Plant Parts: The root

Plant Parts: The root
Plants are like animals and man. They have parts. Each part has it own specific function. Generally, a typical plant has three parts, these are roots, stems and leaves.

There are two kinds of root, called tap and fibrous, The tap root is a type which is made up of the main root, branching sidewise in all directions to form secondary and tertiary roots.

Most dicots have tap roots especially when these are grown from seed.
Examples of a tap root types plants are: raddish, carrots and turnips.

The fibrous type root is made up of hair-like structures of uniform sizes growing like a brush. Example of plants belonging to this type, are most monocot plants like rice, bamboo, corn and grasses.

The root is that leafless plants part which absorbs the dissolved nutrients from the soil and water. The roots also serve as anchorage, storage and reproduction organs. Sweet potato, carrots and breadfruits are examples.

The root is readily separable into epidermis, cortex and stele.

To these regions new cellars are added by an apical meristem. The outer surface of the meristem builds a root cap which protects the roots from mechanical injury as it pushes through the soil.

Cell division, elongation and maturation are progressive processes taking place at the back region of the rootcap which result in a vertical stratification of the root.

In this region successive stages in tissue differentiation are going on at the back area of elongation.

The epidermal cells produce long and cylindrical outgrowth called the root hairs, which increase the absorbing power of the root.

The cortex of the root is the same as those found in the stem. Stele is made up of strand of primary xylem and primary phloem. Roots of plants capable of marked increase on diameter develop as vascular cambium in the form of a cylinder just outside the primary xylem inside the primary phloem.

Secondary xylem is produced starting from the inner section of the cambium and secondary phloem from the outer section.

In the process of development extensive increase in diameter rupture the epidermis and cortex. At this ruptures region cork is developed either in the inner section of the cortex in the pericycle or in the area of secondary phloem.
Plant Parts: The root

Pesticide use for Crops

The increases in crop yields throughout this century have been partly credited to pesticide technology.

Pesticides have contributed greatly to increased agricultural productivity and crop quality.

Pesticides are applied annually to the majority of the crops. One or more pesticides are used to control weeds and other pests of crops.

Use of pesticide in corps is dependent on the disease and pest infestations and also type of crops grown.

There is widespread acceptance that modern varieties of crops are much more prone to insect, pest and disease infestations.

There are many types of pesticides. They are based on their mode of action and this bais they could be group as follows:
*Repellants
*Fumigants
*Smokes
*Stomach poisons
*Contact poisons
*Systemic poisons

Pesticides play an important role in food production – controlling plant disease, weeds, insects and other pests.

Pesticide protect crops and ensure a substantial yield, thus assuring consumers of a wide variety of foods at affordable prices.
Pesticide use for Crops

Fruit Crops and Global Trade

Fruit Crops and Global Trade
Humankind’s relationship with fruiting plants began long before the origin of agriculture in 8,000 to 10,000 BC, when all human beings practiced the hunter gatherer lifestyle.

Fruit mainstay of our diet, being excellent sources of fiber, vitamins and other healthful or medicinal compounds unbeknownst to us then.

While cereal grains, such as wheat and barley, were probably the first crop plants domesticated by humans, several of today’s fruit crops, were not far behind, since they were native to the very same area – the Fertile Crescent of Asia Minor.

Domestication of wild fruiting plants may have been inadvertent; the first groves of fruit trees probably sprang from seeds thrown in waste heaps at the edge of villages.

Careful observation and selection for useful traits, such as larger size, better taste and higher yield, started the transformation of those wild plants into the crops, which cultivate and enjoy today.

During the age of discovery, fruit, seeds or live plants were often taken on transoceanic, voyages and exchanges in both direction helped spread many crops throughout the world.

Christopher Columbus and his contemporaries may not have realized the impact they would have on agriculture and society when they brought crops such as coffee and citrus to the New World, returning to Europe with previously unknown but now common, foods such as cocoa and pineapple.

