Soluble Carbohydrates In Roots Research Articles

Physiological responses of NaCl stressed cowpea plants grown in nutrient solution supplemented with CaCl2

Pitiuba cowpea (Vigna unguiculata (L.) Walp.) plants were grown in nutrient solution and kept in a greenhouse up to pre-flowering stage. They were subjected to four different treatments: nutrient solution; nutrient solution containing 75 mmol.L-1 NaCl; nutrient solution containing 75 mmol.L-1 NaCl and 5 mmol.L-1 CaCl2; and nutrient solution containing 75 mmol.L-1 NaCl and 10 mmol.L-1 CaCl2. Salt stress strongly inhibited plant growth, caused a disturbance in plant-water balance, and increased the total content of inorganic solutes in the different plant parts, due mainly to accumulation of Na+ and Cl-. It also increased leaf and root soluble carbohydrates, reduced soluble amino nitrogen both in root tips and in the youngest trifoliate leaves, and reduced proline levels in root tips. Although the addition of CaCl2 to the root environment of salt stressed plants caused a reduction in Na+ content, specially in roots, it did not ameliorate the salt stress effects on plant-water relations and growth. Therefore, the results obtained do not support the hypothesis that supplemental calcium would ameliorate the inhibitory effects of NaCl-stress.

622 Initiation of Flowering, Runner Formation, and Carbohydrate Distribution in Strawberry (Fragaria × ananassa Duch.) Mother and Daughter Plants Grown at Different Temperatures

The present research was undertaken to examine carbohydrate composition and distribution patterns and induction of flowering and runner formation in attached and detached strawberry plants grown under varying temperature conditions. There was an interaction between attached mother and daughter plants. Daughter plants affected flowering in mother plants, and mother plants influenced vegetative growth in daughter plants. Attachment and high temperature decreased root soluble carbohydrate concentration and promoted runner formation in both mother and daughter attached plants, suggesting that changes in carbohydrate concentration in the roots may be correlated with changes in vegetative growth. According to the results of this research, high temperatures are likely to enhance vegetative growth, whereas lower temperatures are likely to enhance the floral response. Differential temperature regimes applied to the mother/daughter plant experimental system could be an alternative to photoperiod treatments as a tool to study the correlation between environmental conditions and changes in vegetative and reproductive growth in strawberry.

Influence of organic manures on arbuscular mycorrhizal fungi associated with Vigna unguiculata (L.) Walp. in relation to tissue nutrients and soluble carbohydrate in roots under field conditions

The interaction of plant nutrients, root-soluble carbohydrate availability and arbuscular mycorrhizal (AM) fungi was examined in field grown cowpea [Vigna unguiculata (L.) Walp.]. Plant nutrients were altered through application of farmyard (cow dung, sheep manure) and green (sunnhemp, pongamia) manures. Organic amendments increased plant growth, AM fungal colonization, soluble carbohydrate concentration in roots, and spore numbers. Percent total colonization, root length with vesicles and spore numbers in soil were negatively correlated with the concentration of soluble carbohydrates within roots, which in turn were related to tissue nutrient levels. However, a positive correlation existed between soluble carbohydrate concentrations within root and root length with arbuscules. But the mycorrhizal parameters were related more to plant nutrient level and their ratios, indicating that tissue nutrients have another level of control in addition to their effect on soluble carbohydrate concentration in roots. Increased AM colonization due to organic amendment significantly reduced nutrient imbalances. The strong relationship between colonization and root-soluble carbohydrate concentration levels validates the basic assumption that mycorrhizal fungi act as a 'strong sink' for photosynthates. This study indicates that the host influences AM colonization by regulating the formation of AM fungal structures and spore formation via availability of root carbohydrates.

