Indirect selection for environmental sensitivity in Nicotiana rustica

Abstract

Indirect selection for high and low sensitivity to macroenvironmental differences for final height (FH) has been practised among F2individuals of the cross of varieties 2 and 12 of Nicotiana rustica using a selection index (R7) proposed by Boughey and Jinks (1978), which is the proportion of FH achieved by the middle of the growing season. The F3progenies of the selections and of unselected controls were assessed in the range of environments in which the selection index was both measured and originally validated (2 sowing dates ×2 planting densities at the University site), as well as in a similar set of environments at the poorer Avoncroft site. A correlation analysis combined with a significant response to selection confirms that pattern of growth as summarised by R7 is a major determinant of environmental sensitivity of FH to the environmental treatments at the University site and that it has a high repeatability and heritability. The same analysis and the absence of a response to selection at the Avoncroft site show that the usefulness of the selection index is limited to the University site. © 1984, The Genetical Society of Great Britain.