Sunday, February 27, 2011

Breeding of Emu


Emus form breeding pairs during the summer months of December and January, and may remain together for about five months. During this time they wander around in an area a few miles in diameter. It is believed they guard or find territory during this time. Both males and females increase in weight during this time and the female is slightly heavier at between 45 and 58 kg. This weight is lost during the incubation period, the males losing around 9 kg.Mating occurs in the cooler months of May and June, and the exact timing is determined by the climate, as the birds nest during the coldest part of the year. During the breeding season, males experience hormonal changes, including an increase in luteinizing hormone and testosterone levels, and their testicles double in size.

It is the females that court the males, and during the mating season, they become physically more attractive. The female's plumage darkens slightly and the small patches of bare, hairless skin just below the eyes and near the beaks turn turqoise-blue, although this is a subtle change. The female strides around confidently, often circling the male, and pulls its neck back while puffing out her feathers and crying out a low, monosyllabic sound that has been compared to human drums. This calling can occur when the males are not in view and more than 50 metres (160 ft) away and when the male's attention has been gained, the female can circle in a radius of 10–40 m. As the female circles its prospective mate, it continues to look towards him by turning its neck, while keeping its rump facing him. During this time, the female's cervical air sac may remain inflated as it calls outs. The passive male retains the same colour hair, although the bare patches of skin also turn a light blue.The female has more black hairs on its head but gender differentiation can be difficult for humans. If the male shows interest in the parading female, he will move closer; the female continues to tantalise its target by shuffling further away and continuing to circle him as before.

Females are more aggressive than males during the courting period, often fighting one another for access to mates. Fights among females accounted for more than half of the violent incidents in one mating season study.[40] If a female tried to woo a male that already had a partner, the incumbent female will try and repel the competitor by walking towards her challenger and staring in a stern way. If the male showed interest in the second female by erecting his feathers and swaying from side to side, the incumbent female will attack the challenger, usually resulting in a backdown by the new female.
Some female-female competitions can last up to five hours, especially when the target male is single and neither female has the advantage of incumbency. In these cases, the animals typically intensify their mating calls and displays, which increase in extravagance. This is often accompanied by chasing and kicking by the competing females.
Males lose their appetite and construct a rough nest in a semi-sheltered hollow on the ground from bark, grass, sticks, and leaves. The nest almost a flat surface rather than a segment of a sphere, and although in cold conditions the nest is taller, up to 7 cm tall, and more spherical to provide more insulation. When other material is lacking, it can also use spinifex grass bushes more than a metre across, despite the prickly nature. The nest can be placed in open ground or near scrubs and rocks, although thick grass is usually present if the emu takes the former option. The nests are usually placed in an area where the emu has a clear view of the surrounds and can detect predators.

If a male is interested, he will stretch his neck and erect his feathers and bend over and peck at the ground. He will then sidle up to the female, swaying his body and neck from side to side, and rubbing his breast against his partner's rump, usually without calling out. The female would accept by sitting down and raising her rump.

The pair mates every day or two, and every second or third day the female lays one of an average of 11 (and as many as 20) very large, thick-shelled, dark-green eggs. The shell is around 1 mm thick also indigenous Australians say that northern eggs are thinner. The number of eggs varies with rainfall.[2] The eggs are on average 134 by 89 millimetres (5.3 × 3.5 in) and weigh between 700 and 900 grams (1.5 and 2.0 lb), which is roughly equivalent to 10–12 chicken eggs in volume and weight. The first verified occurrence of genetically identical avian twins was demonstrated in the Emu. The egg surface is granulated and pale green. During the incubation period, the egg turns dark green, although if the egg never hatches, it will turn white from the bleaching effect of the sun.

About Emu


Emus are large birds. The largest can reach up to 150 to 190 centimetres (59–75 in) in height, 1 to 1.3 metres (3.3–4.3 ft) at the shoulder. Emus weigh between 18 and 48 kilograms (40 and 106 lb) Females are usually larger than males by a small amount, but substantially wider across the rump.