Effects of a 4 °C increase in temperature on partitioning of leaf area and dry mass, root respiration and carbohydrates

1. Plants of Bellis perennis, Dactylis glomerata and Poa annua were grown from seed in controlled‐environment cabinets at either 16 or 20 °C; at the higher temperature all three species had increased total dry mass and leaf area when assessed on the basis of chronological time. On the basis of thermal time (summation of degree‐days above 0 °C; days °C) temperature decreased the dry mass in P. annua. 2. Partitioning was assessed as a change in the allometric coefficients relating shoot and root dry mass, leaf and plant mass, leaf area and plant mass, and leaf area and leaf mass. Of the 12 relationships examined only three were affected by temperature: there was increased partitioning towards the shoot relative to the root in D. glomerata and increased partitioning towards leaf area rather than leaf mass in D. glomerata and B.perennis. 3. Root respiration was unaffected by temperature of growth in D. glomerata and P.annua but was lower in B. perennis grown at elevated temperature. 4. Root respiration acclimated to temperature in P. annua and B. perennis (i.e. when measured at the same temperature, respiration was higher in plants grown at 16 °C). 5. Root soluble carbohydrate concentration was unaffected by temperature of growth in any of the species. Feeding sucrose to the roots for a short period had no effect on the rate of respiration of B. perennis or D. glomerata but increased root respiration of P. annua.

Genotypic Differences in the Production and Partitioning of Carbohydrates Between Roots and Shoots of Wheat Grown under Zinc or Manganese Deficiency

Abstract The partitioning of soluble carbohydrates and starch between roots and shoots was investigated in wheat genotypes differing in Zn or Mn efficiency. The plants were grown for 11 d in a chelate-buffered nutrient solution with sufficient or deficient Zn and Mn supply. The Zn-efficient cultivar Warigal had a greater shoot fresh weight under sufficient Zn compared with the Zn-inefficient cultivar Durati. When supplied with sufficient Zn, Warigal had a greater concentration and content of soluble carbohydrates in roots and shoots in comparison with Durati. Under deficient Zn supply, Durati had a greater concentration and content of starch in roots and shoots compared with Warigal. In an experiment with varying supply of Mn, the Mn-efficient genotype C8MM had a greater shoot fresh weight than the Mn-inefficient cultivar Bayonet under sufficient or deficient Mn supply. The concentration of soluble carbohydrates in roots and shoots was decreased by deficient Mn supply in C8MM but not in Bayonet. Starch accumulated in the roots of Bayonet under deficient Mn supply. The results suggest that synthesis of carbohydrates is decreased under Zn deficiency, while they are preferentially partitioned to the roots to increase growth and thus the surface area available for Zn uptake. In the case of Mn deficiency, carbohydrate production was limited, but partitioning between roots and shoots was not altered.

Management of marine construction works using ecological modelling

A system of bridges and tunnels between Denmark and Sweden is being constructed. The environmental management of the dredging and reclamation work includes planning using a mathematical model which can forecast the effect of different spill scenarios in order to minimize adverse effects on eelgrass beds. To develop the model, plots of eelgrass beds (4 m 2 ) were covered with nets excluding 30, 60 and 90% of the light. Shoot density, leaf and root/rhizome biomass, and soluble carbohydrates in roots and rhizomes were observed in order to determine the response of the plants to shading. In selected plots, all aboveground biomass was harvested to assess the re-growth potential. The minimum level of soluble carbohydrates necessary for securing re-growth was 60-90 mg g -1 . The inclusion of the subsediment parts of the eelgrass permits model runs beyond one growth season, and the prediction of re-growth after subsequent shading and winter dormancy. The model has been satisfyingly calibrated and validated. A feedback monitoring system has been developed based on field studies of eelgrass variables, a set of pre-fixed environmental criteria and forecasting of the effects of the construction works. The system facilitates planning and management of the dredging and reclamation operations, and mitigating actions during the progression of the work.

