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1.
Magdi M. Ali 《Hydrobiologia》2006,570(1):101-105
The paper reports on the flora along the banks of Lake Nubia and the long-term changes that have taken place since the formation
of the Aswan High Dam Lake 30 years ago. The study also aims to determine the main factors that govern plant distribution
in this area. Shoreline vegetation was studied from Debeira at the Sudanese–Egyptian border to the ‘Dal’ Cataract at the south
end of the lake, in Sudan. The shoreline was classified into four moisture gradient zones depending on the period of inundation,
namely: wet zone (frequently inundated and recently exposed); moist zone (periodically inundated); semi-dry zone (rarely inundated);
and dry zone (never inundated). Plants characterising each zone were identified. Soil texture and thickness of the deposits
were measured for each zone at each site. According to Grime’s strategy, the study revealed that species of the wet and the
moist zones are mainly disturbance-tolerant; species observed in the ‘semi-dry’ zone are competitive-stress-tolerant; and
those of the ‘dry’ zone are stress-tolerant. The present study indicates that elevation above mean sea level, and period of
inundation and texture of deposits play an important role in governing the distribution of the shoreline vegetation. 相似文献
2.
Phragmites or Common Reed (Phragmites australis) is a tall rhizomatous cosmopolitan grass. While native to Australia, it can be invasive in wetlands, forming dense monocultures and reducing their ecological integrity. We assessed the potential for the cutting of Phragmites reeds prior to planting to promote the establishment of indigenous shrubs that might ultimately outcompete Phragmites. We established ten 5 m × 5 m quadrats in an area dominated by Phragmites, brush‐cut the reeds to ground level in five of them and left five uncut as controls. Within each quadrat, we planted 20 plants (~40 cm tall) of each of five indigenous shrub species, unguarded (4 plants/m2). We surveyed the plants one month after planting and annually for the following four years for survival, height and browsing damage. Browsing damage to plants was common (>50%) and unaffected by cutting. After four years, overall plant survival rates were ~25% and mean plant heights for the five shrub species ranged between 120 and 174 cm. Cutting of Phragmites had no positive effect on plant survival or height. In fact, two Melaleuca species grew taller in the uncut quadrats. Cutting of Phragmites reed beds prior to planting is unlikely to promote the establishment of woody plantings. However, planting within established Phragmites with or without prior brush‐cutting is worthy of further trialling as a potential tool for reinstating native diversity at Phragmites‐dominated sites. 相似文献
3.
Kyung Won Seo Su Jin Heo Yowhan Son Nam Jin Noh Sue Kyoung Lee Chun Gyeong Yoon 《Landscape and Ecological Engineering》2011,7(1):93-99
This study was conducted to examine the influences of soil-moisture conditions on soil nitrogen (N) dynamics, including in
situ soil N mineralization, N availability, and denitrification in a pure Alnus japonica forest located in Seoul, central Korea. The soil N mineralization, N availability, and denitrification were determined using
the buried bag incubation method, ion exchange resin bag method, and acetylene block method, respectively. The annual net
N mineralization rate (kg N ha−1 year−1) and annual N availability (mg N bag−1) were 40.26 and 80.65 in the relatively dry site, −5.43 and 45.39 in the moist site, and 7.09 and 39.17 in the wet site,
respectively. The annual net N mineralization rate and annual N availability in the dry site were significantly higher than
those in the moist and wet sites, whereas there was no significant difference between the moist and wet sites. The annual
mean denitrification rate (kg N ha−1 year−1) in the dry, moist, and wet sites was 2.37, 2.76, and 1.59, respectively. However, there was no significant difference among
sites due to the high spatial and temporal variations. Our results indicate that soil-moisture condition influenced the in
situ N mineralization and resin bag N availability in an A. japonica forest, and treatments of proper drainage for poorly drained sites would increase soil N mineralization and N availability
and consequently be useful to conserve and manage the A. japonica forest. 相似文献
4.
