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1.
The time it takes for ingested seeds to pass through the gut of animals is an important aspect of endozoochorous seed dispersal
because it influences seed dispersal distance. Variations in the physical characteristics of seeds, such as their weight,
volume, and specific gravity, can affect their movement through the gastrointestinal system of a given animal. We conducted
feeding experiments with captive Japanese martens, Martes melampus (n = 4), at Toyama Municipal Family Park Zoo, central Japan to examine the effects of the physical characteristics of seeds
on their passage times. The mean (±SD) transit time, mean retention time, and time of last appearance of four different types
of commercial seeds were 2.6 ± 0.3 h (range 0.6–5.4), 9.7 ± 1.1 h (3.8–17.3), and 23.8 ± 3.1 h (12.2–51.8), respectively.
All of these values are greater than those found during previous experiments conducted with mustelids. Similar to previous
studies, however, none of these passage time variables was correlated with the physical characteristics of seeds. Our results
thus indicate that martens disperse seeds of different plant species, whose size, volume, and specific gravity all fall within
the range of those used in the present study, from parent plants at similar distances. 相似文献
2.
Mesua ferrea 《Acta Oecologica》1999,20(6):599
Effect of fruit size and seediness (seed number per fruit) was examined on germination and early growth of seedlings in Mesua ferrea L. Fruiting incidence (number of fruited trees in a population) and fruit loading (number of fruits per tree) vary from one year to the other, and were greater in 1997 than in 1998. Seeds from large fruits (> 40 g) are preferred for forestry plantations and those from small fruits (< 40 g) are discarded, despite a greater proportion of small fruits (63.2 %) than large fruits (36.8 %). A fruit, large or small in size, may contain one, two, three or four seeds. The germination percentage of seeds increased from 1-seeded through 4-seeded fruits both in laboratory and greenhouse conditions, and both in case of large and small fruits. Conversely, the mean seed weight and germination time decreased along this gradient, i.e. seeds from 1-seeded fruits were the heaviest and required maximum time for germination, and the seeds from 4-seeded fruits were the lightest and required minimum time for germination. The seeds from small fruits were lighter in weight, achieved lower germination percentages and required greater germination time than the seeds from large fruits in all four seeded categories. Seedlings from seeds from 1-seeded fruits survived better and with stronger vigour after 1 year of growth than seedlings from 2-, 3- and 4-seeded fruits. Further, seedling survival and vigour were greater for seeds from large rather than small fruits. 相似文献
3.
The experimental study was conducted during the period of 2008–2010 at the experimental field of the Institute of Forage Crops
in Pleven. The hybridization scheme included direct and back crosses covering four varieties of forage pea (Pisum sativum L.), namely two spring ones, Usatii 90 and Kamerton from Ukraine, and a winter one from Bulgaria, Pleven 10. There was analyzed
the inheritance of quantitative traits such as plant height, height to first pod, pod number per plant, seed number per plant,
seed number per pod, seed weight per plant and number of fertile nodes per plant of parental components (P1 and P2) and both first (F1) and second (F2) hybrid generations. The cross Usatii 90 × Pleven 10 showed the highest real heterosis effect for plant height (8.26%), pods
per plant (158.79%), seeds per plant (272.16%), seeds per pod (42.09%), seed weight per plant (432.43%) and number of fertile
nodes per plant (117.14%). The cross Pleven 10 × Usatii 90 had the highest real heterosis effect height to first pod (11.06%).
In F2 plants, the strongest depression for plant height (5.88%), seeds per plant (57.88%), seeds per pod (55.93%) and seed weight
per plant (55.99%) was in the cross Usatii 90 × Pleven 10, for height to first pod (1.47%) in the cross Kamerton × Pleven
10 and for number of fertile nodes per plant (15.91%) in the cross Pleven 10 × Usatii 90. The highest positive degree of transgression
for number of fertile nodes per plant (165.64%) and seed weight per plant (162.10%) was in the cross Pleven 10 × Kamerton
and for pod number per plant (102.54%) and seeds per plant (99.13%) in Kamerton × Pleven 10. The stability of the characters
was determined. Low variability in F1 and F2 was found in plant height (3.97–6.85%). Variability of number seeds per plant in F1 was highest (11.86–33.23%). For all other traits, the variability varied from average to high. A lower narrow-sense heritability
coefficient was observed for plant height, height to first pod, pods per plant, seeds per plant and seed weight per plant
(from 0.001 to 0.230). In few cases, such as in fertile nodes per plant (0.39 and 0.81) and seeds per pod (0.44), the coefficients
of broad-sense heritability were higher. 相似文献
4.
