Maharashtra Board Class 12 Biology Chapter 11 Enhancement of Food Production PDF Download

Enhancement Of Food Production

11.1 Improvement In Food Production

Food is one of the basic needs as it gives us energy for everything. It keeps us alive, strong and healthy. It can be defined as anything solid or liquid, which when swallowed, digested and assimilated in the body, keeping us well. It is organic, energy rich, non-poisonous, edible and nourishing substance.

Green plants synthesize their own food through photosynthesis. But animals including humans can not synthesize their food on their own, hence are dependent on plants directly.

The famine is responsible for dearth of food, besides the rapid and dramatic increase in world population over the time. To meet the increasing demand for food, there is need for improvement of food production, both quantity wise and quality wise (nutritive). Plant breeding and animal breeding help us to increase the food production.

11.2 Plant Breeding

The improvement or purposeful manipulation in the heredity of crops and the production of new superior varieties of existing crop plants, constitute what is called plant breeding. It is, therefore, an applied branch of botany. It is infact an art and the science of changing and improving the heredity of plants. Plant breeding can be carried out by using the applications of principles of genetics, taxonomy, physiology, pathology, agriculture, rDNA technology, etc.

Plant breeding is a method of altering the genetic pattern of plants to increase their value and utility for human welfare. The plant breeding is done to increase crop yield, improve quality, increase tolerance to environmental stresses, make the plants resistant to pathogens and increase tolerance to insect pest. Green Revolution was the result of a sequence of scientific breakthroughs and developmental activities that successfully fought hunger by increasing food production. Seeds with superior quality, use of chemicals - pesticides and fertilizers, and multiple cropping system supported by the use of modern farm machinery and proper irrigation system, helped for the development of high-yielding and disease resistant varieties in wheat, rice, maize, etc.

In fact, plant breeding dates back to about 10,000 years ago. The present day crops are the result of domestication and acclimatization.

Teacher's Note

Plant breeding helps farmers grow better crops. For example, in India we now grow rice that gives more food from the same land.

Exam Trick

Remember: Plant breeding = mixing good plants together to make super plants. Just like your parents give you their good qualities, farmers mix two good plants.

Points to Remember

Plant breeding changes the genes of plants to make them better.
It helps make more food and stop diseases in plants.
Green Revolution happened because of new plant varieties.
Hybridization is mixing two different plants to make a new one.
Scientists have been doing this for 10,000 years.

A. Hybridization And Its Technique

It is the chief method that offers greater possibilities in the crop improvement than other methods. The use of this method is the only effective means of combining together the desirable characters of two or more varieties. By this method, one can create new genetic combinations of already existing characters and new genetic variations. It also exploits and utilizes hybrid-vigour.

Hybridization can be intravarietal, intervarietal (between two varieties of the same species), interspecific (between two species of the same genus) and intergeneric (between two genera of the same family). As parental plants are distantly related, such crosses are also called wide/ distant crosses. Interspecific and intergeneric hybrids are seldom to occur in the nature.

The main steps of the plant breeding program (Hybridization) are as follows:

1. Collection Of Variability

Wild species and relatives of the cultivated species having desired traits, should be collected and preserved. The entire collection having all the diverse alleles (i.e. variations) for all genes in a given crop, is called germplasm collection. Variations are useful in the selection.

Germplasm conservation can be done in following ways-

In situ conservation: It can be done with the help of forests and Natural Reserves.

Ex situ conservation: It is done through botanical gardens, seed banks, etc.

2. Evaluation And Selection Of Parents

It is an important and essential step. The collected germplasm is evaluated (screened) to identify plants with desirable characters. The selected parents must be healthy, vigorous and should show desirable but complementary features. The selected parents are selfed for three to four generations to make them pure or homozygous. It is made sure that only pure lines are selected, multiplied and used in the hybridization.

3. Hybridization

The variety showing maximum desirable features is selected as female (recurrent) parent and the other one as male parent (donor) which lacks good characters found in recurrent parent.

The pollen grains from anthers of male parent are collected and then artificially dusted over stigmas of emasculated flowers of female parent. Pollination is followed by seed and fruit formation in due course. The seed, thus obtained represents the hybrid generation.

The hybrid F1 progeny is selected and evaluated for the desired combinations of characters.

Teacher's Note

Hybridization means crossing two plants to get a better plant. Like in India we crossed different wheat types to make more powerful wheat.

Exam Trick

Remember: Hybridization = parent plant 1 + parent plant 2 = super baby plant with best qualities from both.

Points to Remember

We collect seeds from many plants first.
We choose the best healthy parents.
Male pollen is put on female flower.
Seeds from this cross are the F1 hybrids.
These new plants are then tested to see if they are good.

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