Winter Rest Period Research Articles

Spectral assessment of varieties and breeding lines of winter wheat during the restoration of spring vegetation

The development of new and implementation of existing methods of field assessment of winter wheat genotypes is one of the key tasks of modern breeding. The use of modern screening methods in breeding allows the breeder to get a more objective assessment, as well as to increase the volume of the studied samples several times. The time of spring vegetation recovery (TSVR) is one of the key stages of the vegetation period of winter wheat. Biometric and spectral assessment of winter wheat with the onset of the TSVR allows establishing how plants of a certain genotype overwintered, as well as the state of their growth and development before the start of the second growing season. The purpose of this study was to determine the characteristics of plant growth and development of modern varieties and promising breeding lines of winter wheat of The V.M. Remeslo Myronivka Institute of Wheat (MIP) from sowing to the restoration of spring vegetation. The hydrothermal conditions of the seedling-TSVR period had diverse effects on the reproductive process of the genotypes of winter wheat under study. According to the study results, abnormally dry conditions of the period from sowing to the end of the autumn growing season in 2019 adversely affected the condition of winter wheat plants that were in BBCH Phase 10-13, autumn tillering did not take place. Regardless of the genotype, plants were more developed during the first sowing period. According to biometric and spectral parameters, at the time of spring vegetation recovery, the following varieties turned out better than the Podolyanka standard variety (NDVI = 0.52): MIP Dnipryanka (NDVI = 0.58), MIP Lada (NDVI = 0.56), Balada Myronivska (NDVI = 0.56) and lines Lutescens 37519 (NDVI = 0.55) and Erythrospermum 55023 (NDVI = 0.58). During the second sowing period, the variety MIP Dniprнanka (NDVI = 0.45) and the selection lines Lutescens 37519 (NDVI = 0.44) and Erythrospermum 55023 (NDVI = 0.43) were selected. The standard Podolyanka variety had an NDVI index value of 0.43. MIP Lada and Balada Myronivska varieties react more sensitively to the timing of sowing and need a longer period of autumn vegetation to accumulate more dry matter and better pass the winter rest period

Effects of heat treatment and chilling duration on camas growth and development

Great camas (Camassia leichtlinii (Baker) S. Watson [Asparagaceae]) and common camas (C. quamash (Pursh) Greene) are two of the most culturally and ecologically significant native geophyte species in the US Pacific Northwest. Like many geophytes, seasonal thermoperiodicity affects their growth and development. The daughter bulb of great camas grows and develops during the summer rest period. Increasing the duration of the summer rest period results in longer leaves in the subsequent growing season. Great camas, common camas, and meadow death camas (Toxicoscordion venenosum (S. Watson) Rydb. [Melanthiaceae]) require a period of chilling during their winter rest period to induce leaf emergence, and as the duration of chilling increases (1) the odds of leaf emergence increases, (2) the period between the cessation of chilling and leaf emergence decreases, and (3) leaf growth in the first week after leaf emergence increases. These results inform growers as to the proper storage methods for these species during their rest periods. Additionally, the chilling optimum, here defined as the amount of chilling at 4.6 °C that minimizes the duration of the winter rest period, is approximately 80 days for both great camas and common camas. However, this optimum was determined without considering a potential interaction with the heat treatment. Knowing the optimum duration of heat treatment and chilling may allow growers to manipulate native bulb species into emerging for multiple growing cycles in a single year, which could expedite their production.

Studying and modelling winter dormancy in olive trees

The abundance of scientific papers dealing with olive reproductive phenology contrasts with the scarce information available in relation to the winter dormant state of olive vegetative structures. In this study, three experiments with young olive trees were performed in Southern Spain, aiming to provide insight into some features of the winter rest period in this evergreen species. Experiment 1 evaluated the environmental cues triggering dormancy induction by measuring leaf appearance rates in trees subjected to different conditions of temperature and daylength over the course of the 2012 autumn. In Experiment 2, several sets of plants were placed into a greenhouse at different dates along the 2013/2014 winter, testing the ability of dormant plants to resume growth upon the return of favourable temperatures. Finally, Experiment 3 was carried out during the autumns of 2016 and 2017 in two locations, and was devoted to assess differences between five cultivars in the onset of dormancy under natural conditions. Our findings revealed that dormancy induction is not controlled by photoperiod, but by low temperatures. The subsequent winter rest state seems to be easily reversed after 1–2 weeks of exposure to warm conditions, irrespective of the initial date of exposure. With regard to cultivar variability, differences in the timing of growth cessation was found to be rather small. Finally, two simple models for predicting the onset of dormancy based on the accumulation of a certain amount of chilling (either considering or not a reversal of chilling by warm temperatures) are presented. Calibration and validation was performed with independent datasets from Experiments 1, 2 and 3. Validation tests highlighted the reliability of both models in reproducing the date of growth cessation.

