A atividade de enzimas hidrolíticas (fitase e alfa amilase) é decisiva no metabolismo germinativo de sementes de milho sob estresse salino

Abstract

ABSTRACT The mobilization of reserves is essential for seedling formation and can be influenced by seed vigor. This work evaluated how seed vigor and reserve mobilization influence maize seedling formation under salt stress. The high-vigor seeds comprised the seeds directly from the lot, while the low-vigor seeds were subjected to an artificial aging process to reduce the vigor. Seeds were germinated in a substrate moistened with water (control) or saline solution (100 mmol L-1 NaCl) and were submitted to germination and vigor tests (first germination count, cold test, and seedling performance). Biochemical profiling (phytic acid and inorganic phosphorus, total and soluble protein, starch and soluble sugars, α-amylase and phytase activity) was determined at 0 (quiescent seeds), 2, 4, 6, and 8 days after sowing. High-vigor seeds had better physiological performance and higher reserve hydrolysis rates under salt stress than low-vigor seeds. High-vigor seeds also showed earlier enzymatic activity than low-vigor, demonstrating a temporal difference in reserve hydrolysis during the stress. The highest differences in reserve hydrolysis occurred 2 days after sowing and differentiated the germinative metabolism of high and low-vigor seeds under salt stress.