THE EFFECTIVENESS OF NATURAL GROWTH STIMULANTS IN THE CULTIVATION OF SEEDLINGS OF PICEA OBOVATA LEDEB.

Picea obovata Ledeb. is a slow-growing in the early stages of growth type of coniferous trees. The use of growth stimulants in the cultivation of spruce seedlings can accelerate the production of standard planting material. The paper presents the results of research of plant growth regulators influence on spruce seedlings within three years of cultivation in forest nursery conditions. Before sowing seeds of spruce soak in solutions of biological-active preparations Verva and Verva-spruce, obtaining from Abies and Picea wood greenery extracts. The plants growth regulator Verva from Abies needles (operating substance – triterpenic acids) is applied in plant growing at cultivation agricultural and commercial crops. Operating substance of a preparation Verva-spruce used for protection of agricultural plants from diseases, are phenolic compounds of Picea wood greenery possessing fungicidal and insecticidal activity. It is established that spruce seedlings processed before sowing by bio-preparation had higher parameters of growth (seedling height, diameter of seedling tree at root neck) in comparison with control plants within three years of cultivation in conditions of forest nursery. Three-year spruce seedlings which have been grown up with use of growth stimulators Verva and Verva-spruce exceeded control on 20–30% on height and on 19–20% on seedling tree thickness. Bio-preparations Verva and Verva-spruce can be recommended for application in forest nurseries as effective growth stimulators at cultivation of Siberian spruce landing material.

Single nucleotide polymorphism analysis reveals heterogeneity within a seedling tree population of a polyembryonic mango cultivar

Within a polyembryonic mango seedling tree population, the genetic background of individuals should be identical because vigorous plants for cultivation are expected to develop from nucellar embryos representing maternal clones. Due to the fact that the mango cultivar ‘Hôi’ is assigned to the polyembryonic ecotype, an intra-cultivar variability of ethylene receptor genes was unexpected. Ethylene receptors in plants are conserved, but the number of receptors or receptor isoforms is variable regarding different plant species. However, it is shown here that the ethylene receptor MiETR1 is present in various isoforms within the mango cultivar ‘Hôi’. The investigation of single nucleotide polymorphisms revealed that different MiETR1 isoforms can not be discriminated simply by individual single nucleotide exchanges but by the specific arrangement of single nucleotide polymorphisms at certain positions in the exons of MiETR1. Furthermore, an MiETR1 isoform devoid of introns in the genomic sequence was identified. The investigation demonstrates some limitations of high resolution melting and ScreenClust analysis and points out the necessity of sequencing to identify individual isoforms and to determine the variability within the tree population.

Occurrence of Spontaneous Tetraploid Nucellar Mango Plants

A putative polyploid seedling tree appeared among the polyembryonic mango (Mangifera indica L.) `Gomera-1', widely used as a rootstock in the Canary Islands. Initially detected because of its wider and more coriaceous leaves, further studies showed that fruit from this seedling are considerably larger than normal, although all other fruit characteristics (including polyembryony) were similar to those of standard `Gomera-1' (G-1) fruit. The progeny of this plant has, to date, proved to be morphologically identical to the mother plant. Studies of seedlings from normal G-1 trees growing in the same orchard showed that 10% of the plants had morphological characteristics similar to those of the putative polyploid seedling. Flow cytometry and chromosome count analyses confirmed that G-1 is diploid, whereas the putative polyploid is a stable tetraploid. The study also showed that the morphologically abnormal seedlings from diploid parent trees were spontaneous tetraploids.

VIII. On the office of the heart wood of trees. By T. A. Knight, Esq. F .R . S. In a letter addressed to the Rt. Hon. Sir Joseph Banks, Bart. G. C. B. P. R. S

My dear sir, Trees of every species, that afford timber, live many years before any portion of their alburnum becomes converted into heart wood; and vegetation proceeds with as much vigour previously to the existence of that substance, as subsequently. In the oak it is rarely seen till the seedling tree becomes nearly twenty years old; when it is readily distinguishable from the alburnum by a deeper colour, higher specific gravity, and greater hardness. The tubes also, which extend through the tree longitudinally, and are always open in the alburnum, so as freely to permit the passage of air or water, are closed in the heart wood; and the cellular substance of it has appeared, in every experiment that has come under my observation, to be incapable of conveying the ascending fluid. It does not therefore appear to execute any very important office in the vegetable economy; farther than that it obviously gives, as I have remarked in a former communication, much additional strength to the stem and branches, when these, particularly the latter, become more subject to receive injury, both from the influence of winds and gravitation, on account of the increased distance of their foliage from the points of suspension. Its mode of operation in this case appears, however, to be purely mechanical, and not to be in any degree dependent upon the vital power of the tree; and some writers on vegetable physiology have regarded it as a wholly lifeless substance. This opinion I have always rejected, though I was unable to adduce any decisive evidence in opposition to it; but I have now reason to believe that the heart wood becomes, during winter, in common with the alburnum and bark, a reservoir of the organizable matter which the tree expends in germination in the spring; and that the fluid sap passes abundantly into it laterally, though it does not ascend through it. I had long previously been perfectly satisfied that every species of tree, and perennial plant, contains within itself, during winter, all the organizable matter which it employs in the formation of its first foliage, and succulent shoots, in the spring; and that it is owing to the presence or absence of such reservoir, that the lives of plants become annual, biennial, and perennial. The annual plant exhausts itself wholly in feeding its flowers and seeds: it forms no reservoir, and consequently perishes. Its vital powers are not expended, for detached parts of the same plant, and obviously possessing the same life, become perennial, if planted in such season that they cannot exhaust themselves by the production of flowers before winter. A biennial plant (the common turnip affords a good and familiar example) fills its reservoir in one season, and wholly expends it in the following, when it consequently dies, like the annual plant. In the tree, as in the biennial plant, a part of the reserved sap descends early in the spring to form new roots, whilst another portion ascends to feed its buds; but the tree also discharges laterally a large quantity of organizable matter to generated new layer of bark over the whole surface of its alburnum, and it thus adapts its organization to its more permanent state of existence.