Budbreak anomalies in temperate fruit trees grown under mild conditions have often been described. However, only few authors approached the physiological evolution of leaf buds all along the dormancy period according to the temperature pattern. The aim of this study was to characterize the evolution of peach leaf bud dormancy through some physi...ological and biochemical parameters under temperate winter conditions and under total cold deprivation after the endodormancy onset. Two treatments were applied in peach trees cv. Redhaven: (i) Regular Chilling Amounts — RCA and (ii) Total Chilling Deprivation — TCD. Buds were sampled periodically from different parts of the stem (terminal, medium and basal ones). We recorded the evolution of: carbohydrate concentrations (glucose, fructose, sucrose, sorbitol and starch), respiration rate, water contents and energy metabolism (ATP and ADP ratio). The dynamics of these parameters were compared and correlated with dormancy evolution ("one node cuttings" test) and budbreak patterns in plank:. The endodormancy intensity of terminal buds was significantly lower than those of median and basal buds in early October. Under RCA treatment, this gradient faded and the bud endodormancy release was completed at the same time in all positions along the stem. Thereafter, the "cuttings" test indicated that terminal buds grew slightly faster than median and basal buds, and, consistently, budbreak in planta started with the terminals buds, followed by the medians and then by the basal ones. The carbohydrate contents showed a transitory change only when the buds began to grow after the endodormancy was released under RCA. Respiration, water content and ATP/ADP changed dynamics only under RCA and only after the end of the endodormancy (their respective changes were very parallel). The dynamics of none of the tested parameters could be related with the endodormancy dynamics, but respiration, water content and ATP/ADP could be consistent markers of the actual bud growth before bud break (in this respect, ATP/ADP could not show differences between the terminal and axillary buds while respiration and water content could).
The phenological processes of flower bud development of stone fruits during dormancy are not thoroughly known. The yield of these species, especially of almond, apricot and peach is determined basically by dormancy of flower buds, the survival rate of buds during winter frosts and by their ability to develop normal floral organs in the next spr...ing. After the initiation of floral primordia, flower bud development is taking place in continuous space until blooming, though at different speed characteristic to the species. To study flower bud development during dormancy we applied two alternative methods in different genotypes of almond, apricot and peach: (1) examination of pollen development (microsporogenesis), and (2) the measurement of pistil length. The samples were collected from the central part of Hungary during the dormancy period of 2004/2005. The three fruit species differed significantly in the speed of flower bud development, it was the quickest in almond, followed by apricot and peach. In addition to the species, there were significant differences in the process of microsporogenesis and pistil development between genotypes within species and also between the different types of shoots on which the buds were located. On short shoots buds developed at a higher speed, than on long shoots. Based on our observations, on the short shoots the period of endodormancy was shorter with 5-30 days, according to genotypes, compared to the long shoots. This difference, however, decreased to 2-3 days by the time of blooming.
Pear cultivars of variable frost tolerance were tested as for frost injuries suffered as a consequence of artificial freezing temperatures during the endodormancy as well as the ecodormancy. Damages were registered according to a visually defined scale, then peroxidase and polyphenol-oxidase activity was checked in buds, spurs and limbs. Accord...ing to our results, 'Packham's Triumph' was the most frost tolerant cultivar. Regarding enzyme activity of both enzymes, the performance of cultivars displaying different susceptibility was also different in spurs as well as in buds. Results referring to the endodormancy were especially instructive. During the ecodormancy, data obtained at the same time indicated the differences existing between the developmental stages of dormancy in the respective cultivars.
