Pre-harvest sprouting in wheat costs farmers millions of dollars every year. Pre-harvest sprouting tolerance (PST) has minimized this problem, but improvement of PST is still necessary. Synthetic hexaploid wheats (synthetics) have been used as sources of
genes coding for many useful traits. Two studies evaluated the PST of a synthetic (Altar 84/Aegilops tauschii) and investigated its potential as a source of PST in crosses with wheat cultivars.
The first study compared the synthetic with selected wheat checks for PST and with its parent Altar 84 for the germination response of these genotypes to controlled wetting treatments applied to field-grown intact spikes and threshed seed. Spikes were
rolled in wet germination paper and the percentages of germinated seed were determined after seven days. Threshed seeds in Petri dishes were wetted with water and vegetative floral tissues (chaff) extracts. Germinating seeds were counted daily for 14 days. The synthetic was more tolerant than Altar 84 and was classified as moderately sensitive. The improved PST of the synthetic over Altar 84 was attributed to Aegilops tauschii. Seed dormancy and water-soluble substances in the chaff of the synthetic and other genotypes appeared to contribute to their PST.
The second study used random inbred F��� lines obtained from single and backcrosses between the synthetic (red-seeded) and the sensitive wheat cultivars Opata F��� (red-seeded) and Bacanora 88 (white-seeded). Seed coat color and germination responses of the F5 lines subjected to a five-day spike wetting treatment were evaluated. Pre-harvest sprouting tolerance was moderately to highly inheritable and largely controlled by additive gene effects in the studied populations. An association between red seed coat color and PST was observed but white recombinant lines more tolerant than their sensitive parent were obtained. The synthetic can be used to improve wheats with red and white seed coats. The potential use of the synthetic as a PST source was discussed and a breeding strategy suggested. / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33608 |
| Date | 04 January 1999 |
| Creators | Rosa, Andre Cunha |
| Contributors | Kronstad, Warren E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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