Today, we have well established world trade networks and sophisticated cultural and postharvest technologies that allow fruits to be enjoyed throughout much of the year, instead of mere weeks per year, as our ancestor experienced.

Global trade has made formerly rare and exotic treats derived from fruit crops commonplace in countries with no hope of cultivating the plants.

Fruit crops are important agricultural commodities they add tens of billions of dollars per year to the global economy and are major source of income for developing countries.

World wide, over 100 millions acres of land has been devoted to their production, and the livehood of literally millions of farming families depends on continued global trade.
Fruit Crops and Global Trade

Early Food Crops

Early Food Crops
The angiosperms provide most of our food crops. They first appeared in the early Mesozoic or late Paleozoic era about 200 – 250 million years ago, but fossil evidence of them is extremely limited until they began to dominate during the Cretaceous (136 – 190 million years ago). The angiosperms were the first plants to have double fertilization and the enclosure of seeds in fruit. Double fertilization provided zygotes with copious resource to help them get established and fruits attracted animals for dispersal, it was the appearance of the angiosperm that set the stage for the development our mammal ancestors.

A wide range of hypotheses implicating selection have been presented for a rapid emergence and diversification of the angiosperms. The most popular hypothesis is that the concomitant rise of pollinating insects led to powerful divergent selection as foragers and hosts developed complex relationship.

It was the angiosperms that ultimately provided us with most of our crops and their emergence predated the appearance of our species, Homo sapiens. In fact, most of our food families or their close relatives were in existence long before we began farming. The only completely new crop type to appear after the advent of agriculture was maize, Zea mays, which has an ear and tassel arrangement not found in its progenitors. In most cases, human beings did not influence the overall structure of crop species, only the size of their edible organs and their ease of harvest.

Human beings now consume a diverse array of plant structure, and at least 64 families of angiosperms and 180 genera are utilized as crops. This is a broad systematic group, but represents only a small fraction of the total number of angiosperm families (300) and genera (3000). The dicotyledons provide the highest number of crop plants; however, the bulk of the world is fed by a few monocotyledonous grains (maize, rice and wheat).
Early Food Crops

Production of Corn (Zea mays L.) in United States

Production of Corn (Zea mays L.) in United States
Corn (Zea mays L.) or maize as it is known in Europe and other parts of the world, originated in the Western hemisphere. Although it is now grown around the world, production of field corn in the United States (270 million tones annually) exceeds that in any other country and is usually about equal to that of the rest of the world put together. Illinois and Iowa lead all other states, but Nebraska, South Dakota, Minnesota, Indiana and Ohio also have substantial crops, and some is grown in every state.

Field corn is entirely different as a food crop from the sweet corn (Zea mays var. rugosa) that is harvested immature in summer and cooked fresh on the cob or cut from the cob in food plants and preserved by canning or freezing for later consumer use as vegetable. Field corn is allowed to mature before harvest in the fall. It is shelled as a part of the harvesting operation and typically requires drying on the farm before storage or delivery to country elevator, grain terminal, or mill.

A very small part of the field corn syrup crop is of white corn varieties, used for the making the hominy grits and white cornmeal sold at retail in the United States, the grits being for use as a vegetable menu item or hot breakfast cereal, and the meal for making white corn bread and muffin. However, since corn is grown primarily for animal feed, for which the yellow varieties are preferred, availability and economics dictate that yellow corn must be the grain of choice for most food ingredient uses, including breakfast cereals.

The corn is dry-milled to separate the germ and bran from the endosperm, the larger particles of which go into the flaking grits, which are then cooked (with other ingredients), dried, tempered, flaked, and toasted. Progressively smaller endosperm particles form corn meal and corn flour, which can be used as ingredients in extruded corn or mixed cereal grain. The bran fraction, for many years used only in animal feed, and the germ press-cake, after extraction of its oil content, are now recovered and made available in an edible grade as a fiber ingredient for cereals and other food products.
Production of Corn (Zea mays L.) in United States