Inheritance of two seedling characters in Sorghum almum Parodi, and cross pollination within S. almum and between S. almum and S. halepense (L) Pers.

1965 ◽  
Vol 16 (4) ◽  
pp. 533 ◽  
Author(s):  
AJ Pritchard
Keyword(s):  
Marker Gene ◽  
Genetic Isolation ◽  
Natural Conditions ◽  
Green Seedling ◽  
Cross Pollination ◽  
Segregation Ratios ◽  
The Mean ◽  
Natural Crossing ◽  
Seedling Characters ◽  
Pale Green

An albino seedling character in Sorghum almum Parodi was shown to be tetrasomically inherited. Segregation ratios for a pale green seedling character were very variable, and it is probable that more than one gene is involved. With the albino seedling character as a marker gene, it was found that the average natural crossing in S. almum was approximately 54% at one location and 70% at another. The maximum natural crossing between S. almum and S. halepense (L.) Pers. was 57%, but the mean was only 20%. This may indicate that some S. almum plants exhibit a degree of genetic isolation from S. halepense when these species are grown together under natural conditions.

Natural crossing in cotton (Gossypium hirsutum L.)

2000 ◽  
Vol 51 (8) ◽  
pp. 979 ◽  
Author(s):  
F. P. Xanthopoulos ◽  
U. E. Kechagia
Keyword(s):  
Gossypium Hirsutum ◽  
Genetic Markers ◽  
Marker Gene ◽  
Leaf Traits ◽  
Cotton Field ◽  
Gossypium Hirsutum L ◽  
The Mean ◽  
Natural Crossing

The extent of natural crossing in cotton (Gossypium hirsutum L.) was studied in 2 experiments conducted in Greece during 1998 and 1999, using glandless and red-leaf traits as genetic markers. The glandless line was planted in the middle, and the red-leaf both in the middle and the corners, of a commercial cotton field. In the first experiment where estimation of natural crossing was based upon gland status, the percentage ranged from 1.67% to 2.67% in adjacent rows, dropped to 1.42% in plants 2 m apart, and declined to almost zero after 10 m. In the second experiment, where the red-leaf marker gene was used, the mean of natural crossing was 3.85% in adjacent rows, fell to 2.79% in plants 2 m apart, and progressively diminished to 0.31% after 10 m. The mean natural outcrossing in different rows was almost the same in both experiments at the middle of the field and was actually double at the corners. Differences in the extent of natural crossing between the middle and the corners of the field continued to be significant up to 4 m distance. In all cases, distances greater than 10 m among cottons were sufficient to minimise out-crossing ranges.

scholarly journals Development of Genic Male-sterile Watermelon Lines with Delayed-green Seedling Marker

HortScience ◽  
1996 ◽  
Vol 31 (1) ◽  
pp. 123-126 ◽  
Author(s):  
X.P. Zhang ◽  
B.B. Rhodes ◽  
W.V. Baird ◽  
H.T. Skorupska ◽  
W.C. Bridges
Keyword(s):  
Male Sterility ◽  
Seed Production ◽  
Citrullus Lanatus ◽  
Nuclear Gene ◽  
Hybrid Seed Production ◽  
Male Sterile ◽  
Green Is ◽  
Green Seedling ◽  
Segregation Ratios ◽  
Pale Green

Hybrid seed production can be facilitated by using male sterility coupled with a seedling marker. This research was initiated to combine the ms male sterility and dg delayed-green seedling marker into watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] lines. Male-sterile plants of the male-sterile line G17AB were crossed with plants of delayed-green breeding line Pale90, which has yellow cotyledons and pale-green, newly developed, true leaves. The double-recessive recombinants, male sterile and delayed green, from the F2 population were backcrossed to the male-fertile plants of G17AB. The pedigree method was used for selection in the progenies. The segregation ratios obtained from F2 and BC1F2 populations suggest that the male-sterile and delayed-green traits are inherited independently and that delayed green is inherited as a single recessive nuclear gene. Two male-sterile watermelon lines with delayed-green seedling marker have been developed. These lines will provide a convenient way to introduce male sterility and the delayed-green seedling marker into various genetic backgrounds. These two lines can be used for testing the efficiency of a new, hybrid, watermelon, seed production system.