Ulf Sperens 《Oecologia》1997,109(3):368-373
Variation in fruit production and pre-dispersal seed predation by Argyresthia conjugella was studied in␣four populations of Sorbus aucuparia in northern Sweden.␣The number of infructescences, fruits per infructescence, consumed seeds and developed unattacked seeds
per fruit were scored in marked trees from 1984 to 1990. The results showed that the number of fruits produced in each population
determined the number of seed predators occurring in the host population, as the yearly number of seed predators was significantly
and positively correlated with yearly number of fruits, in all but one population. The seed predators showed a delay in response
to variation in number of fruits produced. This lag in response resulted in a large proportion of fruits being attacked and
seeds consumed in a bad fruiting year that followed a good fruiting year, and vice versa. The proportion of fruits attacked
and seeds consumed was largest in the population showing the greatest between-year variation in fruit production and lowest
in the population showing the lowest between-year variation in fruit production. Furthermore, the individuals within the former
population were synchronised, while they were not in the latter population. These results contradict one of the possible explanations
of mast-seeding, where large synchronised between-year variation is supposed to reduce pre-dispersal seed predation. Instead,
differences in attraction of the seed predator to differences in fruit crop size could explain the observed difference in
seed predation between the two populations with opposite fruiting patterns. Within each population, irrespective of year,
the proportion of fruits attacked and seeds consumed was independent of a tree's fruiting display. Therefore, trees with high
fruit production, despite harbouring the largest number of seed predators, produced the largest number of developed seeds
in absolute numbers, compared to trees that produced few fruits.
Received: 25 February 1996 / Accepted: 30 November 1996 相似文献
5.
The paper brings data set of seed reproduction of about 500 wild herbaceous species of Central Europe and presents a number
of produced seeds in a new way. Number of seeds — reproductive capacity of a population (RCP) was defined as a number of seeds
produced by one species per 1 m2 at its one-hundred-per-cent cover per one season. About 23% of seed weight variability and about 26% of variability in RCP
were explainable on a family level. The trade-off between RCP and seed weight was confirmed both within families and also
among families. Both characteristics had higher variability on a family level and on lower taxonomic levels than on subclass
and class levels. Species with an annual life cycle have a larger number of seeds than perennials. Geophytes and species without
lateral spread have a tendency to produce a large amount of relatively weighty seeds in comparison to other life forms, and
to species with vegetative lateral spread. Species with seeds dispersed by wind usually have a large number of lightweight
seeds. Multivariate analyses confirmed some tendencies of reproductive traits which correspond to the definition of C-, S-,
R- strategies by Grime — “verification” of the RCP as ecological trait. The R- strategy was well distinguished from the C-
and S- strategies by reproductive traits, whereas C- and S- strategies are very similar to each other. Species with insect
pollination agent often correspond to C- strategy, wind agent to S- strategy, and species with self-pollination to R- strategy. 相似文献
6.
The spatial distributions of dispersed seeds have important evolutionary consequences for plants. Repeated defecations in
sites frequently used by seed dispersers can result in high seed concentrations. We observed the resting behavior of a mixed-species
group of tamarins in Peru and recorded the occurrence of seed dispersal (over 8 mo) and seed fate (over 11–22 mo) to determine
whether the location and use of resting sites influenced the spatial distribution of dispersed seeds and seedlings. The tamarins
rested mostly on trees (Saguinus fuscicollis: 60.6%, S. mystax: 89.2%) and dead trunks (S. fuscicollis: 24.4%) and used 61% of their resting sites repeatedly. During both the dry and wet seasons, tamarins dispersed significantly
more seeds within resting areas (0.00662 and 0.00424 seeds/m2, respectively) than outside them (0.00141 and 0.00181 seeds/m2). Seed survival and seedling recruitment did not differ significantly between resting and other areas, resulting in a higher
seedling concentration around the resting sites. Seed density did not increase with the duration or the frequency of use of
the resting sites but did increase when we pooled the seasonal resting sites together in 50 m × 50 m quadrats, ultimately
causing a clumped distribution of dispersed seeds. The use of resting sites in secondary forest, particularly during the dry
season, allows the creation of seedling recruitment centers for species coming from the primary forest. Our findings show
that tamarin resting behavior affects the spatial distribution of dispersed seeds and seedlings, and their resting sites play
an important role in plant diversity maintenance and facilitate forest regeneration in degraded areas. 相似文献
7.
