Prepared for B.Sc. Part III Botany Hons. by Prof. (Dr.) Manorma Kumari

Plant Breeding

Plant breeding is the branch of applied Botany and concerned with the improvement of agriculture crops. Plant breeding as a science is however of recent origin. It can be defined “as plant breeding deals with the improvement in the heredity of crops and production of new crops varieties which are far better than original types in all respects” Thus, plant breeding is the art and science of changing and improving the heredity of plants. Objective of Plant Breeding The aims and objective of plant breeding are to improve the quantities and qualities of plants so that they are much desirable agronomically and economically. Objects of improvement vary with different crops. The main objectives of plant breeding are as follows. i. Higher yields – Most of the breeding programmes aim at higher crop yields. This is achieved by developing more efficient genotypes, eq. Hybrid varieties of maize, wheat, sorghum etc.

ii. Improved Quality – Quality is an important aspect for plant breeders. The quality of the plant product determines its suitability for various uses. The quality characters vary from one crop to another, So the objective of the plant breeding is to improve grain size, colour, milling and baking quality in wheat, cooking quality in rice, malting in barley, size, colour and flavour of fruits keeping quality of vegetables, protein content in cereals and legume, lysine content in cereals etc.

iii. Disease and Insect Resistance – Production of varieties that are resistant to fungal and bacterial diseases, insects and pests. These resistant varieties offer the cheapest method of disease and insect control.

iv. Change in maturity duration – The duration of crop maturation according to need is changed. It permits new crop rotations.

2 v. Agronomic Characteristics – Modification of agronomic characteristics is done to obtain suitable varieties for particular agroclimatic region. These characteristics may be Plant height, tillering, branching erect or trailing habit etc. vi. Photoinsensitivity – Development of photo-insensitivity and temperature in sensitivity wheat and rice varieties has permitted their cultivation in new areas. Rice is now cultivated in Punjab, while wheat is a major rabi crop in west Bengal. vii. Synchronus Maturity – It is highly desirable in crops like mung (vigna radiata) where several pickings are necessary. viii. Nonshattering – Characteristics would be of great value in a crop like mung. ix. Determinate growth – Development of varieties with determinate growth is desirable in crops like mung, Pigeon Pea, cotton etc. x. Dormancy – In some crops, seeds germinate even before harvesting if there are rains at the time of maturity e.g. mung, barley, etc. A period of dormancy in such cases would check the loss due to germination. In some other cases, however, it may be desirable to remove dormancy. xi. Varieties for New Seasons – Traditionally maize is a Kharif crop. But scientist are now able to grow maize as rabi crops. Similarly, mung is grown as a summer crop in addition to the main kharif crop. xii. Moisture stress and salt Tolerance – Development of varieties for rainfed areas and for saline soils would be helpful in increasing crop production in India.

3 xiii. Elimation of Toxic Substances – Some crops have toxic substances which must be eliminated to make them safe for consumption. Eg. Khesari (Lathyrus sativa) seeds have a neurotoxin, βN-Oxalyamine alanine that causes paralysis. Similarly, Brassica oil has eruic acid which is harmful to human health. Removal of such toxic substances would increase the nutritional value of these crops. xiv. Winter hardiness would be desirable in certain situations. xv. Creation of response to heavy manuring in some situation. xvi. Induction of tolerance to storage condition.

……….