Germinação de sementes de pinhão manso em diferentes temperaturas, luz e substratos

Abstract

ResumoA cultura do pinhão manso (Jatropha curcas L.) vem ganhando destaque nos últimos anos pelo seu uso como matéria prima para a produção de biodiesel. Sua reprodução pode ser realizada por estacas e/ou sementes. Neste contexto, se desenvolveu o presente estudo com o objetivo de avaliar o efeito do substrato, temperatura e luz sob a germinação e índice de velocidade de germinação (IVG) de sementes de pinhão manso. O delineamento experimental utilizado foi o fatorial do tipo 4x2x2 sendo quatro temperaturas (25, 30, 35 e 40 °C) dois substratos (areia e papel) e duas condições de luz (presença e ausência), com três repetições por tratamento. As maiores percentagens de germinação foram obtidas com as temperaturas de 25, 30 e 35 °C com luz e 30 ºC na ausência de luz para o substrato areia. Com a temperatura de 30 °C tanto na presença como na ausência de luz, para o substrato papel. A semeadura entre areia sem luz na temperatura de 30 °C foi a que melhor promoveu o desenvolvimento das plântulas, com maior IVG. A combinação do substrato entre areia, temperatura de 30 °C e ausência de luz é a melhor condição para avaliação da germinação e IVG de sementes de pinhão manso. Palavras-chave: Biodiesel, IVG, Jatropha curcas L. e oleaginosa AbstractThe physic nut crop (Jatropha curcas L.) has been gaining some importance in the last years due to its use as a raw material for biodiesel production. The Physic nut can be propagated through stakes and/ or seeds. In this context, it was developed this study in order to evaluate the effects of the substrate, temperature and light on the germination and germination speed index (GSI) of physic nut seeds. The experimental design used was a factorial 4x2x2 with temperature (25, 30, 35 and 40 °C) x substrate (sand and paper) x light (presence and absence) with three replicates per treatment. The best germination percentages were obtained with the temperatures of 25, 30 and 35 °C with light and 30 ºC in light absence for the sand substrate and at a temperature of 30°C, whether in presence or absence of light for the paper substrate. The sowing in sand without light at 30 °C was that best promoted the seedling development with higher GSI. The combination of substrate between sand, temperature of 30 °C and absence of light showed the best condition for evaluating germination and GSI of physic nut seeds.

Standard germination test in physic nut (Jatropha curcas L.) seeds

“…There was no germination below 20 °C, or at 45 °C or above (Dias et al, 2007), while for Martins et al (2008) (Vanzolini et al, 2010). More recently, Pascuali et al (2012), when evaluating different temperatures and substrates for germination, found higher germination at 30 °C in sand substrate and in the absence of light. However, Nobre et al (2007) found higher germination at 30 °C or at 20-30 ºC under light.…”

“…In addition, there is no information in the Rules for Seed Testing (Brasil, 2009) on conducting germination tests with seeds of physic nut. In this context, standardized methods should be established for seed quality assessment to enable quality control of marketed lots (Silva et al, 2008;Pinto et al, 2009;Pascuali et al, 2012). The germination test is one of these methods.…”

Effect of Drying Temperature in the Physiological Quality of Jatropha curcas Seeds

“…Souza, Bruno, and Andrade, (2005) verified that seeds of Tabebuia serratifolia stored in laboratory environment (27±3 °C and 62±2% UR) showed total loss of vigor at 120 days of storage. Pascuali, Da Silva, Porto, Silva Filho, and Meneghello (2012), examining the substrate effect, temperature and light under germination and germination speed index (GSI) of jatropha seeds, observed that the highest percentages of germination were obtained at temperatures of 25, 30 and 35 °C, with light and 30 °C in the absence of light for the substrate sand and that sowing between sand without light at 30 °C was the one that best promoted the development of the seedlings, with higher Germinate Speed Index (GSI). The combination of the substrate between sand, temperature of 30 °C and absence of light is the best condition for evaluating the germination and Germinate Speed Index (GSI) of jatropha seeds.…”

Physiological quality of seeds of shepherds purse (Zeyheria montana M. Bignoniaceae) as a function of substrate temperature and storage

“…Tests carried out with seeds from other forest species recorded that the thermal range suitable for seed germination of these species are between 20 and 30°C (Pascuali et al, 2012). However, variations can occur even among populations of the same species due to environmental conditions and adaptive and ecological characteristics (Mattana et al, 2012); for example, for other species of the family, Bignoniaceae at 35°C is the most recommended for germination of T. aurea (Pacheco et al, 2008) and Pyrostegia venusta (Ker Gawl.)…”