Large floral displays should theoretically provide advantages to plants through increased pollinator visitation and resulting
fruit and seed set. However empirical tests of the response of pollinators to floral display size have been limited by a lack
of direct experimentation, and the results of such studies have been equivocal. In addition, other selective agents such as
pre-dispersal seed predators might modulate effects of floral display on pollination. By artificially altering flower number,
we examined the direct effects of floral display in the monocarpic herb, Ipomopsis aggregata (Polemoniaceae), on visitation rates by broad-tailed and rufous hummingbird pollinators, as well destruction of fruits by
a pre-dispersal seed predator (Hylemya: Anthomyiidae). In addition, we quantified the ultimate effects of flower number on female reproductive success. Plants with
larger floral displays were most likely to be visited first in any given foraging bout (P < 0.01). As expected, plants with more flowers received more total flower visits. However, we found no gain in the proportion
of flowers visited for many- versus few-flowered plants, or the total number of approaches/hour. In fact, a significantly
greater percentage of flowers were visited on few-flowered plants. Plants did not compensate for our reduction in flowers
by increasing investment in the number or proportion of flowers that set fruit, the number of seeds/fruit, or seed weight.
Pre-dispersal seed predation was greater for many- than for few-flowered plants (P < 0.001), but this did not offset the potential fitness gains of producing large displays. Our data support the hypothesis
that large floral displays function primarily in long-distance attraction of pollinators, and enhance maternal success.
Received: 21 March 1996 / Accepted: 24 October 1996 相似文献
8.
Crisp lettuce plants cv. Saladin were grown from the time they started flowering, at 20/10°C (16 h day, 8 h night), 25/15°C and 30/20°C in glasshouses on two occasions in 1985. Yields of seed increased from, on average, 15 g to 27 g and then fell to 20 g per plant with progressive increases in temperature. The number of mature florets per plant increased with temperature but the number of seeds per mature floret was lower at 20/10°C and 30/20°C than at 25/15°C. An increase in temperature reduced mean seed weight by up to 45%, seed volume by 15%, cell numerical volume density (Nv) by 27% and the number of cells per seed by 39%. Percentage seed germination reached a maximum early in seed development at the stage when the pappus appeared through the involucral bracts. Differences in percentage germination and vigour of seeds (slope test) from different temperatures were accounted for largely by the effects on mean seed weight. However, when germinated at 30°C seeds produced at 30/20°C germinated more readily than those produced at 25/15°C or 20/10°C. Seed vigour gradually increased with an increase in the length of storage after harvest, reaching a maximum after 260 days. In general, seeds produced at 25/15°C exhibited a greater variation in numbers of seeds per floret, Nv, seed weight, times of seedling emergence, seedling and mature head weight than seeds produced at lower or higher temperatures. 相似文献
9.
Rosane G. Collevatti Raquel Estolano Silmara F. Garcia John D. Hay 《Tree Genetics & Genomes》2009,6(4):555-564
We investigated pollen dispersal and breeding structure in the tropical tree species Caryocar brasiliense Camb. (Caryocaraceae), using genetic data from ten microsatellite loci. All adult trees (101) within a patch of 8.3 ha were
sampled, and from these adults 18 open-pollinated maternal progeny arrays were analyzed (280 seeds from 265 fruits). Most
fruits presented only one seed (median equal to 1.000) and mean number of ripened seeds per fruit was 1.053 (SD = 0.828).
