Which factor contributes to the development of stronger root systems in rice plants during dry periods?

The development of stronger root systems in rice plants during dry periods is primarily influenced by effective draining of the paddy. When water is properly drained, it encourages the rice plants to extend their roots deeper into the soil in search of moisture. This adaptation helps the plants survive periods of drought by securing access to water and nutrients that may be located further below the surface.

In contrast, increased flooding can lead to waterlogging, which may suffocate roots and restrict their growth. A lack of nutrients, while important for overall plant health, does not directly promote the strengthening of root systems under dry conditions. Lower temperatures can affect plant metabolism and growth but do not have a direct positive effect on root development during dry periods. Effective drainage creates conditions that necessitate deeper root growth, allowing the rice plants to thrive in challenging environments.