Shoot

About: Shoot is a research topic. Over the lifetime, 32188 publications have been published within this topic receiving 693348 citations.

The distribution of polyphenols in the tea plant (Camellia sinensis L.).

Abstract: 1. Methods for the separation and determination of the polyphenolic components of the tea plant by thin-layer chromatography and colorimetric reactions have been devised. 2. High concentrations of catechins, flavonols and depsides were found to be restricted to the young vegetative and floral shoots, whereas leucoanthocyanins or flavylogens were characteristic of the more bulky axial tissues of the plant. 3. In the young shoots cell growth was correlated with an increasing degree of flavonoid B-ring hydroxylation. 4. Maximal flavylogen concentrations occurred in the outer protective layers of stem and of seed coat. 5. Mature leaves were shown to contain derivatives of the flavones apigenin and luteolin. 6. Developing seedlings showed a steady increase in polyphenol complexity; flavylogens were concentrated at shoot and root apices and accumulated at the stem base. 7. It is postulated that the flavanols (leucoanthocyanins and catechins), because they can co-polymerize, are of use to the plant for protection of wood and bark against infection and decay.

Effects of Nutrients and Light on Growth and Root Formation in Pisum sativum Cuttings

Abstract: Cuttings obtained from seedlings of Pisum sativum L. were rooted in water solution. Shoot growth continued after excision and shoot length increased considerably before roots emerged. Increase in dry weight was strongly dependent on light supply. Continued growth was dependent on supply of mineral nutrients to the rooting solution. Mineral nutrients had no or slight influence on the number of roots formed on cuttings from stock plants grown in fertilized soil, but the growth in length of the roots was dependent on the presence of calcium in the solution. Root formation was dependent on photosynthetic products formed after excision. No roots were formed on cuttings kept in the dark. The number of roots increased with increasing irradiance given to the leafy part of the cutting. At a low level of irradiance sucrose supply through the rooting medium increased the number of roots. Light given to the basal part of the cuttings had a strongly inhibitory effect on the number of roots formed. It is concluded that the carbohydrate level easily becomes a limiting factor for root formation in growing pea cuttings. Availability of mineral nutrients influences in the first place the growth of the shoots.

Beneficial effects of silicon in alleviating salinity stress of tomato seedlings grown under sand culture

Abstract: Sand culture experiments were designed to investigate the effect and mechanism of exogenous silicon on salt tolerance of tomato plants. Plant growth, photosynthetic gas exchange, water status, ion accumulation, root morphological traits, root water uptake and antioxidant defense were analyzed under 150 mM NaCl without or with application of 2 mM silicon. Application of silicon improved tomato growth, photosynthetic pigment and soluble protein contents, net photosynthetic rate and root morphological traits under salt stress. The leaf transpiration rate and stomatal conductance were not decreased, but increased by application of silicon under salt stress. Meanwhile, silicon decreased the concentrations of Na and Cl in the roots, stem and leaves, but without any sign of decrease in the root-to-shoot translocations. Leaf water status, root hydraulic conductance and antioxidant ability were all improved by exogenous silicon under salt stress. Results suggest that silicon application could decrease Na and Cl accumulation and increase antioxidant defense in tomato roots, which improved the root growth and hydraulic conductance, and therefore improved leaf water status and shoot growth. The study also suggests a potential value of silicon application in soilless culture (sand culture) in tomato production.

Dynamics of leaf water relations components in co‐occurring iso‐ and anisohydric conifer species

Abstract: Because iso- and anisohydric species differ in stomatal regulation of the rate and magnitude of fluctuations in shoot water potential, they may be expected to show differences in the plasticity of their shoot water relations components, but explicit comparisons of this nature have rarely been made. We subjected excised shoots of co-occurring anisohydric Juniperus monosperma and isohydric Pinus edulis to pressure-volume analysis with and without prior artificial rehydration. In J. monosperma, the shoot water potential at turgor loss (Ψ(TLP)) ranged from -3.4 MPa in artificially rehydrated shoots to -6.6 MPa in shoots with an initial Ψ of -5.5 MPa, whereas in P. edulis mean Ψ(TLP) remained at ∼ -3.0 MPa over a range of initial Ψ from -0.1 to -2.3 MPa. The shoot osmotic potential at full turgor and the bulk modulus of elasticity also declined sharply with shoot Ψ in J. monosperma, but not in P. edulis. The contrasting behaviour of J. monosperma and P. edulis reflects differences in their capacity for homeostatic regulation of turgor that may be representative of aniso- and isohydric species in general, and may also be associated with the greater capacity of J. monosperma to withstand severe drought.