Answer:
The diffusion of fast-ripening rice help to grow population because the more the rice, the more will be the food to feed the under nutrition and hungry children.
Earlier when rice took considerable time to grow, children were left without food which caused malnutrition and that would eventually lead to death. This kept the population in control.
Now when the production of rice is faster, lesser children and people die due to malnutrition leading towards increased population.