Nature of Reduced Productivity of Anther‐Derived Dihaploid Lines of Flue‐Cured Tobacco 1

Abstract

Anther-derived dihaploid lines from highly inbred cultivars of flue-cured tobacco, Nicotiana tabacum L. are lower yielding and agronomically inferior to selfed progenies of the parental anther source. Investigations were conducted to determine if productivity reductions were dissipated in heterozygous dihaploid synthetics, and whether nuclear or cytoplasmic mechanisms were responsible for the genetic changes seen in dihaploid lines. Ten dihaploid lines from each of two cultivars, Coker 139 (C 139) and NC 95, were crossed in all combinations within cultivars, excluding reciprocals. Equal quantities of seed of each cross were bulked, and each F1 synthetic was compared to its source cultivar. A diallel analysis with reciprocals and selfs was also conducted among the two cultivars and a high and low yielding dihaploid selection from each. Parents and dihaploid synthetics were evaluated in two environments and the diallel in three environments for nine agronomic characters and leaf constituents. The C 139 and NC 95 dihaploid synthetics were 21.5 and 12.5 %, respectively, lower yielding, and generally agronomically inferior to the respective source cultivars. Significant general combining ability effects were detected for all traits, and specific combining ability (sca) effects were observed for six of the traits in the diallel analysis. The magnitude of sca effects was larger than that normally observed in flue-cured tobacco crosses. Maternal effects were observed only for plant height. These experiments show that productivity depressions among flue-cured anther-derived tobacco lines are not dissipated with the establishment of heterozygosity, and that nuclear rather than cytoplasmic factors are responsible for dihaploid variants.