The Influence of Mineral Nutrition on the Root Development of Trees: I. THE GROWTH OF SITKA SPRUCE WITH DIVIDED ROOT SYSTEMS

Sitka spruce seedlings were grown with their root systems dividedbetween two contrasting nutrient regimes. One half of the rootsystem was supplied with a solution containing N, P, and K ata range of concentrations while the untreated half receivedwater only. High-nutrient treatments induced two flushes ofshoot growth resulting in a large shoot system, whereas plantsin the low-nutrient treatments flushed once only and showedsymptoms of nutrient deficiency. Root growth, assessed in terms of dry weight and diameter ofboth primary and woody tissues, was stimulated in the rootsto which the nutrients were actually applied, whereas in theuntreated roots on treated plants only the primary root diameterwas enhanced. However, internal nutrient concentrations on bothsides of the root system were related to the concentrationsapplied, though to a slightly lesser extent in the untreatedroots. Thus, the nutrients which had been internally translocatedto the untreated roots had little effect on their growth. The localized stimulation of xylem production in the woody rootsextended into the stem along a spiral pathway which was demonstratedby the movement of dye. Possible mechanisms are discussed by which differential rootgrowth is brought about by a localized supply of mineral nutrients.     

The Influence of Mineral Nutrition on the Root Development of Trees: II. THE EFFECT OF SECIFIC NUTRIENT ELEMENTS ON THE GROWTH OF INDIVIDUAL ROOTS OF SITKA SPRUCE

Sitka spruce seedlings were grown with divided root systemsin sand culture and the application of N, P, and K was variedwhile maintaining a complete supply of other nutrients. Therewas a localized stimulation of the growth of roots to whichnutrients were applied and N produced the greatest stimulation;P was also important but K did not enhance growth. Measurements of Ca and Mg concentrations in the roots showedthat differential root growth, which is influenced by the concentrationof N and P in the bathing medium, could not be adequately explainedby the effect of N or P on the uptake of the immobile cations. The two parts of the divided root system appeared to competefor assimilates; the enhanced growth of one root was accompaniedby reduced growth in the other, and vice versa.     

PHENOTYPIC PLASTICITY IN POLYGONUM PERSICARIA. III. THE EVOLUTION OF ECOLOGICAL BREADTH FOR NUTRIENT ENVIRONMENT

Norms of reaction for a number of growth and reproductive characters were determined for 15 randomly sampled Polygonum persicaria genotypes, from two natural populations originating in sites with very different nutrient availabilities. Under severely limiting nutrient conditions, these genotypes shared not only plastic responses such as increased root-to-shoot ratio, but a surprising constancy in such functionally essential characters as leaf area ratio, leaf nitrogen concentration, and propagule nitrogen content. Because functional homeostasis depends on flexibility in underlying characters, similar homeostatic results can be achieved through different combinations of underlying plastic and fixed responses in genetically different entities. For example, plants in each population maintained a relatively constant propagule nitrogen content under extreme low-nitrogen conditions by varying either the size or the tissue nitrogen concentration of propagules. These genotypes also tolerated excessive nutrient levels toxic to many plants, evidently by storing excess nutrients in shoots. Although development was altered under such circumstances, reproductive fitness was maintained.     

CHANGES IN THE RESPONSE OF CARROT ROOT CALLUSES TO THE ROOT EXTRACT OCCURRING DURING THEIR SUCCESSIVE CULTURES

1. Alcohol extract of carrot root promoted the growth of the carrotroot callus which had been succesively cultured for more than18 months (CCL) on the medium containing WHITE'S inorganic salts,sucrose, yeast extract and 2, 4-D, but only a weak promotionwas observed for the growth of the carrot root callus whichhad been cultured for less than 14 months (CCS).
2. The activesubstances were fractionated by Amberlite IR-120and AmberliteIRA-400 into four fractions; C, D, E, and F. Eachfraction seemedto act synergistically to produce the effectof the whole carrotroot extract on the growth of CCL.
3. Fraction F of the carrotroot extract, which was adsorbed byAmberlite IRA-400 but notby Amberlite IR-120, promoted thegrowth of CCL in the presenceof other fractions, but had noeffect on the growth of CCS.So the different responses to thealcohol extract of the carrotroot calluses having differentlengths of successive cultureperiod seemed to depend mainlyon the ability of respondingto fraction F.
4. Using four strains of carrot root callusesof different origin,it was ascertained that different responsesof carrot root callusesto fraction F depended on the lengthof their culture and noton their strain-specific characters.
5. The substances active for the growth of CCL in the carrotrootextract passed through a dialysis membrane. These substanceswere little affected by autoclaving and remained in the aqueouslayer when shaken with several organic solvents: n-butanol,ethyl acetate, chloroform, benzene, ethyl ether and carbon tetrachloride.
6. Alcohol extract of carrot root also promoted the growth ofcarrotroot explant, tobacco stem callus and sunflower crowngall tissue.