Influence of Fertilizer Rregime on Leaf Chlorosis/Necrosis of Two Varieties of Chrysanthemum

`Tara' and `Boaldi' were fertilized with 150 and 450 ppm from 20N–4.7P–16.6K soluble fertilizer and moved at flowering to postproduction conditions (21 ± 2C and 10 μmol·m–2·s–1). Shipping was simulated for 1 week at 26C. `Tara' exhibited burned leaf margins (necrosis) and chlorosis following shipping. At 150 ppm, leaves had brown, dried margins, but the damage did not progress indoors. Necrosis was worse at 450 ppm. Leaf chlorosis/necrosis of non-shipped plants at the 450 fertilizer level did not appear until the 3rd week indoors. At experiment termination, no leaf damage occurred in non-shipped `Tara' or `Boaldi' with 150 ppm. `Boaldi' did not show damage after shipping regardless of the treatment but symptoms (necrosis and wilting of leaves) evolved during the first 2 weeks indoors on plants fertilized with 450 ppm. A 50% reduction in root soluble carbohydrates was found at the highest fertilizer rate at flowering, suggesting that leaf chlorosis/necrosis is related to carbohydrate depletion in chrysanthemum.

Influence of vesicular–arbuscular mycorrhizal fungi and phosphorus on growth, carbohydrate partitioning and mineral nutrition of greenhouse cucumber (Cucumis sativus L.) plants during establishment

The growth response of greenhouse cucumber (Cucumis sativus L.) to infection by vesicular–arbuscular mycorrhizal (VAM) fungi and to 4, 12 and 20 mg L−1 of phosphorus (P) nutrition was characterized over 38 d of plant establishment. Although maximum growth rates were not reached with the P levels studied, foliar concentrations of P were consistent with those published for healthy cucumber plants. Plants were highly receptive to colonization by Glomus mosseae, G. dimorphicum and G. intraradices. Infection by all species decreased as P nutrition increased; however, growth rates of primary yield components (e.g., stem and leaf dry weights, leaf area) of VAM-infected plants were greater than those of noninfected plants at all levels of P nutrition. The VAM-enhanced growth was similar to that induced by increases in P nutrition. The VAM-infected plants had lower concentrations of soluble nitrogen (N) than noninfected plants early in development; however, N concentrations were equal by 38 d after planting. Total soluble carbohydrate concentration of leaves of noninfected plants increased 62% faster than that of leaves of VAM-infected plants, possibly due to decreased export and a higher degree of P stress in the non-infected plants. Relative to noninfected plants, higher concentration of soluble carbohydrates in roots of VAM-infected plants may indicate increased sink demand to support the symbiosis. Since VAM stimulated growth at levels of P nutrition considered nondeficient by tissue analysis, use of VAM to accelerate the early development of transplants may be advantageous to the greenhouse industry. Key words:Cucumis sativus L., phosphorus, vesicular–arbuscular mycorrhizal fungi, mineral nutrition

Root soluble carbohydrates of Afzelia africana Sm. seedlings and modifications of mycorrhiza establishment in response to the excision of cotyledons

Stem length, number of secondary lateral roots, shoot dry weight and reducing sugar concentrations of root were significantly reduced when translocation of reserves from cotyledons to the roots of Afzelia africana seedlings was interrupted by complete or partial cotyledon excision. The sucrose but not the glucose concentration of lateral roots also decreased significantly after complete cotyledon excision. Hartig net development rather than fungal sheath formation was affected after inoculation with the early fungal isolate E1 and by both late-stage fungal isolates L1 and L2 after partial or complete cotyledon excision. However, mycorrhizal colonization by the early fungal isolate E2 was not affected by cotyledonary reserves, suggesting that this fungal isolate has a lower carbohydrate requirement than fungal isolates E1, L1 and L2. The late-stage fungal isolates L1 and L2 induced a hypersensitivity reaction by epidermal cell walls of the host plant after complete cotyledon excision, suggesting they are more dependent than the early fungal isolate E1 on available root carbohydrate substrates for ectomycorrhizal colonization. These results are discussed in the light of the hypothesis that early and late-stage fungi were different carbohydrate requirements, and that the time sequence of colonization was related to the root carbohydrate status, which increased with time.

