Germination responses to temperature and water potential in Jatropha curcas seeds: a hydrotime model explains the difference between dormancy expression and dormancy induction at different incubation temperatures

Abstract

This study revealed (a) the extremely narrow thermal range within which dormancy problems (either through expression or induction of dormancy) may not be encountered; and (b) the high sensitivity displayed by these seeds to water shortage. In addition, this work is the first one in which temperature effects on dormancy expression could be discriminated from those on dormancy induction using a hydrotime analysis.

Development of a Threshold Model to Predict Germination of Populus tomentosa Seeds after Harvest and Storage under Ambient Condition

“…Effect of temperature on seed germination has been successfully predicted and characterized by the thermal time (TT) model [11]–[16]. Generally, this model assumes that at a suboptimal range of temperatures, the base temperature for germination ( T b ) is constant and the thermal time required for germination of a given fraction of seeds ( θ T ( g )) is a normal or log normal distribution among seeds in a population; while at a supraoptimal range, the maximum temperature for the germination of a given percentage g ( T c (g)) distributes normally, and the thermal time is constant among seeds in a population [16]–[21]. However, this general assumption does not apply to all species, for example, rangeland grass species [14], [22], [23], tropical pasture species [24] and Lithospermum arvense [15].…”

Effects of pre-sowing treatments on Jatropha curcas seed germination and seedling growth

“…Its basic agronomic needs are only partially understood, the growing and management practices are not enough documented for a lot of areas of new introduction, and the environmental effects should more deeply investigated (Achten et al, 2010a, b, c;Contran et al, 2013;Yamada and Sentelhas, 2014). Studies on vegetative (cutting) or generative (seed) propagation of J. curcas, representing a critical stage in the plant-life cycle, have been carried out so far (Ginwal et al, 2005;Achten et al, 2008;Kumar and Sharma, 2008;Islam et al, 2009;Severino et al, 2010;Windauer et al, 2012;Moncaleano-Escandon et al, 2013).…”

“…High variability of seed germination has been recorded as influenced by the observed genotype (cultivar, seedling or population), time after harvest and storage conditions, environmental characteristics of plant growing, pre-sowing and after-sowing treatments (temperature and water potential of seed tissues and substrates) (Islam et al, 2009;Pompelli et al, 2010;Windauer et al, 2012;Duong et al, 2013;MoncaleanoEscandon et al, 2013). Some authors report on a loss of seed viability and germinability after medium and long term storage (Duong et al, 2013;Moncaleano-Escandon et al, 2013), while others suppose that the presence of seed coat, may be the responsible of a physical dormancy, and furthermore generates the need to remove this inhibition by pre-sowing treatments (Baskin and Baskin, 1998;Islam et al, 2009;Windauer et al, 2011).…”

“…Among the studies on the effects of pre-sowing treatments of J. curcas seeds on different germination parameters, Islam et al (2009) demonstrated that J. curcas seeds, kept under stone sand and moistened with water for 72 h before sowing, showed a significantly higher germination percentage than the untreated and directly sown control in all the twenty different genotypes tested in the experiment. Windauer et al (2012) tested the effects of different temperatures (from 15 to 35°C) on J. curcas seed germination percentage. This study revealed that an incubation of seeds at 25°C before sowing caused the highest final germination percentage, even if at 30°C seeds germinated faster than any other temperature.…”

Ação inibitória do endosperma na germinação in vitro de embrião zigótico de pinhão manso

“…Morfologicamente, o embrião e o endosperma são bastante distintos, pois, enquanto o primeiro tornouse uma estrutura lamelar, o segundo tornou-se hipertrofi ado (LIU et al, 2009 A detecção da presença de inibidores nas sementes de pinhão manso tem fundamental importância, visando ao tratamento das sementes para fi ns de estímulo à germinação, tanto para à dinâmica de degradação ao decorrer do armazenamento. WINDAUER et al (2012) afi rmam que uma limitação importante para germinação em pinhão manso está relacionada com a alta sensibilidade exibida por essas sementes à escassez de água: esse fator pode não só evitar a germinação por si só, mas também pode atrasar sufi cientemente a germinação, por permitir a indução de dormência secundária, em caso de exposição prolongada a temperaturas que possam desencadear esse processo. No entanto, MUKHERJEE & JHA (2009) buscaram, na cultura de embriões zigóticos, uma alternativa para minimizar os efeitos da dormência de sementes e, com isso, facilitar os programas de melhoramento genético da espécie.…”