Soil Germination Problems

You ever wonder why those seeds don’t germinate? Here are some things that might stop your seeds from germinating in soil!

Too Wet
Seeds need to be damp, not wet for germination. Excess water prevents oxygen getting to the seed. Poorly drained soils may also cause soil fungus diseases. The condition of wet soils may be improved by adding perlite. which will aerate your soil.

Too Dry
A certain amount of water is essential for germination, so maintaining a constant soil moisture during the germination period is vital, cover containers with glass or glad wrap to prevent you soil drying out.

Too Hot
High temperatures result in excessive soil desiccation and injury to seeds and seedlings.

Too Cold
Cold temperatures can kill seedlings and prevent germination. Cool temperatures can result in slow, uneven germination, and attack by soil diseases. You may want to start your seeds indoors, before out planting. Make sure planting dose not done too early, when it is still cold and there is a frost hazard.

Planting Too Deep
This will result in delayed emergence. seeds may not be able to grow enough to reach the surface on the limited food storage within the seed. Soil temperature is also lower with depth. Plant your seed 1/2 and inch to an inch down for best results.

Planting Seeds Too Shallow
If you plant your seeds to shallow the seeds can dry out.

Soil Too Firm
Making your soil mix to firm can prevent oxygen getting to your seeds also drainage is also affected.

Soil Too Loose
Soil which is too loose results in too much air surrounding the seed, and they will not absorb moisture and will most likely dry out.

Soil Fungus
Seeds may root or seedlings fall over. Over watering, poor drainage and lack of aeration will increase the likelihood of this occurring. Plant seeds in sterilised potting mix, and make sure you containers are clean.

Non-Viable seeds
If your seeds have not been stored correctly they can deteriorate. Look for dark brown seeds. Avoid and light colour or whitish seeds as they are not mature.

My favourite method to stores seeds is to place your seeds in a film canister, then fill it up to the top with rice, this will absorb any moisture, and either freeze them for long term storage or place in a dry, dark cool place for a shorter time period.

Author: hopefulgrower

Germination

The first space plant to flower and produce in the zero gravity of space is called Arabidopsis. It was grown on board the Soviet Union's Salyut-7 space station in 1982.

Germination happens when a baby plant is growing. The plant is between the cotyledons This is a seed. The seed is underground and is collecting nutrients.

When a seed starts to grow, we say it germinates. The cotyledons store food for the baby plant inside the seed. When the seed starts to germinate, the first thing to come out is the main root. The skin starts to split and the tiny shoot straightens, carrying the cotyledon(s) with it. The main root gets bigger. Side roots appear and so do leave. To grow, the seed's growing conditions usually have to be damp, warm, and dark, like springtime soil. A dry seed will stay dormant unless it soaks in some water. Then it will start to germinate

Source: Oracle Think Quest

Organic farming-advance sowing

Advance Sowing (also known as "no kill cropping") is an agricultural method developed by Bruce Maynard in 1996 in NSW, Australia that allows the production of annual crops from perennial grasslands. It consists in dry-sowing crops directly into existing pastures without using tillage, fertilizer or chemicals.

Advance Sowing has 5 major principles:

1. Sowing is done when the topsoil is dry.
2. Counter type sowing equipment must be used.
3. No Herbicides or pesticides are applied at any stage.
4. No Fertilizers are applied at any stage.
5. Grazing management must be good.

The rationale behind the method is to produce crops without simplifying the biodiversity. All other commonly used sowing methods of cropping rely on eliminating some or all of the plant and animals present to create an advantage for the growing crop. Advance Sowing relies on complementarity of plant/animal interactions to produce biomass that can be utilised directly for human consumption or fed to animals.

Source Wiki

Organic farming-companion plants

Companion planting is the planting of different crops in proximity (in gardening and agriculture), on the theory that they assist each other in nutrient uptake, pest control, pollination, and other factors necessary to increasing crop productivity. Companion planting is a form of poly culture.

Companion planting is used by farmers and gardeners in both industrialized and developing countries for many reasons. Many of the modern principles of companion planting were present many centuries ago in cottage gardens in England and home gardens in Asia.

For farmers using an integrated pest management system, increased yield and/or reduction of pesticides is the goal. For gardeners, the combinations of plants also make for a more varied, attractive vegetable garden, as well as allowing more productive use of space

In China, the mosquito fern has been used for at least one thousand years, as a companion plant for rice crops. It hosts a special cyanobacteria that fixes nitrogen from the atmosphere, and also blocks out light from getting to any competing plants, aside from the rice, which is planted when tall enough to stick out of the water above the azolla layer.

Companion planting was practiced in various forms by Native Americans prior to the arrival of Europeans. One common system was the planting of corn and pole beans together. The cornstalk would serve as a trellis for the beans to climb while the beans would fix nitrogen for the corn. The inclusion of squash with these two plants completes the Three Sisters technique, pioneered by Native American peoples.

Companion planting was widely touted in the 1970s as part of the organic gardening movement. It was encouraged for pragmatic reasons, such as natural trellising, but mainly with the idea that different species of plant may thrive more when close together. It is also a technique frequently used in permaculture, together with mulching, poly culture, and changing of crops.

