IFEVA   02662
INSTITUTO DE INVESTIGACIONES FISIOLOGICAS Y ECOLOGICAS VINCULADAS A LA AGRICULTURA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Germination responses to temperature and water potential in Jatropha curcas L. seeds
Autor/es:
WINDAUER L.B. ; WASSNER D.; BENECH-ARNOLD R.L.
Reunión:
Congreso; 10 th Conference of the International Society for Seed Science; 2011
Institución organizadora:
ISSS
Resumen:
GERMINATION RESPONSES TO TEMPERATURE AND WATER POTENTIAL IN Jatropha curcas L. SEEDS. 1Windauer, L.B., 1Wassner, D., 1Benech Arnold, R.L. 1Cátedra de Cultivos Industriales, FAUBA, Av. San Martín 4453, Capital Federal (1417), Argentina. windauer@agro.uba.ar Jatropha curcas is a drought-resistant tree whose seeds are a good source of oil that can be used for producing biodiesel. A successful crop establishment depends on a rapid and uniform germination of the seed. In this work we aimed to characterize the responses of Jatropha curcas seeds to temperature and water availability, using thermal time (T) and hydrotime analysis(H ). Thermal and hydrotime analysis was performed on germination data obtained from the incubation of seeds at different temperatures and at different water potentials. Base and Optimum Temperatures were 14.6ºC and 30-35ºC, respectively. Approximately 20 % of the seed population displayed absolute dormancy and part of it displayed relative dormancy which was progressively expressed in further fractions when incubation temperatures departed from 25ºC. The thermal time model, but not the hydrotime model, failed to adequately describe final germination percentages at temperatures other than 25ºC. The H constant was reduced when incubation temperature was increased until 30ºC, base water potential Ψb(50) was less negative at 20 and 30ºC than at 25ºC, indicating either expression or induction of dormancy; but while at 20ºC this less negative Ψb(50) explained satisfactorily germination curves obtained at all water potentials, at 30ºC it had to be corrected towards even less negative values to match observed curves at water potentials other than 0. Hence, Ψb(50) appeared to have been further displaced to less negative values as exposition to 30ºC was prolonged by osmoticum. Taken together these results suggest expression of dormancy at 20ºC and induction of secondary dormancy at 30ºC. This study revealed i) an the extremely narrow thermal range within which dormancy problems (either through expression or induction of dormancy) may not be encountered; ii) 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.