Vegetative Buds Research Articles

Effect of foliar applications with urea and active dry yeast on the number of vegetative and floral buds, leaf ammonium content, flowering behaviour, fruiting and fruit quality of Washington novel orange trees.

Effect of foliar applications with urea and active dry yeast on the number of vegetative and floral buds, leaf ammonium content, flowering behaviour, fruiting and fruit quality of Washington novel orange trees.

IMPACT OF ENVIRONMENTAL VARIABLES ON SPORE DISPERSAL TREND OF FUSARIUM MANGIFERAE CAUSING MANGO MALFORMATION DISEASE IN PAKISTAN

Malformation is one of the most destructive mango diseases. Although trees are not killed, the vegetative phase of the disease impedes canopy development during vegetative phase of the host plant and floral phase dramatically reduces fruit yield with overwintering inoculums during dormant phase of the host plant. Environmental conditions and trend of spore liberation of its pathogenic fungus “Fusarium mangiferae” were recorded during flowering phase (Feb-April, 2014), fruit development phase (May-July, 2014), vegetative phase (Aug-Oct, 2014), and dormant phase (Nov-Jan, 2014-15), of the mango plants. Through installation of spore traps of various distance levels containing Nash-Synder media in petri plates. During these phases, different environmental variables including temperature (T), relative humidity (R.H) and wind speed (W.S) were observed. Maximum number of colonies were observed through the spores trapped from the centre of the experimental block (0m) while minimum numbers of colonies were developed from the spores trapped at 150 m distance. Amongst different phenological phases of mango, fruit development remained very much contaminated with spores of the fungus while minimum spore liberation was noted during flowering phase of mango indicating very rare infection during this phase. This study also reflected that maximum number of airborne macro conidia of F. mangiferae were recorded when R.H was below 55%. Low R.H appeared to be a major factor associated with the diurnal conidial dispersal of airborne pathogen. Hence primary infection of F. mangiferae starts from vegetative and floral buds differentiation and control strategy including spray of systemic fungicides should start at this stage of development.

Effects of initial propagule size and water depth on Butomus umbellatus L. growth and vegetative propagation

Over the last century, flowering rush (Butomus umbellatus L.: Butomaceae) has escaped its native Eurasian range and has become a problematic species in parts of North America. As an aquatic invasive species, flowering rush has degraded wetlands in introduced areas and has interfered with human water usage. Although experimental work has been published regarding the reproductive biology of the species, we found few manipulative experiments aimed at testing ecological attributes of this species in the literature. The research reported here demonstrates that flowering rush is capable of aggressive clonal growth and propagation, whether from vegetative rhizome buds or from fragments of rhizomes themselves. This species was capable of growth along a depth gradient from zero to 132 cm and showed an ability to adjust biomass allocation along that gradient; however, biomass and asexual propagule production declined at depths beyond approximately 50 cm. The combination of regrowth from relatively small propagules, ability to tolerate depths of greater than one meter, and plasticity of biomass allocation along habitat gradients make this species a potential threat in many aquatic and wetland habitats in its introduced range. However, certain aspects of its biomass allocation strategies may enhance chemical control for plants growing at greater depths or those regenerating from rhizome buds, both of which tend to have greater S:R biomass ratios.

Metabolic mechanisms underpinning vegetative bud dormancy release and shoot development in sweet cherry

Few studies have focused on the metabolic characterization of bud dormancy and shoot growth in temperate fruit species, although this is an intresting framework to anticipate adaptation in global climate changes. To examine this issue, two experimental approaches were applied, using sweet cherry (Prunus avium L. cv ‘Grace Star’) bud and shoot tissues. Initially, annual shoots containing vegetative buds that collected at endodormancy and ecodormancy stages were used to compare changes in shoots- and buds-specific metabolic profiles under chamber-controlled conditions. Detailed analysis suggested that primary metabolites, such as arabitol, fucitol and tryptophan were modified in buds from endo- to eco-dormancy. Differences between buds and shoots metabolic fingerprints were also found in various secondary metabolites, including quercetin, glucosides and osmotic-associated metabolites. In order to investigate the mechanism underlying shoot developmental during bud dormancy break, metabolic analysis was also conducted in annual shoots, that were sampled at five distinct bud-related vegetative stages from ecodormancy to fully developed leaf stage under natural orchard conditions. Several amino acids (ornithine, alanine, isoleucine, GABA, asparagine and tryptophan) and classes of secondary metabolites, including anthocyanidins (peonidin-3-O-galactoside), flavonoids (apigenin, isorhamnetin, chrysin and trilobatin) and lignin-related compounds (sinapyl and coniferyl alcohols) were altered across developmental stages. Additionally, nutrient homeostasis was altered during shoot development, as N, P, Ca, Mg, B steady-state level as well as Ca/Mg + K and N/P stoichiometry were significantly changed. This study provides a bud- and shoot-based metabolic framework at different conditions and dormancy stages, thereby helps to understand dormancy release and bud-break in temperate fruit trees.

