Temperature and light in seed germination of Myrceugenia myrtoides O. Berg

Myrceugenia myrtoides (Myrtaceae) is a species of tree size, occurring restricted to the state of Rio Grande do Sul state in Brazil, and Uruguay, presenting ornamental potential. The interest in native species for diverse uses is increasing, but their insertion is limited due to the lack of information on its propagation and cultivation. Thus, the objective of this study was to evaluate the effects of temperature and light on the germination of M. myrtoides seeds, in order to generate information that could aid in the propagation of the species and the exploration of its potential. The effects of constant temperatures of 20, 25 and 30 °C under a 16-hour photoperiod were evaluated. To evaluate the effect of light, the germination was tested in continuous darkness and under photoperiod of 16 hours, at a temperature of 25 °C and light intensity of 27 and 33.75 μmol m-2s-1 under white light quality and diffuse green light. The results showed a lower average germination time at temperatures of 25 and 30 ºC and a higher accumulation of dry mass under 30 ºC. There was superiority in the variables of seedling formation, shoot and root length and seedling formation under the number of seeds germinated at 25 ºC. However, the different light conditions tested did not affect the percentage of ermination. It is concluded that the temperature of 25 °C was the most adequate for seed germination and development of M.myrtoides seedlings and their seeds are classified as neutral photoblasts

Composición bioquímica y vigor de las semillas de soja en diferentes condiciones de envejecimiento acelerado

Resumen El deterioro de las semillas es un proceso natural y envuelve la interacción de cambios de citológicos, fisiológicos, bioquímicos y físicos que ocasionan la pérdida de vigor y viabilidad. El objetivo fue evaluar los efectos de diferentes soluciones en ensayo de envejecimiento acelerado de semillas de soja en la movilización de las reservas, la germinación y rendimiento temprano de las plántulas. Se utilizaron 200 semillas por tratamiento, que consistieran en el control (sin envejecimiento), solución tradicional (agua destilada), solución salina (1,8 M) y solución salina saturada (6,8 M). Los vasos fueran incubados a 41 °C durante 24, 48 y 72 horas. La germinación disminuyó con el tiempo de incubación y aumento de la concentración de NaCl, mientras que la conductividad eléctrica aumentó. Los niveles de azúcares totales, azúcares reductores y proteínas aumentaron con el tratamiento tradicional después de 24 horas. El tratamiento con solución salina saturada presentó una mayor acumulación de peso fresco de las plántulas a los 14 días. Se concluye que en el caso de la soja el uso de solución salina saturada tuve efectos más graves en comparación con el envejecimiento tradicional de semillas. A deterioração das sementes é um processo natural e envolve a interação de mudanças citológicas, fisiológicas, bioquímicas e físicas, resultando na perda de vigor e viabilidade. O objetivo do trabalho foi avaliar os efeitos de diferentes soluções no teste do envelhecimento acelerado de sementes de soja sobre a mobilização de reservas, germinação e o desempenho inicial das plântulas. Foram utilizadas 200 sementes por tratamento que consistiram de testemunha (sem envelhecimento), solução tradicional (água destilada), solução salina (1,8 M) e solução salina saturada (6,8 M). Os recipientes foram incubados a 41 °C, durante 24, 48 e 72 horas. A germinação diminuiu com o tempo de incubação e aumento da concentração de NaCl, enquanto a condutividade elétrica aumentou. Os teores de açúcares totais, açúcares redutores e proteínas aumentaram com o tratamento tradicional, após 24 horas. O tratamento com solução salina saturada foi o que resultou no maior acúmulo de matéria fresca de plântulas aos 14 dias. Conclui-se que no caso da soja a utilização da solução salina saturada teve efeitos mais severos em relação ao envelhecimento tradicional de sementes.AbstractThe deterioration of the seeds is a natural process and involves the interaction of cytological, physiological, biochemical, and physical changes, resulting in the loss of vigor and viability. The objective of this work was to evaluate the effects of different solutions in the accelerated aging test of soybean seeds on the mobilization of reserves, germination, and early seedling performance. Two hundred seeds were used for treatment that consisted of witness (without aging), traditional solution (distilled water), saline solution (1.8 M), and saturated saline solution (6.8 M). The containers were incubated at 41° C for 24, 48 and 72 hours. Germination reduced with the incubation time and increasing the concentration of NaCl, while the electrical conductivity increased. The concentration of total and reducing sugars, and proteins have increased with the traditional treatment, after 24 hours. Treatment with saturated saline solution was what resulted in the largest accumulation of fresh matter of seedlings to 14 days. It is concluded that in the case of soybeans, the use of saturated saline solution had the severest effects in relation to the traditional aging seeds.