Organic farming-crop rotation

Effects of crop rotation & monoculture: On the left field, the "Norfolk" crop rotation sequence (potatoes, oats, peas, rye) is being applied; on the right field, rye has been grown for 45 years in a row. (Source: Swojec Experimental Farm, Wroclaw University of Environmental and Life Sciences.)

Crop rotation is the practice of growing a series of dissimilar types of crops in the same area in sequential seasons for various benefits such as to avoid the build-up of pathogens and pests that often occurs when one species is continuously cropped. A traditional element of crop rotation is the replenishment of nitrogen through the use of green manure in sequence with cereals and other crops. It is one component of poly culture. Crop rotation can also improve soil structure and fertility by alternating deep-rooted and shallow-rooted plants.

Crop rotation avoids a decrease in soil fertility, as growing the same crop in the same place for many years in a row disproportionately depletes the soil of certain nutrients. With rotation, a crop that leaches the soil of one kind of nutrient is followed during the next growing season by a dissimilar crop that returns that nutrient to the soil or draws a different ratio of nutrients, for example, rice followed by cotton.

Organic farming

Organic farming is the form of agriculture that relies on techniques such as crop rotation, green manure, compost and biological pest control  to maintain soil productivity and control pests on a farm. Organic farming excludes or strictly limits the use of manufactured fertilizers, pesticides (which include herbicides, insecticides and fungicides), plant growth regulators such as hormones, livestock antibiotics, food additives, and genetically modified organisms.
Organic agricultural methods are internationally regulated and legally enforced by many nations, based in large part on the standards set by the International Federation of Organic Agriculture Movements (IFOAM), an international umbrella organization for organic farming organizations established in 1972. IFOAM defines the overarching goal of organic farming as:

"Organic agriculture is a production system that sustains the health of soils, ecosystems and people. It relies on ecological processes, biodiversity and cycles adapted to local conditions, rather than the use of inputs with adverse effects. Organic agriculture combines tradition, innovation and science to benefit the shared environment and promote fair relationships and a good quality of life for all involved.."

—International Federation of Organic Agriculture Movements

Since 1990, the market for organic products has grown from nothing, reaching $55 billion in 2009 according to Organic Monitor (www.organicmonitor.com). This demand has driven a similar increase in organically managed farmland. Approximately 37,000,000 hectares (91,000,000 acres) worldwide are now farmed organically, representing approximately 0.9 percent of total world farmland (2009) (see Willer/Kilcher 2011).

Pollination (part 4)

Flower shape and nectar provision

Flower pollination is also aided by the very shape of the flower, and the way in which insects come into contact with its sexual parts (the carpels and stamen). For example, even within the bee families, the shapes, sizes and weights of the bees vary, as do the tongue lengths.

Whilst honey bees have quite short tongues for sucking up nectar, some of the bumblebees have long tongues, meaning they may target deep, tubular shaped flowers. For example, with their furry, roundish bodies, they are ideal pollinators for foxgloves, their coats being efficient catchers of pollen as they make their way up inside the flowers.

Flowers have different nectar re-fill rates - yes, once the nectar is taken by one insect, the flower may replenish the nectar ready for the next passing insect. This helps to ensure that a plant can be visited more than once, increasing its chances of pollination.

 However, insects may cheat the plant!

In cases where short tongued bumblebees cannot get at nectar stores in the base of flowers, they may bite a hole, and access the nectar in that way. This is called ‘nectar robbing’. The hole may then be visited by other insects also keen to take the nectar, as the nectar supply is replenished. This is called ‘secondary robbing’.

Opinions vary, but some state that flower pollination is not necessarily hindered, because the flower may still be targeted by other bees that are engaged in gathering pollen, rather than nectar.

On the other hand, flowers may cheat insects too!

The Bee Orchid (Ophyrys apifera) is believed to have evolved to emulate the appearance of the female bee of the species required to pollinate it. The male bee lands on the female with the intention to mate. In his attempt, the orchid is pollinated. The bee, however, is disappointed!

Orchid pollination is not only carried out by bees. Certain beetles such as the beetle Strangalia maculata , are also able to assist in orchid pollination, as they can efficiently access the complex flower structures of some wild orchids.

Buzz about bee net

Pollination (part 3)

It’s well known that insects have a vested interest in visiting flowers – that is, they’re not merely visiting the flowers with the altruistic intention of performing a passing pollination service. They’re usually gathering nectar and/or pollen. Thus both the plant and insect benefit from their relationship with each other.

However, flowers come in all sorts of shapes and sizes, and so do insects. The flowers vary their features to appeal to their target visitors. When flowers have adapted to attract certain pollinators, they are said to have developed ‘pollination syndromes’.

Scent

Humans love fragrance, and so do insects. But different insects like different fragrances. On the one hand, sweet peas have a scent that can charm the bees. Butterflies also like fresh, but very delicate scents.

A number of flowers produce what humans would consider to be a foul stench. For example, the Vodoo Lily - Sauromatum guttatum (pictured), from the ‘Aroideae’ plant family, emits an odour that is likened to rotting flesh.