Root soluble carbohydrates of Afzelia africana Sm. seedlings and modifications of mycorrhiza establishment in response to the excision of cotyledons

Root soluble carbohydrates of Afzelia africana Sm. seedlings and modifications of mycorrhiza establishment in response to the excision of cotyledons

The development of endomycorrhizal root systems

SUMMARYConcentrations of phosphorus in shoot and soluble carbohydrates (fructose, glucose, sucrose and fructans) in root were measured in non‐mycorrhizal and vesicular‐arbuscular (VA) mycorrhizal (Glomus mosseae) leek plants (Allium porrum) raised at six concentrations of soil phosphate. In conditions when an increased concentration of soil phosphate reduced VA mycorrhizal infection, the concentrations of soluble carbohydrates in the root were at a maximum. Therefore the hypothesis that greater concentrations of soluble carbohydrates in roots favour VA mycorrhizal infection is discounted. There was a specific effect of VA mycorrhizas, in that infected roots contained a larger concentration of sucrose than did uninfected roots, in plants with similar phosphorus concentrations in dry matter of shoots.We conclude, first, that increased phosphorus supply from either phosphate addition to soil or VA mycorrhizal infection increases concentration of soluble carbohydrates in leek roots and, secondly, that the VA mycorrhizal root behaves as a particularly strong physiological sink when there is an excess concentration of sucrose in the host.

Accumulation and partitioning of biomass and soluble carbohydrates in maize seedlings as affected by source of nitrogen, nitrogen concentration, and cultivar1

Abstract Seedlings of four maize hybrids were grown hydroponically to investigate the impact of different N sources (Ca(NO3)2, (NH4)2SO4 and a 1:1 mixture of both) on (i) production and partitioning of root and shoot dry matter, (ii) concentration of soluble carbohydrates in roots and shoots and their partitioning to these plant parts, (iii) concentration of starch in the shoot, and (iv) N uptake. During the main phase of the experiments (duration 14d), the plants were grown in a greenhouse at 25/22°C day/night temperatures and a photoperiod of 16h. Nitrogen was supplied at three concentrations (2.8, 28, and 280 ppm). The root‐zone pH was 6.5. Under the lowest N supply, the N sources produced similar root and shoot dry matters. At the highest N level (280 ppm), NO3‐fed plants were superior. In contrast, the mixture of NH4 and NO3 − was optimum at 28 ppm. More or less pronounced N form by N concentration interactions were also found in the concentration and distribution of soluble carbohydrates and in all ...

Soil mediated effects of phosphorus supply on the formation of mycorrhizas by Scutellispora calospora (Nicol. & Gerd.) Walker & Sanders on subterranean clover

summaryA split‐root technique was used to separate plant and soil mediated effects of phosphorus (P) supply on the formation of mycorrhizas by Scutellispora calospora (Nicol. & Gerd.) Walker & Sanders on subterranean clover (Trifolium subterraneum L.). There were 10 split‐root treatments, incorporating four concentrations of P (0, 18, 105 and 280 μg P g−1 soil) ranging from severely deficient for plant growth to luxurious. Increasing the supply of P to plants decreased the percentage of root length infected and the total length of roots infected by S. calospora. Applications of 18 and 105 μg P g−1 soil to half of the root system of plants reduced the percentage of root length infected in that half of the root system and in the other half of the root system to the same extent. The effects of severely deficient and moderately deficient rates of P on infection by S. calospora were therefore mediated through the plant. These effects could be related directly to effects of P supply in decreasing the concentrations of soluble carbohydrates in roots because carbohydrate concentrations in roots did not differ between each half of the root system. In contrast to the concentrations of soluble carbohydrates in roots, the length of roots and the concentrations of P in roots were generally greater in the half of the root system that received the highest application of P. Applications of 280 μg p g−1 soil to half of the root system of plants also reduced the percentage of root length infected by S. calospora in both halves of the root system but to a greater extent in the half that received 280 μg P g−1 soil. This effect was associated with greater length of roots, higher concentrations of P in roots and higher concentrations of P in the soil in the half of the root system that received 280 μg P g−1 soil. We concluded that the effects of luxury amounts of P on infection by S. calospora could be mediated through the soil.

