Factors Affecting the Growth of Daughter Bulbs in the Tulip

The relative growth rate (R_w) of daughter bulbs of the tulipcultivar Rose Copland was remarkably constant during the springperiod of growth in four seasons at two sites. The Q₁₀ of R_wwas 2.2, and the long period of constant R_w is attributed tocompensation of a fall with age by increasing temperatures inthe spring. Final bulb weight differed among four cultivarsbecause of differences in R_w and in initial daughter bulb weights. Partial defoliation reduced R_w roughly in proportion to theleaf area removed, and removal of mother bulb scales resultedin reduced leaf area, fewer daughter bulbs, and a lower daughterbulb R_w. Heat-treatment of mother bulbs before planting (blindstoken)killed the flower within the bulb, inactivated the apical dominanceexerted by the flower, and resulted in a higher initial daughter-bulbweight at the start of the spring period of exponential growth.The R_w of heat-treated and control daughter bulbs were not different,neither were the leaf areas, so it is assumed that final daughter-bulbweights were higher following treatment because of increasedsink strength. The economic implications of these findings arediscussed.     

Effect of Bulb Size on the Growth of Tulips

A study of the growth in the field of tulip plants from bulbsof four different sizes showed marked differences of leaf areaand shoot dry weight, those produced by larger bulbs being thegreater. Relative growth rates of the smaller plants were higherthan those of the large ones; this was due to different proportionsof total plant weight being non-growing mother bulb, as therelative growth rates of the shoots were not affected by bulbsize. The relative growth rates of daughter bulbs were alsounaffected by the mother bulb size, being very similar to previouslydetermined values in other sites and seasons. The final bulbyield was proportional to daughter bulb weight early in theseason. It is suggested that daughter bulb weight, shoot weight,and leaf area are directly related to the size of the motherbulb, and controlled by the factors determining mother bulbsize during its development.     

The Initiation and Growth of Narcissus Bulbs

Plants of two Narcissus cultivars were dissected periodicallyover a year to study initiation, growth, and dry-weight changesof flowers and daughter bulb units in relation to the positionof the daughter bulbs in the branching system. A Narcissus bulbis a branching system comprising terminal and lateral bulb units;the former bear both terminal and lateral bulb units, but lateralscontain only terminal ones. This basic pattern may be modifiedby the failure of lateral bulb units or the development of supernumeraryones. Differences in bulb unit size, in scale and leaf number,and in flowering, related to position in the branching system,are probably due to the initiation of lateral bulb units somemonths after terminal ones. This affects the growth and behaviourof the laterals and daughter bulb units borne by these lateralsin the next generation. Bulb units live about four years; after the loss of their leafblades and flowers, the scales and leaf bases act as storageorgans whose weight increases or decreases according to thecarbohydrate status of the plant. Growth of bulb units showsan externally controlled alternation of rapid and slow growth.This is likely to be an effect of day length on bulbing.     

Seasonal variation in antimicrobial and phytochemical properties of frequently used medicinal bulbous plants from South Africa