They have small vestigial wings that are around 20 centimetres (7.9 in) long and have a small claw at the tip of this wing. The Emu flaps its wings when it is running and it is believed that they stabilise the bird when it is moving. It has a long neck and legs. Their ability to run at high speeds, 48 km/h (30 mph), is due to their highly specialised pelvic limb musculature. Their feet have only three toes and a similarly reduced number of bones and associated foot muscles; they are the only birds with gastrocnemius muscles in the back of the lower legs. The pelvic limb muscles of emus have a similar contribution to total body mass as the flight muscles of flying birds. When walking, the Emu takes steps of around 100 centimetres (3.3 ft), but at full gallop, a stride can be as long as 275 centimetres (9.02 ft). The Emu's legs are devoid of feathers and underneath its feet are thick, cushioned pads. Like the Cassowary, the Emu has a nail on its toe akin to the blade of a knife, which is its major defensive attribute. This is used in combat to inflict wounds on opponents by kicking. The toe and claw are a total of 15 centimetres (5.9 in). They have a soft bill, adapted for grazing.

The Emu has good eyesight and hearing, which allows it to detect nearby threats. Its legs are among the strongest of any animals, powerful enough to tear down metal wire fences.

The neck of the Emu is pale blue and shows through its sparse feathers.They have brown to grey-brown plumage of shaggy appearance; the shafts and the tips of the feathers are black. Solar radiation is absorbed by the tips, and the loose-packed inner plumage insulates the skin. The resultant heat is prevented from flowing to the skin by the insulation provided by the coat, allowing the bird to be active during the heat of the day. A unique feature of the Emu feather is its double rachis emerging from a single shaft. Both of the rachis have the same length, and the texture is variable; the near the quill it is rather furry, but the external ends resemble grass. The sexes are similar in appearance, although the male's penis can become visible when it defecates. The plumage varies in colour due to environmental factors, giving the bird a natural camouflage. Feathers of Emus in more arid area with red soil have a similarly tinted plumage but are darker in animals residing in damp conditions.

The eyes of an Emu are protected by nictitating membranes. These are translucent, secondary eyelids that move from the end of the eye closest to the beak to cover the other side. This is used by the Emu as a protective visor to protect its eyes from dust that is prevalent in windy and arid deserts. The Emu also has a tracheal pouch, which becomes more prominent during the mating season. It is often used during courting, and it has speculated that it is used for communication on a day-to-day basis. The pouch is more than 30 centimetres (12 in), is spacious and the wall in very thin. The width of the opening is only 8 centimetres (3.1 in). The quantity of air that goes through the pouch, as determined by the Emu deciding to open or close it, affects the pitch of an Emu's call. Females typically cry more loudly than males.

On very hot days, emus pant to maintain their body temperature, their lungs work as evaporative coolers and, unlike some other species, the resulting low levels of carbon dioxide in the blood do not appear to cause alkalosis. For normal breathing in cooler weather, they have large, multifolded nasal passages. Cool air warms as it passes through into the lungs, extracting heat from the nasal region. On exhalation, the Emu's cold nasal turbinates condense moisture back out of the air and absorb it for reuse. As with other ratites, the Emu has great homeothermic ability, and can maintain this status from -5 to 45 degrees. The thermoneutral zone of Emus lies between 10–15 degrees and 30 degrees.

As with other ratites, the Emu has a relatively low rate of metabolism compared to other types of birds, but the rate depends on activity, especially due to resulting changes to thermodynamics. At -5 degrees, the metabolism rate of an Emu while sitting down is around 60% of the value for one that is standing, as the lack of feathers under its stomach leads to a higher rate of heat loss when it is standing up and exposing the underbelly.
 

Taxonomy of Emu


There are reports the Emu was first sighted by European explorers in 1696 when they made a brief visit to the coast of Western Australia. It was thought to have been spotted on the east coast of Australia before 1788 when the first European settlement occurred. It was first described under the name of the New Holland Cassowary in Arthur Phillip's Voyage to Botany Bay, published in 1789. The species was named by ornithologist John Latham on a specimen from the Sydney, Australia area, which was referred to as New Holland at the time. He collaborated on Phillip's book and provided the first descriptions of and names for many Australian bird species; its name is Latin for "fast-footed New Hollander". The etymology of the common name Emu is uncertain, but is thought to have come from an Arabic word for large bird that was later used by Portuguese explorers to describe the related Cassowary in Australia and New Guinea. Another theory is that it comes from the word "ema", which is used in Portuguese to denote a large bird akin to an ostrich or crane. In Victoria, some terms for the Emu were Barrimal in the Dja Dja Wurrung language, myoure in Gunai, and courn in Jardwadjali. It was known as murawung or birabayin to the local Eora and Darug inhabitants of the Sydney basin.