Soluble carbohydrate allocation to roots, photosynthetic rate of leaves, and nitrate assimilation as affected by nitrogen stress and irradiance.

Upon resupply of exogenous nitrogen to nitrogen-stressed plants, uptake rate of nitrogen is enhanced relative to nonstressed plants. Absorption of nitrogen presumably is dependent on availability of carbohydrates in the roots. A buildup in soluble carbohydrates thus should occur in roots of nitrogen-stressed plants, and upon resupply of exogenous nitrogen the increased uptake rate should be accompanied by a rapid decline in carbohydrates to prestress levels. To evaluate this relationship, three sets of tobacco plants growing in a complete hydroponic solution containing 1.0 mM NO3- were either continued in the complete solution for 21 d, transferred to a minus-nitrogen solution for 21 d, or transferred to a minus-nitrogen solution for 8-9 d and then returned to the 1.0 mM NO3- solution. These nitrogen treatments were imposed upon plants growing at photosynthetic photon flux densities of 700 and 350 micromoles m-2 s-1. Soluble carbohydrate levels in roots increased during onset of nitrogen stress to levels that were fourfold greater than in roots of non-stressed plants. Following resupply of external nitrogen, a rapid resumption of nitrogen uptake was accompanied by a decline in soluble carbohydrates in roots to levels characteristic of nonstressed plants. This pattern of soluble carbohydrate levels in roots during onset of and recovery from nitrogen stress occurred at both irradiance levels. The response of net photosynthetic rate to nitrogen stress could be expressed as a nonlinear function of concentration of reduced nitrogen in leaves. The net photosynthetic rate at a given concentration of reduced nitrogen, however, averaged 10% less at the lower than at the higher irradiance. The decline in net photosynthetic rate per unit of reduced nitrogen in leaves at the lower irradiance was accompanied by an increase in the nitrate fraction of total nitrogen in leaves from 20% at the higher irradiance to 38% at the lower irradiance.

Soluble carbohydrates in roots of leek (Allium porrum) plants in relation to phosphorus supply and VA mycorrhizas

Leek plants (Allium porrum L.) inoculated with Glomus mosseae were raised on sterilized soil/sand medium amended with Ca(H2PO4)2.H2O to test the hypothesis that high concentration of soil P inhibits formation of vesicular-arbuscular (VA) mycorrhizas by reducing concentration of soluble carbohydrate in the root. When P supply was increased, from either P addition or VA mycorrhizal infection, there was initially also an increase in concentration of soluble carbohydrate in the root. At the concentration of soil P at which infection was reduced, concentration of soluble carbohydrate was at its maximum. Therefore the above hypothesis is discounted. An increased delay in infection establishment and a greater number of abortive entry points would suggest that high concentration of soil P reduces VA mycorrhizal infection by changing the anatomy of the root to make it resistant to fungal penetration.

Mycorrhizas formed by Gigaspora calospora and Glomus fasciculatum on subterranean clover in relation to soluble carbohydrate concentrations in roots