From a different plant family, the Orontiods, the Eastern Skunk Cabbage (Symplocarpus foetidus) and Western Skunk Cabbage (Lysichiton americanus), are also said to give off the horrible odour of decaying flesh.  Primarily carrion flies and beetles (i.e. flies and beetles that are attracted to dead and rotting bodies of animals etc.).

The time of day also plays a role in attracting pollinators. In some cases, flower pollination actually takes place in the evening. Flowers pollinated by bats and moths, for example, are strongly scented at night, such as night-scented Stocks, Evening primrose, and  Jasmine (Jasminum officinale).

Colors and patterns

 Like humans, bees are trichromatic. This means their eyes (like ours) have 3 color receptors. However, whereas humans base their color vision on the color receptors red, green and blue, bees base their color vision on Ultra Violet, blue and green.

Although bees cannot see red, however, they do visit red flowers. Why? Because flower petals have Ultra Violet patterns on them, not visible to humans in normal light, but visible to bees. The patterns are believed to guide the bees onto the flower ‘landing platform’, and then into the flower. With regard to red flowers, bees may also use other cues, such as scent. However, all in all, it is also thought that bees prefer different shades of blues, whites, and purple flowers.

In general, it’s believed that swathes of color are also more helpful to foraging bees and butterflies, providing a stronger visual signal that suggests ‘plenty of food here’ , and of course, it is more energy efficient for bees and other pollinators to find areas of denser food provision.

Buzz about bee net

Pollination (part 2)

There are 2 type of pollination

Abiotic

Abiotic pollination refers to situations where pollination is mediated without the involvement of other organisms. Only 10% of flowering plants are pollinated without animal assistance. The most common form of abiotic pollination, anemophily, is pollination by wind. This form of pollination is predominant in grasses, most conifers, and many deciduous trees. Hydrophily is pollination by water and occurs in aquatic plants which release their pollen directly into the surrounding water. About 80% of all plant pollination is biotic. In gymnosperms, biotic pollination never takes place. These plants always exhibit anemophily that is wind pollination. Of the 20% of abiotically pollinated species, 98% is by wind and 2% by water.

Biotic

More commonly, the process of pollination requires pollinators: organisms that carry or move the pollen grains from the anther to the receptive part of the carpel or pistil. This is biotic pollination. The various flower traits (and combinations thereof) that differentially attract one type of pollinator or another are known as pollination syndromes.

There are roughly 200,000 varieties of animal pollinators in the wild, most of which are insects.Entomophily, pollination by insects, often occurs on plants that have developed colored petals and a strong scent to attract insects such as, bees, wasps and occasionally ants (Hymenoptera), beetles (Coleoptera), moths and butterflies (Lepidoptera), and flies (Diptera). In zoophily, pollination is performed by vertebrates such as birds and bats, particularly, hummingbirds, sun birds, spider hunters, honey eaters, and fruit bats. Plants adapted to using bats or moths as pollinators typically have white petals and a strong scent; while plants that use birds as pollinators tend to develop red petals and rarely develop a scent (few birds have a sense of smell).

Insect pollinators such as honeybees (Apis mellifera), bumblebees (Bombus terrestris), and butterflies (Thymelicus flavus) have been observed to engage in flower constancy, which means they are more likely to transfer pollen to other con specific plants. This can be beneficial for the pollinisers, as flower constancy prevents the loss of pollen during inter specific flights and pollinators from clogging stigmas with pollen of other flower species.

Pollination (part 1)

Pollination is the process by which pollen is transferred in plants, thereby enabling fertilization and sexual reproduction. Pollen grains, which contain the male gametes (sperm) to where the female gamete(s) are contained within the carpel in gymnosperms the pollen is directly applied to the ovule itself. The receptive part of the carpel is called a stigma in the flowers of angiosperms. The receptive part of the gymnosperm ovule is called the micropyle. Pollination is a necessary step in the reproduction of flowering plants, resulting in the production of offspring that are genetically diverse.

Plant beneficial pest- Nabidae (part 4)

The insect family Nabidae contains the damsel bugs. The terms damsel bug and nabid are synonymous. There are over 400 species. They are soft-bodied, elongate, winged terrestrial predators. Many damsel bugs catch and hold prey with their forelegs, similar to mantids. They are considered helpful species in agriculture because of their predation on many types of crop pests, such as cabbage worms, aphids, and lygus bugs.

Damsel bugs of the genus Nabis are the most common. They and other genera are most numerous in fields of legumes such as alfalfa, but they can be found in many other crops and in non-cultivated areas. They are yellow to tan in colour and have large, bulbous eyes and stilt like legs. They are generalist predators, catching almost any insect smaller than themselves, and cannibalizing each other when no other food is available.

Plant beneficial pest-Geocoris(part 3)

Geocoris is a genus of insects in the family Lygaeidae (although sometimes the subfamily is elevated to the family "Geocoridae"). Commonly known as the big-eyed bug, Geocoris is a beneficial predator often confused with the true chinch bug, which is a pest.