In his original 1816 description of the Emu, Vieillot used two generic names; first Dromiceius, then Dromaius a few pages later. It has been a point of contention ever since which is correct; the latter is more correctly formed, but the convention in taxonomy is that the first name given stands, unless it is clearly a typographical error. Most modern publications, including those of the Australian government, use Dromaius, with Dromiceius mentioned as an alternative spelling.

Introduction to Emu


The Emu (pronounced /ˈiːmjuː, ˈiːmuː/) (Dromaius novaehollandiae) is the largest bird native to Australia and the only extant member of the genus Dromaius. It is also the second-largest extant bird in the world by height, after its ratite relative, the ostrich. There are three extant subspecies of Emus in Australia. The Emu is common over most of mainland Australia, although it avoids heavily populated areas, dense forest, and arid areas.[5]

The soft-feathered, brown, flightless birds reach up to 2 metres (6.6 ft) in height. They have long thin necks and legs. Emus can travel great distances at a fast, economical trot and, if necessary, can sprint at 50 km/h (31 mph) for some distance at a time. Their long legs allow them to take strides of up to 275 centimetres (9.02 ft)[5] They are opportunistically nomadic and may travel long distances to find food; they feed on a variety of plants and insects, but have been known to go weeks without food. They also ingest stones, glass shards and bits of metal that help squash food in the digestive system. They drink infrequently, often once every day or two, and ingest copious fluids when the opportunity arises. Emus will sit in water and are also able to swim. They are curious and nosy animals who are known to follow and watch other animals and humans. Emus do not sleep continuously at night but in several short stints sitting down.

Emus have a nail on their toes, akin to a knife, which is used in kicking away predators and opponent Emus. Their legs are among the strongest of any animals, allowing them to rip metal wire fences. They are endowed with good eyesight and hearing, which allows them to detect predators in the vicinity. The plumage on an eye varies regionally, matching the surrounding environment and improving its camouflage. The feathers allow the Emu to prevent heat from flowing into the skin, permitting it to be active during the midday heat. They can tolerate a wide range of temperatures and thermoregulate effectively. Males and females are hard to distinguish visually, but can be differentiated by the types of loud sounds they emit by manipulating an inflatable neck sac. Emus breed in May and June and are not monogamous; fighting among females for a mate is common. Females can mate several times and lay several batches of eggs in one season. The animals put on weight before the breeding season, and the male does most of the incubation, losing significant weight during this time as he does not eat. The eggs hatch after around eight weeks, and the young are nurtured by their fathers. They reach full size after around six months, but can remain with their family until the next breeding season half a year later. Emus can live between 10 and 20 years in the wild and are predated by dingos, eagles and hawks. They can jump and kick to avoid dingos, but against eagles and hawks, they can only try to run and swerve.

The Tasmanian Emu subspecies that previously inhabited Tasmania became extinct after the European settlement of Australia in 1788; and the distribution of the mainland subspecies has been influenced by human activities. Once common on the east coast, Emu are now uncommon; by contrast, the development of agriculture and the provision of water for stock in the interior of the continent have increased the range of the Emu in arid regions, and it is neither endangered or vulnerable. They were a food and fuel source for indigenous Australians and early European settlers. Emus are farmed for their meat, oil, and leather. Emu is a lean meat and while it is often claimed by marketers that the oil has anti-inflammatory and anti-oxidative effects, this has not been scientifically verified in humans. The Emu is an important cultural icon of Australia. It appears on the coat of arms, various coins, features prominently in Indigenous Australian mythology, and hundreds of places are named after the bird.

Sunday, February 20, 2011

Cultivation and uses of sunflower


To grow best, sunflowers need full sun. They grow best in fertile, moist, well-drained soil with a lot of mulch. In commercial planting, seeds are planted 45 cm (1.5 ft) apart and 2.5 cm (1 in) deep. Sunflower "whole seed" (fruit) are sold as a snack food, after roasting in ovens, with or without salt added. Sunflowers can be processed into a peanut butter alternative, sunbutter. In Germany, it is mixed together with rye flour to make Sonnenblumenkernbrot (literally: sunflower whole seed bread), which is quite popular in German-speaking Europe. It is also sold as food for birds and can be used directly in cooking and salads. American Indians had multiple uses for sunflowers in the past,such as in bread, medical ointments, dyes and body paints.