Bud dormancy during winter is a critical factor in peach production in Hungary. The yield is determined basically by the survival rate of flower buds during winter frosts and by their ability to develop normal floral organs. It is important to investigate the genetic basis of slow floral development during dormancy for the purpose of breeding p...each varieties with better winter hardiness. The aim of the present research was to examine microsporogenesis in 14 peach varieties during three successive winters in a Hungarian germplasm collection and to study the effectiveness of this method in variety evaluation. There were significant differences in the dynamics of microsporogenesis both between the varieties and between the years. Of the varieties, ‘Mayfire', bred in California, possessed the quickest pollen development rate. The microsporogenesis of `Piroska', a Hungarian local variety, was the slowest. Rapid floral bud development was observed in `Aranycsillag', `Springcrest' and 'Venus'. A medium developmental rate was characteristic of `Babygold 6', Fairlane', `Michelini' and `Red June', while development was slow in 'Champion', 'Early Redhaven', `Redhaven', `Harko' and `Mariska'. Based on these results, the study of microsporogenesis represents a reliable method for the phenological description of peach varieties during dormancy. The application of this method makes it possible to identify varieties and landraces with slow flower bud development, suggesting better winter hardiness.
The aim of the study was the study of winter frost damages, especially their changes expressed in temporal frequencies on the main fruit growing regions of the country. In our earlier paper, we introduced the calculation with the term LT50 as the quantitative expression of temperature threshold, when the lethality halves the survival of plant o...rgans, buds or cells causing 50% death rate. The damage is highly dependent on the temperature and on its duration (length of time), but not at least on the frost tolerance of the fruit trees. The incidence and severity of damage is analysed according to the apricot and peach varieties of their different susceptibility or tolerance too. Four fruit growing regions, two of the in Transdanubia and two belonging to the regions east of the Tisza river have been selected to trace the incidence and severity of frost damages. For that purpose, we analysed the history of the past 60 year period, 1951–2010, utilising the database of the network of 16 meteorological stations of the countrywide service. Being aware of the values of LT50 during the rest period and afterward, the compulsory dormancy caused by low temperature, the number of days, the probability of frost damage could be predicted. The role of the orographical profi le, the height above sea level and the exposition of plantations are also decisive. Within the same plantation, 20–30 m difference of level may cause large diversity in temperature and frost damage. Air circulation and regular incidence of winds within the Carpathian basin modify the occurrence and severity of damages. Lowlands near the southern and northern country borders are particularly exposed to winter frosts. Most damages are reported in February, as temperatures below –20 °C especially if the fi rst part of the winter was mild, or in January was a warm period. With the end of the physiological rest period of the trees, the frost-susceptibility increases signifi cantly, and a cold period of –15 °C may cause heavy damage. This study proves that tolerance of varieties infl uence the damages substantially. By planting frost tolerant varieties, winter frost damages could be diminished by 40–50% at the same growing sites. Present results may also offer a tool to estimate the risk of frost damages and express the security of yields at a given site based on the data accumulated in the database over many years.
The flower bud development is an especially complex process from initiation to blooming. Our main objective was to analyze paradormancy; the first stage of this process in our collection of varieties in the vicinity of Budapest, in Hungary. We have analyzed three varieties with different winter hardiness. `Ceglédi bíborkajszi' is one of the m...ost frost susceptible in our collection of varieties, when the flower bud differentiation started in early August, and all flower organ initials evolved in beginning of September. The flower bud differentiation of the most winter hardy variety, `Rózsakajszi C.1406' started in the end of August, and all flower organs were noticed at middle of September. `Gönci magyar kajszi' is a medium frost hardiness apricot variety, its phenological process composes transition between two mentioned above varieties.