The growing popularity of traditional medicine and the unrestricted collection of medicinal plants from the wild have put many of the slow growing bulbous plant species at the risk of over-exploitation and extinction in South Africa. This study was aimed at comparing the phytochemical composition and biological (antibacterial and anticandidal) activities of bulb and leaf extracts of Tulbaghia violacea, Hypoxis hemerocallidea, Drimia robusta and Merwilla plumbea between spring, summer, autumn and winter seasons, with the view of promoting the use of leaves, as a conservation strategy. Antibacterial and anticandidal activities of petroleum ether (PE), dichloromethane (DCM), 80% ethanol and water extracts of bulbs and leaves were tested against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae bacteria and the fungus Candida albicans using the microdilution bioassay. Spectrophotometric methods were used to evaluate saponin and phenolic compositions for the four seasons. Leaf and bulb extracts exhibited comparable anticandidal activity (MIC < 1 mg/ml) in all the plant species in all seasons. Only ethanol and water extracts of H. hemerocallidea corms (autumn and winter) showed correspondingly good fungicidal activity amongst the bulbs tested. Antibacterial activity was fairly comparable between bulbs and leaves with at least one extract of each plant species showing some good MIC values in most of the seasons. The best antimicrobial activities were recorded in winter and autumn seasons, with MIC values as low as 0.2 mg/ml in the DCM bulb extracts of T. violacea (winter) against K. pneumoniae and S. aureus. The amounts of total phenolic compounds in all plant samples were generally higher in spring compared to the other seasons. Condensed tannin, gallotannin and flavonoid levels, depending on the sample, were either higher in spring or winter except for H. hemerocallidea (corm) which had higher gallotannin levels in autumn. Total saponin levels were higher in winter in all plant samples. Although variation was observed in the phytochemical concentrations between the bulbs and leaves of each plant species, their antimicrobial activities were fairly comparable. Leaves may be used as substitutes for bulbs in the treatment of bacterial and fungal ailments.     

兰州百合鳞茎发育及低温解除休眠过程中内源激素的变化

以兰州百合为试材,研究了鳞茎发育过程中以及2、6、10℃条件下保湿贮藏101 d内母鳞茎与新鳞茎中内源激素的变化。结果表明：鳞茎发育过程中内源ABA含量以及母鳞茎的GA₃与ZR含量增加,而内源IAA含量以及新鳞茎的GA₃与ZR含量下降。低温贮藏期间,母鳞茎与新鳞茎的GA₃、IAA含量均有升高过程,而ABA含量呈下降趋势;新鳞茎的ZR含量呈下降趋势,母鳞茎的ZR含量也有升高过程。低温处理初期的34 d内,内源激素变化最为显著。不同贮藏温度相比较,ABA含量差异不大,GA₃含量随温度升高而下降。在富含淀粉的新鳞茎中,GA₃和ABA表现出极显著的负相关关系,而在淀粉含量较低的母鳞茎中GA₃和ABA无相关性。通径分析结果表明,母鳞茎与新鳞茎的物质代谢机制不同,母鳞茎的物质变化受内源GA₃的调控,新鳞茎主要是ABA作用的结果。     

Bulbil production in Narcissus: the effect of temperature and duration of storage on bulb unit development and subsequent propagation by twin-scaling

The growth of bulb components and carbohydrate content of Narcissus bulbs was followed during storage at 5–30 ^oC, and the productivity of twin-scale propagules cut from bulbs after these storage treatments was studied. Growth of daughter bulb unit components was greatest during storage at 9–15 ^oC, and greatly inhibited at 30 ^oC. Concentrations of soluble sugars were highest following 30 ^oC storage, and higher in intermediate bulb scales than in outer or inner scales. Bulbil production on twin-scales was greatest on propagules cut from the intermediate scales, and in bulbs previously stored at 15 or 30 ^oC.     

The Morphology and Growth of Pteridium aquilinum var. esculentum (Forst.) Kuhn

Pteridum aquilinum var. esculentum has three main types of shoot;long, transitional, and short. All bear leaves and the shoottypes are distinguishable from one another only by the lengthof the internodes. The shoot structure is plastic, and eachtype may convert into either of the other types if subjectedto an appropriate environmental stimulus. Long shoots contributeabout 50 per cent. of the shoot length and grow all the yearround with peaks of activity in autumn and spring. Short andtransitional shoots grow only in the autumn and winter period.Frond buds appear macroscopically on the rhizome in spring andsummer but do not elongate rapidly till autumn and winter. Frondsemerge in early spring and continue to emerge till autumn. Somesurvive for two summers, but the majority survive only one summerand are killed by the autumn and winter frosts.     

