Improvement in Food Resources

6468 Words Oct 8th, 2011 26 Pages
METHODS OF CROP VARIETY IMPROVEMENT
An improved variety of a crop is superior to the other existing varieties in respect to one or more characters. A crop variety must possess several desirable characters like, high yield, superior quality, early maturity, resistance to important diseases and insect pests, etc.
There are two major methods of obtaining an improved variety of a crop.
(i) HYBRIDIZAITON
It is the most common method of incorporating desirable characters into crop varieties. “Hybridization” refers to a cross between genetically dissimilar plants. It involves:
1. Selection of parents, one used as female and other as male.
2. Before the flowers of the female parent open, their anthers are carefully removed, this is called
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Each of these elements fulfils the following requirements to be an essential element;
(i) In the absence of the element, the plant cannot complete its life cycle,
(ii) The shortage and deficiency of the element can be corrected only by supplying that element, and
(iii) The element has the direct influence on the plant nutrition and metabolism.
All elements found in the plants are derived from atmosphere, water and soil.

CLSSIFICATION OF PLANT NUTRIENTS:-
On the basis of the plant requirements the plant nutrients are chiefly classified as:
a) Micro Nutrients:- These include those nutrients, which are required by a plant in very small amounts for growth and development. These are also called as Minor nutrients and their deficiency in the soil lead to malnutrition of the crop plants. These nutrients act as activators for some important enzymes and are generally required in less than 1.0 mg per gram of dry weight of a plant. These nutrients may be required in small quantities but they are as essential for the growth and development of plant as the macro nutrients. The micro nutrients required by plants are iron, manganese, copper, molybdenum, zinc and chlorine.
b) Macro Nutrients:- The mineral elements required by the plants in large amounts are called as Macro Nutrients. These are also called as Major Nutrients. These are the nutrients which are involved in the synthesis of organic molecules
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