VARIATION AMONG 7 GENOTYPES OF LYCOPERSICON-ESCULENTUM AND 36 ACCESSIONS OF L-HIRSUTUM FOR INTERSPECIFIC CROSSABILITY

To improve the efficiency of introgressing genes from Lycopersicon hir sutum (H) into L. esculentum (E), environmental and genetic variation for the number of progeny per fruit from E x H crosses was quantified. Over three dates in a year, 36 H accessions were crossed to seven E a ccessions in a greenhouse. The proportion of total variation for the n umber of E x H progeny per fruit due to environment (dates, location, and error), H accession, E accession, interactions between E and H, an d interactions between accessions and environments was 0.42, 0.26, 0.1 2, 0.11, and 0.09, respectively. Sampling greater numbers of fruit on a single date improved the efficiency of recovering progeny more than increased sampling over time. The specific combination of E and H pare nts can profoundly affect the number of E x H progeny recovered and th erefore the efficiency of gene introgression. Accessions of H from the southern edge of the species' natural geographic range generally yiel ded few to zero progeny per fruit in crosses with E. In contrast to th e southern H accessions, most northern accessions produced greater tha n 40 E x H progeny per fruit. Most genes within H should be readily ac cessible for tomato breeding but genes that are found only in southern H accessions may be challenging to introgress.