scholarly journals The differential transmissibility of myxoma virus strains of differing virulence grades by the rabbit flea Spilopsyllus cuniculi (Dale)

1975 ◽  
Vol 75 (2) ◽  
pp. 237-247 ◽  
Author(s):  
A. R. Mead-Briggs ◽  
J. A. Vaughan
Keyword(s):  
Host Resistance ◽  
Oryctolagus Cuniculus ◽  
Selective Advantage ◽  
Myxoma Virus ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Male And Female ◽  
The Mean ◽  
Virus Strains ◽  
Sampling Times

SUMMARYLaboratory studies showed that few rabbit fleas (Spilopsyllus cuniculi (Dale)) transmitted myxomatosis after removal from wild rabbits (Oryctolagus cuniculus (L)) that had been infected for fewer than 10–12 days, irrespective of the virulence of the myxoma virus strain involved. Rabbits infected with fully virulent (Grade I) strains died within 10–15 days and few fleas from these hosts became infective; averaging all the samples taken, 12% of the fleas were infective. Also, few fleas acquired infectivity on individual rabbits which recovered from infection with attenuated strains; the mean was 8% infective. Rabbits which died between 17 and 44 days after infection had higher proportions of infective fleas at all sampling times; the mean was 42% infective. Male and female fleas transmitted virus with equal efficiency.For rabbits infected with any of the attenuated virus strains the mean percentage of infective fleas was inversely related to the survival time of the host. Rabbits infected with moderately attenuated strains (Grades IIIA and IIIB) had, on average, the highest proportion of infective fleas; hence such strains have a selective advantage and have become predominant under natural conditions in Britain. The changes that might occur if there is an increase in host resistance to myxomatosis are discussed.

Karyotypes and morphological variation in the sessile-flowered trilliums of North Carolina

1969 ◽  
Vol 47 (8) ◽  
pp. 1223-1232 ◽  
Author(s):  
Cornelia Ann Serota
Keyword(s):  
North Carolina ◽  
Cold Treatment ◽  
Morphological Data ◽  
Geographic Isolation ◽  
Flower Scent ◽  
Cross Pollination ◽  
Western North Carolina ◽  
Wide Range ◽  
Coefficient Of Variability ◽  
The Mean

Six populations of apparently morphologically similar sessile-flowered Trillium (known taxonomically as T. cuneatum Raf. and T. luteum (Muhl.) Harb.) observed growing at elevations between 800 and 1700 ft in the Appalachians of western North Carolina and eastern Tennessee exhibit a wide range of variability by observation. The extent of variability was assessed by using statistical and karyotypic methods of analysis and by intraspecific cross-pollination. A correlation exists between the mean coefficient of variability and (1) the size of the population and (2) the degree of geographic isolation. The number of types of each kind of chromosome (A–E), as resolved by cold treatment, varies by one type from population to population. The homozygosity for the six populations is 85.8%, and the distribution of euchromatin is not complex. Intraspecific cross-pollination was effective among 76% of the test crosses. A review of the statistics and other morphological data indicates that the presence or absence of anthocyanins, flower scent, and the degree of geographic isolation are the three major variants among the six populations. These kinds of Trillium grow sympatrically with T. grandiflorum (Michx.) Salisb., T. simile Gleason, T. erectum var. album (Michx.) Pursh, T. flexipes Raf. (T. gleasoni Fern.), and T. erectum L. The cumulative karyotype for the six stands indicates that these plants have not hybridized with any of the above species and varieties. Although these plants have been classified as T. cuneatum Raf. in some stands and as T. luteum (Muhl.) Harb. in others the data demonstrate that these six stands represent one discontinuous population of a sessile-flowered Trillium. Trillium discolor Wray, although relatively rare in western North Carolina, also grows here. Although T. discolor is not directly involved in this problem, its description and distinctive karyotype are included.