(Received December 24, 1964; )     

秋季牧草根系中营养含量和酶活性变化和及其抗寒性研究

 本文研究了秋季高寒山区垂穗披碱草(Clinelymus nutans)根系中碳水化合物、蛋白质含量和过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性变化及与牧草抗寒性的关系。结果表明,秋季随着气温的下降,牧草根系中碳水化合物和可溶性蛋白质含量增加,CAT和SOD活性增强。其中火烧地的全期平均碳水化合物、可溶性蛋白质含量和CAT、SOD活性明显高于未火烧地,总增幅度也较大。秋季牧草根系中碳水化合物和可溶性蛋白质含量增加是多年生牧草贮藏能量物质安全越冬和翌年再生芽萌动的能量需要,而CAT和SOD活性的增强可阻止低温下细胞中氧自由基的积累,使植物生物膜系统免受伤害,是决定植物抗寒性的另一重要因子。火烧地牧草春季萌动早,长势强,产量高,秋季其根系中碳水化合物和可溶性蛋白质含量高及CAT和SOD活性强是重要原因。     

The Influence of Temperature on Root Hair Infection of Trifolium parviflorum and T. glomeratum by Root Nodule Bacteria: II. EFFECTS OF CHANGES IN ROOT TEMPERATURE

When seedlings grown at low (6 or 12°C) or high (36°C)root temperatures were transferred to 24°C the rates ofroot hair infection increased rapidly, generally to above thatof plants kept at 24°C. This ‘switching-on’of the infection process occurred irrespective of the time oftransfer between 6 and 14 d, but transfers from 36 to 24°C,at times later than 6 d showed a small lag period before thenumbers of infections increased. Responses to late transferat 22 d from either 6 or 36°C to 24°C were less striking.A reverse transfer from 24°C to 6 or 36°C at any timelater than 4 d caused no change in the infection rate. Whenplants at 6°C were moved at different times to temperaturesin the range of 12—36°C for 8 h and then returnedto 6°C (double transfer) rates of infection were most increasedat 30°C; 36°C was inhibitory. The greatest and the quickestresponse was with plants transferred at 2 d; transfer at 10d had no effect. When plants grown at 6°C for 6 d were exposed to 24°Cfor 0.5, 1... 24 h and then returned to 6°C rates of infectionwere enhanced compared with plants held at 6°C; responseswere directly proportional to time (>1 h) spent at 24°C.Rates of infection were greatest immediately after transferand thereafter declined.     

CHANGES OF ENZYME PATTERN IN THE SYMPATHETIC NERVOUS SYSTEM OF ADULT MICE AFTER SUBMAXILLARY GLAND REMOVAL; RESPONSE TO EXOGENOUS NERVE GROWTH FACTOR

—Removal of the submaxillary glands, the apparent site of NGF synthesis in adult mice, caused a decrease in the activity of all the enzymes involved in the biosynthesis of noradrenaline in the peripheral sympathetic nervous system. Thus, tyrosine hydroxylase (phenylalanine 4-monooxygenase, EC 1.14.16.1) DOPA decarboxylase (EC 4.1.1.28.) and dopamine β-hydroxylase (EC 1.14.17.1.) showed reduced activity 10 days after removal of the submaxillary glands in both superior cervical and stellate ganglia. This decrease in enzyme activity persisted up to 100 days after surgery. The fourth enzyme studied, choline acetyl-transferase (EC 2.3.1.6.) which is exclusively localized within the presynaptic cholinergic terminals of the ganglia was not affected by sialectomy. A dose of 50 μg NGF/animal/day given over 4 days was only able to restore the enzyme activity to control levels in the superior cervical ganglia of sialectomized mice whereas in stellate ganglia the enzyme activities rose above control levels to a similar extent in sialectomized and non-sialectomized animals. These results provide biochemical evidence that NGF may play a role not only during the growth and normal development of the peripheral sympathetic nervous system but also in the maintenance of its functional integrity in the adult animal.     