The aim of onion bulb storage is to meet consumer demand for extended availability of onions whilst maintaining product quality. The principal biological factors leading to onion bulb deterioration are respiration, resumption of growth and pathogen attack. In onion bulbs a dormant period, when sprouting and rooting cannot be induced, is followe...d by a period of internal changes that prepare the bulb for breaking of dormancy and subsequent growth. Out of storage, the bulb then proceeds towards flowering and seed production. Two successive winter seasons of 2008/2009 and 2009/2010 were conducted under sandy soil conditions to study the effect of spraying with 12 commercial compounds on yield and yield components of onion seeds and storage The seed yield of each commercial compounds plot from previous experiment was divided into two groups, storage under room temperature and 5°C. Seeds transferred immediately after drying to Increasing Export Competition of Some Vegetable Crops Project Laboratory located in Faculty of Agriculture, Cairo University. The effects of storage temperature, storage period and foliar with some commercial compounds on onion seed quality were considered. Storage in 5°C had the higher germination percentage than storage in room temperature. Results indicated that as storage period increased the germination percent decreased. The treatment with boron or amica in the first season had the highest germination percentage. While, the treatment with union Zn, union feer, union Mn, boron, elga 600, caboron, amica, hummer or amino X had the highest germination percentage in the second season. Storage in 5°C resulted in higher moisture content than storage in room temperature. Regarding the effect of storage period on moisture content, the water content was significantly increased with prolongation of storage period. The lowest values of water content were recorded for treatments with union feer, shams K or boron in the first season, and union feer, shams K, boron, magnesium, shetocare or hummer in the second one. Catalase activity was significantly decreased as storage period increased. The treatment with shams K, boron, shetocare or amino X had the highest catalase activity in both seasons. Peroxidase activity was significantly decreased as storage period increased. Foliar application with boron had the highest peroxidase activity in both seasons. Seed stored in room temperature had the higher malondialdehyde content than those stored in 5°C in the second season. The malondialdehyde content increased as storage period increased. The treatment with magnesium, caboron and the control in the first season, and the treatment with magnesium and the control in the second season had the highest malondialdehyde content.
Vegetative propagation by hardwood cuttings is a very simple and cheap method for production of plum rootstocks. The aim of this study was to examine if this propagation technique is suitable for practice of three plum rootstocks and find the time or period when the percent of rooted cuttings is maximal. Based on our results, hardwood cuttings...of the rootstocks tested have the rooting potential acceptable for practice, however, for Fehér besztercei in the previous literature leafy cuttings are recommended. Fehér besztercei reached 74.0% rooting, cuttings of Sainte Julien GF 655/2 rooted in as high percentage as 78.3%, and Marianna GF 8-1 had 88.3% rooted cuttings. Rooting potential of hardwood cuttings depends on more factors, one of them can be their dissimilar sensitivity for the diverse environmental circumstances at the different propagating dates, affecting through the internal biochemical changes that can be in relation with the differences in their dormancy.
The cuttings of Marianna GF 8-1 take root easily, but in some years the conditions were less favourable for reaching maximal rooting. For taking cuttings the period from the beginning of October until December was optimal. For Fehér besztercei the optimal date of cutting collection was around the end of October, but in some years the rooting in the middle of December was also high. Sainte Julien GF 655/2 definitely rooted best in October. The treatments with different IBA concentrations in two years affected differently the rooting percentage. The rooting of Marianna GF 8-1 and Sainte Julien GF 655/2 is barely influenced by the different hormone dose in both years. Hardwood cuttings of Fehér besztercei rooted definitely better when treated with 2000 ppm IBA in comparison to untreated ones, while in 2001-2002 there was no difference between 2000 and 4000 ppm.
Sour cherry production in the world is increasing gradually. Profitable production, i.e. yield, depends largely on weather conditions. If Hungary wishes to keep up with the most successful countries, attention should be paid to the weather during the dormancy period, being definitely decisive from the points of view of quality as well as quanti...ty. In order to predict the expected risk factors, characterisation of the most important weather parameters is necessary. For that purpose, the database of the Institute of Research and Extension Service for Fruit Growing at Újfehértó Ltd. has been utilised. Records of weather conditions were collected throughout the period 1984-2005, i.e. daily minimum, maximum and mean temperatures (°C), and phenological diary of sour cherry varieties ’Újfehértói fürtös’, ’Kántorjánosi’ and ’Debreceni bôtermô’. For the future expectations study we have used the RegCM3.1 regional climate model with 10 km resolution. Data of 4 indicators have been traced: Average temperatures, Number of days without frost, Maximum length of periods without frost, Maximum length of frosty period. On the one hand, we surveyed the changes; on the other hand, estimates have been attempted for the future changes expected during the following decades.