Big-eyed bugs are true bugs in the order Hemiptera. The two most common species are Geocoris pallens and Geocoris punctipes. Both are predators and occur in many habitats, including fields, gardens, and turf grass. Big-eyed bugs are considered an important predator in many agricultural systems and feed on mites, insect eggs, and small insects such as pink boll worm, cabbage loppers and white flies. Adult big-eyed bugs are small (about 3 mm) black, gray, or tan with proportionately large eyes. Eggs are deposited singly or in clusters on leaves near potential prey. They develop with incomplete metamorphosis (there is no pupa) and take approximately 30 days to develop from egg to adult depending on temperature. Both nymphs and adults are predatory, but can survive on nectar and honeydew when prey are scarce. Big-eyed bugs, like other true bugs, have piercing-sucking mouth parts and feed by stabbing their prey and sucking or lapping the juices. Although their effectiveness as predators is not well understood, studies have shown that nymphs can eat as many as 1600 spider mites before reaching adulthood, while adults have been reported consuming as many as 80 mites per dayinsects such as pink boll worm, cabbage loppers and white flies. Adult big-eyed bugs are small (about 3 mm) black, gray, or tan with proportionately large eyes. Eggs are deposited singly or in clusters on leaves near potential prey. They develop with incomplete metamorphosis (there is no pupa) and take approximately 30 days to develop from egg to adult depending on temperature. Both nymphs and adults are predatory, but can survive on nectar and honeydew when prey are scarce. Big-eyed bugs, like other true bugs, have piercing-sucking mouth parts and feed by stabbing their prey and sucking or lapping the juices. Although their effectiveness as predators is not well understood, studies have shown that nymphs can eat as many as 1600 spider mites before reaching adulthood, while adults have been reported consuming as many as 80 mites per day

Plant pest –Caterpillars (part 2)

Caterpillars have been called "eating machines", and eat leaves voraciously. Most species shed their skin four or five times as their bodies grow, and they eventually pupate into an adult form. Caterpillars grow very quickly; for instance, a tobacco hornworm will increase its weight ten-thousand fold in less than twenty days. An adaptation that enables them to eat so much is a mechanism in a specialized midget that quickly transports ions to the lumen (midget cavity), to keep the potassium level higher in the midget cavity than in the blood.

                                                                A Gypsy Moth caterpilars

Most caterpillars are solely herbivorous. Many are restricted to one species of plant, while others are polyphagous. A few, including the clothes moth, feed on detritus. Most predatory caterpillars feed on eggs of other insects, aphids, scale insects, or ant larvae. Some are cannibals, and others prey on caterpillars of other species (e.g. Hawai'ian Eupithecia ). A few are parasitic on cicadas or leaf hoppers. Some Hawai'ian caterpillars (Hyposmocoma molluscivora) use silk traps to capture snails

                                       Hypsipyla grandela damages mahogany in Brazil

Caterpillars cause much damage, mainly by eating leaves. The propensity for damage is enhanced by monoculture  farming practices, especially where the caterpillar is specifically adapted to the host plant under cultivation. The cotton bollworm causes enormous losses. Other species eat food crops. Caterpillars have been the target of pest control through the use of pesticides, biological control and agronomic practices. Many species have become resistant to pesticides. Bacterial toxins such as those from Bacillus thuringiensis which are evolved to affect the gut of Lepidoptera have been used in sprays of bacterial spores, toxin extracts and also by incorporating genes to produce them within the host plants. These approaches are defeated over time by the evolution of resistance mechanisms in the insects.

Plants evolve mechanisms of resistance to being eaten by caterpillars, including the evolution of chemical toxins and physical barriers such as hairs. Incorporating host plant resistance (HPR) through plant breeding is another approach used in reducing the impact of caterpillars on crop plants

Plant pest- Cabbage Moth (part 1)

The Cabbage Moth (Mamestra brassicae) is a common European moth of the family Noctuidae.

This species varies considerably in size, with a wingspan of 34–50 mm. The fore wings are brown and mottled with a prominent white-edged stigma and a broken white sub terminal line. The hind wings are grey, darker towards the termen. The prominent spur on the tibia of the foreleg is a diagnostic feature, though is best viewed with a magnifying lens. This moth has a rather complex life history: two or three broods are produced each year and adults can be seen at any time from May to October, occasionally at other times [The flight season refers to the British Isles. This may vary in other parts of the range.  ]. It flies at night and is attracted to light, sugar and nectar-rich flowers.

The larva is green or brown with dark spots. As the common and scientific names suggest, it can be a pest of cultivated brassicas but it feeds on a wide range of other plants . Due to its complex life history, this species overwinters either as a larva or a pupa

Source : Wiki

Stomata

Stomata are minute structures on plants found on the outer leaf skin layer, also known as the epidermis. They consist of two specialized cells, called guard cells that surround a tiny pore called a stoma. The word stomata means mouth in Greek because they allow communication between the internal and external environments of the plant. Their main function is to allow gases such as carbon dioxide, water vapor and oxygen to move rapidly into and out of the leaf. Stomata are found on all above-ground parts of plants including the petals of flowers, petioles, soft herbaceous stems and leaves. They are formed during the initial stages of the development of these various plant organs and therefore reflect the environmental conditions under which they grew.

