Strategies for Enhancement in Food Production in Biology

Introduction:

Food is necessary for the development and survival of all the organisms. To deal with the need of food with the increasing population, it is necessary to increase food production.There are so many technologies which increase yield such as  plant breeding, animal husbandry and modern technologies like tissue culture, genetic engineering, embryo transfer. An improved variety can be produced by three methods only:

1. Plant breeding: Classical, less efficient and time consuming

2. By induced mutation and by selecting improved mutants.

3. By genetic engineering

Main Steps Required for Developing New Varieties:

1. Collection of variability: Main reason behind breeding is genetic variability. In many crops pre-existing genetic variability is available from wild relatives of the crop. Germplasm is collected from the same country or from other countries and they are usually maintained at low temperature in the form of propagules. The stored propagules are periodically grown in the field to obtain  fresh propagules. Germplasm is the sum total of all the alleles for all  the genes present in the crop and its related species.

2. Evaluation and selection of parents: the germplasm is evaluated so as to identify plants with desirable combinations of characters. Selection of parents is done by picking up seeds of only those plants which have desired traits. These selected plants are multiplied and used in the process of hybridisation.

3. Hybridisation: Hybridisation is a process of making cross between two genetically diverse parents to obtain a progeny with desired superior traits. 

4. Selection and testing of superior recombination: This step comprises selecting, among the progeny of the hybrids, i.e those plants that have the desired character combination. This is the crucial step for the success of breeding objectives and requires careful scientific evaluation of progeny. Selection is again done in new plants and further selection is of three types:

1. Mass Selection: It is one of the  simplest and oldest methods mainly used in  cross pollinated crops and is based on phenotypic characters. One of the oldest methods of crop improvement. 

2. Pure Line/ Inbreed Selection: Involves isolation of desirable homozygous individuals and is done for self pollinating crops. It is the progeny of a single homozygous self pollinated plant. In this method a plant of desired  characters is selected by a genetically mixed population. 

3. Colonel Selection: It is used for vegetative reproducing crops. Clones are known to be progeny of a single vegetatively propagated plant. Here selection is made between clones not within clones. Example: Kufri safed potato.

5. Testing, release and commercialisation of new cultivators: Evaluation of newly selected lines is done and further they undergo quality, disease resistance, and many more tests.

Aims of Plant Breeding:

A. Plant breeding for disease resistance: Fungal, bacterial, viral and nematode pathogens attack the cultivated crops. So crop loss can be upto 20-30 percent, sometimes even total. In such situations crops are made disease resistant, food production is increased and use of fungicides and bactericides would be reduced.

Methods of Breeding for Disease Resistance: 

1. Screening germplasm for resistance sources: Wild plants can be the best source because they survive without getting protection from humans in any environment. Their characters are useful for plant breeders: for example potato.

2. Hybridisation of selected parents.

3. Selection and evaluation of hybrids.

4. Testing and release of new varieties.

B. Plant breeding for developing resistance to insects/pests: Insects and pest infection is another major cause for large destruction. Insect resistance in host plants is due to morphological, biochemical and physiological characters. Smooth leaves cotton varieties do not attract bollworms. 

C. Plant breeding for improved quality: It is estimated that more than 840 million people in the world do not have adequate food to meet their daily requirements. Breeding of crops with higher levels of vitamins and minerals or higher proteins and healthier fats is called biofortification. 

Mutation Breeding: 

Mutation is sudden, stable and heritable change which alters the gene expression of the organism.This results in a new character not found among parents. The mutation, which are artificially induced mutations for crop improvement is called mutation. The agents which are used to induce mutation for crops improvement is called mutation breeding. Which are used to induce mutations are called mutagens. Various chemicals such as HNO₂, base analogues, acridine dyes, and physical agents such as x-rays, uv rays and gamma rays. 

Polyploid Breeding: 

Organisms having more than two sets of chromosomes are called polyploid. Induced polyploidy is used by plant breeders for improving yield of forage and other crops. Many modern crops such as wheat, rice, sugarcane, potato and cotton are natural polyploids. 

Single Cell Protein (SCPs):

The cells from microorganisms such as bacteria, yeasts, filamentous algae, treated in various ways and used as food are called single cell proteins. They are processed to remove excess nucleic acid. The raw material for single cell protein production include whey, sulphite waste liquor, hydrocarbon waste from petroleum industry, waste water containing scratch from potato processing plants, straw, molasses and animal manure. 

Energy Crop:

It is a manure prepared from young, green crops which can be used for production of alcohol are potato, sugar beet, tapioca and molasses of the sugar industry. Growing crops for production of alcohol and other fuel is known as energy cropping. 

Plant Tissue Culture:

This is one of the latest and most promising methods of crop improvement in such plants, where all other conventional methods of breeding fail. It is based on the totipotent nature of plant cells. Plant tissue culture is the technique of maintaining and growing plant cells, tissues and organs in sterilised culture medium, under controlled aseptic conditions. 

Types of Culture:

1. Callus culture and suspension culture

2. Meristem culture

3. Embryo culture

4. Anther culture

5. protoplast culture

Green Manure:

It is a manure prepared from young, green crop plants by ploughing them back into soil. For example sunn Hemp (crotalaria juncea), Dhaincha (Sesbania aculeata), Cluster Bean (Cyamopsis tetragonoloba), sweet Clover, Lentil.