FACTORS AFFECTING PHENOLOGY OF DIFFERENT Citrus VARIETIES UNDER THE TEMPERATE CLIMATE CONDITIONS OF SANTA FE, ARGENTINA

ABSTRACT The aim of this study was to characterize the phenology of different sweet orange, tangerines and tangerine hybrid varieties growing under the temperate climate conditions of Santa Fe Province, Argentina. Phenological stages were observed weekly during five consecutive years using a BBCH (Biologische Bundesanstalt, Bundessortenamt and Chemical industry) scale adapted for Citrus trees. All varieties showed a winter rest period from June to August. ‘New Hall’ and ‘Navelina’ varieties were the first to reach sprouting stage, whereas ‘Okitsu’ was the last. Inception of flowering occurred from August 13th to September 6th; and full bloom from September 12th to October 2nd. Fruit harvest started with the ‘Okitsu’ cultivar in March, and continued over a 7-month period. Interannual variation for inception of sprouting was high (44 days), and sprouting was correlated with both thermal accumulation (above 13ºC) and the amount of solar radiation measured during July (p<0.0001; r2=0.79). Navel oranges and the ‘Murcott’ hybrid bloomed 5–15 days earlier than other varieties, increasing probability of damage by late frosts.

DEPENDENCE OF VITAMIN CONTENT IN THE GEUM URBANUM AND GEUM RIVALE (GEUM, ROSACEAE) ORGANS ON THE RHYTHM OF SEASONAL DEVELOPMENT

The aim of the research is to determine the optimal terms of the accumulation of vitamins by the organs of Geum depending on the rhythms of their seasonal development. Methods. The method for determining the vitamin C is based on the ability of ascorbic acid to change the color to blue in the acidic medium - 2,6 - dichlorophenolindophenol - to the leucoform, while ascorbic acid is oxidized to dehydroascorbic acid. Determination of vitamins A and E was carried out by reversed-phase high-performance liquid chromatography. Results. It was found that the highest indices of vitamin A and E in the leaves of G. urbanum and G. rivale are observed in July. In the rhizomes of avens, the maximum concentration of vitamins A and E is observed in March during their intensive growth, vitamin C in January. Decrease in the supply of rhizomes of plants with vitamins A and E continues in the autumn period, while for the vitamin C it is observed in the early spring. In the inflorescences, at the beginning of flowering, G. rivale L. and G. urbanum L. are characterized by the greatest content of vitamin A; by the end of flowering, vitamins E and C are accumulated more intensively. Conclusion. The leaves of wintering plants of G. urbanum L. and G. rivale L. continue to contain vitamins A, E, C despite low temperatures under snow cover and are not subject to significant destruction. During the winter rest period, the content of vitamin C in the roots reaches a maximum.

New Insights on the Composition and the Structure of the Acellular Extrinsic Fiber Cementum by Raman Analysis.

Acellular extrinsic fiber cementum is a mineralized tissue that covers the cervical half of the tooth root surface. It contains mainly extrinsic or Sharpey’s fibers that run perpendicular to the root surface to anchor the tooth via the periodontal ligament. Acellular cementum is continuously and slowly produced throughout life and exhibits an alternating bright and dark pattern under light microscopy. However, although a better understanding of the structural background of acellular cementum is relevant to many fields, such as cementochronology, periodontology and tissue engineering, acellular cementum remains rarely studied and poorly understood. In this work, we studied the acellular cementum at the incremental line scale of five human mandibular canines using polarized Raman spectroscopy. We provided Raman imaging analysis and polarized acquisitions as a function of the angular orientation of the sample. The results showed that mineral crystals were always parallel to collagen fibrils, and at a larger scale, we proposed an organizational model in which we found radial collagen fibers, “orthogonal” to the cementum surface, and “non-orthogonal” fibers, which consist of branching and bending radial fibers. Concerning the alternating pattern, we observed that the dark lines corresponded to smaller, more mineralized and probably more organized bands, which is consistent with the zoological assumption that incremental lines are produced during a winter rest period of acellular cementum growth.