Leaves are the main "food manufacturing" organs of plants. They make food from carbon dioxide and water in the presence of light during a process called photosynthesis. As stomata open in the presence of light, carbon dioxide will diffuse into the leaf as it is converted to sugars through photosynthesis inside the leaf. At the same time, water vapor will exit the leaf along a diffusive gradient through the stomata to the surrounding atmosphere through the process of transpiration. Consequently, plants face the dilemma of taking up carbon dioxide while losing water vapor through their stomata. If this water loss remains unchecked, they can deplete their water reserve. This depletion can become catastrophic to the physiological functioning of the plant given that is the most essential solvent in which biochemical and growth processes occur. Based on Darwinian principles, it is presumed that selective adaptation has driven plants to acquire characteristics which enable them to grow more quickly without diminishing the probability of survival. If plants have not acquired the characteristics to withstand changes in water availability in their growth environment, plants may exacerbate their water shortage by not regulating the size of their stomata apertures in an optimal manner and may fail to survive when water availability declines.

Encyclopedia of earth

Bacillus mucilaginosus

Bacillus mucilaginosus is a common soil bacterium, and usually used as a model bacterium in studying microbe-mineral interactions. Several reaction mechanisms of B. mucilaginosus weathering silicate minerals were proposed. However, the molecule mechanisms and detailed processes were still unclear.

Bacterium-mineral interactions were studied in terms of variations in pH value over the experimental period, variations in mineral composition, weathering rates of silicate minerals and volatile metabolites in the culture medium, etc., to further explore the bacterium-mineral interaction mechanisms. The results showed that B. mucilaginosus could enhance silicate mineral weathering obviously. The weathering rates were quite different for various kinds of silicate minerals, and the weathering rate of weathered adamellite could reach 150 mg/m2/d. Although B. mucilaginosus produced little acidic substance, pH in the micro environment of bacterium-mineral complex might be far lower than that of the circumjacent environment; a large amount of acetic acid was found in the metabolites, and was likely to play an important role as a ligand.

These results appear to suggest that acidolysis and ligand degradation are the main mechanisms of B. mucilaginosus dissolving silicate minerals, the formation of bacterium-mineral complexes is the necessary condition for the bacteria weathering silicate minerals, and extracellular polysaccharides played important roles in bacterium-mineral interaction processes by forming bacterium-mineral complexes and maintaining the special physiochemical properties of micro environment

by MO Binbin  and LIAN Bin

Bacillus megaterium

Bacillus megaterium is a gram positive, spore producing bacteria. It is a Eubacteria and is found in the soil. It has a rod shape and is one of the largest Eubacteria. Colonies form in chains due to sticky polysaccharides on the cell wall. It is very important in the biotech industry due to its size and its' enzyme and cloning abilities. The enzymes help produce synthetic penicillin, modifying corticosteroids and several amino acid dehydrogenases. It also is very efficient in cloning due to no protease degradation of product and good stability of recombinant plasmids.

By Rob Hayden

Azotobacter chroococcum

Azotobacter is a genus of free-living diazotrophic bacteria whose resting stage is a cyst. It is primarily found in neutral to alkaline soils, in aquatic environments, and on some plants. It has several metabolic capabilties, including atmospheric nitrogen fixation by conversion to ammonia. Their unique system of three distinct nitrogenase enzymes makes these bacteria of particular interest to scientists, who may work toward a better understanding of nitrogen fixation and its role in agriculture. Azotobacter spp. have the highest metabolic rate of any organisms.

Azotobacters, interestingly, contain more DNA than most other bacteria, but their genome size is typical of most prokaryotes. The reason for this above average amount of DNA is not known, but it is possibly because the cells of Azotobacter are larger than those of other bacteria. The DNA of Azotobacter spp. display many similarities, in terms of gene type and recognition factors, to the DNA of Escherichia coli. Genetic information can be transferred between azotobacters or to other bacteria by way of conjugation or transformation. For NCBI's GenBank entry for Azotobacter's unfinished

Diazotrophic organisms such as Azotobacter play a vital role in every ecosystem, working to make nitrogen available to all organisms. Azotobacters and similar bacteria turn nitrogen into ammonia through the process of nitrogen fixation, after which the ammonia is turned into proteins. Nitrogen fixation is used in agriculture in relation to crop rotation and fertilization; soil-dwelling diazotrophs such as Azotobacter are especially useful in gauging the health and virility of the ground. Azotobacters are found worldwide, in climates ranging from extremely northern Siberia to Egypt and India.

From MicrobeWiki

Rhizobium

A classical example of nitrogen fixation is the symbiosis leguminous plants and bacteria of the genus Rhizobium.The seat of symbiosis is within the nodules that appear on the plant roots. In the symbiotic association between Rhizobium and leguminous plant, two organisms interact in such a way as to influence and coordinate the expression of both prokaryotic and eukaryotic gene.

The communications that occur between the plant and the rhizobia during nodule formation and maintenance constitutes a novel opportunity to study signal transduction in a plant system. The expression of nodulation genes in the bacteria is activated by signals from plant roots and as a result the bacteria synthesise signals that induce a nodule meristem and enable the bacteria to enter this meristem via a plant-made infection thread. The chemical signals synthesised by the bacteria are based on a modified amino acid (homoserine lactone) carrying a variable acyl chain substituent, and are called acyl homoserine lactones (AHLs).