Effect of winter cutting on the passerine breeding assemblage in French Mediterranean reedbeds 总被引:1,自引:0,他引:1
Common reed is increasingly harvested from the Mediterranean region toprovide thatching material to north European countries. The impact of thesemanagement practices on the fauna is poorly known. The aim of this study was toquantify the effect of reed cutting in the Mediterranean region through acomparative analysis of water regime, vegetation structure, arthropoddistribution and passerine assemblage at cut and uncut reedbeds in southernFrance. Cut reedbeds were characterised by a lower salinity, higher water levelin spring, and higher reed biomass than uncut reedbeds. Arthropod distributiondiffered consistently between cut and uncut sites, leading to a higher index offood available to passerines in cut reedbeds. Cut reedbeds had a similar birdspecies richness but a lower bird abundance, due to the significant decrease inMoustached Warblers and Bearded Tits at cut sites. The mild Mediterranean winterfavoured early growth of reed in spring, making harvested reedbeds suitable forbreeding of long-distance migrants such as the Great Reed Warbler and ReedWarbler. However, for the resident species that breed earlier in the season, cutreedbeds presumably lack sufficient vegetation cover to provide adequate nestingand feeding sites. Although biennial cutting (double wale) is considered as agood compromise between conservation and commercial interests in the UK, thejuxtaposition of annually cut and never cut reed patches appears as the onlysustainable alternative for the Mediterranean region. We further hypothesisethat an optimal mosaic design of cut/uncut reed patches could provide as high aconservation value as unmanaged reedbeds. 相似文献
5.
The effects of post harvest application of ethylene, abscisic acid (ABA), indole-3-butyric acid (IBA) treatments or dark storage
on root induction and continued growth of regenerated roots in Pelargonium cuttings were investigated using hydroponics in the greenhouse. Ethylene markedly increased rooting percentage in ‘Greco’
and ‘Surfing’, reduced the number of roots per cutting in ‘Surfing’ and had no effect on the total root lengths in the two
cultivars. Ethylene treatment reduced fresh root mass in ‘Surfing’, increased dry root mass and reduced root water content
in both cultivars. ABA (50 μM) enhanced rooting percentage in ‘Greco’, reduced the number of roots per cutting, reduced total
root lengths and fresh root mass in both cultivars. ABA increased dry root mass and reduced root water content in ‘Surfing’
but this effect was not apparent in ‘Greco’. Storing cuttings in the dark for 4 days had no effect on rooting percentage and
number of roots per cutting in ‘Greco’ and ‘Surfing’. However, dark storage reduced total root lengths in ‘Surfing’ and reduced
fresh root mass in ‘Greco’. Dark storage had no effect on dry root mass and water content in both cultivars. Applying 4 μl l−1 IBA in the rooting solution induced maximum (100%) root induction in ‘Surfing’. However, IBA reduced the number of roots
per cutting in ‘Greco’, reduced total root lengths and fresh root mass in the two cultivars. IBA treatment profoundly increased
and reduced dry root mass and root water content, respectively, in ‘Greco’ and ‘Surfing’. The enhanced root induction observed
after IBA and ABA applications could be ascribed to their influence on ethylene biosynthesis, since ethylene treatment increased
rooting percentage in both cultivars. However, high ABA (100 μM) and IBA (12 μl l−1) levels or dark storage reduced the ability of induced roots to continue growth. We attribute our results to plant stress-response
mechanism and ethylene appears to play an important role in the process of root initiation and root growth in Pelargonium cuttings. 相似文献
6.
Phragmites mauritianus is the dominant herbaceous species colonizing riverine habitats in the Kruger National Park, South Africa. These perennial systems are characterized by high annual and seasonal flow variability and a complex mosaic of patches of reeds, sand, water, rock and other vegetation. Patterns of increase and decrease in reed cover in the Letaba River were determined from aerial photographs covering a 54-year period. An initial period of reed expansion (1942–1965) was followed by a period of reed loss (1965–1977) and subsequent gradual re-establishment (1977–1996). A spatially explicit analysis of changes in reed distribution over an 8-year period (1988–1996) showed that patches of reed vegetation are, in the short term, highly dynamic elements within the river landscape. Analyzing short-term, small-scale change provides information which is not obtainable from long-term, large-scale studies. We propose that causes of reed expansion or decline cannot be determined without an understanding of both long- and short-term patterns of change. 相似文献
7.
