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- Author or Editor: Richard W. Hartmann x
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.
Abstract
Tropical lines of Phaseolus spp. planted in Hawaii in spring or early summer included types which bloomed in the usual 30-45 days and types which did not bloom until days had begun to shorten in the fall. Short day types bloomed at daylengths between 113/4 and 131/4 hr, with the majority blooming between 121/2 and 13 hr. P. vulgaris, P. lunatus, and P. calcaratus included both short-day and day-neutral types. All lines of P. aconitifolius, P. acutifolius, and P. angularis were day-neutral. Single lines of P. erythroloma and P. cf. stenolobus were short-day, and single lines of P. pilosus, P. radiatus, and P. bracteatus were day-neutral.
Abstract
Although previous workers reported that root-knot nematode resistance was controlled by 2 pairs of genes, there were more than 1/16 resistant plants in an F2 population from ‘Alabama No. 1’ (resistant) crossed with ‘Hawaiian Wonder’ (susceptible). The evaluation of F3 families showed that the excess of resistant individuals was not due to escapes. The 2-gene hypothesis was insufficient to account for the segregation patterns in the F3 families, but they could be explained on a 3-gene basis. The simplest genetic explanation is that there are at least 3 pairs of genes which are equal in their action, but a certain minimum number of genes for susceptibility are necessary before all resistance is lost.
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.
Abstract
Interspecific hybridization between Vigna radiata and V. angularis is reported for the first time. Two hybrids developed from embryos which were excised from immature seeds of V. radiata and cultured on artificial medium. The plants flowered early and continuously until death. No seeds were produced. Mean pairing at metaphase I was 2.39II + 17.22I (2n = 22).
Abstract
Interspecific hybridization between Vigna umbellata and V. angularis is reported for the first time. Hybrids were obtained from immature embryos cultured on artificial medium. The hybrids showed normal meiosis (11II) and fertility only slightly reduced from that of the parental species. Viable seeds were produced by self-pollination and by backcrosses to both parents. It appears that these species are closely related and gene transfers in both directions should be possible once embryo abortion is overcome by embryo culture.
Abstract
F3 progeny tests were used to confirm individual F2 plant Rhizoctonia resistance classifications determined from greenhouse inoculations of bean seedlings. F2 segregations within individual disease classes mostly agreed with the hypothesis that genetic control of resistance to Rhizoctonia is controlled by 3 pairs of genes acting equally and additively. Partially resistant families postulated to be homozygous for 2 pairs of genes for resistance were recovered in the segregating generations in the frequencies expected.
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).