F3 seeds from a cross of P. erosus (indeterminate, daylength sensitive) X P. ahipa (determinate, daylength insensitive) were received from M. Sorensen of the Royal Veterinary and Agricultural University in Copenhagen, Denmark and sown in Hawaii in April, 1989 to increase the seed. The F4 seed were planted in March, 1990 and in October, 1990 (the normal time). All F4 progeny included both bush and vine plants in the summer planting, with more bush plants in the progeny of F3 bushes than vines. Likewise, the progeny of earlier-flowering F3 plants had a higher percentage of plants in flower in June than progeny of later-flowering ones. Root sizes and shapes were variable. The F4 progenies of the lines with the highest percentage of bushes and early-flowering plants were regrown in the summer of 1991 and selected for summer-flowering bush plants with acceptable root size. The selections were then grown in the winter of 1991 to test for performance during the normal growing season.
Patrick J. O'Malley and Richard W. Hartmann
The segregation of three characters not previously reported in lettuce and loci involved in anthocyanin production were observed to segregate in crosses within and between the closely related Lactuca species L. saliva L., L. serriola L., and L. aculeata Fisch. & Mey. as well as in crosses with the more distantly related L. saligna L. Pollen color segregated 3 yellow to 1 white. Basal branching was controlled by two loci with epistasis. One of the loci was linked to a leaf-lobing locus. Anthocyanin production in several crosses seemed to be controlled by three loci rather than two loci as previously reported. The distinctive pappus bristle type of L. saligna (one row of vertical cells) was recessive to the bristle type of the other three species (two rows of vertical cells).
Manuel A. Balcita and Richard W. Hartmann
Four races of bean rust were identified from Oahu and Maui by testing on nineteen differential cultivars. All Hawaiian bean cultivars were very susceptible to the four races. F2 segregations of crosses between the differential cultivars and the local cultivars have identified one or more dominant genes for resistance to one, 2, 3 or 4 rust races as well as other genes which do not give qualitative ratios. F3 families are being evaluated to further identify the inheritance of these genes.