Seed development of Araucaria angustifolia: plant hormones and germinability in 2 years of seeds production

During seed development, plant hormones are involved in processes such as the accumulation of reserves, cellular activity and physiological responses. The present study aimed to analyze levels of abscisic acid, gibberellins, auxins, salicylic acid and their role in the physiological responses during development of A. angustifolia seeds in two years of production. Seeds were collected in the stages cotyledonary, II, III and IV during 2 years and submitted to germination, tetrazolium and electrical conductivity tests. The embryonic axes and cotyledons were extracted from the seeds and submitted to hormones analyses. The results demonstrated that environmental conditions during development affected the time when seeds reached physiological maturity and hormone levels. In 2015, seed development occurred under conditions of lower rainfall, cold hours and insolation, providing the formation of larger seeds, favoring a higher abscisic acid synthesis and accumulation, anticipating/shortening seed maturation. The results highlight the antagonistic relationship between abscisic acid and auxins, which acts as a regulatory factor for faster germination. In conclusion, changes in the levels of abscisic acid, gibberellins, auxins, salicylic acid and their role in physiological responses during seed development are linked to climatic conditions during maturation.