Question

The science developing high yielding varieties of crop by _______
A. Emasculation
B. Selection
C. Introduction
D. Plant breeding

Answer 1

It is the scientific technique that is used to improve the cop varieties for better yielding of crops. The plants produced by this technique are having superior and desired traits. The objective of plant breed is to enhance the crop yield, to increase the nutritional value, disease-resistant plants, etc.

Complete answer:
The science develops high yielding varieties of crops by plant breeding. Plant breeding is the technique used to improve crop varieties like varieties of disease-resistant plants (from insect pests etc), drought resistant, high nutritional value.
Method of plant breeding involves: Germplasm collection (collection of those species having all the desired alleles for a gene in a given plant), evaluation and selection of suitable parents, hybridization of selected parents, selection of superior recombinants, then testing of superior recombinants occur for releasing into the market. It leads to the commercialization of new cultivators.
Hence, the correct option is (D)-Plant breeding

Additional Information:
Emasculation is the removal of stamens or male reproductive parts from bisexual flowers. It is done to avoid self-pollination in bisexual flowers. Emasculation is one of the steps of plant breeding.

Note: Examples of crops produced by plant breeding are: Sonalika and Kalyan sona are two hybrid varieties of wheat. Hybrid maize and Bajra are the two-hybrid millet crops that are resistant to water stress as well as high-yielding varieties.