Question

Genetic diversity in agricultural crops is threatened by the

• A. intensive use of fertilisers
• B. introduction of high yielding varieties
• C. extensive intercropping
• D. use of pesticides

Answer 1

The correct option is B introduction of high yielding varieties

During the 1960s, the Green Revolution started by introducing high-yielding varieties of rice and wheat to increase food production in order to meet the demands of the ever-increasing population. Because of the Green Revolution, the production of wheat and rice increased tremendously (during 1960-2000 wheat production increased from 11 million tonnes to 75 million tonnes and rice production went up from 35 million tonnes to 89.5 million tonnes).

This affected the indigenous crop varieties of wheat, rice and millets. The high yielding varieties were preferred over the indigenous varieties as their yield was high as compared to the indigenous varieties. This eventually led to the loss of indigenous crops from cultivation and also caused extinction of some of the varieties.

Though the use of pesticides and chemical fertilisers increased the per capita yield, it also created ecological imbalance by eliminating the interdependent species from the ecosystem. However, they are not responsible for the loss of genetic diversity in agricultural crops.

Intercropping (growing two or more crops simultaneously) is used to maximize nutrient utilization and at the same time check the overuse or depletion of a particular mineral nutrient.