О МОРФОЛОГИИ ПОЧЕЧНЫХ ЧЕШУЙ И КАТАФИЛЛОВ ULMUS GLABRA HUDS. (ULMACEAE)

Background. Specific features of plant development and mechanisms ensuring such processes are expressly linked with the structure of buds and hence the leaf series formed on lateral shoots. Materials and methods . The material of the study was the shoots of the second to fifth orders of nineteen plant samples in their generative age (G1, G2) grown in the well-lighted habitats in the Park of Petrozavodsk and the Park of Komarovo Town (St. Petersburg). All buds on vegetative and vegetative-generative shoots (more than 250) were investigated. The leaf organs of the formed seventy-nine vegetative buds of Ulmus glabra Huds. were consistently disassembled and measured under an MBS-9 binocular. The analysis of the development of bud scales in unfolding buds made it possible to observe structural features unavailable in a static study of buds. Results and conclusions. The growth of the leaf organs in a series was found to occur in different ways. Almost completely suberized external scales represented a thickly grown leaf base fused with poorly developed stipules. The scales from the first to the fourth did not grow at all when the bud was unfolding. The fifth and the sixth scales showed weak intercalary growth during the unfolding. The tips of the seventh up to the tenth scales were weakly suberized and had two blades which formed a cap covering the tip of the bud. The scale which preceded the emergence of a leaf sprout with a leaf blade had on its tip pronounced lobes and a depression between them with a rounded bottom and hairs along the edge. It was followed by a sprout with large separated stipules, an almost unpronounced leaf base and a differentiated leaf blade; hence, there is a threshold in the differentiation of leaf sprouts. In the axil of each growing scale, a small dormant bud was set. Thus, the number of leaf organs on a shoot after unfolding was 10-15, while the leaves of the middle formation did not exceed 3-5, and besides only one growth period was observed in a majority of U. glabra plants in their generative age state. Using U. glabra as an example, the performance of the threshold mechanism within the genetic program of vegetative shoot development was demonstrated.

Variability in the composition of phenolic compounds in winter-dormant Salix pyrolifolia in relation to plant part and age

The phenolic phytochemicals of winter-dormant Salix pyrolifolia were determined from the vegetative buds, and the bark and wood of different-aged twigs by HPLC-DAD and UHPLC-QTOF-MS analyses. All the plant parts were composed of salicylate glucosides and the other Salix-specific, simple phenolic glucosides as well as of phenolic acids, flavonoids and the high molecular-weight condensed tannins. The flavonoid composition was most diverse in buds and they also contained a large amount of chlorogenic acid (5-caffeoylquinic acid IUPAC), while salicylate glucosides and simple phenolic glucosides predominated in bark. The wooden interior part of the twigs contained fewer components and the lowest concentrations of compounds. Salicortin was the main compound in winter-dormant S. pyrolifolia (over 10% of bark biomass), but the concentrations of picein, salireposide, isosalipurposide, catechin and condensed tannins were also high. The flavonoid composition was highly naringenin- and quercetin-biassed. The composition of phytochemicals was organ-specific and remained relatively similar between different-aged trees. However, there were compound-specific fluctuations in the concentrations of phytochemicals with the age of the trees and within plant parts. Generally, the one-year-old plants differed from the older trees in their high concentration of condensed tannins in all the plant parts studied and in the highest concentration of isosalipurposide in bark, while the total amounts of salicylate glucosides in plant parts, and of naringenin glucosides in buds, tended to be highest in 20 year-old-trees.