Our results showed that C. brasiliense presents a mixed-mating system, with 11.4% of self-pollination, multilocus outcrossing rate of t
m = 0.891 ± 0.025, and high probability of full-sibship within progeny arrays (r
p = 0.135 ± 0.032). Outcrossing rate and self-pollination varied significantly among mother trees. We could detect a maximum
pollen dispersal distance of ∼500 m and a mean pollen dispersal distance of ∼132 m. However, most pollination events (80%)
occurred at distances less than 200 m. Our results also indicated that pollen dispersal is restricted to a neighborhood of
5.4 ha with rare events of immigration (∼1% N
e
m = 0.35). C. brasiliense also presents a significant but weak spatial genetic structure (Sp = 0.0116), and extension of pollen dispersal distance was greater than seed dispersal (N
b = 86.20 m). These results are most likely due to the foraging behavior of pollinators that may have limited flight range.
The highly within-population synchronous flowering, high population density, and clumped distribution reinforce pollinator
behavior and affect residence time leading to a short-distance pollen dispersal. 相似文献
10.
A simple method to induce somatic embryogenesis from seeds of rapid-cycling Brassica napus is described. Seedlings cultured on Murashige and Skoog (MS) basal medium produced somatic embryos directly on hypocotyls
and cotyledons after 2 to 3 subcultures onto the same medium. A low pH of the medium (3.5–5) was more conducive to somatic
embryogenesis than a higher pH (6 and 7). Embryogenic potential of the seeds was inversely correlated to seed age: about 41–68%
of immature seeds between the ages of 14 and 28 days after pollination (DAP) formed somatic embryos compared to 0–11% of the
seeds obtained 29–37 DAP. About 54% of the somatic embryos produced secondary embryos after subculturing onto the same medium.
The embryogenic potential of the cultures has been maintained on MS basal medium for 2 years (12 generations) without diminution.
Up to 75% of the secondary embryos developed into plantlets on MS medium enriched with 10–6
M zeatin, and 40% of these produced flowers when transferred to an optimised flower-induction medium. Viable seeds were produced
in self-pollinated in vitro flowers.
Received: 15 February 2000 / Revision received: 18 July 2000 / Accepted: 19 July 2000 相似文献
11.
Xiaojie Li Guanpin Yang Yuanyuan Shi Yizhou Cong Shi Che Shancun Qu Zhiling Li 《Journal of applied phycology》2008,20(6):1097-1102
Eighteen microsatellite markers were used to determine the genetic distances between the parental gametophyte clones of 14
Laminaria hybrids, which were then used to establish a linear relationship with the heterosis (hybrid vigor) of economic traits including
yield, mean blade try weight, mean blade fresh weight, blade length, blade width and mean blade thickness using regression
analysis. Significant regression was found between the genetic distance (x) and the heterosis (y) of yield (y = 115.10x − 77.97,
r = 0.8151, p = 0.00038), mean blade dry weight (y = 115.23x −77.97, r = 0.8154, p = 0.00038), mean blade fresh weight (y = 100.08x − 57.85, r = 0.7306, p = 0.0030) and blade length (y = 204.11x − 46.77, r = 0.6963, p = 0.00566). The prediction of the heterosis of Laminaria hybrids with the genetic distance between parental gametophyte clones will facilitate the selection of elite Laminaria hybrids by avoiding the time-consuming and labor-intensive trait evaluation of a large number of hybridization combinations. 相似文献
12.
Variation and Allometry of Seed Weight inAeschynomene americana 总被引:1,自引:0,他引:1
One hundred and fifty seeds from each of 72Aeschynomene americanapopulationswith world-wide origin were weighed individually and the meanand distribution of seed weight were calculated and comparedbetween populations. Mean seed weight varied less than five-foldbetween populations with about 80% having a mean seed weightbetween 23 mg. However, differences between the largestand smallest seeds (28 mg) ranged two-17-fold withinpopulations. Populations that had larger mean seed weights alsohad larger maximum and minimum seed weights but not larger standarddeviations than those with smaller mean seed weights. Seed distributionsfor populations with a mean seed weight2 mg were positivelyskewed while those for all populations with a mean seed weight4mg were negatively skewed. Populations that flowered later producedsmaller seeds than those that flowered earlier.Copyright 1998Annals of Botany Company. Seed weight, weight distribution, inter-population variation, correlation among traits,Aeschynomene americana. 相似文献
13.
