Plant Breeding Objectives and Reproduction in Plants

Plant breeding is the science of changing the traits of plants in order to produce desired characteristics.

The objectives of plant breeding include improving yield, quality, resistance to diseases, and adaptation to various environments. The scope of plant breeding covers a wide range of crops and techniques to achieve the desired traits.

Undesirable effects of plant breeding may include loss of genetic diversity, increased susceptibility to pests and diseases due to uniformity, and potential negative impacts on the environment.

<p>Self-pollination is the transfer of pollen from the anther to the stigma of the same flower or a different flower on the same plant. Mechanisms promoting self-pollination include cleistogamy, homogamy, and herkogamy. Genetic consequences of self-pollination can lead to inbreeding depression or fixation of deleterious alleles.</p> Signup and view all the answers

<p>Cross-pollination is the transfer of pollen from the anther of one flower to the stigma of another flower on a different plant. Mechanisms promoting cross-pollination include anemophily, entomophily, and hydrophily. Genetic consequences of cross-pollination can lead to increased genetic diversity and hybrid vigor.</p> Signup and view all the answers

<p>Self-incompatibility is a genetic mechanism that prevents self-fertilization in plants. Different types of self-incompatibility in crop plants include gametophytic self-incompatibility and sporophytic self-incompatibility.</p> Signup and view all the answers

<p>The different types of plant introduction are: 1) Primary introduction - introducing a crop from its center of origin to a new area, e.g. introducing wheat from the Fertile Crescent to Europe. 2) Secondary introduction - introducing a crop from an area where it was previously introduced, e.g. introducing wheat from Europe to North America. 3) Direct introduction - introducing a crop directly from its center of origin, e.g. introducing maize from Mexico to India.</p> Signup and view all the answers

<p>Qualitative characters are those that show distinct classes without an overlapping range, e.g. seed color, flower color. Quantitative characters show a continuous variation and can be measured, e.g. plant height, yield, maturity period.</p> Signup and view all the answers

<p>Mass selection is a breeding method where superior plants are selected from an existing population based on phenotypic superiority. Procedure: A large population is grown, superior plants are selected visually, their seeds are bulked and used to grow the next generation. Merits: Simple, inexpensive, useful for highly heritable traits. Demerits: Slow progress, cannot improve traits with low heritability.</p> Signup and view all the answers

<p>Johannsen's pure line theory states that after several generations of selfing in self-pollinated crops, the progenies become homozygous and breed true for all genetic factors. A diagram showing the development of pure lines from an initial heterozygous population over several generations of selfing should be provided.</p> Signup and view all the answers

<p>Mass selection is based on phenotypic selection of superior plants from an existing population, while pureline selection involves developing pure lines by selfing followed by selection among and within the pure lines. Mass selection is useful for highly heritable traits, while pureline selection can improve all genetic factors. Mass selection is quicker but less precise than pureline selection.</p> Signup and view all the answers