Changes in the photosynthetic properties of Australian wheat cultivars over the last century
1994
Watanabe, N. (Gifu Univ. (Japan). Faculty of Agriculture) | Evans, J.R. (Australian National Univ., Canberra. Research School of Biological Sciences) | Chow, W.S. (Commonwealth Scientific and Industrial Research Organisation, Canberra (Australia). Div. of Plant Industry)
A selection of Australian wheat cultivars grown in the glasshouse showed a trend towards higher rates of CO2 assimilation, higher chlorophyll and N contents per unit leaf area over time. The increase in leaf N and photosynthetic rate is most probably due to the introduction of the Rht dwarfing genes. There were declines in rate of electron transport per unit chlorophyll, chlorophyll a-b ratio and photosystem II content per unit chlorophyll. Because the chlorophyll to N ratio was similar between cultivars, lowering of the rate of electron transport per unit chlorophyll in modern cultivars results in a fall in the rate of electron transport per unit of N. There was no variation in the ratio of intercellular to ambient CO2 partial pressures, or leaf mass per unit leaf area. The comparison of a near isogenic pair, with or without a portion of a rye chromosome that is associated with high yield, did not reveal any association with photosynthetic characteristics. Selection for higher chlorophyll a-b ratios for a given leaf chlorophyll content may provide a feasible surrogate for selecting higher photosynthetic capacity.
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