NUTRIENT REFERENCE LEVELS FOR FERTIGATION SCHEDULING IN OLIVE GROVES OF AN ARID REGION OF ARGENTINA (SAN JUAN)

The diagnosis of tree nutritional status in fruit trees by leaf-nutrient analysis allows for fertilization scheduling by fertigation. In olive, a specific equilibrium in leaf nutrient concentration occurs that depends on the dominant edaphic and climatic conditions as well as the time of year. Therefore, the objective of this study was to determine leaf-nutrient reference values in olive in an arid region of central-western Argentina at two different times of the year. Leaf samples were taken during the winter rest period (July) and summer (January; a month after pit hardening) over three consecutive years in 100 commercial olive orchards from several cultivars in the Tulum Valley of San Juan, Argentina. These periods have been proposed previously in other regions. Leaf nutrient contents were analyzed and the obtained values were compared with those reported elsewhere. Confidence intervals (95%) of nitrogen (N), phosphorus (P) and potassium (K) in the winter were 1.73-1.83, 0.14-0.16 and 0.92-0.98%; respectively, while summer values were 1.56-1.70% (N), 0.16-0.18% (P), and 1.14-1.26% (K). The N concentrations were somewhat lower than those reported for the mediterranean basin with P and K values in contrast being similar or greater. Values of the remaining nutrients (Ca, Mg, Mn, Na, Cu, Zn, B and Fe) were generally similar to those reported for the Mediterranean. However, boron levels were somewhat high in the winter (25.38 ppm), and magnesium (0.13%) and manganese (33.04 ppm) were low in the summer. Given that the winter period showed narrower confidence intervals than the summer period for N, P, and K, winter sampling could be considered for annual fertilizer scheduling in intensive olive orchards in arid central-western Argentina. However, sampling during the early summer period may provide critical information just prior to oil accumulation.

Activities of peroxidase (soluble and cell wall bound) and of other H2O2 scavenging enzymes are markers of the flower bud development stage in lemon

Specific activities of H 2 O 2 scavenging enzymes, soluble peroxidase (G-POD), catalase (CAT) and ascorbate peroxidase (APX), and cell wall bound (CWB) G-POD, have been characterized in flower buds and leaves in potted lemon trees ( Citrus limon L. Burm.) growing in a glasshouse in Tunisia. In leaves during the winter rest period (from September to December), enzyme activities did not change markedly. Then, leaf G-POD (soluble and CWB activity) increased 4-5 fold in January as the buds reached dormancy release. In growing buds, the activities of the three enzymes increased strongly (10-100-fold) between dormancy and full bloom and decreased slightly (3-fold) post-bloom (beginning of fruit-set). Along the shoots, the developmental stages of flower buds advanced from node 1 to node 5. G-POD activity increased from the shoot apex toward the base of the twig in both leaves and buds. A similar trend was observed for APX and CAT but their activities tended to decrease slightly far from the apex. Retardation of flowering by application of growth regulators strongly reduced leaf-specific activities of the H 2 O 2 scavenging enzymes. Therefore, G-POD activity (APX and to a lesser extent CAT) appears to be a good marker of flower formation in lemon (from bud swelling to full bloom). The results also suggest a link between H 2 O 2 production and flower bud development.

SEASONAL CHANGES IN STARCH CONCENTRATION IN RELATION TO TREE PHENOLOGY, ORCHARD MANAGEMENT AND ALTERNATE BEARING IN LITCHI (LITCHI CHINENSIS SONN.) IN SOUTH AFRICA

ISHS III International Symposium on Longan, Lychee, and other Fruit Trees in Sapindaceae Family SEASONAL CHANGES IN STARCH CONCENTRATION IN RELATION TO TREE PHENOLOGY, ORCHARD MANAGEMENT AND ALTERNATE BEARING IN LITCHI (LITCHI CHINENSIS SONN.) IN SOUTH AFRICA

Injector-size and the time of application affects uptake of tree trunk-injected solutions

Three different injectors, each 25 mm in length and with diameters of 6, 4, and 3 mm, respectively, were tested with low-pressure injections of 250 ml of water into 23 different species of fruit-trees, woodland and ornamental trees at different times of year. The 6 and 4 mm injectors performed well, yielding uptake of 75–100% of water volume 1 or 48 h after injection, depending on the species; however, the ornamental species Melia azedarach did not perform well with all three injectors. The 3 mm injector yielded highly irregular results. The 4 mm injector could substitute the more widely-used 6 mm injector in most cases, with the added advantage of reducing healing time. Injection uptake rates were greater on clear than on rainy days, this difference increasing with smaller-diameter injectors. Prunus species took up a high water volume when injected prior to budbreak, and this could avoid leaf burning caused by later injections of some chemicals. Uptake rates were lower during the winter rest period than during the peak growth season (spring). All these factors are to be taken into account in order to ensure the best and most efficient use of low-pressure injection of chemicals in agricultural, forestry or landscape practices.