By detecting and reacting to these chemicals, individual cells can sense how many cells surround them and whether there are enough bacteria, i.e.a quorum , to initiate the change towards acting in a multi cellular fashion. This is known as 'quorum sensing'.

Beijerinck was the first to isolate and cultivate the bacterium responsible for nodulation and he named it Bacillus radicicola which is now placed in the genus Rhizobium.

Rhizobium is found as a free-living organism in the soil but does not fix atmospheric nitrogen in that state. Only after its association with a leguminous plant and after the formation of root nodules does it fix atmospheric nitrogen in the nodules.

Source : microbiologyprocedure.com



Nitrogen fixation

Nitrogen fixation is the process by which nitrogen is taken from its natural, relatively inert molecular form (N2) in the atmosphere and converted into nitrogen compounds (such as ammonia, nitrate and nitrogen dioxide).

Nitrogen fixation is performed naturally by a number of different prokaryotes, including bacteria, actinobacteria, and certain types of anaerobic bacteria. Microorganisms that fix nitrogen are called diazotrophs. Some higher plants, and some animals (termites), have formed associations with diazotrophs.

Nitrogen fixation also occurs as a result of non-biological processes. These include lightning, industrially through the Haber-Bosch Process, and combustion.

Biological nitrogen fixation was discovered by the Dutch microbiologist Martinus Beijerinck.

Biological Nitrogen Fixation (BNF) occurs when atmospheric nitrogen is converted to ammonia by a pair of bacterial enzymes called nitrogenase. The formula for BNF is:

N2 + 8H+ + 8e− + 16 ATP → 2NH3 + H2 + 16 ADP + 16 Pi

Although ammonia (NH3) is the direct product of this reaction, it is quickly protonated into ammonium (NH4+). In free-living diazotrophs, the nitrogenase-generated ammonium is assimilated into glutamate through the glutamine synthetase/glutamate synthase pathway.

In most bacteria, the nitrogenase enzymes are very susceptible to destruction by oxygen (and many bacteria cease production of the enzyme in the presence of oxygen). Low oxygen tension is achieved by different bacteria by: living in anaerobic conditions, respiring to draw down oxygen levels, or binding the oxygen with a protein such as Leghemoglobin - also spelled leghaemoglobin..

The best-known plants which contribute to nitrogen fixation in nature, are in the legume family - Fabaceae, which includes such  as clover, beans, alfalfa, lupines and peanuts. They contain symbiotic bacteria called rhizobia within nodules in their root systems, producing nitrogen compounds that help the plant to grow and compete with other plants. When the plant dies, the fixed nitrogen is released, making it available to other plants and this helps to fertilize the soil The great majority of legumes have this association, but a few genera (e.g., Styphnolobium) do not. In many traditional and organic farming practices, fields are rotated through various types of crops, which usually includes one consisting mainly or entirely of clover or buckwheat (family Polygonaceae), which were often referred to as "green manure", since the other natural way of adding nitrogen to the soil is via animal waste products. The entire plant is often ploughed back into the field, thus not only adding more nitrogen, but also improving the soil's organic content and volume.

2008/9 Schools Wikipedia Selection. Related subjects: Biology; Chemistry

Sea Slug

A green sea slug appears to be part animal, part plant. It's the first critter discovered to produce the plant pigment chlorophyll.

The sneaky slugs seem to have stolen the genes that enable this skill from algae that they've eaten. With their contraband genes, the slugs can carry out photosynthesis.

"They can make their energy-containing molecules without having to eat anything," said Sidney Pierce, a biologist at the University of South Florida in Tampa.

Pierce has been studying the  unique creature, officially called Elysia chlorotica, for about 20 years. He presented his most recent findings Jan. 7 at the annual meeting of the Society for Integrative and Comparative Biology in Seattle. The finding was first reported by Science News.

"This is the first time that multi cellar animals have been able to produce chlorophyll," Pierce told LiveScience.

The sea slugs live in salt marshes in New England and Canada. In addition to burglarizing the genes needed to make the green pigment chlorophyll, the slugs also steal tiny cell parts called chloroplasts, which they use to conduct photosynthesis. The chloroplasts use the chlorophyll  to convert sunlight into energy, just as plants do, eliminating the need to eat food to gain energy.

Rarely seen creatures

"We collect them and we keep them in aquarium for months," Pierce said. "As long as we shine a light on them for 12 hours a day, they can survive [without food]."

The researchers used a radioactive tracer to be sure that the slugs are actually producing the chlorophyll themselves, as opposed to just stealing the ready-made pigment from algae. In fact, the slugs incorporate the genetic material so well; they pass it on to further generations of slugs.

The babies of thieving slugs retain the ability to produce their own chlorophyll, though they can't carry out photosynthesis until they've eaten enough algae to steal the necessary chloroplasts, which they can't yet produce on their own.

The slugs accomplishment is quite a feat, and scientists aren't yet sure how the animals actually appropriate the genes they need.

"It certainly is possible that DNA from one species can get into another species, as these slugs have clearly shown," Pierce said. "But the mechanisms are still unknown

By Clara Moskowitz

LiveScience

updated 1/12/2010 2:50:19 PM ET 2010-01-12T19:50:19

Photosynthesis

Photosynthesis is a process in which green plants use energy from the sun to transform water, carbon dioxide, and minerals into oxygen and organic compounds. It is one example of how people and plants are dependent on each other in sustaining life.