Developmental changes and tissue distribution of lectin in Tulipa

A sensitive enzyme-immunoassay was developed to quantify the tulip lectin and used to follow its distribution during the life cycle of tulips cv. Attila.The tulip lectin is predominantly located in the bulbs. At planting time the absolute lectin concentration is approximately the same in all bulb scales. However, as the shoot grows and the plant turns on to flowering, the lectin concentration rapidly decreases, first in the inner bulb scales but later also in the outer bulb scale. Soon after flowering the lectin rapidly accumulates in the new daughter bulbs.Lectin levels in leaves, stems and flowers are very low. The lectin in these tissues is already present before the sprout emerges. During the first two weeks after planting, there is a small increase in lectin concentration, followed by a rapid decrease as the plant turns on to flowering. By flowering time all the lectin has disappeared from the aerial parts.Abbreviations DW dry weight - ELISA enzyme-linked immunosorbent assay - FW fresh weight - PBS phosphate-buffered saline - PBSN phosphate-buffered saline containing 0.02% sodium azide - PBST phosphate-buffered saline containing 0.02% sodium azide and 0.05% Tween 20 - TL tulip lectin - Tris 2-amino-2-(hydroxymethyl)-1,3-propanediol     

The effects of climate change on the phenology of selected Estonian plant, bird and fish populations

This paper summarises the trends of 943 phenological time-series of plants, fishes and birds gathered from 1948 to 1999 in Estonia. More than 80% of the studied phenological phases have advanced during springtime, whereas changes are smaller during summer and autumn. Significant values of plant and bird phases have advanced 5–20 days, and fish phases have advanced 10–30 days in the spring period. Estonia’s average air temperature has become significantly warmer in spring, while at the same time a slight decrease in air temperature has been detected in autumn. The growing season has become significantly longer in the maritime climate area of Western Estonia. The investigated phenological and climate trends are related primarily to changes in the North Atlantic Oscillation Index (NAOI) during the winter months. Although the impact of the winter NAOI on the phases decreases towards summer, the trends of the investigated phases remain high. The trends of phenophases at the end of spring and the beginning of summer may be caused by the temperature inertia of the changing winter, changes in the radiation balance or the direct consequences of human impacts such as land use, heat islands or air pollution.     

Annual variation in energy reserves in male three-spined stickleback, Gasterosteus aculeatm L. (Pisces, Gasterosteidae)

Wet and dry weights of tissue were measured and concentrations of glycogen, lipid and protein were estimated for the liver, gonad and carcass of male sticklebacks from an annual population collected each month over one complete year. In young-of-the-year there is one period of rapid weight gain, in all three body regions (liver, carcass and gonads) but particularly of the carcass, in the autumn and a second in spring and early summer. This is accompanied by an increase in the water content of all three body regions. The gonadosomatic index also increases sharply in spring and early summer. Young sticklebacks accumulate lipid and glycogen slowly during the autumn and winter of their first year of life and more rapidly from late winter to early summer. Thus, the period of most rapid accumulation of these reserves coincides with the time when body weight and gonad maturation are also increasing sharply. Lipid and glycogen levels fall during the reproductive season in those males that breed, so that by July they are reduced to 43% and 37% (respectively) of their peak values in May. Levels of protein increase throughout the year as the fish grow, but in breeding males by July the concentration of protein in the carcass falls to 70% of pre-breeding levels. Breeding males therefore reach the end of the reproductive season with their total energy reserves severely reduced, and consequently they suffer a very high mortality. In contrast, adult males that fail to reproduce survive beyond the breeding season. They continue to gain weight and to accumulate lipid and glycogen from August to September, but these energy reserves fall (to levels comparable to those of post-breeding fish) in December, when these fish probably die. These results demonstrate that in male sticklebacks, growth and gonad maturation can be sustained in parallel with the accumulation of energy reserves, which are subsequently extensively depleted as a result of reproductive activities.     