The isolation of the IGT family genes in Malus × domestica and their expressions in four idiotype apple cultivars

IGT family genes share the highly conserved motif GφL-(A/T) IGT in domain II and play an essential role in plant form. The tree architecture of apple (Malus × domestica Borkh.) affects fruit quality and yield. However, little information is available regarding IGT family genes in apple. Apple cultivars of four ideotypes (columnar, tip bearer, spur, and standard) were selected to characterize IGT family genes. Four IGT family members named MdoTAC1a, MdoTAC1b, MdoLAZY1, and MdoLAZY2 were found in the apple genome, sharing four conserved domains. In addition, MdoLAZY1 and MdoLAZY2 contain a fifth domain (EAR motif) at the C-terminus. There was no difference in the coding sequences of each gene in the four cultivars, but several mutated sites were found in their promoters. The four genes displayed lower expression levels in all tested tissues and organs of the columnar cultivar than in the other three cultivars, while expression levels of MdoTAC1a and MdoTAC1b in shoot tips and vegetative buds were highest in the standard cultivar, followed by spur, tip bearing, and columnar cultivars in decreasing order. These results indicate that IGT gene promoters are of great importance in the development of apple tree architecture and lay a theoretical basis for developing gene-specific markers for marker-assisted selection in breeding programs.

Performance of an elite, hybrid family of a northern × southern highbush cross (‘Draper’ × ‘Jewel’)

A family of the cross of the northern highbush blueberry ‘Draper’ × the southern highbush ‘Jewel’ (D × J) was propagated and phenotyped for plant size, yield, rate of flower, bud, and fruit development, leafing ability, winter hardiness, and fruit quality for 2 years in the field in Florida (FL), Georgia (GA), Michigan (MI), and Oregon (OR). In addition, a controlled greenhouse study was conducted on these progenies to estimate their chilling requirements. Significant levels of genotypic variability were observed for all the traits and the majority showed significant location and genotype × environmental interactions. Most of these traits were normally distributed across genotypes. There were many more flower buds per cane in GA than FL and OR, and many more vegetative buds broke in OR than in the southeastern states. Most of the various yield and growth traits were significantly correlated, except for flower buds per cane with plant height and width, and strength of leafing with plant width and flower buds/cane. Plants in OR developed much more slowly than those in FL and GA. There was a significant G × E effect on days to early green tip, floral bud break, and full bloom. Significant correlations were observed between all the developmental rates except between floral bud break and the days to full flowering and first blue fruit. Most individuals were severely damaged by winter cold in MI, although a few showed good tolerance. Significant location effects were observed for pH, titratable acidity (TA), soluble solids (SS), and SS/TA. Fruit in FL were a little softer and had higher SS/TA ratios than those in GA. There were significant interactions between genotype and environment for all the fruit quality traits except for fruit scar, firmness, anthocyanin content (ACY), and % juice. Fruit scar had a significant positive relationship with firmness and a significant negative relationship with flavor. Fruit color was significantly associated positively with soluble solids and ACY. Firmer fruit had significantly lower levels of ACYs. Fruit pH showed significant positive correlations with TA, TA/SS, and % juice, and significant negative relationship with SS and ACY. TA was significantly associated negatively with TA/SS and positively with ACY and % juice. TA/SS and ACY were positively correlated significantly with % juice. Two or three individuals were identified at each location that had high yields, were very early or late ripening and had excellent overall fruit quality. There were significant levels of genotypic, environmental (chilling hours) and G × E interaction among vegetative and floral buds for numbers of buds per shoot, percentage that developed and their developmental rate. The chilling requirement of highbush blueberry appears to be regulated polygenically as the D × J family segregated normally. On average, genotypes did more poorly at 250 and 350 chilling hours than the other chilling treatments.

Infection criteria, inoculum sources and splash dispersal pattern of Colletotrichum acutatum causing bitter rot of apple in New Zealand

Infection of Malus x domestica cv. Royal Gala fruit by Colletotrichum acutatum causing bitter rot was studied in the temperate climate of New Zealand. Temperatures above 15 °C were required for lesions to develop on detached apple wound-inoculated or inoculated without wounding with C. acutatum spores, regardless of maturity. A wetness period of 72 h was required for infection of mature detached apple fruit without wounding. On wound-inoculated detached apple fruits, sporulation was related to temperature and followed a similar pattern. In the field, a mean temperature above 15 °C for 72 h after wound-inoculation was required for lesions to develop. Buds were a more important source of inoculum than twigs, and it was shown that C. acutatum could be isolated more frequently from outer bud scales than from inner scales. Asymptomatic infection of vegetative and reproductive buds was detected. C. acutatum was detected on asymptomic surface-sterilised petals and fruit, more commonly during summer than spring. Symptomless sterilised leaves generally yielded C. acutatum throughout the season, but isolations were more frequent in summer. Recovery of inoculum using a splash meter to detect vertical dispersal showed that in summer inoculum was primarily splashed up from the ground. In spring, inoculum was recovered in similar quantities from all heights up to a metre, suggesting that splash dispersal occurs from the canopy as well as from the ground. A disease cycle for C. acutatum infecting apples and causing bitter rot in New Zealand is suggested.