The resumption of development in ecodormant buds in terms of establishing a functional vascular connection between the inflorescence primordia and spur tissues in apple trees was investigated. Differentiation of the xylem elements could be observed first in the pedicel of the flower primordium, in the middle of January. Much later (at the begin...ning of April) there were mature xylem vessels in the wall of the receptacle and, merely a procambial strand for the ovule primordium which was at this time an undifferentiated protrusion of meristematic cells, only. As for phenological development of buds incubated at a temperature of 20 °C, it was the slowest in buds sampled in January, faster in buds sampled in the middle of February and, buds from the middle of March responded very quickly. The function of temperatures needed both for xylem differentiation and for the flower primordium to achieve maturity is pointed out. The nature of frost damage in vessel elements, as well the relationship between chilling requirement and growth features of apple cultivars will be discussed.
Frost tolerance of pear cultivars was checked after artificial cold treatment in 2003-2005. Limbs collected during the endodormancy were exposed in a climatic chamber for 24 hours to —25; —28 °C, while those collected in the ecodormancy were kept at —15 and —18 °C. Frost damages of buds were registered according to a visually defined...scale, then peroxidase (POD), polyphenol oxidase (PPO) enzyme activities and carbohydrate contents were checked in buds and spur-part below the buds. POD activity of untreated control in tissue below buds was higher than in the buds, which were increasing continuously during the endodormancy and decreased at the end of the ecodormancy. During endodormancy, cold treatment of —25 and —28 °C effected different changes of enzyme activity in buds of the cultivars. In the ecodormancy, enzyme activities increased after a cold treatment of —15 °C, whereas the activities decreased significantly after —18 °C. `Kaiser' — susceptible to frost — with its higher values of both enzyme activities marked out from other cultivars, which is correlated with its stress response. Changes in carbohydrate components — especially in glucose — of buds monitored well the different stress responses of tolerant and resistant pear cultivars induced by frost stress.
During the winter dormancy period of 1998-99, the differentiation process of xylem and the formation of annual and pseudo-annual growth rings was studied in sections of the central stem of Thuja orientalis of different age (1-14 year old), starting from the top (the tip of leader shoot) towards the bottom. In the apical 1-2 cm portion...of the one year-old leader shoot, only the protoxylem was formed by the end of vegetation. The protoxylem elements appeared first in 6 bundles than gradually merged into 2 semiquadrangular (triangular) bands (each containing 3 protoxylem bundels) around the pith. In this stem portion, the pith was cross-formed first and became gradually flattened at the lower stem parts, following the generally flattened shape of the stem and the respective facial and marginal position of leaves. A continuous xylem ring (with formation of metaxylem elements) apeared 3-5 cm below the shoot tip. In fact, it was the stem part where a "real" annual ring was formed by the end of vegetation. The first pseudo-annual rings were observed 16 cm below the top. The "regular" annual rings were completely continuous all around the stem, consisted of strongly flattened in radial direction thick-walled latewood tracheids and had a distinct border (demarcation line) at the end of the year. The "pseudo-annual" rings formed incomplete dark rings or semicircular bands within the earlywood. They were composed of tracheids with thick cell walls but somewhat wider radial diameter than those of the "real" annual rings, and the border between their outside margin and the next earlywood was less distinct.
In the xylem of two year old stem portion, the innermost central annual ring appeared not at the transition zone between the current and the former years of growth, but about 2 cm lower. Above that, only the thick-walled bundles of the former years protoxylem were found. Down the stem, the older sections showed similar features: the next annual ring appeared always somewhat lower than the borderzone of the given and the former years growth. The "pseudoannual" rings (or more correctly the growth rings) continued regularly to appear in the lower (older) sections of the stem as well. They were found untill the age of up to 14 years (the bottom of the studied plants). Their number was 3-4 per year first, than (from the 5th annual ring counted from the centre) decreased to 3,2,1, and in the youngest outer part of the xylem there was no pseudo-annual ring at all. The development of pseudo-annual rings was usually more marked on the thicker (more branched) than on the thinner side of stem. Stems older than 14 years were not studied.