Effects of alien cytoplasmic variation on carbon assimilation and productivity in wheat

In glasshouse studies of four alloplasmic wheat series, phenotypic characters were least affected when the recipient parent cytoplasm was replaced by donor cytoplasm of the S or D plasmatype. In the T. aestivum cv. 'Selkirk' series, cytoplasm substitution did not affect P_max per unit leaf area, although the flag leaf area (and photosynthetic rate per leaf) of each alloplasmic line was greater than that of euplasmic 'Selkirk'. In field trials, all the D plasmatype alloplasmics tested produced more ears m_-2 than did euplasmic 'Selkirk'. The increased tiller number and leaf area of alloplasmic lines resulted in greater canopy light interception than euplasmic 'Selkirk' early in the season. This characteristic was associated with reduced weed populations under crops of alloplasmic 'Selkirk' lines grown under low-, but not high-input, agronomic regimes, with Ae. cylindrica- and Ae. ventricosa 'Selkirk' significantly outyielding alloplasmic 'Selkirk' under low-input conditions. The F₂ populations from crosses between European wheat varieties and 'Selkirk' lines exhibited higher standard deviations for grain yield for alloplasmic than for euplasmic 'Selkirk', suggesting potential for selecting heterotic nuclear-cytoplasmic combinations with alien cytoplasms.