PHYSIOLOGICAL IMMATURITY AND HYDROPRIMING OF <i>Parkia nitida</i> Miq. SEEDS WITH PHYSICAL DORMANCY

Abstract

Parkia nitida (Fabaceae Mimosoideae) is a neotropical timber tree of economic e ecological importance due to its wood and the possibility of rapid growth in degraded areas. is a neotropical tree species of economic and ecological importance. That study aimed to verify if the freshly harvested seeds exhibit physiological immaturity and apply hydropriming on seeds with different degrees of imbibition to enhance the germination performance. The same seed lot was tested immediately after collection and after one year of storage. The treatments were 0, 20, 40 and 60% of partial imbibition in water at 15°C, followed by a drying period of 7 days. The seeds were sown in washed sand in the nursery (4 x 25 seeds / treatment). Seed moisture was assessed before and after imbibition, and after drying. Statistical tests ANOVA and Kruskal-Wallis showed significant difference between treatments for final germination percentage and mean germination time (p> 0.05). Fresh seeds of Parkia nitida showed 35% of normal seedling development, this value increased after one year of storage to 76%. Hydropriming of the fresh seeds was able to increase the germination to the same value as the stored seeds and reduced the mean emergence time from 7 to 4 days. The positive action of hydropriming was observed only after a partial imbibition of 20% (29 hours), longer imbibition periods significantly reduced the germination. The results indicate on a "critical imbibition level" between 20 and 40% of turgency. The need for a post-harvest maturation for Parkia nitida seeds could be overcome with hydropriming of the fresh seeds. Keywords: physical dormancy; tropical forest seed; priming; Fabaceae. RESUMOParkia nitida (Fabaceae Mimosoideae) é uma árvore madeireira neotropical de importância econômica e ecológica devido à sua madeira e à possibilidade de crescimento rápido em áreas degradadas. Esse estudo teve como objetivo verificar se as sementes recém-colhidas apresentam imaturidade fisiológica e aplicar hidrocondicionamento com diferentes graus de embebição para melhorar o desempenho germinativo. O mesmo lote de sementes foi avaliado imediatamente após a colheita e após um ano de armazenamento. Os tratamentos foram 0, 20, 40 e 60% de embebição parcial em água a 15°C, seguida de um dessecamento por 7 dias. A semeadura ocorreu em areia lavada no viveiro (4 x 25 sementes/tratamento). O teor de água das sementes foi determinado antes e após a embebição, e após o dessecamento. Os testes estatísticos ANOVA e Kruskal-Wallis mostraram que existe diferença significativa entre os tratamentos para a percentagem final e o tempo médio de germinação (p>0.05). Sementes recém-colhidas de Parkia nitida apresentaram 35% de desenvolvimento de plântulas normais, este valor incrementou para 76% após um ano de armazenamento