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Which of the following is not an inhibitory substance governing seed dormancy?
Abscisic acid (ABA), Phenolic acids, and Para-ascorbic acid are well-known chemical inhibitors that enforce and govern seed dormancy. Gibberellic acid (GA) stimulates alpha-amylase synthesis to BREAK seed dormancy and promote germination! Mark Gibberellic acid (Option 1) in 5 seconds.
In many plants, viable seeds fail to germinate even when external environmental conditions (moisture, temperature, oxygen) are favorable. This state is called seed dormancy.
NCERT explicitly identifies chemical inhibitors present in the seed coat or embryo that induce and maintain dormancy: Abscisic acid (ABA), phenolic acids, and para-ascorbic acid.
Dormancy can be overcome by treating seeds with gibberellic acid and nitrates. Gibberellins induce the synthesis of hydrolytic enzymes (such as alpha-amylase in aleurone layer of cereals) that mobilize food reserves, triggering seed germination.
Therefore, Gibberellic acid acts antagonistically to ABA as a promoter of germination, NOT an inhibitory substance governing dormancy.
Diagnose every choice: Know exactly why the right option works and why distractors fail.
Accurate; gibberellic acid is a germination promoter that overcomes seed dormancy, not an inhibitor.
Incorrect; abscisic acid (ABA) is the primary endogenous dormin/inhibitor that induces and maintains seed dormancy.
Incorrect; phenolic acids are chemical inhibitors explicitly listed in NCERT that cause seed dormancy.
Incorrect; para-ascorbic acid is an endogenous chemical inhibitor governing seed dormancy cited in NCERT.
The question asks: "Which is NOT an inhibitory substance governing seed dormancy?" Three options are inhibitors (ABA, phenolic acid, para-ascorbic acid); only Gibberellic acid is a PROMOTER.
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