Joint selection for both extremes of mean performance and of sensitivity to a macro-environmental variable: III. The determinants of sensitivity

Abstract

Examination of the growth curves of four selections which combine high and low final height with high and low sensitivity to sowing date and planting density have confirmed earlier indications that heritable differences in the pattern of growth are major determinants of environmental sensitivity for final height in J'Iicotiana rustica. The two high-sensitivity selections on the one hand and the two low-sensitivity selections on the other differed in pattern of growth, as expressed by the ratio of 6-week height either to height at flowering time or to final height. The generality of this finding was confirmed by the correlation between these ratios and environmental sensitivities in 59 inbred lines derived from a single cross. No evidence could be found that the mop head, non-mop head difference in habit of growth has any effect on the environmental sensitivity. © 1978 The Genetical Society of Great Britain.