Sunflower oil, extracted from the seeds, is used for cooking, as a carrier oil and to produce margarine and biodiesel, as it is cheaper than olive oil. A range of sunflower varieties exist with differing fatty acid compositions; some 'high oleic' types contain a higher level of monounsaturated fats in their oil than even olive oil.

The cake remaining after the seeds have been processed for oil is used as a livestock feed. Some recently developed cultivars have drooping heads. These cultivars are less attractive to gardeners growing the flowers as ornamental plants, but appeal to farmers, because they reduce bird damage and losses from some plant diseases. Sunflowers also produce latex and are the subject of experiments to improve their suitability as an alternative crop for producing hypoallergenic rubber.

Traditionally, several Native American groups planted sunflowers on the north edges of their gardens as a "fourth sister" to the better known three sisters combination of corn, beans, and squash. Annual species are often planted for their allelopathic properties.
However, for commercial farmers growing commodity crops, the sunflower, like any other unwanted plant, is often considered a weed. Especially in the midwestern US, wild (perennial) species are often found in corn and soybean fields and can have a negative impact on yields.

Sunflowers can be used to extract toxic ingredients from soil, such as lead, arsenic and uranium. They were used to remove cesium-137 and strontium-90 from a nearby pond after the Chernobyl disaster .

Cultivation


To grow jute, farmers scatter the seeds on cultivated soil. When the plants are about 15–20 cm tall, they are thinned out. About four months after planting, harvesting begins. The plants are usually harvested after they flower, but before the flowers go to seed. The stalks are cut off close to the ground. The stalks are tied into bundles and soaked in water (retting) for about 20 days. This process softens the tissues and breaks the hard pectin bond between the bast & Jute hurd (inner woody fiber stick) and the process permits the fibres to be separated. The fibres are then stripped from the stalks in long strands and washed in clear, running water. Then they are hung up or spread on thatched roofs to dry. After 2–3 days of drying, the fibres are tied into bundles.

The suitable climate for growing jute is a warm and wet climate, which is offered by the monsoon climate during the fall season, immediately followed by summer. Temperatures ranging from 70-100 °F and relative humidity of 70%-80% are favorable for successful cultivation. Jute requries 2"-3" of rainfall weekly with extra needed during the sowing period.

Friday, February 18, 2011

Structure and physiology


Maize stems superficially resemble bamboo canes and the internodes can reach 44.5 centimetres (17.5 in). Maize has a distinct growth form; the lower leaves being like broad flags, generally 50–100 centimetres long and 5–10 centimetres wide (2–4 ft by 2–4 in); the stems are erect, conventionally 2–3 metres (7–10 ft) in height, with many nodes, casting off flag-leaves at every node. Under these leaves and close to the stem grow the ears. They grow about 3 millimetres a day.



The ears are female inflorescences, tightly covered over by several layers of leaves, and so closed-in by them to the stem that they do not show themselves easily until the emergence of the pale yellow silks from the leaf whorl at the end of the ear. The silks are elongated stigmas that look like tufts of hair, at first green, and later red or yellow. Plantings for silage are even denser, and achieve a lower percentage of ears and more plant matter. Certain varieties of maize have been bred to produce many additional developed ears. These are the source of the "baby corn" used as a vegetable in Asian cuisine.

Maize is a facultative long-night plant and flowers in a certain number of growing degree days > 50 °F (10 °C) in the environment to which it is adapted. The magnitude of the influence that long nights have on the number of days that must pass before maize flowers is genetically prescribed and regulated by the phytochrome system. Photoperiodicity can be eccentric in tropical cultivars, while the long days characteristic of higher latitudes allow the plants to grow so tall that they do not have enough time to produce seed before being killed by frost. These attributes, however, may prove useful in using tropical maize for biofuels.
male flowers

The apex of the stem ends in the tassel, an inflorescence of male flowers. When the tassel is mature and conditions are suitably warm and dry, anthers on the tassel dehisce and release pollen. Maize pollen is anemophilous (dispersed by wind) and because of its large settling velocity most pollen falls within a few meters of the tassel. Each silk may become pollinated to produce one kernel of maize. Young ears can be consumed raw, with the cob and silk, but as the plant matures (usually during the summer months) the cob becomes tougher and the silk dries to inedibility. By the end of the growing season, the kernels dry out and become difficult to chew without cooking them tender first in boiling water. Modern farming techniques in developed countries usually rely on dense planting, which produces one large ear per stalk.

Diseases