Developing a census method based on sight counts to estimate rabbit (Oryctolagus cuniculus) numbers

2003 ◽  
Vol 30 (5) ◽  
pp. 487 ◽  
Author(s):  
Dylan W. Poole ◽  
Dave P. Cowan ◽  
Graham C. Smith
Keyword(s):  
Population Size ◽  
Field Trials ◽  
Population Estimates ◽  
Economic Costs ◽  
Natural Conditions ◽  
Commercial Farms ◽  
The Mean ◽  
The Difference ◽  
Study Sites ◽  
Autumn And Winter

A rabbit-census method, based on systematic counts conducted at night or at dawn and dusk, was developed and validated in terms of estimating the total number of rabbits present in a given area. Initially, models were developed under semi-natural conditions to describe the relationships between the numbers of rabbits counted and population size. Confidence limits were also calculated. The models were developed by comparing rabbit counts with the actual number of rabbits present, from a known population of animals. Only spotlight counts at night were considered reliable enough to estimate rabbit population size. During the autumn and winter months these represented ~60% of the population present. The model was subsequently validated, in two different exercises, following a series of field trials conducted under a variety of conditions on commercial farms. Initially, population estimates derived from the model were compared with those calculated using an alternative census technique. Population estimates, using the two techniques, were very similar at nine of the ten study sites. A second validation exercise was also conducted whereby the number of rabbits removed at each of the sites was compared with the difference between the mean pre- and post-removal spotlight counts. The results further supported the proposition that spotlight counts represent ~60% of the population present, with the difference between the two mean spotlight counts representing 61.2% (± 11.0, s.d.) of the number of rabbits removed. The census method therefore shows considerable promise as a means to estimate rabbit numbers under a range of agricultural conditions and therefore has the potential to predict accurately the economic costs of rabbit damage and also to gauge the effectiveness of various methods of rabbit control.

Incubation of eggs of three species of Chelid tortoises, and notes on their embryological development

1968 ◽  
Vol 16 (5) ◽  
pp. 749 ◽  
Author(s):  
J Goode ◽  
J Russell
Keyword(s):  
Individual Differences ◽  
The Other ◽  
Large Individual ◽  
Embryological Development ◽  
Natural Conditions ◽  
Early Embryos ◽  
Incubation Periods ◽  
The Mean ◽  
Main Factors ◽  
Chelodina Longicollis

Incubation periods and nest contents of three species of chelid tortoises in northern Victoria were recorded. Mean incubation period for eggs of Emydura macquari (Cuvier) was 75 days and average number of eggs per nest was 15.7; for Chelodina longicollis (Shaw), 138 days and 10.7 eggs per nest; for Chelodina expansa Gray, normally exceeding 324 days and 15.4 eggs per nest. In abnormal seasons C. expansa hatchlings may emerge from the nest in less than 193 days or more than 522 days after eggs were deposited. Eggs artificially incubated at 30�C consistently develop more quickly than those at lower temperatures under natural conditions. In the field nest temperatures closely approximate the mean daily air temperature. Embryos of C. expansa are tolerant to nest temperatures ranging from 4.9�C minimum to 29.6�C maximum. The other species are subject to variations of about 15 degC with up to 8.5 degC variation being recorded in 1 day. Development of early embryos approximated that recorded for cryptodire tortoises. However, there are large individual differences in the period of incubation needed for specific stages to be reached, especially between embryos of the short-necked and long-necked species of these pleurodire tortoises. It is suggested that differences in the anatomy of their eggs are the main factors in the different incubation periods between short-necked and long-necked species.

Natural cross pollination in Egyptian cotton (Gossypium barbadense L.)

