Seed germination at different stratification temperatures and development of Phytelephas macrocarpa Ruiz & Pavón seedlings

Abstract

-Phytelephas macrocarpa (ivory palm) is an Amazonian palm vulnerable to exploitation pressure, as its seeds are widely used in regional handicrafts. The aims of this study were to evaluate the effectiveness of different stratification temperatures in overcoming seed dormancy and to analyze the seedling development stages of this species. In germination under stratification, the seeds were placed in plastic bags containing moistened vermiculite, and maintained at the constant temperatures of 25, 30, 35 and 40 °C, and an alternating temperature from 26 to 40 °C. In the study about the development of seedlings, seeds were sown in vermiculite under plastic cover (growing house), and the evolution of the seedling was evaluated, from the formation of germinative button to the complete blade expansion of the first eophyll. Stratification at alternating temperatures (26 to 40 °C) helped overcoming seed dormancy. Stratification at 25 °C kept the seed viability for nine months. Germination, characterized by the formation of the germinative button took an average of 114 ± 24 days, and the seedling development until the first extended eophyll lasted 244 ± 57 days.Index terms: Arecaceae, vegetable ivory, dormancy, seedling stages.Germinação de sementes em diferentes temperaturas de estratificação e desenvolvimento pós-seminal de Phytelephas macrocarpa Ruiz & Pavón RESUMO -Phytelephas macrocarpa (jarina) é uma palmeira amazônica vulnerável à pressão extrativista, em virtude de suas sementes serem bastante utilizadas no artesanato regional. Os objetivos deste trabalho foram avaliar a eficiência de diferentes temperaturas de estratificação na superação da dormência das sementes e analisar os estádios de desenvolvimento da plântula dessa espécie. Na germinação sob estratificação, as sementes foram acondicionadas em sacos plásticos, contendo vermiculita umedecida, e mantidas nas temperaturas constantes de 25, 30, 35 e 40 ºC, e alternada de 26 a 40 ºC. No estudo sobre o desenvolvimento da plântula, as sementes foram semeadas em vermiculita, sob estufim, e avaliada a evolução da plântula, desde a formação do botão germinativo até a completa expansão laminar do primeiro eofilo. A estratificação em temperatura alternada (26 a 40 ºC) favoreceu a superação da dormência das sementes. A estratificação a 25 ºC conservou a viabilidade das sementes por nove meses. A germinação, caracterizada pela formação do botão germinativo, levou em média 114 ± 24 dias, e o desenvolvimento da plântula até o primeiro eofilo expandido durou 244 ± 57 dias.Termos para indexação: Arecaceae, jarina, dormência, estádios da plântula.

Germination of tucumã (Astrocaryum aculeatum G. Mey.) as a function of thermal pretreatment and stratification temperature

“…The stratification temperature of 26 -40 °C had a better germinative result for tucumã seeds, with low percentages of dormant and dead seeds (Table 3), similarly to what was verified in seeds of other Amazonian palms (Rodrigues et al, 2014;Ferreira and Gentil, 2017). The germination speed was also higher at this temperature, differing significantly from the others, which demonstrates its positive effect on overcoming dormancy and on the germination of tucumã seeds.…”

“…Germination was evaluated every thirty days for four months, being considered as germinated the seed with the developed germinative bud (Queiroz, 1986;Ferreira and Gentil, 2006;Ferreira and Gentil, 2017;Cui et al, 2020). The substrate (vermiculite) was sprayed with water after each germination count and before the bags were closed again aiming to maintain its moisture.…”

“…However, the temperature of 40 °C was beneficial for Butia odorata only when used in a short period (21 days) (Schlindwein et al, 2013), showing that the response to high temperatures may be related to the combination between temperature and time of exposure. Optionally, high temperatures can be used by alternation (Carpenter et al, 1993;Pimenta et al, 2010;Neves et al, 2013;Rodrigues et al, 2014;Ferreira and Gentil, 2017) or succession (Schlindwein et al, 2013) with relatively lower temperatures.…”

“…High temperatures seem to have some effect in overcoming seed dormancy in some palm trees (Rees, 1962;Comont and Jacquemard, 1977;Carpenter et al, 1993;Fondom et al, 2010;Guerrero et al, 2011;Green et al, 2013;Schlindwein et al, 2013;Lima et al, 2014;Rodrigues et al, 2014;Ferreira and Gentil, 2017;Green et al, 2019). Some associations between high temperatures and the physiological effect on seed dormancy have been pointed out, such as the reduction in the concentration of abscisic acid in the embryo and endosperm (Finch-Savage and Leubner-Metzger, 2006;Jiménez et al, 2008), the alteration in the balance between abscisic acid and other plant hormones (Cui et al, 2020), and changes in sensitivity to plant hormones (Jiménez et al, 2008).…”

“…Finch-Savage and Leubner-Metzger (2006) mentioned the need for warm stratification to overcome dormancy in seeds with small but fully developed embryos, which is associated with the decline in the concentration of abscisic acid. Favorable results have been observed at constant temperatures of 25 to 35 °C in Pritchardia remota (Pérez et al, 2008) and alternating temperatures of 25 -40 °C in Rhapidophyllum hystrix (Carpenter et al, 1993) and 26 -40 °C in Bactris maraja (Rodrigues et al, 2014) and Phytelephas macrocarpa (Ferreira and Gentil, 2017).…”