Explore the fascinating role of plant growth regulators (PGRs) in modern agriculture, understanding how they influence growth, development, and crop management. This balanced quiz covers key concepts, practical applications, and examples to boost your knowledge of these essential agrochemicals.
Which plant growth regulator is primarily responsible for promoting cell elongation and is commonly used to encourage root formation in cuttings?
Explanation: Auxin is known for stimulating cell elongation and initiating root growth, which is why it is applied to cuttings in horticulture. Gibberellin mainly promotes stem elongation and seed germination. Ethylene regulates fruit ripening and leaf abscission, while cytokinins promote cell division and shoot formation.
A farmer wants to increase the size of seedless grapes; which plant growth regulator should they apply?
Explanation: Gibberellin is commonly used in viticulture to increase the size of seedless grape berries. Abscisic acid is mainly involved in stress responses and dormancy. Ethylene influences fruit ripening but does not enlarge fruit size. Brassinosteroids promote overall plant growth but are not specifically used for this purpose.
Which PGR is often applied in controlled environments to uniformly ripen fruits like tomatoes and bananas?
Explanation: Ethylene is a gaseous hormone widely used to promote synchronized fruit ripening. Auxin mainly affects elongation and rooting, not ripening. Cytokinins promote cell division but do not induce ripening. Gibberellin influences growth processes but is not central to fruit ripening.
To stimulate shoot proliferation in tissue culture, which plant growth regulator should be increased in the growth medium?
Explanation: Cytokinins encourage cell division and are critical for initiating and proliferating shoots in plant tissue culture. Abscisic acid typically induces dormancy and is not used for shoot stimulation. Ethylene does not promote shoot growth directly, and auxins alone favor root formation over shoot development.
When crops experience drought, which plant growth regulator increases to help plants conserve water by closing stomata?
Explanation: Abscisic acid (ABA) accumulates under drought conditions, triggering stomatal closure to reduce water loss. Gibberellins promote growth, which is counterproductive during stress. Auxin is not directly involved in drought response. Brassinosteroids influence growth and stress tolerance but are not the main factor in stomatal closure.