Needles Of Pinus Radiata Research Articles

Secondarily-forming Coated Vesicles in Ray Parenchyma Cells of Pinus radiata Needle Traces

Secondarily-forming Coated Vesicles in Ray Parenchyma Cells of Pinus radiata Needle Traces

Pinus radiata needle trace studies: Fine structure of immature sieve cells in the primary phloem.

The development of sieve cells in the primary phloem of Pinus radiata needle traces was followed with the electron microscope. Sieve cell precursors have thin walls, a more or less spherical nucleus containing small evenly scattered masses of condensed chromatin, dense cytoplasm and several small vacuoles. Among the most obvious early changes are increase in cell size, condensation of chromatin, nuclear lobing, changes in the location and orientation of microtubules, modifications in the ER, increase in vacuolar size, increase in wall thickness, and sieve pore development. Later in the development of sieve cells and prior to their maturation the nucleus with greatly condensed chromatin and disrupted envelope assumes a necrotic appearance, and most of the cytoplasmic structures disappear with the exception of mitochondria, plastids and elements of ER. Callose and P-proteins are not seen at any stage in the development of sieve cells.

Pinus radiata needle studies: Fine structure of epidermal cells of the needle primordium.

Pinus radiata needle primordia were examined for ultrastructural features of their epidermal cells. Epidermal cells consisted of thin walls, a thin cuticle over the outer tangential wall, plasmodesmata in all except the outer tangential wall, moderately dense cytoplasm with poorly differentiated plastids, abundant mitochondria, dictyosomes and rough endoplasmic reticulum, cortical microtubules, and several small vacuoles. A prominent nucleus with often two or more nucleoli was characteristic of these cells.

Effect of Pinus radiata needle monoterpenes on spore germination and mycelial growth of Dothistroma pini in vitro in relation to mature tree resistance

Mixtures of volatile compounds have been obtained from Pinus radiata foliage of populations of young, Dothistroma pini susceptible and mature, resistant trees. Gas-liquid chromatographic analysis showed the mixtures to consist mainly of 13 monoterpene hydrocarbons. Yields of volatile compounds from young trees were about twice that of mature trees. Relative amounts of monoterpenes, in particular β-pinene, β-phellandene and car-3-ene, in the mixtures varied with population age. The monoterpene mixtures stimulated the germination of D. pini spores, and also stimulated mycelial growth when incorporated into D. pini liquid shake cultures at concentrations of 10, 100, and 300 p.p.m. Inhibition of mycelial growth occurred only at 1000 p.p.m. The monoterpene composition does not bear any simple relationship to mature tree resistance.

Needle Structure and Development of the Stomatal Complex in Cotyledons, Primary Needles, and Secondary Needles of Pinus radiata D. Don

Structurally the cotyledons, primary needles, and secondary needles of Pinus radiata D. Don form a series of increasing complexity. The cotyledons lack a hypodermis and resin canals; primary needles may have a hypodermis and external resin canals; and secondary needles always have a distinct hypodermis, frequently two or more layers thick, and medial resin canals. Epidermal cells vary from thin walled with little cuticularization on the cotyledons to thick walled with conspicuous cuticularization on the secondary needles. In cotyledons, the mesophyll has undulate cells; in the primary and secondary needles, plicate cells. The stomates in all three foliar structures are eumesoperigenous; i.e., the guard cell-mother cell and polar subsidiary cell arise from an equal division of a protodermal cell. In both primary and secondary needles, but not the cotyledon, the stomatal complex includes cells in a hypodermal position. This difference may be the result of the rapid growth of the cotyledon compared with that of the primary and secondary leaves. The changing structure of the stomatal complex may account for differences in the physiological response of the different foliar organs to experimental conditions.

Hydrogen sulphide uptake by vegetation

Deposition velocities for hydrogen sulphide uptake by needles of Pinus radiata and leaves of Lolium perenne have been measured in the field using H 2 35S. Values up to 0.17 cms −1 were obtained with considerable variation with season and metabolic activity. The unexpectedly high deposition velocity has been interpreted on a metabolic basis assuming a direct entry of hydrogen sulphide into the sulphur assimilatory pathway at a point subject to little metabolic control.