Wolfgang Ostendorp 《Wetlands Ecology and Management》1995,3(4):233-248
The fringing reeds (Phragmites australis (Cav.) Trin. ex Steud., Poaceae) at Lake Constance-Untersee were mown or burnt in winter thereby drastically reducing the addition of decomposable organic matter to the sediment. The purpose of this study was to test whether or not this management significantly decreased the contents of organic matter and nutrients in the surface sediment layer and if the oxygen conditions in the withinreed water body improved. Hypotheses were tested by monitoring 6 treated reed beds and 3 reference fields over a period of up to 4 years. The sediment/water system of reed beds was found to be well buffered against the removal of the current year's crop of dead Phragmites straw, because only slight, and mostly insignificant, differences between treated and untreated reeds were detected. Hence, the benefit of winter reed harvesting to reduce nutrient overloading of the reed-belts and the die-back of reeds remains dubious. 相似文献
8.
David Sternberg Stephen R. Balcombe Jonathan C. Marshall Jaye S. Lobegeiger Angela H. Arthington 《Environmental Biology of Fishes》2012,93(1):95-104
The ecology of dryland rivers is driven by their highly variable hydrology, particularly flooding regimes, whereby intermittent
floods typically generate ‘booms’ of primary and secondary productivity, including massive fish production. We tested these
concepts in the Moonie River, Australia, using the percichthyid, Macquaria ambigua, a dryland river species known to display pronounced ‘boom and bust’ abundance patterns in response to floodplain inundation
followed by extended periods of low to no channel flow. We expected that body condition (as measured by whole body lipid content)
and biomass of M. ambigua would be related to prey biomass, and that these factors would all ‘spike’ following widespread flooding. Instead we found
more subtle responses. There were ‘booms’ in biomass of Macrobrachium and zooplankton, two important food items, whereas M. ambigua maintained relatively low but sustained lipid and biomass levels following flooding. It appears that instead of a ‘boom’
in fish biomass, abundant invertebrate food resources and sustained lipid levels contributed to high survivorship of this
species during the ‘bust’ period over cool dry months. 相似文献
9.
Flux of organic carbon in a riverine mangrove wetland in the Florida Coastal Everglades 总被引:1,自引:1,他引:0
Melissa M. Romigh Stephen E. Davis III Victor H. Rivera-Monroy Robert R. Twilley 《Hydrobiologia》2006,569(1):505-516
Short-term (daily) and seasonal variations in concentration and flux of dissolved organic carbon (DOC) were examined over
15 tidal cycles in a riverine mangrove wetland along Shark River, Florida in 2003. Due to the influence of seasonal rainfall
and wind patterns on Shark River’s hydrology, samplings were made to include wet, dry and transitional (Norte) seasons. We
used a flume extending from a tidal creek to a basin forest to measure vertical (vegetated soil/water column) and horizontal
(mangrove forest/tidal creek) flux of DOC. We found significant (p < 0.05) variations in surface water temperature, salinity, conductivity, pH and mean concentration of DOC with season. Water
temperature and salinity followed seasonal patterns of air temperature and rainfall, while mean DOC concentration was highest
during the dry season (May), followed by the wet (October) and ‘Norte’ (December) seasons. This pattern of DOC concentration
may be due to a combination of litter production and inundation pattern of the wetland. In contrast to daily (between tides)
variation in DOC flux between the mangrove forest and tidal creek, daily variations of mean water quality were not significant.
However, within-tide variation of DOC flux, dissolved oxygen content and salinity was observed. This indicated that the length
of inundation and water source (freshwater vs. saltwater) variation across tidal cycles influenced water quality and DOC flux
in the water column. Net DOC export was measured in October and December, suggesting the mangrove forest was a source of DOC
to the adjacent tidal creek during these periods. Net annual export of DOC from the fringe mangrove to both the tidal creek
and basin mangrove forest was 56 g C m−2 year−1. The seasonal pattern in our flux results indicates that DOC flux from this mangrove forest may be governed by both freshwater
discharge and tidal range. 相似文献
10.
