Explore the essential roles, types, and applications of plant growth regulators and plant growth-promoting substances in modern agriculture. Challenge your knowledge across plant physiology, signaling, and yield enhancement.
Which of the following is a primary function of the plant growth regulator auxin in agriculture?
Explanation: Auxin primarily stimulates cell elongation, especially in shoots, which is crucial for plant growth. It does not inhibit seed germination—some auxins may actually promote it. Promoting leaf abscission is typically the role of ethylene, not auxin. Reducing fruit size is not a direct effect of auxin; in fact, auxin can promote fruit development.
A farmer wants to improve seed germination rates in a cold climate. Which plant growth regulator is most likely beneficial?
Explanation: Gibberellins break seed dormancy and stimulate germination, making them especially useful for overcoming environmental stresses like cold. Ethylene is more involved in fruit ripening, abscisic acid typically enforces dormancy, and cytokinins promote cell division, not targeted at germination.
Which best describes one way plant growth-promoting rhizobacteria (PGPR) enhance crop yield?
Explanation: PGPR enhance nutrient availability and uptake, positively impacting crop yield. Inducing leaf senescence reduces yield; blocking transpiration entirely would harm the plant; increasing soil salinity is detrimental to plant growth.
When crops experience drought, which hormone is largely responsible for promoting stomatal closure to conserve water?
Explanation: Abscisic acid triggers stomatal closure, helping plants minimize water loss during drought. Gibberellins, auxins, and cytokinins have crucial roles but are not directly responsible for this water conservation mechanism.
In commercial agriculture, which role is most associated with ethylene application?
Explanation: Ethylene is widely used to promote uniform fruit ripening, aiding in harvest management. Delaying flowering and inhibiting root growth are not typical uses for ethylene, and it does not primarily function to decrease seed dormancy.