Postgraduate Project at University of Queensland Gatton/QWRI Toowoomba
In 1996-97, four laboratory trials were carried out to investigate the effect of temperature, the period of growth and the effect of humidity on the expression of potential coleoptile length. The cigar technique previously developed was used with eight semidwarf wheat cultivars (two representing each possible Rht1/Rht2 allele, in combination with long and short coleoptile lengths).
A temperature of 14± 1 oC, a 15 -17 day growth regime, and 80% relative humidity in the relevant growth cabinet in which the cigars were placed would be the optimal physical conditions for measurement of relative potential coleoptile length amongst segregating materials in a wheat breeding program.
Ten crosses have been made between eight semidwarf wheat cultivars to study the genetics of coleoptile length, and F1, BC1F1 and F2 seeds are now in hand. Parents include QT 5633 and Warigal (Rht1 long coleoptile parents), Batavia and 11 IBWSN 45 (Rht1 short), Spear and Dagger (Rht2 long) and Hartog and QT 4337 (Rht2 short).
A 6x6 diallel cross also has been made between near-isogenic lines to observe the nature of gene action for coleoptile length, and F1 seeds are in hand now.
In order to define a minimum coleoptile length necessary for adequate crop establishment in the field, a trial was conducted at three sites in 1997 (Biloela, Gatton and Roma) and in the glass house at Gatton to observe the effect of different sowing depth on seedling establishment in a conventional tillage system. Sowing depths of 5, 8 and 10 cm were used, along with ten currently or potentially commercial cultivars. Results are being analysed.
The potential coleoptile lengths of 53 cultivars from seed grown from four sites in 1996 have been measured to observe the stability of the coleoptile length of the cultivars across the sites.
Publications
Alam, R., Fletcher, R.J. and Banks, P. Optimal physical conditions for maximum expression of coleoptile length of semidwarf wheat. (About to be submitted to Aust. J. Agr. Res.)
Alam, R., Fletcher, R.J. and Banks, P. (1999) Optimal physical conditions for the maximum expression of coleoptile length in semidwarf wheat. In Proceedings, 11th Australian Plant Breeders' Conference, Adelaide, April, 1999. 2pp.
Alam, R., Fletcher, R.J. and Banks, P. (1996) Comparison between semidwarf wheat genotypes for coleoptile extension at six temperatures. Proceedings, Fourth Annual Research Conference, The University of Queensland Gatton, October, 1996, 65.
Contact: Dr Rob Fletcher, School of Agriculture and Horticulture, The University of Queensland Gatton, 4343; Telephone: 07 5460 1311 or 07 5460 1301; Facsimile: 07 5460 1112; International facsimile: 61 7 5460 1112; Email:
r.fletcher@mailbox.uq.edu.au[
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