1976 ◽  
Vol 86 (1) ◽  
pp. 205-209 ◽  
Author(s):  
M. A. Elfawal ◽  
M. A. Bishr ◽  
E. K. Hassoub
Keyword(s):  
Gossypium Barbadense ◽  
Cotton Variety ◽  
Cross Pollination ◽  
Growing Seasons ◽  
Natural Crossing ◽  
Egyptian Cotton ◽  
Natural Cross

SUMMARYThe percentage of natural cross pollination was estimated in the Alexandria area (Egypt) in two sites near and far from an apiary. The Egyptian cotton variety Giza 45 and the glandless strain Bahtim 110, as a marker parent, were used during three growing seasons. The average natural crossing within the square of the marker parent were 3·54 and 0·34% near and far from the apiary respectively. For the plants around the square of pollen source, however, the average of natural crossing was 0·56% near the apiary, while it was 0·21% far from the apiary. The natural crossing steadily decreased as the distance from the marker variety increased.

Biology and Ecology of the Garden Chafer, Phyllopertha horticola (L.). III.—The Growth of the Larva

1957 ◽  
Vol 48 (1) ◽  
pp. 127-154 ◽  
Author(s):  
R. Laughlin
Keyword(s):  
Population Density ◽  
Larval Growth ◽  
The Other ◽  
Pupal Weight ◽  
Lake District ◽  
Natural Conditions ◽  
Grass Roots ◽  
The Mean ◽  
Phyllopertha Horticola ◽  
Pasture Plants

Previous work has shown that, under natural conditions in the Lake District, larvae of Phyllopertha horticola (L.) hatch in early July and feed actively on the roots of pasture plants during the next 3½–4 months, undergoing two moults. They then empty the gut and enter hibernation, pupating the following spring. Stores of organic material in grass roots are at their highest level during this autumn feeding period. It has also been shown that the egg production depends almost entirely on the weight of the hibernating larva or of the pupa, which thus plays an important part in determining the reproductive rate of the population, and studies were accordingly made on larval growth and certain factors affecting it.Newly hatched larvae were cultured at 15°C. in moistened plaster-of-paris containers filled with a mixture of soil and germinating grass seeds. They moulted at about 20 and 45 days after hatching, and stopped feeding and entered hibernation at about 100 days. When the seeds were scattered on the soil surface, larval growth was slower. The mean larval weight, plotted against age, gave a sigmoid curve; in the. first instar and most of the second, the rate of increase in weight was proportional to the weight, but thereafter, up to the time of hibernation, it was more or less constant. The rate of growth of the individual larva was irregular, being slower at the moults and variable even in the middle of the instar.Larvae cultured under semi-natural conditions in pots of growing grass in the open moulted about 3–4 and 7–9 weeks after hatching and entered hibernation at 100–120 days. Growth is possible on a wide variety of food plants, larvae cultured on 13 species of pasture plants grown in pure stands surviving to the hibernation stage on all but two of them.During hibernation, the larva loses 20–25 per cent, of its weight, mostly in the first few weeks. The pupal weight is almost constant and does not appear to be affected by the temperature treatment of the hibernating larva. It is thus a useful index of effective larval growth.The mean and (in brackets) range of the weights of all pupae collected in two fields in the Lake District between 1950 and 1953 were 139·3 mg. (65–242) for males and 171·3 mg. (72–310) for females. Field samples of hibernating larvae and of pupae show considerable variation in weight from place to place, from year to year and within apparently homogeneous areas.Variation in the time at which larval growth takes place is a major cause of variation in pupal weight. The growth period of larvae in a field at Buttermere was three weeks earlier in 1952 than in 1950, though of the same duration, and the resulting pupae in 1953 were heavier than those in 1951. Two lots of larvae of similar parentage, grown in adjacent plots of grass out of doors, one of which both hatched and entered hibernation three weeks before the other, likewise showed a difference in weight at hibernation, the earlier lot being the heavier. A series of weighed samples of larvae taken from part of a field at Ambleside in 1953 at weekly intervals during the period when they were entering hibernation showed that heavier individuals did so before lighter ones, and males before females. Factors inducing mortality during this period thus operate selectively against females, because these are exposed to them for longer.Field-collected larvae fed in the third instar on roots of lettuce produced pupae the following spring that were significantly heavier than those from larvae fed on roots of either ryegrass or clover.There is no evidence to show that population density affects the weight of the hibernating larva or the pupa. On the other hand, larvae from soil from which the damaged turf had been stripped by birds were significantly lighter than those from the surrounding undisturbed sward.When moving through the soil, larvae may meet and fatally injure each other by an undirected “ snapping ” reaction. This mechanism may limit population density. In an experiment in which larvae were reared in loose soil on grass roots, the mortality rate was seen to increase with the size and activity of the larvae, and also with the larval density.