The fatty acid composition and content of membrane and storage lipids of two transgenic laurate-producing rape (Brassica napus L.) lines were monitored during seed development. The two lines, the medium-laurate (ML) line and the high-laurate (HL) line,
accumulated 34 mol% and 55 mol% of laurate in their seed triacylglycerols, respectively. The diacylglycerols contained about
17 and 33 mol% of laurate in the ML- and HL-lines, respectively, from the mid-stage of seed development up to seed maturity.
The ML-line showed a maximal relative laurate content in phosphatidylcholine (17 mol%) at the mid-stage of seed development
whereafter the content decreased to 2.7 mol% with seed maturity. The laurate content in phosphatidylcholine was observed to
remain high (26 mol%) in the HL-line from the mid-stage to the end of triacylglycerol deposition. Thereafter, the relative
content decreased and reached 6.6 mol% in the mature seeds. There was an enhanced activity of lauroyl-phosphatidylcholine-
metabolizing enzymes in the seed membranes from laurate-producing lines compared with control lines, which might explain the
decrease seen in laurate content in phosphatidylcholine during seed maturation. A comparison of the laurate distribution in
the lipids from developing laurate-producing rape seeds and developing seeds from three species naturally accumulating laurate
at similar levels revealed differences in laurate metabolism compared with these species. The results suggest that phospholipids
and triacylglycerols are synthesized from the same diacylglycerol pool in rape seeds and that rape lysophosphatidic acid acyltransferase
and diacylglycerol acyltransferase do not have the same preference for laurate substrates as the corresponding enzymes in
seed tissues naturally accumulating this acyl group. In addition, the mechanisms that specifically remove or exclude laurate
from membrane lipids appear less effective in rape seed than in tissues naturally evolved to synthesize laurate-rich oils.
Received: 23 December 1996 / Accepted: 16 April 1997 相似文献
14.
Melike Bor Ozden Ozkur Filiz Ozdemir Ismail Turkan 《Plant Molecular Biology Reporter》2009,27(4):518-525
Myrosinase (EC 3.2.1.147) catalyzes cleavage of glucosinolates, which consist of a thioglucoside moiety linked to amino acid-derived
side chains. Myrosinase activity and expression profiles were investigated together with glucosinolate contents in Capparis ovata (caper) in order to characterize the glucosinolate–myrosinase system. The desulfoglucosinolates—glucocapparin, glucoiberin,
progoitrin, epiprogoitrin, sinigrin, gluconapin, glucosinalbin, and glucobrassicin—were extracted and quantified from leaves,
seeds, flowers, flower buds, and young shoots. The major desulfoglucosinolate was glucocapparin, which accumulated to values
of 39.35 ± 0.09 and 25.56 ± 0.11 μmol g−1 dry weight in seed and leaf extracts, respectively. Myrosinase has high activity in caper seeds, leaves, flowers, and flower
bud tissues having the highest total activities in seed extracts (79.23 ± 0.18 U). However, specific activities were the highest
in flower bud extracts (200.44 ± 0.09 U mg−1 protein). The myrosinase protein migrated as a single band with a molecular weight of 65 kDa on sodium dodecyl sulfate polyacrylamide
gel electrophoresis and on Western blots probed with the myrosinase-specific 3D7 antibodies. Native gel electrophoresis revealed
two putative myrosinase isoenzymes in seeds, leaves, and flower tissues. The caper homolog of the Arabidopsis thaliana TGG1 gene was differentially expressed in seeds, leaves, flowers, and flower buds with the highest expression levels in leaves
and flower bud tissues. 相似文献
15.