饲料糖对彭泽鲫生长和生理机能的影响

用分别含20%(低)、40%(高)葡萄糖和糊精的等氮(粗蛋白为35%风干物质)等能(16.4kJ/g)饲料饲养平均尾重为(2.40±0.16)g澎泽鲫Carassius auratus var. Pengze 16周,研究饲料糖种类和水平对鲫鱼生长、抗氧化力、非特异性免疫力和镉耐受性的影响,探讨鲫鱼对糖的利用能力及糖的生理功效。另用相同的饲料在相似的条件下饲养初重为(7.14±0.85)g的鲫鱼8周后胸腔注射12.5mg/kg体重的氯化镉溶液,观察其24h的存活率。实验结果表明饲料糖种类和水平都没有对鲫鱼的生长、脾指数和肝指数造成显著影响。高糖组糖化血红蛋白GHb值较高(P<0.05)。肝胰脏超氧化物歧化酶SOD活性、血浆SOD活性和总抗氧化力T-AOC各组差异不显著,肝胰脏的T-AOC为葡萄糖组显著高于糊精组(P<0.05)。补体溶血活性、血浆溶菌酶活性各组差异不显著。红细胞脆性高糖组显著低于低糖组(P<0.05)。镉染毒存活率各组差异不显著。上述结果提示40%饲料糖对鲫鱼生理功能没有不良影响,一定量的饲料糖有利于提高鲫鱼的抗氧化力。       

AN ANALYSIS OF THE GROWTH RESPONSE OF YOUNG TOMATO PLANTS TO INFECTION BY VERTICILLIUM ALBO-ATRUM: II. THE PRODUCTION OF GROWTH SUBSTANCES

Bioassays on ether-soluble acid extracts from healthy and Verticillium -infected tomato plants, showed the presence of substances inhibiting growth of wheat coleoptiles in both healthy and infected leaves and stems, but the amounts were greater in the infected.
Assays of infected stems and leaves showed increases in growth-promoting activity expressed as indole-3-acetic acid equivalents (IAAe), up to 200% of those for healthy controls.
Similar assays of cultures of V. albo-atrum showed growth-promoting activity. No acid substance capable of inhibiting the growth of wheat tissue was detected in the culture filtrate. IAA was identified by colour test with Ehrlich's reagent on chromatograms from extracts of both infected stems and fungal culture filtrates.
The vertical distribution of IAAe was determined in healthy and infected plants at the eight-leaf stage by assaying individual leaves and four stem segments separately. In healthy plants the IAAe content was greatest in the young leaves (6–8) but no gradient was observed as between leaves 1–5. In infected leaves increases over the controls were found in leaves, 1, 3 and 6 and a decrease in leaf 8.
In healthy stems IAAe was highest in the distal segment and infected stems showed higher values at all four levels, with the relative increase greatest in the distal region.
It is suggested that the major part of the Verticillium syndrome including petiolar epinasty, tylosis, pith hyperplasia and the formation of adventitious roots is the result of an accumulation of growth substances in infected tissue.     

INTERSPECIFIC VARIATION IN GROWTH,BIOMASS PARTITIONING,AND DEFENSIVE CHARACTERISTICS OF NEOTROPICAL MANGROVE SEEDLINGS: RESPONSE TO LIGHT AND NUTRIENT AVAILABILITY

Seedlings of three mangrove species—Rhizophora mangle L., Avicennia germinans (L.)Stearn., and Laguncularia racemosa (L.) Gaertn. f.—were subjected to different light and nutrient regimes in two separate growth chamber experiments. At higher nutrient or light availability, relative growth rate, leaf production, and branch growth differed significantly among species in the following order: Rhizophora < Avicennia < Laguncularia. At lower nutrient or light levels, however, species’ differences were greatly minimized. Lower nutrient or light levels caused greater investment in root biomass by all species, whereas higher nutrient availability resulted in greater investment in leaf area and maximized species’ differences in total leaf area, number of leaves, and leaf area ratio. Mangrove leaves also differed among species in quantity and composition of secondary compounds that may protect seedlings against herbivores or stress factors such as excessive solar radiation. Relative amounts of condensed tannins, gallotannins, and nitrogen were significantly affected by light and nutrient regimes, but patterns of response differed among species. The results indicate that these sympatric species differ substantially in their potential for growth, acquisition of resources, stress tolerance, and susceptibility to herbivores during the seedling stage, but that these characteristics are significantly modified by availability of resources.     

