Wade, L.J. and Hammer, G.L. and Davey, M.A. (1993) Response of germination to temperature amongst diverse sorghum hybrids. Field Crops Research, 31 (3-4). pp. 295-308.
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Abstract
Temperature is known to affect germination of sorghum, with lines differing in the manner of their temperature response. Such variation has been related to preferential adaptation to either low- or high-temperature environments. Depending upon how germination is defined, however, lines may differ in base temperature or in temperature responsiveness of germination rate. A broken linear model, incorporating line coefficients for base temperature and temperature responsiveness of germination rate, was used to examine the response of germination rate to temperature among 16 hybrids of grain sorghum. The coefficients were utilised to assess the genetic basis of the variability, and its implications for selection and crop adaptation. The temperature treatments were obtained using a thermogradient plate apparatus, and germination was recorded as protrusion of the coleoptile. The response of germination rate to temperature converged on a similar base temperature for each of the 16 hybrids. Base temperature varied from 5.9 to 9.8°C, with only four hybrids differing significantly from the overall mean of 7.9°C. Goldrush and AT × 623/RE × 16-6 were lower, and A6990/RE × 16-6 and A6990/RT × 430 were higher in base temperature. Temperature responsiveness of germination rate varied greatly among the 16 hybrids, ranging from 0.00114 to 0.00276 gh−1 °C−1. The hybrids A6990/RE × 16-6 and A399/T × 430 were significantly less responsiveness, and AT × 622/RT × 430, AT × 623/RT × 430 and A399/RE × 16-6 significantly more responsiveness to temperature. Partitioning variance components showed both base temperature and temperature responsiveness of germination rate were subject to strong genetic control, with narrow sense heritability low and specific combining ability high. Whilst statistically significant genotypic variation in base temperature and in temperature responsiveness of germination rate was demonstrated, the rankings showed little relationship to groupings reported for adaptation to temperate or tropical conditions, nor to rankings for rates of growth or development in other ontogenetic phases. Because narrow sense heritability was low and specific combining ability high, it would not be possible to predict the value of a cross without testing the F1 progeny. We conclude that base temperature and temperature responsiveness of germination rate are unlikely to provide a valid basis for identifying tropically adapted germplasm. Nevertheless, these characters may have value in identifying germplasm with describe attributes for crop establishment in particular temperature regimes, especially if combined with other worthwhile attributes. The analysis of genotypic coefficients, for base temperature and temperature responsiveness of germination rate, derived from a modelling framework, aided interpretation of the data. The heritability of the genotypic coefficients could be examined, and their implications for selection and adaptation could be discussed, with respect to a rigorous biological framework.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | Sorghum hybrids, Temperature, Variability, Ontogenetic phases, germplasm |
| Author Affiliation: | Queensland Department of Primary Industries, P.O. Box 81, Emerald, Qld. 4720, Australia |
| Subjects: | Plant Production Crop Improvement |
| Divisions: | Sorghum |
| Depositing User: | Ms Ishrath Durafsha |
| Date Deposited: | 23 Feb 2014 12:46 |
| Last Modified: | 23 Feb 2014 12:46 |
| Official URL: | http://dx.doi.org/10.1016/0378-4290(93)90068-X |
| URI: | http://eprints.icrisat.ac.in/id/eprint/12659 |
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