Effect of an Alien Cytoplasm and Fertility Restoring Factor on Growth, Agronomic Characters, and Chemical Constituents in a Male‐Sterile Variety of Flue‐Cured Tobacco1

Abstract

Experiments conducted with cytoplasmic male‐sterile lines of flue‐cured tobacco (Nicotiana tabacum L.) have shown that male‐sterile inducing cytoplasms can adversely affect plant growth rate and agronomic characters.In the present study isogenic lines of a cytoplasmic male sterile and two fertility‐restored male steriles (N. suavveolens Leh. cytoplasm) were compared with normal fertile tobacco to determine the effect of fertility restoration on growth rate, agronomic performance, and chemical characteristics. The two fertility‐restored tobacco lines possessed N. suaveolens cytoplasm and were homozygous and heterozygous, respectively, for a chromosomal segment from N. suaveolens marked by a factor for fertility restoration.The N. suaveolens cytoplasm exerted a retarding effect on growth rate, causing plants to be taller, to mature later, and to produce more leaves. Nevertheless, the effect of the cytoplasm per se did not cause yield or quality reductions in cured leaf.Genetic activity associated with the N. suaveolens chromosomal segments in the fertility‐restored lines overcame some of the suppressing effects of the cytoplasm on growth rate, yet their final productivity was inferior to the male sterile and normal fertile control. A dosage effect of the introgressed chromosomal segment was evident since the fertility‐restored heterozygote deviated less from the control than the homozygote.Differences among treatments for chemical constituents in cured leaf were minimal, although all entries with N. suaveolens cytoplasm had lower quantities of reducing sugars and the fertility‐restored lines exhibited a twofold increase in nornicotine over the control.