Dry Matter Distribution between the Shoot and Storage Root of Carrot (Daucus carota L.): I. Comparison of Varieties

The distribution of dry matter between shoot and storage rootof a wild variety and cultivars of carrot was investigated ina glasshouse experiment and a field experiment. In both experimentsthe deliberate introduction of variation in plant size revealeda linear relationship between the log weights of these partsat any time throughout growth. In the glasshouse experiment,in which growth was examined from approximately 10–600mg mean dry wt per plant, the slope of the relationship betweenIn shoot and In storage root dry wts decreased markedly duringdevelopment to 100 mg. Subsequently the slope became reasonablyconstant and the intercept progressively more negative. Datafrom the field experiment covered a similar timescale (48–115days) to the glasshouse experiment but the plants grew morequickly and were much heavier (180 mg–6 g dry wt). Therelationship between shoot and storage root for these data wassimilar to that for the plants of comparable size in the glasshouseexperiment. Over the range of development for which the slopeof the relationship was constant, data from both experimentswere described fairly well by the following equations: In shoot = – time+ In storage root where , and are constants. Between cultivars the slope ()and time constant () were similar, but the intercept () increasedwith maturity time of the cultivars. For wild carrot the slopewas larger and the time constant smaller than estimates forthe cultivars. These results on dry matter distribution arediscussed in relation to a model for partitioning assimilatein an individual plant. Daucus carota L., carrot, assimilate distribution, dry matter distribution, storage root, partitioning model     

Dry Matter Distribution Between the Shoot and Storage Root of Carrot (Daucus carota L.): II. Effect of Foliar Application of Gibberellic Acid

The effects of foliar sprays of gibberellic acid (GA) on drymatter distribution in carrots were investigated in three fieldexperiments between 1977 and 1979. The results were interpretedby using a simple quantitative model of assimilate partitioningbetween storage root and shoot. Although the response to GAvaried depending on the year in which the experiment was done,the model successfully described the effects of spraying time,GA concentration, planting density, plant age and cultivar.The maximum effects on repartitioning were achieved with concentrationsof 100–500 mg 1_–1 GA and, except for very earlyor late sprays, the effect was constant with time over a roughly4-week period. The multiplicative nature of the model was usefulin that despite the occurrence of various interactions, a similarassimilate partitioning response to GA in all four cultivarswas demonstrated. The model did not suggest an explanation forthe seasonal effects. Daucus carota L., carrot, assimilate distribution, dry matter distribution, storage root, gibberellic acid, partitioning model     

Survival of Tillers and Distribution of Dry Matter between Ear and Shoot of Barley Varieties

Plants of Plumage Archer barley grown in pots produced moreshoots than did Proctor, but had fewer ears at maturity, becausesome shoots died about 7 days before ear emergence. The numberand position on the plant of the shoots that died were consistentfor particular growing conditions. Shoots that died were notalways the last to be produced. There were no consistent differencesin dry weight, leaf area, nitrogen content, or apex developmentbetween shoots that did and did not survive; nor did removingthree developing ears on older shoots affect the survival ofother shoots. Growth of Plumage Archer plants was not checkedby death of shoots; dry matter, nitrogen, and leaf area wereredistributed so that increase in surviving shoots compensatedfor losses in the dead shoots. The dry-weight ratio of ear to shoot was smaller for Proctorthan for Plumage Archer at ear emergence and anthesis, but atmaturity it was greater for Proctor, both when ears were shadedto prevent them photosynthesizing and when they were unshaded.The varietal difference in ear: shoot dry-weight ratio was reversedbecause the relative growth-rate of ears of Proctor was greaterand because more dry matter was lost from its shoots. Both changesmay have been caused by translocation to the ear of a greaterproportion of the assimilate from the shoots of Proctor thanof Plumage Archer. Leaves of Proctor appeared to be more efficientin producing dry matter for the ear than those of Plumage Archer.     

Distribution of Dry Matter between Ear and Shoot of Plumage Archer and Proctor Barley grown in the Field

In a field experiment where Proctor barley yielded slightlymore grain than Plumage Archer but had similar total dry weight,the dry-weight ratio of ear to shoot was greater for PlumageArcher than for Proctor at ear emergence and greater for Proctorat maturity, as in a previous pot experiment. When ears wereshaded, the ear: shoot dry-weight ratio at maturity of Proctorwas not significantly greater than that of Plumage Archer. Thevarietal difference in ear: shoot ratio was reversed becauseears of Proctor had a greater relative growth-rate than earsof Plumage Archer, apparently because they photosynthesizedmore. Proctor shoots decreased in weight slightly less thanshoots of Plumage Archer.     