Photosynthesis happens when water is absorbed by the roots of green plants and is carried to the leaves by the xylem, and carbon dioxide is obtained from air that enters the leaves through the stomata and diffuses to the cells containing chlorophyll. The green pigment chlorophyll is uniquely capable of converting the active energy of light into a latent form that can be stored (in food) and used when needed.

The initial process in photosynthesis is the decomposition of water (H2O) into oxygen, which is released, and hydrogen; direct light is required for this process. The hydrogen and the carbon and oxygen of carbon dioxide (CO2) are then converted into a series of increasingly complex compounds that result finally in a stable organic compound, glucose (C6H12O6), and water. This phase of photosynthesis utilizes stored energy and therefore can proceed in the dark. The simplified equation used to represent this overall process is 6CO2+12H2O+energy=C6H12O6+6O2+6H2O. In general, the results of this process are the reverse of those in respiration, in which carbohydrates are oxidized to release energy, with the production of carbon dioxide and water.

The intermediary reactions before glucose is formed involve several enzymes, which react with the coenzyme ATP (see adenosine triphosphate) to produce various molecules. Studies using radioactive carbon have indicated that among the intermediate products are three-carbon molecules from which acids and amino acids, as well as glucose, are derived. This suggests that fats and proteins are also products of photosynthesis. The main product, glucose, is the fundamental building block of carbohydrates (e.g., sugars, starches, and cellulose). The water-soluble sugars (e.g., sucrose and maltose) are used for immediate energy. The insoluble starches are stored as tiny granules in various parts of the plant—chiefly the leaves, roots (including tubers), and fruits—and can be broken down again when energy is needed. Cellulose is used to build the rigid cell walls that are the principal supporting structure of plants.

Plant Micronutrient Functions (part 2)

Manganese

Manganese is needed   during photosynthesis, nitrogen metabolism and to form other compounds required for plant metabolism.  For severe shortage of manganese intake, brown necrotic spots appear on leaves and resulting in leaf drop prematurely. For some plants, deficiency of manganese intake results in late maturity.

Manganese deficiencies mainly occur on organic soils, high-pH soils, sandy soils low in organic matter, and on over-limed soils. Soil manganese may be less available in dry, well-aerated soils, but can become more available under wet soil conditions when manganese is reduced to the plant-available form. Conversely, manganese toxicity can result in some acidic, high-manganese soils. Uptake of manganese decreases with increased soil pH and is adversely affected by high levels of available iron in soils.

Molybdenum

Molybdenum is involved in enzyme systems relating to nitrogen fixation by bacteria growing symbiotically with legumes. Nitrogen metabolism, protein synthesis and sulphur metabolism are also affected by molybdenum. Molybdenum has a significant effect on pollen formation, so fruit and grain formation are affected in molybdenum-deficient plants. Because molybdenum requirements are so low, that most plants do not exhibit molybdenum-deficiency symptoms. These deficiency symptoms in legumes are mainly exhibited as nitrogen-deficiency symptoms because of the primary role of molybdenum in nitrogen fixation. Unlike the other micronutrients, molybdenum-deficiency symptoms are not confined mainly to the youngest leaves because molybdenum is mobile in plants. The characteristic molybdenum deficiency symptom in some vegetable crops is irregular leaf blade formation known as whiptail, but interveinal mottling and marginal chlorosis of older leaves also have been observed.

Molybdenum deficiencies are found mainly on acidic, sandy soils in humid regions. Molybdenum uptake by plants increases with increased soil pH, which is opposite that of the other micronutrients. Molybdenum deficiencies in legumes may be corrected by liming acid soils rather than by molybdenum applications. However, seed treatment with molybdenum sources may be more economical than liming in some areas.

Zinc

Zinc is an essential component of various enzyme systems for energy production, protein synthesis, and growth regulation. Zinc deficient plants also exhibit delayed maturity. Zinc is not mobile in plants so zinc-deficiency symptoms occur mainly in new growth. Poor mobility in plants suggests the need for a constant supply of available zinc for optimum growth. The most visible zinc deficiency symptoms are short internodes and a decrease in leaf size. Delayed maturity also is a symptom of zinc-deficient plants.

Zinc deficiencies are mainly found on sandy soils low in organic matter and on organic soils. Zinc deficiencies occur more often during cold, wet spring weather and are related to reduced root growth and activity as well as lower microbial activity decreases zinc release from soil organic matter. Zinc uptake by plants decreases with increased soil pH. Uptake of zinc also is adversely affected by high levels of available phosphorus and iron in soils.

Chloride

Because chloride is a mobile anion in plants, most of its functions relate to salt effects (stomata opening) and electrical charge balance in physiological functions in plants. Chloride also indirectly affects plant growth by stomata regulation of water loss. Wilting and restricted, highly branched root systems are the main chloride-deficiency symptoms, which are found mainly in cereal crops.