The reproductive period and life-history parameters were investigated for the hoplonemertineAmphiporus lactifloreus found on the tidal flats of the island of Sylt in the northern Wadden Sea. Every six weeks 20 individuals were collected
and then histologically examined to determine the development stage of their reproductive organs.A. lactifloreus reproduces in the late autumn, its peak reproduction being in the second half of November. Individuals from all size classes
>20 mm body length produced gametes. Individuals of the cohorts that reproduced in the late autumn of 1992 persisted and grew
until July 1993, indicating thatA. lactifloreus is an iteroparous species. The length of relaxed individuals was significantly correlated with their length under anaesthetized
conditions, but the regression changed significantly after the reproductive period. Length under ‘relaxed’ conditions was
significantly correlated with weight (wet weight, dry weight, and ash-free dry weight); these relationships did not vary significantly
before or after the reproductive period. Our results show that important life-history data of intertidal nemertines can be
obtained without time-consuming histological studies. On the basis of these findings, recommendations for future studies on
the population biology of intertidal nemertines are given. Regular length measurements of nemertines under ‘relaxed’ conditions
are proposed as a useful tool for tracking the growth and survival of annual cohorts of intertidal nemertines. 相似文献
11.
Variation in timing and amount of rainfall in California has been noted to cause strong year-to-year differences in the composition
of vernal pool communities. We explored the effects of possible variation of the “rainy season” in a seedbank germination
study conducted with three factors: monthly timing of first soil moistening, length of moist period before inundation, and
length of inundation. Monthly timing was the most important factor in determining the number of plants and number of species
that germinated in the pots. Many species, mostly generalist wetland and pool-endemic species, showed sharp decreases in number
in later trials. Five species did not germinate in the final trial, and two of these were abundant only in the first trial.
Inundation was required for the germination of two species. Treatments with a combination of inundated and moist conditions
resulted in higher numbers of species and numbers of plants compared to treatments with only moistness or only inundation.
Our results indicate that vernal pool species have mechanisms that keep them from emerging under unfavorable conditions. The
sensitivity of vernal pool species to out-of-season germination suggests that they could be negatively affected by climatic
change, with generalist species like non-native Lythrum hyssopifolium having a potential advantage.
Received: 15 July 1996 / Accepted: 14 July 1997 相似文献
12.
Patrick H. Brown Steven A. Weinbaum Geno A. Picchioni 《Trees - Structure and Function》1995,9(3):158-164
The influence of alternate bearing on nutrient utilization and total tree nutrient content was investigated in mature pistachio
(Pistacia vera L. cv Kerman trees). Removal of N, P and Zn in fruit and abscised leaves of cropping (‘on’) trees averaged 5, 6, and 2 times,
respectively, the removal in abscised leaflets of the non-fruiting, ‘off’ year trees. One hundred and thirty-five kg N, 131
kg K, 86 kg Ca, 39 kg Mg and 18 kg P per hectare were removed in fruits and abscised leaves in ‘on’ year trees. Tree nutrient
contents and, presumably, the size of nutrient storage pools in dormant trees varied between ‘on’ and ‘off’ years. There was
22% and 14% more N and P, respectively, in dormant trees following ‘off’ than ‘on’ years. The greater N and P accumulation
in ‘off’ year trees is depleted in support of the large fruit demand for N and P during ‘on’ years. In contrast to N and P,
there was greater K and Ca accumulation in perennial tree parts during ‘on’ years than during ‘off’ years. The greater K accumulation
in perennial tree parts and approximately 30% greater removal of K in annual organs during ‘on’ than ‘off’ years suggests
that K uptake could be 4 times higher in ‘on’ year trees than in (non-cropping), ‘off’ year trees. 相似文献
13.
Yves Hingrat Michel Saint Jalme Frédéric Ysnel Eric Le Nuz Frédéric Lacroix 《Journal of Ornithology》2007,148(1):39-52
Studies of the movements and home-ranges of houbara bustards (Chlamydotis undulata undulata) showed sexual and seasonal differences in the use of space, with a polygynous mating system similar to an ‘exploded-lek’
or a ‘resource-defence-polygyny’, that remains undefined. We used the arthropod biomass as an index of the trophic quality
of six defined habitats and we radio-tracked 7 females and 13 males to test whether sexual and seasonal variations in habitat
use were related to resource availability, and to verify if critical resources for breeding females were monopolised by males.
We analysed habitat selection in both sexes separately. We used the habitat type composition of buffer zones around radio-locations
to study annual and seasonal habitat selection and to identify preferred habitats, using the chi-square goodness-of-fit test.
Habitat use between sexes and between seasons were compared using MANOVA based on log-ratios of habitat proportions. During
the year, and in each season, both sexes appeared to be significantly selective for habitats in comparison to their availability.