Effect of Root and Shoot Meristem Temperature on Shoot to Root Dry Matter Partitioning and the Internal Concentrations of Nitrogen and Carbohydrates in Maize and Wheat

Maize (Zea mays L.) and spring wheat (Triticum aestivum L.)were grown in nutrient solution at uniformly high air temperature(20 °C), but different root zone temperatures (RZT 20, 16,12 °C). To manipulate the ratio of shoot activity to rootactivity, the plants were grown with their shoot base includingthe apical meristem either above (i.e. at 20 °C) or withinthe nutrient solution (i.e. at 20, 16 or 12 °C). In wheat, the ratio of shoot:root dry matter partitioning decreasedat low RZT, whereas the opposite was true for maize. In bothspecies, dry matter partitioning to the shoot was one-sidedlyincreased when the shoot base temperature, and thus shoot activity,were increased at low RZT. The concentrations of non-structuralcarbohydrates (NSC) in the shoots and roots were higher at lowin comparison to high RZT in both species, irrespective of theshoot base temperature. The concentrations of nitrogen (N) inthe shoot and root fresh matter also increased at low RZT withthe exception of maize grown at 12 °C RZT and 20 °Cshoot base temperature. The ratio of NSC:N was increased inboth species at low RZT. However this ratio was negatively correlatedwith the ratio of shoot:root dry matter partitioning in wheat,but positively correlated in maize. It is suggested that dry matter partitioning between shoot androots at low RZT is not causally related to the internal nitrogenor carbohydrate status of the plants. Furthermore, balancedactivity between shoot and roots is maintained by adaptationsin specific shoot and root activity, rather than by an alteredratio of biomass allocation between shoot and roots.Copyright1994, 1999 Academic Press Wheat, Triticum aestivum, maize, Zea mays, root temperature, shoot meristem temperature, biomass allocation, shoot:root ratio, carbohydrate status, nitrogen status, functional equilibrium     

The Effects of Aqueous Extracts of Red Beet Root on Salt Accumulation and Respiration of Discs of Red Beet Root

An account is given of the preparation of aqueous extracts ofred beet root which are shown to stimulate potassium uptakein beet discs washed for a short period, but inhibit potassiumuptake in discs washed for four days or more. Analysis of extractsshowed them to contain organic anions (especially citrate andmalate) which affect both the metabolic phase of potassium uptakeand respiration of the tissue. The effects of extracts and organicacids on uptake of manganese by beet discs is described andcompared with effects on potassium absorption. The results arediscussed with respect to current theories of salt accumulationand in relation to the hypothesis relating an inhibitor of saltaccumulation to the lag phase of ion uptake by beet discs.     

Investigation of Quantitative Relationships in Dry Matter Distribution Between Tops and Storage Roots in Sugarbeet

Data from both controlled environment and field experimentson sugarbeet are used to support the concept that dry matterdistribution between top and storage root growth can be adequatelyquantified by over a large part of the growing season. Very young plants,prior to cambial ring development, had higher slopes for thelog-log relationship at each harvest. Estimates of the slopesbecame relatively constant about 30 d after emergence indicatingthat the pattern for dry matter distribution was determinedat an earlier stage of growth than is apparent from considerationof linear growth scales. Estimates of and are similar to thosereported for other storage root crops with differences in reflectingrelative size differences. Differences in applied N in the fieldwere detected as a shift in the intercept of the relationshipfor dry matter distribution. In general, the results with sugarbeetare agreement with the Barnes' model, which relates assimilatepartitioning to relative sink activities, respiration rates,and initial weights of plant parts. Beta vulgaris L., sugarbeet, dry matter distribution, assimilate partitioning, storage root, growth pattern, nitrogen, root/shoot weight     

The Effect of Photon Flux Density and Duration of the Photosynthetic Period on Growth and Dry Matter Distribution in Carrot