Diversity of Xylella fastidiosa host suitability among siblings from a non-traditional interspecific Prunus cross

Ten F2 clones from an initial hybridization of Prunus webbii × Prunus persica cv Harrow Blood were evaluated under greenhouse conditions for their reaction to Xylella fastidiosa subsp. fastidiosa strain M23 during two growing seasons. Clonal accessions used for the study were selected on the basis of horticultural diversity, and were a small subset of trees from a large F2 population. Foliar symptoms of M23-inoculated trees were monitored weekly throughout the 20-week growth period. Clones were then sampled for bacterial titer determinations. With the exception of parental accession Harrow Blood, all clones yielded measurable titer; however, almond leaf scorch disease symptoms were never observed in five of the ten sibling clonal accessions. Vegetative bud break and bloom phenology data collected from field-grown mother trees over a 7 year period as well as leaf morphology characters of the clonal accessions were examined for associations with bacterial titers of inoculated clones using a principal components analysis. No clear associations were noted, with small sample size limiting the predictive ability of the analysis.

Heart-shaped cladodes in commercial cactus pear plantations

Because of the diverse uses it has, and the multiple benefits it contributes to, cactus pear(Opuntia spp.) is considered one of the natural resources of greatest socioeconomicimportance in Mexico. Its intensive production in monoculture, associated with a reducedgenetic variability, has resulted in the proliferation of various physiopathies, and the prevalenceof pests and diseases, which reduce its productivity. In diverse cactus pear producing zones inMexico and other countries, a malformation called in this study cladode ‘acorazonamiento’(heart-shaped cladode), which is derived from the shape the cladode takes, has beenobserved; however, the causal agent is unknown at the time. Considering that its occurrencecould cause economic losses to cactus pear producers, this study describes the visualsymptomatology and the incidence and severity of heart-shaped cladode symptoms incommercial cactus pear plantations in the south and southeast of Zacatecas, Mexico. Thesymptomatology was more evident in tender buds of 6 to 20 days of age, and is characterizedby the presence of diverse malformations in the apical or lateral part of the cladodes, as wellas by the appearance of micro-scarring that reduces the vegetative and floral budding in theaffected zone; the damaged tissue presents rupture of the cuticle and epidermis, and thedetachment of cell walls. Three principal malformation symptoms were found, which werenamed in this study as: ‘heart’, ‘bean’ and ‘saw’, according to the cladode physical appearance,with the first one being the most frequent. All the plantations evaluated showed the presenceof malformed cladodes, with values that fluctuated between 12 and 30 %. Cladodes with heartshapesymptomatology may generate buds with similar appearance in a proportion of 2:1asymptomatic:symptomatic cladodes. Likewise, it was observed that the degree of severityranged between 1 to 38% of photosynthetic area reduction, and damaged cladodes may losebetween 50 to 80% of vegetative and floral buds. Derived from this, it is pertinent to perform
 studies directed towards characterizing its etiology in order to implement managementstrategies and reduce economical losses.

Preservation of sweet chestnut genetic resources (Castanea sativa Mill.) against attack by chestnut gall wasp (Dryocosmus kuriphilus Yasumatsu, 1951)

European sweet chestnut (Castanea sativa Mill.) is one of the most important wood species due to its environmental and economic role in many agro-forestry systems. Chestnut gall wasp (Dryocosmus kuriphilus Yasumatsu, 1951) is currently the most dangerous pest of sweet chestnut, including in Slovenia. Attack on vegetative buds (in which the eggs are deposited and on which galls are subsequently formed) disturbs the growth of shoots and reduces the yield. In the event of a strong attack, the tree can weaken and decay, which is already noticeable on the ground in Slovenia, especially in terms of the monitored genetic resources of the chestnut tree. Following Japanese experience, European countries are increasingly choosing biological control of chestnut gall wasp with the torymid wasp (Torymus sinensis Kamijo, 1982). Micropropagation is a way of ensuring effective preservation and reproduction while optimizing all phases of work. In the micropropagation of Slovenian sweet chestnut genetic resources, problems arise in the rooting phase.