Seasonal Ichthyodiversity and Growth Patterns of Juvenile Flatfish on a Nursery Ground in the Southern Bight of the North Sea (France)

The demersal fish community on a flatfish nursery ground, of the Southern Bight of the North Sea, was sampled monthly between May 1998 and 1999. The studied coastal area is a multispecific nursery area. Although 32 fish species were caught, only nine species had a major influence on the variation in total densities through the year and can be considered as key species. Juvenile sole and plaice exhibited similar seasonal growth patterns with rapid growth during late spring and summer, a growth arrest during autumn and winter and a restart of growth in March. Comparisons of observed growth in length with predicted maximal growth under optimal food conditions suggested that during the summer, growth of 0-group sole and plaice was only determined by prevailing mean water temperature. During autumn and winter, while growth in length of sole followed model predictions, observed length of plaice was less than model predictions, suggesting growth limitation. Analyses of the factors that may be responsible for differences between observed and expected length growth indicated that autumn and winter growth arrest of plaice was not only related to low winter water temperature. It is suggested that for visual feeders such as plaice, the interaction of decreasing food availability and day length during autumn and winter can reduce the access to food resource and therefore feeding success and growth.     

Seasonal variability of macroinvertebrate assemblages in two regions of South Africa: implications for aquatic bioassessment

Seasonal variability of macroinvertebrate assemblages was examined in two regions of South Africa: Western Cape and Mpumalanga. Sampling was undertaken at reference sites using the rapid bioassessment method SASS4 (South African Scoring System, Version 4). This study examined the influence of sampling season on the occurrence of taxa, macroinvertebrate assemblages and SASS scores. In the Western Cape a few taxa were more common at certain times of the year, and multivariate analysis of macroinvertebrate assemblages showed that assemblages grouped by season. The number of taxa and the Average Score per Taxon (ASPT) were significantly different among seasons in the Western Cape, with fewer taxa recorded in winter compared to summer, and significantly higher ASPT values recorded in winter and spring than summer and autumn. Whereas more taxa were recorded in autumn than in spring, a higher proportion of sensitive and high-scoring taxa were recorded in spring. In Mpumalanga macroinvertebrate assemblages did not group by season, and differences in SASS scores were not significant, although more taxa were recorded in winter than in spring or autumn, and ASPTs were slightly higher in winter than in spring. Results are discussed in relation to ecological reference conditions and the interpretation of bioassessment data.     

Influences of the atmospheric patterns on unstable climate-growth associations of western Mediterranean forests

Quantifying climate-growth associations is needed to evaluate how forest productivity will respond to climate change. Year-to-year fluctuations in forest productivity and radial growth are partly explained by local climatic conditions driven by large-scale atmospheric patterns. This is illustrated by Iberian forests in the western Mediterranean Basin, which are subjected to complex climatic and atmospheric influences such as Atlantic and Mediterranean cyclogenesis. The North Atlantic Oscillation (NAO) is one of the major atmospheric circulation patterns affecting Iberian forests since positive winter NAO phases lead to dry and warm conditions. The Western Mediterranean Oscillation (WeMO) may also explain Iberian forest growth in some areas since this index captures Mediterranean cyclogenesis and WeMO negative phases are linked to warm and wet spring to summer conditions. Here, we analyze the associations between atmospheric patterns, climate and tree growth and we determine if they are changing through time. We use dendrochronology to relate radial growth of four tree species (Pyrenean oak, Sweet chestnut, Maritime pine and Scots pine) growing in western Spain to climate conditions and the NAO and WeMO indices. Winter and early spring temperatures increased since the 1950s in the area whereas the negative association between winter precipitation and the NAO strengthened since then. However, mean temperature rise was particularly evident since the 1970s. Growth was reduced by dry conditions during the growing season (spring and summer), but also by cold and dry conditions during the previous autumn and winter. This explains why the NAO January and the WeMo April indices were negative to growth of three species excluding Pyrenean oak. The early 1970s reflected an inflection point in the instability of climate-growth associations in the study area. We conclude that the winter NAO is a relevant driver of forest growth in the western Iberian Peninsula forests but additional atmospheric patterns (WeMO) also affect, albeit to a minor extent, these forests.     