Caffeine content variation in single green Arabica coffee seeds

2010 ◽  
Vol 20 (3) ◽  
pp. 163-167 ◽  
Author(s):  
Paulo Mazzafera ◽  
Maria Bernadete Silvarolla
Keyword(s):  
High Performance Liquid Chromatography ◽  
Coffea Arabica ◽  
High Performance ◽  
Extraction Procedure ◽  
Mean Values ◽  
Caffeine Content ◽  
Cross Pollination ◽  
Content Variation ◽  
Large Numbers ◽  
The Mean

AbstractCoffea arabica L. is highly homozygotic and caffeine content in most cultivars is reported to be similar (approximately 1%). The caffeine content was analysed using individual seeds of cultivars Catuaí Vermelho, Mundo Novo and Bourbon Vermelho, and varieties Mokka and Laurina of C. arabica. Seeds were cut transversely in half, a thin slice from each was extracted in a mixture of chloroform and methanol, and caffeine was measured by high performance liquid chromatography. The extraction procedure was validated by comparison with two conventional methods less suited for analysing large numbers of seeds. The results revealed an unexpectedly large variation [Catuaí Vermelho: 3.72–25.9 mg g− 1 (seeds); Mundo Novo: 5.06–18.59 mg g− 1; Bourbon Vermelho: 6.76–16.59 mg g− 1] even in types naturally low in caffeine such as Laurina (1.17–9.97 mg g− 1) and Mokka (2.01–9.64 mg g− 1). The mean values for all cultivars were always in the range of the caffeine content found in the literature. Several studies showed that C. arabica has approximately 10% cross-pollination, but the variation observed in caffeine content in individual seeds was too large to be explained by cross-pollination.

Buoyancy of Atlantic and Pacific Herring

1969 ◽  
Vol 26 (8) ◽  
pp. 2077-2091 ◽  
Author(s):  
Vivien M. Brawn
Keyword(s):  
Vertical Movement ◽  
Body Volume ◽  
Pacific Herring ◽  
Natural Conditions ◽  
The Pacific ◽  
In Captivity ◽  
The Mean ◽  
Total Body ◽  
Total Body Volume ◽  
The Relationship

Pacific and Atlantic herring after adjustment to water 36 cm deep had sinking-factors between 1000 and 1008 and showed an inverse relationship between oil content and swimbladder volume up to 12% oil. At higher oil contents a swimbladder volume between 2.6 and 3.0% of total body volume was maintained. The mean volumes and densities of various components of the Pacific herring held in captivity were: swimbladder gas 4.1% of total volume,.0013 g/ml; oil 3.5%,.926 g/ml; scales 0.5%, 1.966 g/ml; skeleton 1.2%, 1.993 g/ml; rest of fish 90.6%, 1.057 g/ml. These components on the average exerted upward forces of 41.4 and 3.3 dynes/ml of fish due to gas and oil, and downward forces of 4.6, 11.2, and 32.1 dynes/ml due to scales, skeleton, and the rest of the fish respectively. Under natural conditions herring usually have high oil contents so the relationship observed here suggests they have low swimbladder volumes. This combined with a duct direct from the swimbladder to the exterior and the lack of gas secretion would give the herring freedom of vertical movement and a low change of sinking factor with depth.

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