First report of an exceptional monoecious type of Pistacia atlantica ssp. atlantica in Algeria (North Africa)

The Pistachio Atlas tree ( Pistacia atlantica Desf.) is a dioecious specie that belongs to the Anacardiaceae family. Recently, some researchers have found a monoecious species which belongs to this family in Turkey ( P. atlantica Desf.), ( P. terebinthus L.), Bulgaria and China ( P. Chinensis ). No study has reported the case of monoecious species in Pistacia atlantica Desf. in North Africa. However, our research describes for the first time the phenomen on that takes place in Algeria. During our observation, the tree exhibited seeds and a vestige of pistillate inflorescence. In general, pollen shedding started in staminate clusters as vegetative buds broke. Cluster distribution of both sexes on the tree appeared highly complex and variable. This discovery also proves that there are subjects of this species - a monoecious species - in northern Africa and especially in Rechaiga, Tiaret.

<b>Characterization of blueberry cultivar ‘climax’

The objective of this work was to characterize the blueberry ( Vaccinium spp.) cultivar Climax, Rabbiteye group ( Vaccinium ashei Reade). In order to achieve that, a survey with blueberry plants (cultivar Climax), in full production, was conducted during the 2012/13 and 2013/14 seasons in the mesoregion of Pelotas, Rio Grande do Sul State, Brazil. Data regarding the distribution of flower and vegetative buds on branches of two lengths (long and short) was collected. Another evaluation, considering three positions of flower buds in the branch (apical, medial and basal), the number of flower primordia, open flowers and fruits formed was performed. Data were subject to ANOVA and, when significant, the averages were compared using either the F or Tukey’s HSD test (p ≤ 0.05). The results demonstrate the presence of flower buds intercalated with vegetative ones. The total number of flower and vegetative buds, flower primordia, flowers and fruits was influenced by the length of the branch. Likewise, the position of the bud on the branch affected the results, with a greater number of flower primordia on the basal, a greater number of flowers on the medial and a greater number of fruits on the apical portions of the branches.

Effects of early harvest times on nut quality and physiological characteristics of pistachio (Pistacia vera) trees

Introduction - Pistachio harvesting at the appropriate time is one of the key factors affecting the product quality. The effects of early harvest time on quantitative and qualitative properties of pistachio nuts were investigated. Materials and methods - The 'Ohadi' pistachio cultivar was used as the market reference in Iran. Five harvest times (July 27, August 6, August 16, August 27 and September 6) were studied over four consecutive years (2008-2011) as treatments in the field experiment. Nut weight parameters, hull discoloration, hulling, cracked nuts, early-split nuts, kernel protein, mineral and chlorophyll contents were evaluated at each harvest time. Results and discussion - The fresh and dry nut weights showed the maximum and the minimum nut production rates for the last (September 6) and the first (July 27) harvest times, respectively. Percentages of hull discoloration, cracked nuts and immature nuts were significantly influenced by harvest time. The early-split nut percentage was not significantly different at the various harvest times. The maximum potassium, calcium, magnesium and nitrogen, protein and chlorophyll contents were obtained at the first harvest time. The growth of current year shoots, leaf area, percentages of vegetative and reproductive buds were not influenced by the harvest time, whereas the abscission of reproductive buds was minimum at the first harvest time and significantly different from all other times. Conclusion - Early harvesting of pistachio is preferable in terms of crop health indicators, nutritional value and color of the kernels. However, it is not preferable in terms of yield (nut and kernel production per hectare) for the producers, although potentially more sustainable.