Seasonal hyperphagia does not reduce digestive efficiency in an Arctic grazer

Muskoxen (Ovibos moschatus) consume fibrous plants that grow rapidly over the short Arctic summer. We studied responses of eight castrated male muskoxen to a diet of grass hay and mineral supplements during spring, autumn, and winter. Animals gained body mass in spring (239+/-39 kg) as body fat content increased from 26% to 38% of ingesta-free mass in winter without changes in lean mass and protein. Intakes of dry matter (DM) increased by 74% between spring and autumn as digestible energy increased from 554 to 923 kJ kg(-0.75) d(-1) during mass gain. Digestibility of cellulose (72%-76%) was not affected by increasing food intake between spring and autumn but was reduced to 65% in winter. Digestibility of nitrogen compounds was 61%-66%, even though intake increased by 134% between spring and autumn. Excess dietary nitrogen from hay and supplements increased urea concentrations in plasma and urine. High loads of solutes such as potassium did not affect plasma or urinary osmolality but were associated with increased rates of glomerular filtration and urinary excretion. Low intakes of sodium from grasses may limit intake and digestion during summer, but high food intakes can support deposition of nitrogen, calcium, magnesium, copper, and zinc in body tissue even when dietary concentrations are low. Seasonal increases in digestive and metabolic functions allow muskoxen to rapidly accumulate energy and nutrients in body tissue during the short season of plant growth.     

The impact of changing the season in which cereals are sown on the diversity of the weed flora in rotational fields in Denmark

1. Surveys have shown that there has been a dramatic decrease in the weed flora of fields under rotational cultivation during the last 30 years. This trend has been particularly noticeable in winter cereals, a crop of increasing importance in the landscape.
2. The weed flora of spring and winter cereals was compared in 19 unsprayed fields during a 5-year study to test the hypothesis that cereal type exerts no effect on the flora or on the absolute and relative abundance of single species.
3. Plant and species densities, and accumulated species richness, were lower in winter than in spring cereals.
4. Floristic similarity was greater among spring cereal fields and between spring and winter cereals within the same fields than among winter cereal fields.
5. Species that occurred with unequal density in spring and winter cereals occurred at higher densities in the spring cereals; these species germinated mainly in the spring. However, for a few species the relative plant abundance was highest in winter cereals; these species were able to germinate both in the spring and autumn.
6. Some species – on the relative scale – occurred indifferently of season of sowing; all but one of these species were able to germinate both in the spring and autumn.
7. Plant species and taxa that are important food resources for arthropod herbivores occurred at greater densities in spring than in winter cereals and, in addition, occurred with the highest relative abundance in spring cereals.
8. Change in land use from spring to winter cereals involves not only an immediate reduction of more than 25% in the density of plants and species, but also a change and increased uncertainty in the composition of the weed flora. These findings may have serious implications for the ecology of wildlife in the agricultural landscape.     

Sources ofCycloconium oleaginum (Cast.) conidia for infection of olive leaves and conditions determining leaf spot disease development in the region of Sétif,Algeria

In the region of Sétif, peacock leaf spot disease caused byCycloconium oleaginum was found to be most prevalent in the period from late autumn to spring and of minor significance in the period from the beginning of July until the middle of November. Severity of infection on the lower parts was greater than on the upper parts of the trees. Damage on leaves facing north was much greater than on those facing south. Production of conidia leaf spots was found to be high in spring and late autumn but very low in summer and early autumn. Temperatures from 15 to 18°C were found optimal for the growth of the fungus. Reduced growth was seen at 3, 1 and 25°C with total inhibition at 30°C. Our results suggest that fallen leaves play no role in new infections and the role of the remaining spots on the tree during summer is of little importance. Four phases for the infection of new leaves were determined. In the first, during late spring, three newly opened pairs of leaves were infected, this infection remains hidden until late autumn. The second phase occurs in early autumn after rain. The third stage in late autumn and in the beginning of winter is characterized by the occurrence of new leaf spots which are usually concentrated on the basal pair of newly grown leaves. The fourth phase of infection, at the beginning of spring, is the most important of all. The infected leaves at this stage, comprise the infection source for all the following stages.     