In grain crops, total sink capacity is usually analysed in terms of two components, seed number and individual seed weight. Seed number and potential individual seed weight are established at a similar timing, around the flowering period, and seed weight at maturity is highly correlated with the potential established earlier. It is known that, within a species, available resources during the seed set period are distributed between both yield components, resulting in a trade-off between seed number and seed weight. Here we tested if this concept could apply for interspecific comparisons, where combinations of numbers and size across species could be related to the total available resources being either allocated to more seed or larger potential individual seed weight during the seed set period. Based on this, species differences in seed weight should be related to resource availability per seed around the period when seed number is determined. Resource availability per seed was estimated as the rate of increase in aboveground biomass per seed around the period of seed set. Data from 15 crop species differing in plant growth, seed number, seed weight and seed composition were analysed from available literature. Because species differed in seed composition, seed weight was analysed following an energy requirement approach. There was an interspecific trade-off relationship between seed number per unit of land area and seed weight (r = 0.92; F(1, 13) = 32.9; n = 15; P < 0.001). Seed weight of different species was positively correlated (r = 0.90; F(1, 13) = 52.9; n = 15; P < 0.001) with resource availability per seed around the seed set period. This correlation included contrasting species like quinoa (Chenopodium quinoa; ∼100000 seeds m−2, ∼4 mg equivalent-glucose seed−1) or peanut (Arachis hypogaea; ∼800 seeds m−2, ∼1000 mg equivalent-glucose seed−1). Seed number and individual seed weight combinations across species were related and could be explained considering resource availability when plants are adjusting their seed number to the growth environment and seeds are establishing their storage capacity. Available resources around the seed set period are proportionally allocated to produce either many small seeds or few larger seeds depending on the particular species. 相似文献
16.
The monophagous weevil Rhinoncomimus latipes Korotyaev (Coleoptera: Curculionidae) has been introduced into North America as a biological control agent for the invasive vine mile-a-minute weed, Persicaria perfoliata (L.) H. Gross. This weevil has been shown to reduce the percent cover of mile-a-minute and the number of seed clusters produced, as well as altering the phenology of seed production. However, prior work has not examined the potential impact of the weevil on seed viability and numbers of seeds per cluster. When both adult and larval weevils fed on whole plants in the greenhouse, seed production and fruit maturation were delayed and both the total number of seeds and number of seeds per cluster were reduced. Overall, weevils in greenhouse cages reduced the reproductive potential of P. perfoliata by 35%. When adult weevils were confined on developing seed clusters in the field, the number of seeds produced per cluster, the weight of seeds produced, and seed viability all decreased. Overall, the number of viable seeds per cluster was reduced by 37% in the presence of adult weevils. Taken together, these findings demonstrate that this biological control agent can have important impacts on the reproductive potential of its target weed through mechanisms that have not previously been shown. 相似文献
17.
Continuing loss of native orchid habitat has lead to an increased emphasis on orchid conservation. Major obstacles in the production of native orchid seedlings for use in conservation have been: (1) development of efficient and reliable seed germination protocols and (2) an understanding of early seedling growth and development. Effects of six asymbiotic media (Modified Lucke, Murashige & Skoog, Lindemann, Vacin & Went, Malmgren Modified, Knudson C), four exogenous cytokinins (BA, Zea, Kin, 2-iP), and three photoperiods (0/24, 16/8, 24/0 h L/D) were examined on seed germination and early protocorm development of Habenaria macroceratitis, a rare native Florida terrestrial orchid. Finally, the effects of three photoperiods (8/16, 12/12, 16/8 h L/D) on in vitro seedling development were examined. Percent seed germination was highest on both LM and KC after seven weeks culture (LM = 89.1%, KC = 89.2%); however, protocorm development was enhanced on MM after both seven and 16 weeks. Both zeatin and kinetin at 1 μM enhanced seed germination (Zea = 58.1%, Kin = 47.2%). Final percent seed germination (91.7%) and protocorm development (Stage 4) was increased in the absence of light (0/24 h L/D). In␣vitro seedlings cultured under 8/16 h L/D conditions produced the highest number of tubers per seedling (1.06) with the greatest tuber (42.7 μg) and shoot (fwt = 69.5 μg) biomass and tuber diameter (3.1 mm). 相似文献
18.
The composition and positional distribution of lipids in developing and mature transgenic Brassica napus seeds accumulating up to 7 mol% of caprylate (8:0), 29 mol% caprate (10:0) or 63 mol% of laurate (12:0) were examined. The
accumulation of 8:0 and 10:0 resulted from over-expression of the medium-chain-specific thioesterase (Ch FatB2) alone or together with the respective chain-length-specific condensing enzyme (Ch KASIV). Seeds containing high levels of 12:0 were obtained from plants expressing bay thioesterase (BTE) alone or crossed
with a line over-expressing the coconut lysophosphatidic acid acyltransferase (LPAAT), an enzyme responsible for the increase
in acylation of 12:0 at the sn-2 position. In all instances, 10:0 and 12:0 fatty acids were present in substantial amounts in phosphatidylcholine during
seed development with a drastic decrease of 80–90% in mature seeds. At all stages of seed development however, 8:0 was barely
detectable in this membrane lipid. Altogether, these results indicate that these transgenic seeds exclude and/or remove the
medium-chain fatty acids from their membrane and that this mechanism(s) is more effective with the shorter-chain fatty acids.
