Drought is a major limiting abiotic stress influencing wheat production in
many parts of the world. The erratic nature of water deficits makes breeding
and selection for drought resistance deficient. In environments with late
season drought stress, yield losses are usually associated with kernel abortion
or reduction in kernel growth. Remobilization of soluble carbohydrates from
the stem has been associated with drought resistance. The objectives of this
investigation were i) to asses the role of soluble carbohydrates in the
determination of drought resistance, ii) their association with productivity, and
iii) to evaluate a rapid technique to identify genotypes with higher capacity of
soluble carbohydrate remobilization. Nine winter wheat cultivars differing in
their response to drought stress were grown under irrigated and nonirrigated
conditions during the grain filling period at the Sherman Branch Experiment
Station, Moro. The cultivars were also grown at the Hyslop Crop Science Laboratory, where plots were chemically desiccated with Sodium Chlorate or
left untreated. All control and treated plots were evaluated for soluble
carbohydrates in two vegetative fractions, stem plus sheath and leaf blades. These values were correlated with the relative reductions in kernel weight and yield observed on the treated plots.
Differences among cultivars were observed for the concentration of soluble carbohydrates in the stem and leaf fractions. Time elapsed from anthesis was a major determinant of the variation in carbohydrates concentration observed during grain filling. Stem soluble carbohydrates accumulated to a much greater extent than leaf soluble carbohydrates. The concentration of stem carbohydrates was not related with the reductions caused by chemical desiccation or drought stress. However, potential contributions from stem reserves (ratio between potential spike weight and stem reserves) were marginally associated with drought resistance. Stem soluble carbohydrates were positively associated with productivity, suggesting that stems are not competitive sinks, but temporary storage organs of excess of assimilates. Under chemical desiccation most of the soluble carbohydrates were lost in respiration, and the reductions in kernel weight and yield observed were not correlated with those observed under drought. It was concluded that the technique did not reasonably simulated drought in terms of yield reductions nor carbohydrate remobilization. / Graduation date: 1998
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/34149 |
| Date | 08 July 1997 |
| Creators | Cerono, Julio Cesar |
| Contributors | Kronstad, Warren |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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