But males avoided esparto grass, while females used all habitats. Habitat use differed between sexes in the breeding season,
but not in the non-breeding season. In spring, when food resources were abundant and uniformly distributed in space, males
preferred ‘temporarily flooded areas’ and females preferred ‘reg with tall perennials’ that offered both food and cover for
brooding. Critical resources were not monopolised by males and the mating system fulfilled the definition of the ‘exploded-lek’.
Leks are key sites for reproduction and should be considered as priority areas in further conservation plans. 相似文献
14.
Annika Vaksmaa Simon Guerrero-Cruz Theo A. van Alen Geert Cremers Katharina F. Ettwig Claudia Lke Mike S. M. Jetten 《Applied microbiology and biotechnology》2017,101(18):7075-7084
Paddy fields are a significant source of methane and contribute up to 20% of total methane emissions from wetland ecosystems. These inundated, anoxic soils featuring abundant nitrogen compounds and methane are an ideal niche for nitrate-dependent anaerobic methanotrophs. After 2 years of enrichment with a continuous supply of methane and nitrate as the sole electron donor and acceptor, a stable enrichment dominated by ‘Candidatus Methanoperedens nitroreducens’ archaea and ‘Candidatus Methylomirabilis oxyfera’ NC10 phylum bacteria was achieved. In this community, the methanotrophic archaea supplied the NC10 phylum bacteria with the necessary nitrite through nitrate reduction coupled to methane oxidation. The results of qPCR quantification of 16S ribosomal RNA (rRNA) gene copies, analysis of metagenomic 16S rRNA reads, and fluorescence in situ hybridization (FISH) correlated well and showed that after 2 years, ‘Candidatus Methanoperedens nitroreducens’ had the highest abundance of (2.2 ± 0.4 × 108) 16S rRNA copies per milliliter and constituted approximately 22% of the total microbial community. Phylogenetic analysis showed that the 16S rRNA genes of the dominant microorganisms clustered with previously described ‘Candidatus Methanoperedens nitroreducens ANME2D’ (96% identity) and ‘Candidatus Methylomirabilis oxyfera’ (99% identity) strains. The pooled metagenomic sequences resulted in a high-quality draft genome assembly of ‘Candidatus Methanoperedens nitroreducens Vercelli’ that contained all key functional genes for the reverse methanogenesis pathway and nitrate reduction. The diagnostic mcrA gene was 96% similar to ‘Candidatus Methanoperedens nitroreducens ANME2D’ (WP_048089615.1) at the protein level. The ‘Candidatus Methylomirabilis oxyfera’ draft genome contained the marker genes pmoCAB, mdh, and nirS and putative NO dismutase genes. Whole-reactor anaerobic activity measurements with methane and nitrate revealed an average methane oxidation rate of 0.012 mmol/h/L, with cell-specific methane oxidation rates up to 0.57 fmol/cell/day for ‘Candidatus Methanoperedens nitroreducens’. In summary, this study describes the first enrichment and draft genome of methanotrophic archaea from paddy field soil, where these organisms can contribute significantly to the mitigation of methane emissions. 相似文献
15.
Monica Santa-Maria Kenneth V. Pecota Craig G. Yencho George Allen Bryon Sosinski 《Plant Cell, Tissue and Organ Culture》2009,97(1):109-117
Sweetpotato (Ipomoea batatas L.) is an important crop in North Carolina with annual production of 0.33 million tons, accounting for 37% of total US supply
(USDA, Louisiana Farm Reporter 8(12), August 2008). To target industrial use, novel high-starch industrial-type varieties that contain more than 30% dry matter were developed
by conventional breeding methods. In vitro cultures from selected genotypes were established using meristem culture. To establish
regeneration procedures that could be coupled with transformation experiments, conditions for the induction of rapid shoot-organogenesis
in leaf explants were compared using varying concentrations of the auxins ‘NAA’, ‘IAA’, ‘2,4-D’, and ‘4-FA’ either alone or
in combination with zeatin riboside. Regeneration efficiencies, defined as the number of explants developing shoots out of
the total number tested, were as high as 57% for the best genotypes, with a significant genotype-dependent response observed
in all the hormone regimes evaluated. In all treatments, shoot regeneration was observed within 2 months. Our results led
to the establishment of optimized in vitro regeneration procedures for the novel high-starch sweetpotato (SP) genotypes ‘DM01-158’,
‘FTA94’, ‘FT489’, and ‘PDM P4’ that are rapid and reliable. 相似文献
16.