SUMMARYAt several times during plant growth, we compared the effects of two irradiances (plants were either not shaded or were shaded to reduce 60–70% of the photon flux in the glasshouse) and two concentrations of soil phosphorus (P) (35 and 105 μg−1 P g−1 soil) on the formation of vesicular‐arbuscular (VA) mycorrhizas on Trifolium subterraneum L. by Gigaspora calospora (Nicol. & Gerd.) Gerd. and by Glomus fasciculatum (Thaxter sensu Gerd.) Gerd. & Trappe.By the fifth week from sowing, the proportion of root length infected by both G. calospora and G. fasciculatum was reduced in plants grown at the greater concentration of P and in plants grown without shade. These effects were associated with decreased concentrations of soluble carbohydrates in roots at earlier harvests. Decreased concentrations of soluble carbohydrates in the roots of unshaded plants were not associated with increased concentrations of P in the plant.The percentage of root length infected by G, calospora was decreased to a greater extent than that of G. fasciculatum with similar reductions in the concentrations of soluble carbohydrates in roots. This effect may partly explain why the percentage of root length infected by G. calospora is more sensitive than that of G. fasciculatum to increasing P supply. G. calospora and G. fasciculatum may also differ in the extent to which P may directly affect their ability to form mycorrhizas.The effects of P supply and shading on the percentage of root length infected by G. calospora and by G. fasciculatum were not apparent before the fourth week from sowing. These factors may have affected the ability of the mycorrhizal fungi to spread by secondary infections.

Sulfur supply and the formation of vesicular-arbuscular mycorrhizas by Glomus fasciculatum on subterranean clover

Sulfur supply and the formation of vesicular-arbuscular mycorrhizas by Glomus fasciculatum on subterranean clover

Growth, Ectomycorrhizal Development, and Root Soluble Carbohydrates of Black Oak Seedlings Fertilized by Two Methods

Growth, Ectomycorrhizal Development, and Root Soluble Carbohydrates of Black Oak Seedlings Fertilized by Two Methods

Interdependence of Root and Shoot Activities in Determining Nitrogen Uptake Rate of Roots

Tobacco plants (Nicotiana tabacum L.) were grown under PAR with accumulated daily totals of 10.5, 18.0, 25.5, 33.0, and 40.5 Einsteins m-2day-1 and day/night temperatures of 26/22 and 22/18 C. Plants were sampled at 2-day intervals during exponential growth. Total dry matter and nitrogen in the whole plant and dry matter in the roots increased with PAR and temperature; however, their proportionalities were not constant. The RGRR and RARNP were nearly equal to each other at each PAR and temperature, and both were approximately equal to the RARSR. Depending on treatment conditions, soluble carbohydrates in roots remained constant during exponential growth at 5%-9%. These results support a model for dependence of the nitrogen-supplying function of roots on the concurrent transport of soluble carbohydrate from the shoot.

Nitrate Uptake during Recovery from Nitrogen Deficiency

AbstractTwo‐week‐old nitrogen‐deficient wheat plants attained a high rate of nitrate uptake on the first day of exposure to nutrient solutions supplemented with KNO3. Ammonium uptake from similar solutions supplemented with NH4NO3 was also high during the first day of exposure, but nitrate uptake from this solution was lower than from the KNO3 treatment. During the next two to three days there was a progressive decrease in uptake of both nitrogen ions. A steady increase in uptake then occurred as the plants fully recovered from the nitrogen‐deficient state.The transient low nitrate uptake after three or four days of exposure to KNO3 was not due to an excessive accumulation of nitrate in the tissue, nor to a failure in nitrate reduction as indicated by the rate of nitrate accumulation relative to the uptake rate. Nitrogen supplied as 15N‐nitrite during the low uptake period was effectively incorporated into organic forms and effectively translocated to the shoots. Failure of the root tissue to increase in soluble carbohydrates during illumination was characteristic of the low uptake period. This contrasted with an increase in root soluble carbohydrates in the light during rapid uptake associated with full recovery from the nitrogen‐deficient state. It is concluded that carbohydrate translocation to the root system was insufficient during the intermediate recovery period for optimal nitrate uptake, although it was sufficient for effective reduction and translocation of nitrate and reduced nitrogen.Ammonium uptake from NH4NO3 was restricted during darkness by the third day whereas there was little difference between light and dark periods in nitrate uptake from KNO3 until about the sixth day of recovery. The extent to which ammonium restricted nitrate uptake increased progressively for two or three days following which a lessening influence seemed evident, and the effects were not directly associated with the rate of ammonium uptake.