| Quantitative studies of the amphidiploid (Aegilops
sharonensis x Triticum monococcum) and the origin of the B genome
of wheat U. KUSHNIR and G.M. HALLORAN School, of Agriculture & Forestry, Univ. of Melbourne Parkville, Victoria, Australia 3052 A number of lines of evidence have recently been advanced for Ae. sharonensis as putative donor of the B genome of wheat (KUSHNIR & HALLORAN 1981) using as evidence, cytoplasmic compatibility, chromosome pairing, plant morphology and karyomorphology. Additionally PARODA (1977) has found Ae. sharonensis to contain smaller divergences in DNA base sequences from tetraploid and hexaploid wheat than the other proposed B-genome donor species, Ae. longissima and Ae. speltoides. The aim of the present study was to investigate whether developmental and plant morphological characters in present day wild tetraploid wheat could have originated from hybridisation between T. monococcum and Ae. sharonensis. Materials and Methods The Ae. sharonensis line chosen for this study was collected by one of us (U.K.) from the coastal plain of Israel from an undisturbed habitat having no contact with Ae. longissima populations. The lines of Triticum turgidum dicoccoides were collected in Israel, the early type from Upper Galilee and the late type from the slopes of Mt. Hermon. The line of T. monococcum was collected in Turkey. The amphidiploid of (Ae. sharonensis x T. monococcum) and (Ae. sharonensis x T. turgidum dicoccoides) were produced by the application of 0.05% Colchicine solution to the apices of seedlings of the respective hybrids at the 5 leaf stage for 5 hours. To quantify the influence of vernalization on rate of development and spikelet number two sets of the above plant material were vernalized, one for 30 days and the other for 60 days. Imbibed seed was placed in a cold room at 4C under 8 hour photoperiod provided by low intensity (photoinductive) in candescent light. After the vernalization treatment eight vernalized and non-vernalized seedlings of each line were planted in two 18 cm diameter pots (four seedling per pot) containing a potting mix (1 part washed sand : 1part Perlite : 1 part Derrimut red brown loam by volume). The non-vernalized lines were grown under two photoperiod regimes (short day- 12 hours and long day-24 hours) and the vernalized material was grown under long photoperiod only. All plants grew under temperatures of 20C (day) and 15C (dark). The number of days from sowing to floral initiation was determined by the non-destructive method of AITKEN (1976). Observations were made of final leaf number, days to anthesis and spikelet number on the main shoot of each plant. Plant height, tiller no., grain number per spikelet, fertility (%) and kernel weight were measured for the main shoot of the unvernalized plants grown under the short day regime. |
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