Iwona Żur Ewa Dubas Elżbieta Golemiec Magdalena Szechyńska-Hebda Franciszek Janowiak Maria Wędzony 《Plant Cell, Tissue and Organ Culture》2008,94(3):319-328
The accumulation of abscisic acid (ABA) and the activities of antioxidative enzymes along with cell metabolic activity were
monitored during androgenesis induction in triticale (×Triticosecale Wittm.). Tested cultivars ‘Mieszko’ and ‘Wanad’ were selected due to their significantly different responses to androgenic
induction. Significant variation was observed in respect of superoxide dismutase activity and endogenous ABA content in anthers
isolated from freshly cut tillers. For both cultivars, tillers pretreatment with low temperature decreased peroxidase activity
by 36%, highly accelerated respiration rate and reduced heat production. At the same time, the level of ABA in ‘Mieszko’ was
increased to the level measured in ‘Wanad’. This effect was associated with higher microspore culture viability and increased
stress tolerance in ‘Mieszko’. Low temperature and metabolic starvation during 4-day anther preculture did not influence activities
of antioxidative enzymes, while it resulted in slight decrease in respiration rate and heat emission. The importance of these
changes for effective androgenesis induction is discussed. 相似文献
17.
Tadeusz Zaj c Stanisław Grzesiak Bogdan Kulig Milan Polá ek 《Acta Physiologiae Plantarum》2005,27(4):549-558
In three year field experiments (2001 – 2003) the growth, yield and productivity of 8 flax cultivars were compared. Cultivars
‘AC Linora’, ‘Flanders’, ‘Linola™ 947’, ‘Norlin’ and ‘Omega’ were obtained from Canada, ‘Barbara’ and ‘Hungarian Gold’ from
Hungary and ‘Opal’ from Poland. Apart from the estimation of the yield of aboveground parts dry matter and seed yield the
determinations of the primary index value of growth analysis were done and on their basis the indices LAI, LAD, RGR, CGR and
HI were calculated.
The obtained yield results of the examined flax cultivars show significant genotypic — environmental relationships pertaining
to the dynamics of dry matter accumulation and the amount of seed yield. Meteorological conditions in the successive years
significantly influenced the particular phases of growth and development of cultivars and the factor which increased the amount
of dry matter was the air temperature during the period of plant emergence — budding. During the vegetative season with a
large amount of rainfall the average seed yield was about 40 % lower than compared with a year of average precipitation and
a warm second part of the second period of flax vegetation. Among the analyzed cultivars a stable yield in all the years was
characteristic for cultivars ‘Flanders’, ‘Barbara’ and ‘AC Linora’ (that cultivar, however, during a wet year yielded at a
low level). The assimilation leaf surface of the linseed quickly increased during the period from budding to flowering and
the accumulation of dry matter of the aboveground parts lasted up to the green maturity. In the successive years of the experiment
there were observed significant (linear or logarithmic regressions) relationship between the yield of dry matter and the indices
of growth analysis. The biggest values of the CGR indicator were observed for the period from budding to flowering. The maintaining
of a high CGR value after plant flowering in the year with a favourable course of climatic parameters was beneficial for a
better yield of all flax cultivars. The low values of the RGR index after flowering of cultivar ‘Hungarian Gold’ and ‘Opal’
strictly corresponded to their low yield of seed and straw biomass. 相似文献
18.
Theophilus M. Mutui Vallantino E. Emongor Margaret J. Hutchinson 《Plant Growth Regulation》2006,48(3):207-214
Leaf yellowing is a major problem in Alstroemeria and absence of leaf senescence symptoms is an important quality attribute. Two Alstroemeria cultivars ‘Yellow King’ and ‘Marina’ were sourced from a commercial farm and harvested when sepals began to reflex. Stems
were re-cut under water and kept in vase solutions of gibberellin A4+7 (0, 2.5, 5.0, 7.5, 10.0, 12.5 or 15.0 mg l−1 [Provider]). Treatments and cultivars were combined in a factorial fashion and arranged in a completely randomised design. Application
of GA4+7 in the holding solution at 2.5–10.0 mg l−1 significantly delayed the onset of leaf senescence by around 7 days and significantly increased days to 50% petal fall by
ca. 2 days. Additionally, these GA4+7 concentrations resulted in higher retention of leaf nitrogen, leaf chlorophyll and also increased leaf water content, while
reducing leaf dry weight, all relative to untreated controls. Cultivar ‘Yellow King’ had significantly longer vase life and
a better retention of leaf quality than ‘Marina’. Our results suggest that a concentration of 10 mg l−1 GA4+7 can be used to prolong vase life, delay leaf senescence and enhance post-harvest quality of Alstroemeria cut flowers during their transport to market. 相似文献
19.