Most soils contain sufficient levels of chloride for adequate plant nutrition. Chloride deficiencies have been reported on sandy soils in high rainfall areas or those derived from low-chloride parent materials. There are few areas of chloride-deficient so this micronutrient generally is not considered in fertilizer programs.  The role of chloride in decreasing the incidence of various diseases in mall grains is perhaps more important than its nutritional role from a practical viewpoint.

Plant Micronutrient Functions (part 1)

Boron

The function of boron is for the wall formation, so boron-deficient plants may be stunted. Sugar transport in plants, flower retention and pollen formation and germination also are affected by boron.Insufficient of boron intake result in reduction of  seed and grain production . Boron-deficiency symptoms first appear at the growing stage. This results in a stunted appearance (resetting), barren ears due to poor pollination, hollow stems and fruit (hollow heart) and brittle, discoloured  leaves and loss of fruiting bodies.

Boron deficiencies are easily detected  in acid, sandy soils in regions of high rainfall, and those with low soil organic matter. Borate ions are mobile in soil and can be leached from the root zone. Boron deficiencies are more prominient during dry periods when root activity is restricted.

Copper

Copper is needed for carbohydrate and nitrogen metabolism and, inadequate copper results in stunting of plants. Copper also is required for lignin synthesis which is needed for cell wall strength and prevention of wilting. The sign of deficiency  in copper are dieback of stems and twigs, yellowing of leaves, stunted growth and pale green leaves that wither easily.

Copper deficiencies are mainly happened  on sandy soils which are low in organic matter. Copper uptake decreases as soil pH increases. Increased phosphorus and iron availability in soils decreases copper uptake by plants

Iron

Iron is involved in the production of chlorophyll, and iron chlorosis is easily recognized on iron-sensitive crops growing on calcareous soils. Iron also is a component of many enzymes associated with energy transfer, nitrogen reduction and fixation, and lignin formation. Iron is associated with sulphur  in plants to form compounds that catalyse other reactions. Iron deficiencies are mainly manifested by yellow leaves due to low levels of chlorophyll. Leaf yellowing first appears on the younger upper leaves in inte veinal tissues. Severe iron deficiencies cause leaves to turn completely yellow or almost white, and then brown as leaves die.

Iron deficiencies occured on high pH soils, although some acid, sandy soils that is low in organic matter also may be iron-deficient. Cool, wet weather enhances iron deficiencies, especially on soils with marginal levels of available iron. Poorly aerated or compacted soils also reduce iron uptake by plants. Uptake of iron decreases with increased of  soil pH, and is adversely affected by high levels of available phosphorus, manganese and zinc in soils.

Misai Kucing (Orthosiphon Stamineus)

                                                 Flowering   time (white or dark purple flower)

                                                                         Structure of stem

Morphological characteristics

This herb grow fast and could easily could reach 1.5 m in height. The stem is square, short hairy or red-colored gondola, grow upright and branching.  The leaves are arranged in opposite pairs, smooth, dark green, conical shape at the tip and finger like leave.

A short petiole , about 0.3m length and purple-red.

In our country, we categorized based on the color of the flower, which is white and dark purple. The white flower is recognized as MOS 1 and MOS 2 as dark purple herb .  Mos 1 has a bigger canopy, higher trunk and more fertile look(bigger size). Mos 1  has a  faster and more  twig growth compare to Mos 2  .

This herb is easy to plant and suitable for any kind of soil including sandy soil such as  bris soil  and alluvium soil . For a healthy and fruitful growth an average rain per month of  180-200cm. During dry season need irrigation.

If the plant is lack of water, the leaves are small, hard and brittle. Compare with other plant, this plant can with stand stagnant water up to  24 hour . These plants need a moist area for maximum vegetative growth.  For bris soil, this plant  needs   30-40% shading  especially during dry season  (Jan-Jun)

Land preparation

Planted area is usually plowed at least one month before planting.  This is to ensure that weeds and shrubs are cleared and eliminated.   Calcification with grounded magnesium limestone (GML) was conducted after the first fertilization. This activity ensure the soil mix and blend well with the GML

The amount of GML usage depends on the soil pH. The optimum soil pH is between 5.5 to 6

Planting preparation

The plant is  propagated by  cutting the stem at  6 inches All the stem section can be used as to plant.

The cut stems are planted in poly bags,  roots began to grow  after 2 weeks. The seedlings can be converted to farm after  4-5 weeks after sowing

Farming

The recommended planting distance is 60cm x 60cm.. The distance of these plants will produce a density of 25,000 per hectare

Fertilization

The recommended fertilizer rates are 75 kg / ha urea  for  every 3 times during  harvesting  or every  6-9 weeks . Compound or bio fertilizer  is sown in shallow run between rows of crops and covered the ground immediately.    

Irrigation system

There are a few irrigation system to be used depend on soil condition and water source.  For commercial planting, rotating or spinning irrigation system is suitable .

Drip irrigation system is ideal when used plastic mulch.

Nutritional content and  usage

Misai  kucing has been used since the old days to cure kidney disease  and  kidney stone.

Ortosifonim content and potassium salts (found in the leaves) is the main component  that dissolve uric acid, phosphate and oxalate  in our body bile and kidney. Saponin and tannin content in leaves can cure diseases suffered by  women whom are pale . This herb also can use as anti-allergy