Furthermore, seeds of 8:0- and 10:0-producing lines had only negligible levels of these fatty acids present in the sn-2 position of the triacylglycerols. In contrast, all 12:0-producing seeds had a substantial amount of this fatty acid in
the sn-2 position of the triacylglycerols, suggesting that the endogenous LPAAT is able to acylate 12:0 if no other acyl-CoA species
are available.
Received: 11 February 2000 / Accepted: 2 May 2000 相似文献
19.
Ling Cao Biyu Song Jinmiao Zha Chengtai Yang Xinfu Gong Jianbin Li Weimin Wang 《Environmental Biology of Fishes》2009,86(1):75-88
This study presents fundamental information on the reproductive biology, size and age composition, and growth of yellow catfish,
Peltobagrus fulvidraco. Sampling was carried out monthly from Ce Lake in Hubei province from January 2004 and December 2004. Overall female/male
(F/M) sex ratio was 1.08, not significantly different from expected 1.0 ratio. But sex ratio (F/M) of the spawning group was 1.14:1 with skewness towards females (p < 0.05). The smallest sexually mature male and female massed 20.51 and 16.93 g, and measured 100.1 and 94.3 mm in total length,
respectively. Reproductive period for this species is from April to August when GSI is considerably higher than the rest months
(p < 0.05). The highest GSI values were measured from May to July for both sexes and this period was presumably the peak spawn.
First maturation occurred at age 1+ for both sexes. Fish of age 1+ and 2+ comprised the greatest portion of spawners. The absolute fecundity (AF) of P. fulvidraco ranged from 657 to 11,696 eggs per fish, with mean AF value of 3,570 ± 122 (S.D.) eggs per fish, varying considerably at
given length, weight and age. The fecundity relative to total length (F/L) fluctuated from 58 to 680 eggs/mm, with a mean value of 246 ± 34 (SD) eggs/mm, and fecundity relative to total weight (F/W) varied from 29–133 eggs/g, with a mean value of 67 ± 7 (SD) eggs/g. P. fulvidraco is a single spawner, with low fecundity compared with other Bagrid fish. 相似文献
20.
In this study we examined seed supply (seed banks and seed rain) and vegetation of seeded cultivated grasses and naturally occurring native grasses following a wildfire in northern New Mexico, USA. We specifically examined density of native and cultivated grass seeds and plants in areas of high, moderate, and low fire severity. We also examined the similarity between density of native and cultivated grass seeds to density of above ground plants. Density of native grass seed per square meter was higher in areas that burned under low fire severity (85.18 ± 44.83) compared to areas of moderate (18.52 ± 11.26) and high (7.41 ± 4.90) fire severity; however, differences were not statistically significant due, in part, to the high error associated with estimates. Density of cultivated grass seed per square meter was higher than that of native grass seed in areas of high (439.60 ± 117.98) and moderate (437.02 ± 146.50) fire severity, areas that were seeded with cultivated grasses after the wildfire for erosion control. Density of seeded grass plants per square meter was also higher than that of native grass plants in areas of high (18.78 ± 4.59 versus 0.33 ± 0.24) and moderate (8.22 ± 1.76 versus 0.22 ± 0.15) fire severity. There was a higher correspondence between the density of cultivated grass seeds and plants (highest value 0.32 ± 0.11) compared to density of native grass seeds and plants (highest value 0.05 ± 0.04). The high density of seeds, plants, and correspondence indicated that seeds from cultivated grasses are more likely to establish as post-fire vegetation than seeds from native grasses. Seeding with cultivated grasses following a wildfire may slow or inhibit recovery of native grasses in the short term. Longer-term implications for site occupancy deserve further study. 相似文献