Nutrient Supply and the Growth of the Seminal Root System in Barley: III. COMPENSATORY INCREASES IN GROWTH OF LATERAL ROOTS, AND IN RATES OF PHOSPHATE UPTAKE, IN RESPONSE TO A LOCALIZED SUPPLY OF PHOSPHATE

Responses to a localized supply of phosphate were studied inbarley grown in continuous flow solution culture. Root systemswere either uniformly supplied with 50 µM phosphate (controls)or the same solution was supplied to only a 4 cm or 2 cm lengthof a seminal root (localized supply), the remainder of the rootsystem receiving a nutrient solution lacking phosphate. Little development of laterals occurred on those parts of theroot system receiving no phosphate from the external solution,while an increase in the number and extension of laterals tookplace in the 4 cm zone enriched with phosphate. Compared withsimilar zones on controls, the total length of laterals wasincreased 15-fold in 21 d plants. In addition, rates of ³²P-phosphateuptake and translocation to shoots per unit root weight werehigher than in controls by a factor of 2?5–5?0. Furtherincreases in the growth of lateral roots, and rates of phosphateuptake, were induced when the segment initially supplied withphosphate was restricted to only 2 cm. These localized modifications to root growth and uptake of phosphatelargely compensated for the deficient supply of phosphate tothe remainder of the root system. After an early period of retardedgrowth and phosphate stress, the relative growth rate of plantsand the concentration of phosphate in shoots were restored tolevels similar to that of the controls. The manner in which the supply of phosphate may control rootdevelopment, and the nature of the co-ordination between rootgrowth, phosphate uptake, and shoot growth, are discussed.     

PHENOTYPIC PLASTICITY IN DRAPARNALDIA (CHLOROPHYTA: CHAETOPHORACEAE). I. EFFECTS OF THE CHEMICAL ENVIRONMENT1

Eight axenic isolates of Draparnaldia spp. were in defined media under controlled condidom of day length, light intensity and temperature to study effects of the nutrientions on genera; pheuotype and development of main text cells. Phosphate (0–6,8 mg/l P), magnesium (0-9.6 mg/l Mg), sulfate (1.2 –14.0 mg/l S) and chloride (0.2-48.2mg/l Cl) had no effect. Small, but significant, concentration-independent, isolate-specific differences due to sodium and patassium (as the phosphate salt) occured in main axis cell length. The presence of calcium (>1.7 mg/l) was required by all isolates for main axis differentiation. In the absence of calcium, only zoospores and stunted Stigeoclonium- like plants were produced. Nitrate (>5 mg/l N) depressed main axis cell size;at higher levels (> 15 mg/l N) hair prooduction was depressed and several isolates developed a very typical Cloniophora appearance, Several of the isolates did not produce typical Draparnaldia- like phenotypes under any of the chemical formulations tried; therefore, it is suggested that chemical factors alone do not account for either the phemotypec plasticity of Draparnaldia in the field or the failure of others to grow typical plants in culture.     

Studies on the Physiology of Rice: XV. CHANGES IN THE NITROGEN METABOLISM OF SEEDS DURING GERMINATION AND THEIR RELATION TO THE APPLICATION OF GROWTH REGULATORS

Seeds of rice variety ‘Chinsurah Boro’ were treatedwith two concentrations of indoleacetic acid (IAA) and maleichydrazide (MH), 0.1 mg. per litre and 0.01 mg. per litre, duringthe first 7 days of germination, and the resulting changes innitrogen metabolism of both endosperm and embryo were determined.The seedling growth at different times during the treatmentwas recorded. Uptake of water by the embryo increased up to 72 hours, butthereafter the percentage water content fell, owing to large-scaletranslocation of dry matter to it. The endosperm showed increasingwater content for 5 days. There are two marked stages of nitrogen metabolism of the seedduring germination. During the first 72 hours hydrolysis ofprotein in the endosperm and translocation of soluble nitrogento the embryo are the predominant features. Thereafter the embryoactively synthesizes protein from the products of translocation. IAA and MH affected the seedling growth similarly. Initiallythere was a small retardation of leaf growth, but at later periodsrecovery took place. Root growth was more adversely affectedthan shoot growth, the effect also persisting longer. Thesechanges in growth were reflected in the nitrogen metabolismof the seedlings. For the first few days IAA and MH retardedthe supply of soluble nitrogen from the endosperm to the embryo,consequently there was less soluble nitrogen in the embryo thoughprotein synthesis there was affected only slightly. The differencein soluble nitrogen between the treated and untreated embryospersisted throughout the seven days. An attempt is made to explainthis on the basis that primarily IAA and MH retard the enzymaticactivity responsible for the hydrolysis of protein in the endosperm.