A farmer observes that his wheat crop is heavily infested with broad-leaved weeds. Which of the following plant growth regulators should he spray to eliminate the weeds without damaging the wheat crop?

Step-by-step solution

Wheat is a monocotyledonous crop, while the broad-leaved weeds are dicotyledonous. According to NCERT, 2,4-D (a synthetic auxin) is widely used as a herbicide to kill dicotyledonous weeds and it does not affect mature monocotyledonous plants. Therefore, spraying 2,4-D will selectively eliminate the broad-leaved weeds without harming the wheat crop. Cytokinin, abscisic acid, and gibberellic acid do not possess this selective herbicidal property. Answer: 2,4-D