| The tiller which produced the fertile spike was cut back after the spike
was harvested, and repotted. It sprouted again and produced six partly fertile
spikes, one of which was sacrificed for meiotic investigations. The other
five spikes produced 25 kernels in 87 spikelets after self-pollination.
These C2 kernles will most likely produce a new fertile decaploid
Agrotricum species which will be of use in wheat breeding programmes.
It will resemble the semi-fertile C1 plant which developed from
the repotted fertile tiller reported above. This plant is approximately
1 meter tall and produces spikes which are 15 cm long and contain up to
20 spikelets. Each spikelet is composed of 5 to 6 florets. The spikes have
a strong rachis and except for a very short tip awn, are awnless-the awned
spikes of Inia 66 is therefore recessive to the awnless spikes of A.
distichum. The plant has a strong perennial tendency and can be readily
maintained by cloning. It has no vernalization requirement and is insensitive
to daylength, coming into flower any time of the year, unlike A. distichum
which flowers only during the latter part of November and early December.
The meiotic investigation of the semi-fertile spike revealed that it was mixoploid - partly pentaploid and partly decaploid. Meiotic prophase in the decaploid pollen mother cells (PMC's) appears to be quite normal because the 7 PMC's observed at diakinesis had a mean bivalent frequency of 33.86 (range 33-85). Some bivalents, however, must disjoin before metaphase I, since the mean univalent frequency per PMC at metaphase I as deduced from the 20 scored cells at this stage, is 6.1 (range 2-10). In spite of this the anaphase I distribution appears to be fairly regular - the mean distribution in 20 scored PMC's is 34, 1-1-34, 9. In order to produce a fully fertile amphiploid, selection for meiotic stability will have to be practiced in the C2 and subsequent generations. This investigation was financed from funds obtained from the Department of Agricultural Technical Services and the University of Stellenbosch. The technical assistance of Mr. H.S. ROUX and Mrs. M.H. LAMBRECHTS is gratefully acknowledged. Literature Cited PIENAAR, R. ED V., Roux, H,S., VERMEULEN, E.C. & LOMBARD, M.G. 1977. Proc. 6th Congr. S.A. Genet. soc. pp. 76-83. PIENAAR, R. DE V. 1979. wheat Int. Serv. 49: 24-26. |
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