The purpose of this paper is to investigate the differential responses of flower opening to ethylene in two cut rose cultivars,
‘Samantha’, whose opening process is promoted, and ‘Kardinal’, whose opening process is inhibited by ethylene. Ethylene production
and 1-aminocyclopropane-1-carboxylate (ACC) synthase and oxidase activities were determined first. After ethylene treatment,
ethylene production, ACC synthase (ACS) and ACC oxidase (ACO) activities in petals increased and peaked at the earlier stage
(stage 3) in ‘Samantha’, and they were much more dramatically enhanced and peaked at the later stage (stage 4) in ‘Kardinal’
than control during vasing. cDNA fragments of three Rh-ACSs and one Rh-ACO genes were cloned and designated as Rh-ACS1, Rh-ACS2, Rh-ACS3 and Rh-ACO1 respectively. Northern blotting analysis revealed that, among three genes of ACS, ethylene-induced expression patterns of
Rh-ACS3 gene corresponded to ACS activity and ethylene production in both cultivars. A more dramatic accumulation of Rh-ACS3 mRNA was induced by ethylene in ‘Kardinal’ than that of ‘Samantha’. As an ethylene action inhibitor, STS at concentration
of 0.2 mmol/L generally inhibited the expression of Rh-ACSs and Rh-ACO in both cultivars, although it induced the expression of Rh-ACS3 transiently in ‘Kardinal’. Our results suggests that ‘Kardinal’ is more sensitive to ethylene than ‘Samantha’; and the changes
of Rh-ACS3 expression caused by ethylene might be related to the acceleration of flower opening in ‘Samantha’ and the inhibition in
‘Kardinal’. Additional results indicated that three Rh-ACSs genes were differentially associated with flower opening and senescence as well as wounding. 相似文献
20.
Summary Anthers and ovaries of six grapevine cultivars (three Vitis vinifera L., two V × Labruscana L. H. Bailey, and one complex hybrid) were extracted from flower buds over 2 yr and cultured on three media reported to promote
somatic embryogenesis in Vitis tissues. The highest percent embryogenesis from the hybrid ‘Chancellor’ and V. vinifera ‘Chardonnay’, ‘Merlot’, and ‘Pinot Noir’ occurred on medium C [Nitsch and Nitsch, 1969, basal medium with 3.0% (w/v) sucrose,
0.01% (w/v) inositol. 0.3% (w/v) Phytagel, 2.5 μM 2.4-dichlorophenoxyacetic acid, 2.5μM β-naphthoxyacetic acid, 5.0μM N-(2-chloro-4-pyridyl)-N′-phenylurea, and 0.05% (w/v) glutamine]. Regardless of the media, the labrusca cultivars ‘Concord’ and ‘Niagara’ produced
soft non-embryogenic callus that was sometimes mixed with well-developed somatic embryos. Nine vinifera genotypes were further
tested for several different years on medium C. Embryogenic cultures suitable for transformation were obtained from all genotypes
in more than 1 yr. The average percent embryogenesis from ovaries was 7-fold higher than from anthers. There was significant
annual variation in percent embryogenesis, demonstrating the need for media comparisons to be replicated for more than one
season. Suspension cultures suitable for use in genetic transformation were initiated from ‘Chardonnay’, ‘Merlot,’ and ‘Pinot
Noir’ pro-embryogenic masses. ‘Chardonnay’ suspension cultures plated and grown under conditions developed for recovery of
plants after biolistic transformation yielded approximately 500 non-transformed embryos per plate after 4 mo. of culture,
with 68.6% of the embryos converting to plants. This is the first reported protocol for embryogenesis from ‘Concord,’ ‘Cabernet
Franc,’ and ‘Pinot Noir’ grapevines. 相似文献