had less effect on main stem elongationthan on biomass accumulation. Average dry weight per plant andCDW were reduced by drought by 42 and 38%, respectively, duemainly to similar reductions in the mean rate of growth of thetwo variables. In contrast, cycle length from sowing to themaximum values of dry weight per plant and CDW was only slightlymodified by drought. Copyright 2001 Annals of Botany Company Triticum turgidum L. ‘Durum’, durum wheat, biomass, crop dry weight, stem length, rate of growth, modelling, growth analysis, logistic peak curve     

Influences of Certain Plant Factors on the Growth and Fruiting of the Lower Axillary Shoot of Lycopersicon esculentum Mill

Excision of the first inflorescence at diffrent stages of development,emasculation of the anthers before anthesis, and excision of of the entire root system at transplanting significantly enhahcedthe growth and fruiting of the axillary shoot located directlybelow the first inflorescence of Lycopersicon esculentum Mill.cv. Fireball. Replacement of the inflorescence with a combinationof indol-3yl-acetic acid, gibberellin A_4/7 and N⁶-benyladenineat 5 x 10^–4 M concentration in lanolin delayed the timefor the axillary shoot to attain a length of 20 cm. Enchancementof growth and fruiting of the auxillary shoot below the firstinflorenscence was attributed to a greater availability of assimilate.     

Effects of Low Temperature on Growth and Nutrient Accumulation in Rye (Secale cereale) and Wheat (Triticum aestivum)

Rye (Secale cereale cv. Rheidol) and wheat (Triticum aestivumcv. Mardler) were grown at shoot/root temperatures of 20/20°C (warm grown, WG plants), 8/8 °C (cold grown, CG plants)and 20/8 °C (differential grown, DG plants). Plants fromcontrasting growth temperature regimes were standardized andcompared using a developmental timescale based on accumulatedthermal time (°C d) at the shoot meristem. Accumulationof dry matter, nitrogen and potassium were exponential overthe time period studied (150–550 °C d). In rye, therates of plant dry matter and f. wt accumulation were linearlyrelated to the temperature of the shoot meristem. However, inwheat, although the rates of plant dry matter and f. wt accumulationwere temperature dependent, the linear relationship with shootmeristem temperature was weaker than in rye. The shoot/rootratio of rye was stable irrespective of growth temperature treatment,but the shoot/root ratio of wheat varied with growth temperaturetreatment. The shoot/root ratio of DG wheat was 50% greaterthan WG wheat. In both cereals, nutrient concentrations anddry matter content tended to be greater in organs exposed directlyto low temperatures. The mean specific absorption rates of nutrientswere calculated for the whole period studied for each species/temperaturecombination and were positively correlated with both plant shoot/rootratio and relative growth rate. The data suggest that nutrientuptake rates were influenced primarily by plant demand, withno indication of specific nutrient limitations at low temperatures. Nutrient accumulation, relative growth rate (RGR), rye, Secale cereale cv. Rheidol, temperature, thermal time, Triticum aestivum cv. Mardler, wheat