蒸发需求干旱指数(EDDI)在辽宁省干旱识别中的应用

蒸发需求干旱指数(EDDI)是从大气蒸发需求(E₀)角度出发建立起来的一种多尺度的干旱指标,具有不依赖降水量、适用于各种下垫面类型的特点,具备在不同时间尺度捕捉水胁迫信号的能力。本研究基于1961—2018年辽宁省52个气象站气象观测资料,逐日估算E₀,按年、生长季(4—10月)、春季、夏季、秋季、冬季分别计算EDDI,分6个时间尺度识别近58年辽宁省干旱发生的年际变化特征。结果表明: 研究期间,辽宁省EDDI年际变化阶段性明显,多个时间尺度的EDDI呈两个高值集中期。在20世纪60年代,年、生长季、春季、秋季和冬季5个时间尺度的辽宁省平均EDDI高值区相对集中,这一阶段辽宁省发生干旱的年数多、程度重;除冬季外,2014—2018年是其他5个时间尺度的EDDI高值另一个相对集中的时段;1981—1982年,辽宁省的年、生长季、夏季、秋季的EDDI值偏高。1963—1965年(除夏季外)、1972—1973年(生长季、夏季)、1989—1990年(年、生长季、春季、冬季)、1997—1998年(年、生长季、夏季)、2004—2005年(春季、冬季)和2013—2014年(年、生长季、秋季)都发生了干-湿或湿-干逆转事件。1985—1987、1993—1995和2005—2013年,辽宁省存在明显的干旱空窗期。     

Some aspects of daughter bulb growth and development and apical dominance in bulbous Iris

Apical dominance appears to have minimal direct involvementin daughter bulb formation in the bulbous Iris cultivar Ideal.Daughter bulb number and growth relate to the size and reproductivestate of the mother bulb and are not markedly influenced bymeristem destruction. In contrast, destruction or removal ofthe apical meristem promotes lateral bud sprouting in intactbulbs, and lateral bud elongation in Iris meristem explants.These results show that, in contrast to certain other bulbousplants, apical dominance does not direcdy limit daughter bulbnumber in bulbous Iris, but does prevent lateral bud sprouting. (Received September 6, 1978; )     

BULB ORGANIZATION IN ALLIUM: SOME SPECIES OF THE SECTION MOLIUM

Mann , Louis K. (U. California, Davis.) Bulb organization in Allium: some species of the section Molium. Amer. Jour. Bot. 47(9) : 765–771. Illus. 1960.—Bulb development and organization are described for Allium neapolitanum, A. erdelii, A. hirsutum, A. subhirsutum, A roseum, and A. zebdanense, species of Molium, a Mediterranean section of the genus. These species begin growth in the late fall or midwinter, flower in March and April, and are dormant throughout the summer. The plant axis is commonly a sympodium made up of one or more branches terminated by inflorescences and a final branch ending in a large renewal bulb.. This bulb and one to many increase bulbs are formed each season. The bulbs mature by flowering time or shortly thereafter and the other parts—stem, leaves, roots, etc.—of the current season's plant die. Little change is evident within the bulbs during the summer rest period, but in September and October (or later in one species) the inflorescence and renewal bulb primordia appear. Five distinct types of leaves make up the bulb, including foliage leaves, food-storage leaves, and leaves which develop a heavy sclerotic layer around the bulb. The similar bulb structure of the 6 species indicates their close relationship. The 2 leaves which form the protective layer around the bulb become fused by the time they reach maturity, a condition apparently unique for the section Molium.