The distribution of dry matter between shoot and storage rootof carrot plants grown in light regimes varying in intensity,duration and integral, is used to test an hypothesis for thecontrol of assimilate partition Results from seven varietiesshow that shoot to storage root weight ratios are affected bythe light environment, but that these effects are associatedwith the effect of light on plant size It is concluded thatquantitative alterations to the supply of assimilate, resultingfrom variation in the light regime, do not affect its partitionto different organs This is discussed in relation to other investigationswhich have suggested a relationship between the duration ofthe photosynthetic period, assimilate sequestration in foliarstarch and partition between shoot and root Daucus carota L, carrot, assimilate partition, light intensity, daylength, shoot, storage root, shoot-root ratio, source-sink relations     

Partial Purification of Digitonin-Solubilized beta-Glucan Synthase from Red Beet Root

An enriched glucan synthase fraction was obtained from red beet root microsomes by sequential extraction with the detergents 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate and digitonin. The digitonin suspension was centrifuged on a glycerol gradient, where a glucan synthase peak with a specific activity of 30- to 40-fold over microsomes was recovered. Most protein contaminants were found in the gradient pellet. The glucan synthase-containing fraction was largely free of plasma membrane and tonoplast-derived ATPase activity and was enriched with a protein subunit of 68 kilodaltons.     

The Selective Uptake of Alkali Cations by Red Beet Root Tissue

The selective uptake of alkali cations by red beet root tissuefrom solutions of chlorides has been investigated. It is shownthat when disks are transferred from distilled water to a solutionof salts, there is a rapid initial uptake of cations which isneither particularly selective, nor directly related to metabolism.On the other hand, the prolonged active accumulation of cationsexhibits strong selectivity, Na being preferred to other ions. Evidence is presented to show that the alkali cations competewith one another for the same absorption mechanism. In thisrespect the material apparently differs from that investigatedby Epstein and Hagen, in which the operation of distinct mechanismsfor some of these ions was visualized. The validity of Epsteinand Hagen's conclusion is discussed in relation to the resultspresented here.     

An Inhibitor of Salt Absorption in the Root Tissues of Red Beet

The absorption of manganese ions by discs of beet-root tissueoccurs in two phases. Evidence suggests that the first is physicalin nature, the second physiological. The interval between thetwo phases becomes longer as the thickness of the discs is increasedand reasons are given for attributing this to the presence ofan inhibitor of the physiological absorption process. Aqueous extracts of beet-root contain an inhibitor of ion absorptionwhich also delays the germination of mustard and cress seeds.The extract does not affect the respiration rate of beet-roottissue.     

Partition of 14C Assimilate between Organs and Fractions of Contrasting Varieties of Carrot during Initiation of the Storage Root

This work examines the differences in partition and activityof ¹⁴C in two varieties of carrot (Daucus carota L.) contrastingin shoot to storage root ratio at maturity. Plants were grownin a controlled environment of 20 ?C and 500 µmol m^–2s^–1. During initiation of the storage root (10–25d from sowing) plants were exposed to ¹⁴CO₂ for 1 h and theradioactivity in ethanol-soluble and -insoluble fractions ofshoots, storage and fibrous roots estimated at various timesup to 48 h after exposure. Between 35% and 40% of radioactivityinitially present in the plants was respired during the first24 h and 25–35% of that remaining after 24 h was foundin the roots, depending on age. The proportion found in thestorage region remained fairly constant between 15 and 25 dand was smaller than at 10 d. In the variety with a larger proportionof storage root at maturity (cv. Super Sprite), there was agreater proportion of label in both ethanol-soluble and -insolublefractions of the storage region soon after storage root initiationhad begun than in the variety with a smaller proportion of storageroot at maturity (cv. Kingston). There was no varietal differencein specific activities of the storage roots, but fibrous rootsof cv. Super Sprite showed a greater specific activity thanin cv. Kingston. Differences in shoot to storage root ratiomay thus be associated with characteristics of the fibrous roots.Partition and specific activities are discussed in relationto the initiation and development of the storage organ. Key words: Daucus carota, carrot, assimilate, partition, ¹⁴C, storage root     

Vegetable Plant Part Relationships. I. Effects of Time and Population Density on the Shoot and Storage Root Weights of Carrot (Daucus carota L.)

