Search Results
Abstract
Pod detachment force (PDF) was measured at fresh market maturity (sieve size 4) for the parents, F1, F2, and both backcrosses for the cross ‘Harvester’ × ‘Idelight’. The distribution of the population means for the F1, F2, and backcrosses indicated strongly dominant gene effects were contributed by the ‘Harvester’ parent for high PDF. A minimum of 2 dominant genes controlled PDF and narrow sense heritability was estimated to be 61%.
Abstract
Segregation in F2 populations of Phaseolus vulgaris L. indicates that the reclining foliage character (RF) is controlled by a single recessive gene, rf. The expression of rf appears to be modified by either a recessive or a dominant epistatic factor occuring in some other lines. The RF character contributes to lodging resistance and many reduce yield losses of pods from mechanical harvest when combined with long racemes.
Abstract
Carrot (Daucus carota L.) roots were separated into high and low density groups by placing them in a NaCl solution of known density. The high density roots had mean % soluble solids significantly higher than low density roots. The density of the test solution required for optimum separation of high density roots varied with the cultivar.
Abstract
The r values between core/whole root diameter ratio and soluble solids of roots of carrot (Daucus carota L.) varied from 0.385 to - 0.473 depending upon cultivar and location. The r value for the cultivar means between the same variables was -0.434. Selection for core size has little potential as an indirect method for raising soluble solids. A correlation of 0.621 was found between specific gravity and soluble solids in ‘Nantes Strong Top’.
Abstract
Leaf index (width/length) was measured in the parental lines, F1 and F2 of the cross ‘Gallega’ (rosette type) × ‘Minetto’ (crisphead). The minimum genetic requirement for head formation in the F2 was probably a combination of 3 genes, 1 dominant and 2 recessive. However, none of the heading segregates fully recovered the ‘Minetto’ phenotype. The heading genotype of ‘Minetto’ differed from that of ‘Gallega’ by a mimimum of 3, and probably 4 or more, predominantly recessive genes. The primary effect of “heading genes” was to increase the leaf index, i.e. produce leaves which were wide at the base.
Abstract
Bean pollen treated with 2, 4, 8, and 16 kR of gamma irradiation was used to produce M1 seed. The M1 plants were screened for semisterility of the pollen. The inheritance of the semisterility mutations was studied in crosses to a tester stock with recessive marker genes and in M2 and M3 progeny tests. The 4, 8, and 16 kR treatments produced nearly 100% lethal mutations while 2 kR produced 70% lethality. The semisterility factors behaved genetically like dominant alleles in F1 test cross progeny but segregated again for a ratio of 1 semisterile to 1 fertile plant in the F2, indicating that the mutants are probably chromosome aberrations and not genic mutations. They may in fact be chromosome translocation heterozygotes. The semisterility factors produced 40 to 60 % pollen abortion and a significant reduction in seed set per pod. Semisterility factors were found in about 5% of the M1 plants tested.
Abstract
The inheritance of male sterility was studied in germplasm of common bean (Phaseolus vulgaris L.) obtained from the Centro Internacional de Agricultura Tropical (CIAT), Cali, Colombia. The source was selected for plants with high pollen abortion rates (mean = 91%) and for failure to set any seed or pods by self-pollination when grown in screened greenhouses. These male-sterile plants were crossed with the snap bean ‘Sprite’, and the resulting F1 progenies were all male-sterile under greenhouse conditions. The F1 plants were backcrossed to ‘Sprite’ and the BC1 progenies did not segregate for male-fertile plants under field conditions. Four more backcrosses to ‘Sprite’ have produced progenies that were uniformly male-sterile. It was concluded that the CIAT source of male sterility is inherited through the maternal parent and is cytoplasmic. Nineteen commercial cultivars of snap beans and dry beans were crossed onto BC3 plants, and none of these genotypes restored the pollen fertility in F1 progeny.
Abstract
Comparison of corn (Zea mays L.) kernels derived from common F2 families that were homozygous sugary (su) or homozygous for an allele of brittle (bt), termed bt-A, showed that bt-A kernels germinated nearly as well as su kernels and the time period for silking was identical in the 2 classes. The bt-A gene conditions twice the sucrose level found in su kernels.
Abstract
A single recessive gene was found to be responsible for the abnormal fruit ripening of ‘Alcobaca’ tomato (Lycopersicon esculentum Mill.). This gene causes a ripening syndrome characterized by attenuated respiratory activity and ethylene production, delayed softening of the fruit, low polygalacturonase (PG) activity, and extended shelf life. Allelism tests showed that the mutant gene of ‘Alcobaca’ is allelic to nor. It is proposed that the symbol nor A be used to refer to this mutant. The nor A allele is dominant to the nor allele.
`Redcoat' soldier bean cultivar originated from off-type, virgarcus patterned seeds found in a foundation seed lot of `Red Hawk' dark red kidney bean (Phaseolus vulgaris L.). These off-type seeds were hypothesized to be the result of a single gene mutation. A mutation at either of two loci involved in bean seedcoat pattern expression, T or Z, could convert self-colored seedcoats to a virgarcus pattern. The results of test-crosses of `Redcoat' and `Red Hawk' to lines with known alleles at the seedcoat pattern loci indicate that the dominant T allele of `Red Hawk' mutated to recessive t in `Redcoat'. The mutant t gene prevents expression of red veins in wing petals due to v rk d, and enables expression of the z gene (and possibly other genes) carried cryptically by `Red Hawk'. On the basis of preliminary data, we speculate that the two types of virgarcus patterns observed (classic in `Redcoat' and standard in the tester) may be controlled by different Bip alleles as they interact with t z.