Modelling frost resistance of Scots pine seedlings using temperature, daylength and pH of cell effusate

The annual course of frost resistance (LT50) and the pH of the cell effusate in needles of two-year-old Scots pine seedlings were monitored in a field experiment in Oulu, Northern Finland (65° N, 25° E) during 1995. The aim of the work was to to develop model to predict the annual variation in frost resistance by pH of the cell effusate and meteorological data. The seedlings were covered with a fibre cloth shelter which transmitted sufficient light for them to experience the photoperiod, but prevented the accumulation of snow over them. The shelter above the seedlings was removed at the beginning of May and erected again at the end of September. The seedlings were watered only for the time when the shelter was removed, and received fertilizer only during the previous summer (1994). Frost resistance was only -5° C during the growing season but more than -100° C during the winter rest period. It was about -10° C at the end of August, increased to -55° C in the next three weeks, and reached -100° C at the beginning of October. The pH of the cell effusate was lowest during the growing season and highest in winter, the difference being about one and half pH unit. Needles exposed to -196° C showed pH from 4.0 in summer to 5.5 in winter, while pH of the non-frozen needles varied from 5.0 to 6.5, respectively. Seasonal variation in frost resistance was explained by a regression model well (R2 = 0.9) when day length, minimum air temperature and pH were entered as variables.

Zur Lebensgeschichte der Gattung Helleborus L. (Ranunculaceae)

Summary The growth form and growth rhythm of seven Helleborus species of different sections are investigated on the basis of cultivated plants and herbarium specimens. Special attention is drawn to germination, plant development, radication, stem morphology, leaf sequence, inflorescences, and innovation. H. foetidus is an allo-homorhizous, evergreen, chamaephytic, short-living perennial with dicyclic to pleiocyclic, slightly rhythmically growing stems, many-flowered inflorescences and bracteose hypsophylls. In the mountains of Mallorca, dwarfed, long-living pleiocormous perennials grow which approach shrubs. H. argutifolius is an evergreen rhizomatous perennial with dicyclic, strongly rhythmically growing stems, inflorescence buds, many-flowered inflorescences and bracteose hypsophylls. H. lividus is an evergreen rhizomatous perennial with dicyclic, continuously growing stems without inflorescence buds, and with several-flowered inflorescences and frondose-bracteose hypsophylls. H. niger is an evergreen rhizomatous perennial with basal leaves, very few-flowered, geophilous inflorescences and bracteose hypsophylls. H. orientalis is an evergreen rhizomatous perennial with basal leaves, few-flowered inflorescences and frondose hypsophylls. H. viridis is a summergreen rhizomatous perennial with basal leaves, few-flowered inflorescences and frondose hypsophylls. H. vesicarius is a rhizomatous perennial with monocyclic stems, few basal and cauline leaves, green in winter to spring, several-flowered inflorescences and frondose hypsophylls. In view of morphological character progressions, the results are discussed under consideration of all species and further features, and of the relations to environment and distribution. In conclusion, a hypothetical phylogenetic tree of the genus is presented (fig. 29). The pinnate-palmate leaves of H. vesicarius are considered to be primitive. The pedate leaf, typical to the genus, is derived from it. An additional pedate division of the leaf segments occurs in H. multifidus and related species. The ternate leaf of H. lividus and H. argutifolius is interpreted as neoteny. The generally accepted groups, Caulescentes and Scapigeri, are understood as grade groups. The species belonging to the Caulescentes, with elongated, leafy, usually dicyclic stems grow in the mild winter climate of the Mediterranean-Atlantic range. Derived from this group, the Scapigeri with their basal leaves are, for the most part, submediterranean to south-temperate plants of deciduous forests. The development of a scape is explained by the strict growth rhythm of these species: The inflorescence buds are transferred underground and develop very fast in early spring. The whole part above the leaves belongs to the reproductive region. The scales at the base of the scape are referred to as hypsophylls, which adopt the function of bud scales and have a vaginal structure. In accordance with their environment and distribution, the evergreen H. lividus and H. foetidus are characterized by a vegetation period beginning in autumn and a continual inflorescence development with a long flowering period. They develop no, or only loose, inflorescence buds. On the other hand, H. argutifolius develops compact inflorescence buds that unfold quickly, but not before January. The relatively short flowering period of the Scapigeri is delayed even further towards spring. Among them, the summergreen species have a clearly defined winter rest period. The wintergreen H. vesicarius, though, demonstrates a clearly Mediterranean growth cycle with a rest period in summer. The Sicilian plants of H. multifidus subsp. bocconei diverge considerably in growth rhythm and leaf sequence from the species, and need further morphological and taxonomical investigation. In order to achieve a more natural classification, the genus is differentiated according to the structure of the hypsophylls into two new subgenera, s ubgen . Helleborus with undivided, bracteose hypsophylls, and subgen. Helleborastrum (Spach) W erner & E bel with divided, frondose hypsophylls.