Chantenay carrot plants were grown in replicated plots containingdensities of 25, 64, 130 and 245 plants m^–2 and harvestedon 20 weekly occasions giving a total of 360 pairs of d. wtsand 13908 pairs of f. wts of shoots (s) and roots (r). The relationshipbetween the logarithms of s and r was curved for plants sampledon successive occasions from the same density but it was linearfor plants sampled on a single occasion, both within and betweendensities. A good overall relationship was In s = a+0.805 In r, where the intercept (a) ranged in approximately equal stepsfrom +1.2 to –1.1 at the first and last harvests respectively.Except for some systematic deviation from this equation at earlyharvests, the above relationship fitted the data well irrespectiveof the wide range of density and whole plant weight. Daucus carota L. carrot, root/shoot weight, population density, growth analysis     

A Study of the Relationship between Root and Shoot Metabolism

The influence of light and dark on the respiration rate, sugarlevel, and rubidium uptake of the roots of young sunflower andbarley plants has been investigated. The rate of root respirationwas found to be closely correlated with the rate of carbohydratetransport from the shoots. This enabled the energy requiredfor root growth to be calculated. A period of darkness causeda reduction in rubidium uptake and transport which appearedto be due to the reduced rate of root metabolism in the dark.The experiments of some earlier workers on the effect of transpirationon rubidium uptake by young sunflower and barley plants wererepeated. The results indicated that they were studying themetabolic effect of light and dark on salt uptake as well asthe effect of transpiration.     

籼型三系杂交水稻地上部干物质重的发育遗传研究

采用数量性状的加性--显性发育遗传模型分析了按NCⅡ交配设计的两套籼型三系杂交水稻地上部干物质重的发育遗传规律．结果表明,在不同发育阶段,地上部干物质重以显性效应为主,控制地上部干物质重的加性效应基因几乎不表达,而显性效应基因在两年中的表达呈连续性,且在生长中期活动强度最大,环境和基因型互作会影响地上部干物质重加性效应基因的表达,而对显性效应基因表达的影响不明显,随着发育进程的推进,地上部干物质重杂种优势趋于减弱。     

Variability of Relationships between Transpiration, Shoot and Root Metabolism, and Nutrient Uptake in Intact Plants

Reasons are given for rejecting recent criticisms of methodsused in earlier work on relationships between transpirationand the transfer of nutrients to the shoots of intact plants.     

胡萝卜和白萝卜对果蝇寿命的比较效应

在玉米粉培养基上分别添加胡萝卜汁和白萝卜汁喂养果蝇 ,吃胡萝卜汁的果蝇平均寿命和最高寿命都较长 ;胡萝卜和白萝卜对果蝇生长发育的影响亦显示类似的效应差异。     

Shoot and Root Growth of Lettuce Seedlings Following Root Pruning

Hydroponically-grown lettuce seedlings with 13 to 18 primarylateral roots were root pruned in one of four ways; the rootapices were removed from the main root only (1) or from allthe root membranes (2), or half the total root system was removedwith the remaining apices left intact (3) or removed (4). Duringthe following 8 d the rate of lateral root production on prunedplants increased, decreased, and then increased again relativeto the unpruned control. Conversely, the rate of increase intotal root length decreased, then increased, and if all theroot apices were removed, declined again, prior to increasingon day 8. These changes in the rates of lateral root productionand growth resulted in similar, but less pronounced, patternsof change in the total root length and the total number of lateralroots with time. The changes in total lateral root productionwere related to differences in the rates of primary, secondaryand tertiary root emergence. The shoot d. wt of the most severely root pruned seedlings (treatment4) fell below that of the control 4 d after pruning and remainedlower than the control on day 14, whereas the root d. wt hadrecovered to the control level by day 6. The root: shoot d.wt ratio, which was reduced by root pruning, rose above thatof the control on days 6 and 8. Lactuca sativa L., lettuce, root pruning, root growth, lateral root, nutrient solution     

The Effect of Carbon Dioxide on the Absorption of Manganese by Root Tissues of Red Beet

The absorption of manganese by beetroot tissue is shown to bepartially inhibited by the presence of carbon dioxide. Preliminarytreatment of well-washed tissue slices with carbon dioxide alsoproduces, after placing them in manganese solutions, an inhibitionof absorption for a time similar to that shown by tissue sliceswhen first excised from stored roots. It is suggested that aninhibitory substance is formed in bulky storage roots and tubersby dark fixation of accumulated respiratory carbon dixoide.On cutting thin slices from such organs, the removal of inhibitormay take place by diffusion into water during washing, by reversalof the fixation reaction when the partial pressure of carbondioxide is reduced, and possibly also by oxidation to form asubstance capable of stimulating manganese absorption when sufficientlyhigh oxygen concentrations are available.