6-Hydroxyisocaryophyllene and isocaryophyllenic acid from birches vegetative buds

The new isocaryophyllene derivatives were first detected in the birch vegetative buds. The structure of 6-hydroxyisocaryophyllene [(1R,4Z, 6R, 9S)-8-methylene-11,11-dimethylbicyclo[7.2.0]undec-4-ene-6-ol] isolated from the Betula pendula Roth. birch buds was determined by NMR spectroscopy. The structures of caryophyllenic acid and isocaryphyllenic acid isolated from the Betula grandifolia Litv., B. albo-sinensis Burk., B. fusca Pall.ex Georg, B. obscura A. Kotula, B. litwinowii Doluch., B. hallii Howell, B. grandifolia Litv. birch buds was determined by X-ray diffraction analysis. The physico-chemical characteristics and NMR data of 6-hydroxyisocaryophyllene, epoxide of 6-hydroxyisocaryophyllene and all the isolated acids are given. The gas chromatographic retention indices of all identified compounds were determined.

PmCBFs synthetically affect PmDAM6 by alternative promoter binding and protein complexes towards the dormancy of bud for Prunus mume

The survival in freezing temperature for woody plants is exclusively dependent on the perception of coldness and induction of dormancy. CBF/DREB1 transcriptional factors join cold-response conduits and the DAM genes, especially PmDAM6, are well-known regulators of dormancy. Despite the immense importance, little is documented on the association between CBF proteins and the complexity of the promoter region in PmDAM6 with the function of bud dormancy in P. mume. Therefore, this study was based on the cloning of PmDAM6 and six PmCBFs to evaluate their integral roles in the process of bud development. The consistency of expressions in either vegetative or reproductive buds provided a negative control from PmCBFs to PmDAM6 during the onset of dormancy. Besides, PmCBF5 could form heteromeric complexes with PmDAM1 and PmDAM6. PmCBF1, PmCBF3, and PmDAM4 recognized the promoter of PmDAM6 by the alternative binding sites. Therefore, the interactions of these genes formulated the base of an obvious model to respond to the coldness and engendered dormancy release. Findings of this study will further help the unveil the genetic control of bud dormancy and its augmentation in P. mume and may offer an explanation for the vernalization.

The effects of different tip-pruning times on flowering, yield, and maturity of two mango cultivars in subtropical climate of Northern Territory (Katherine region) from Australia

Abstract The present study aimed to take advantage of the progressively cooler weather in the Katherine regions (Northern Australia) that occurs from April to July to investigate the effects of night temperatures on developing mango buds. The experiment was conducted using seven-year-old commercial mango cultivars Honey Gold and Calypso (B74) grown in separate location sites. Tip-pruning treatments were applied to three replicate single trees at four weekly intervals for five months. All branches around the canopy were pruned 10 cm approximately above the last internode. The length of new vegetative flush growth for 20 randomly selected pruned branches on each tree was recorded on a weekly basis. During experiment from April to November (harvesting time) climate data including temperature (mean, max, min), chill and heat sums, chill and heat cumulative (cum), and relative humidity (RH %) were recorded hourly to find their impact on growth characteristics such as vegetative bud growth, flowering time, canopy flowering (%), inflorescence length, number of fruits/tree, and fruit maturity. Pruned trees produced more inflorescence when the axillary bud below cutting point received over 300 h chill cum

Placozoa

Schierwater & DeSalle introduce the enigmatic phylum Placozoa.

VARIATIONS OF THE CHEMICAL COMPOSITION OF EXTRACTIVE KIDNEYS OF THE KIDNEYS BERES OF ST. PETERSBURG AND THE LENINGRAD REGION

The article is devoted to the differences in the composition of extractive substances of vegetative buds of birch trees in St. Petersburg and the Leningrad region and its change. Buds of birch (Betulae gemmae) are a medicinal product and are included in the state register of medicines. The substances soluble in acetone were studied by chromatography-mass spectrometry method after preliminary methylation with diazomethane. The retention indices of the identified compounds are given. Earlier, the structure of compounds was established by methods of NMR spectroscopy.Birch buds from the surveyed areas contain sesquiterpenoids and flavonoids. These components correspond to the classical notions of the composition of the buds. However, specimens of birch trees were found containing only triterpenoids and fatty acids in the buds, and also a combination of all the listed compounds - the intermediate composition. This tendency was observed in the Betula pendula Roth. birch, Betula pubescens Ehrh., Betula pendula var. carelica Merckl., Betula krylovii G.V.Krylov in the arboretum of the St. Petersburg Forestry University and observed on the Betula pendula and, Betula pubescens in St. Petersburg and the Leningrad region. Presumably one type of chemical composition can be replaced by another in time. The change in the composition was recorded for several years on specimens of birches.Various reasons for this phenomenon are discussed.