Low temperature influence on flowering in Citrus. The separation of inductive and bud dormancy releasing effects

The flowering response of Owari Satsuma mandarin (Citrus unshiu Marc) to low temperature treatments has been determined using potted trees and in vitro bud cultures. In potted trees the chilling treatments released bud dormancy and enhanced both sprouting and flowering, but these two responses could not be separated. However, bud cultures showed no dormancy, and a specific effect of low temperature on flower induction was demonstrated. Low temperature appears to have a dual effect, releasing bud dormancy and inducing flowering. Potential flower buds have a deeper dormancy than vegetative buds, and the first stages of flower initiation seem to occur before the winter rest period.

Fat and weight variations of blackcaps wintering in Southern Spain

Weight and fat variations of Blackcaps Sylvia atricapilla have been studied during several winters, and a “winter rest period” with a slight increase in weight and fat has been detected. These increases do not become substantial until March and April, coinciding with premigratory restlessness. Fat scores varied from 1.6 ± 0.2 in October to 3.6 ± 0.8 and 4.5 ± 0.9 in March and April respectively. Weights were correlated with fat scores, ranging between 17.7 ± 0.7 in October to 20.6 ± 1.6 and 21.1 ± 2.3 in March and April respectively. Interannual differences in weight and fat were recorded between the 1981–82 winter and the subsequent winters 1982–86, mainly due to variations in the resources available in the Pilas area. Changes in the weight and fat scores of recaptured birds and their diurnal variation were analysed, and an average increase during the day of 0.4 g in weight and 0.91 in fat score were detected. The relationship of weight and fat score to the range of diurnal variation in temperature was s...

Inhibition of flowering in vivo by existing fruits and applied growth regulators in Citrus unshiu

In the Satsuma mandarin (Citrus unshiu Marc.) the presence of the fruit results in a gradual inhibition of flowering and of bud sprouting. This inhibitory effect starts several months before the onset of the winter rest period and lasts until the end of the accumulation of carotenoids in the fruit peel, more than one month after the completion of fruit growth. During all this time and until natural bud sprouting, flowering and bud sprouting are inhibited by exogenous gibberellic acid. Peak responses to this growth regulator coincide with periods of maximal rates of flowering inhibition by the fruit. Kinetin and abscisic acid, applied at the time of peak response to gibberellic acid, inhibited flowering and reduced the number of shoots developed through the reduction of the number of shoots formed per sprouted node, but failed to reduce the number of nodes which sprouted. The same pattern of sprouting was obtained in trees treated with gibberellic acid during the winter rest period or several months earlier. It is concluded that some step leading to flowering and which determines the differences in sensitivity of the buds to this growth regulator has taken place already at this early date.

Serum ferritin, transferrin, haptoglobin, and iron in middle- and long-distance runners, elite rowers, and professional racing cyclists.

Serum ferritin, transferrin, haptoglobin, and iron were measured in well-trained middle- and long-distance runners, elite rowers of the West German national team, and professional racing cyclists during the summer training and the winter rest period. None of the male athletes examined, with the exception of the racing cyclists during the summer period, received oral or parenteral iron. The runners were found to have significantly lower ferritin (P less than 0.00001), iron (P less than 0.001), and haptoglobin values (P less than 0.01) than the controls. Their transferrin levels were elevated, however not significantly. Rowers showed significantly higher ferritin levels (P less than 0.01) than the controls. The reduced haptoglobin concentrations in runners are presumed to be caused by a running-induced hemolysis. It is speculated that a recurring hemoglobinuria produced diminished iron reserves in middle- and long-distance runners.

Morphology of Cupressus arizonica: Gametophytes and Embryogeny

1. The steps in the early embryogeny of Cupressus arizonica are described. 2. The number of archegonia in a complex is found to range between 3 and 13. 3. More embryo systems were observed than could be accounted for on a basis of two fertilizations per pollen tube, indicating multiple fertilizations from multiple male cells. 4. The steps in the embryogeny, except for the speed of their passage and the insertion of a winter rest period, closely parallel those of Biota orientalis. 5. The resemblance of the embryogeny of C. arizonica to that of Biota is taken as further evidence that Endlicher's genus Biota is valid, and that it more closely resembles Cupressus than Thuja, with which it is sometimes combined.