Ultrastructural changes in leaf and needle segments treated with herbicides containing picloram

Summary:The herbicide Tordon 50D (picloram+2,4‐D) affected the integrity of the nucleus and cell membranes in Pinus radiata needle segments and caused the swelling of internal chloro plast membranes and the eventual disintegration of the chloroplasts. Tordon 22K (picloram) only affected chloro plast structure.Both herbicides had similar adverse effects on cell membranes and chloroplasts of Eucalyptus viminalis.

THE EFFECTS OF PICLORAM AND 2,4‐D ON PLANT CELL MEMBRANES

Summary. The herbicide Tordon 50D (picloram + 2,4–D) caused severe shrinkage of the protoplasts of all cells of Pinus radiata needle segments within 24 h of treatment. Measurements of the resistance of these tissues to low‐frequency and to high‐frequency electrical currents showed a loss in the integrity of the plasmalemma within 4–8 h of treatment. Tordon 22K (picloram) had no such effects. The results with Tordon 50D could be attributed solely to the 2,4‐D content.Both Tordon 50D and Tordon 22K disrupted chloroplast structure in leaf discs, and the integrity of cell membranes in stem tips, of Eucalyptus viminalis.

Survival of Dothistroma pini on fallen needles of Pinus radiata

Summary The length of time for which Dothistroma pini stromata on fallen needles of Pinus radiata produce viable conidia (survival period) was studied for each month of the year. Needles under study were placed in the litter and suspended above ground in both thinned and unthinned stands. Season did not seem to affect survival period. Stromata of D. pini on needles in litter survived for a shorter time than chose on suspended needles. The longest survival period was between 4 and 6 months.

CUTICLE STRUCTURE AND WATER RELATIONS OF THE NEEDLES OF PINUS RADIATA (D. DON)

SummaryThe fine structure of the cuticle of mature needles of Pinus radiata has been studied from electron micrographs of carbon replicas of the needle surface. The whole of the needle surface appears to be covered by a layer of wax from which, with the exception of the inner surface normally enclosed by the sheath, arise numerous tubular waxy outgrowths similar to those previously observed in P. sylvestris. Unlike P. sylvestris, these outgrowths cover only a portion of the exposed needle surface and the underlying wax layer ranges in appearance from smooth to slightly granular, with no indication of a plate‐like structure.When the needles were immersed in water, very little was taken up into the basal region of the needles normally enclosed by the sheath compared with the exposed surfaces; the tips of the needles showed the highest permeability to water. The inner surfaces of the needles were consistently more wettable than the outer surfaces, and the surfaces normally enclosed by the basal sheath, corresponding to the youngest regions of the needle, were much less wettable than the exposed surfaces. The inner enclosed surface was the least wettable of all; this may be due to differences in the chemical composition of the wax, besides the absence of weathering.When young needles were prematurely exposed by removing the basal sheath, tubular, waxy outgrowths appeared, similar to those found on the exposed surfaces of the mature needles; when young needles were bound together to prevent them from parting, an entirely different structure developed consisting of minute granules forming a reticulum over the surface.The significance of the above findings is discussed in relation to the reputed relatively high cuticular transpiration of P. radiata and its ability to absorb water directly into the foliage from precipitation; it appears that this species is well adapted to the moist atmospheric conditions characteristic of its native habitat in the Californian ‘fog belt’ region.

Phosphorylated intermediates of terpene biosynthesis in Pinus radiata

Isolated needles of Pinus radiata incorporate radioactive orthophosphate into ATP, pyrophosphomevalonic acid, and isopentenyl pyrophosphate. Radioactivity from 2-C 14-labeled mevalonic acid was found in the last two compounds and in phosphomevalonic acid when an extract from Pinus seedlings was used.

NOTES ONCardiastethus consorsB. WhiteANDCardiastethus poweriB. White (HETEROPTERA : Anthocoridae).

Specimens of Cardiastethus consors B. White and Cardiastethus poweri B. White were obtained from samples of Pinus radiata needle litter, collected from a number of forest areas or private woodlots in the North and South Islands of New Zealand. Eggs were obtained and nymphs reared through to the adult stage on a diet of Copeognatha and Thysanoptera nymphs, Lepidopterous eggs and caterpillars including Selidosemu suavis (Butler), Declana floccosa Walk., Oxycanus sp. and Melanchra mutans (Walk.). Incubation in C. consors takes up to twenty one days and the nymphal period, of five instars, up to ninetyfive days. The instar development of C. poweri would appear to be shorter under laboratory conditions. There are two to three generations each year.