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In Puerto Rico, harvesting beans (Phaseolus vulgaris) near physiological maturity enhances the value of the crop. Green-shelled beans are generally harvested 60-65 days after planting avoiding disease and pest problems that occur at the end of the growing season. It is also suited for multiple cropping and intensive rotations. Field experiments were conducted on the northern (Isabela) and southern (Fortuna) coastal plains of Puerto Rico to measure the effect of genotype, planting date and level of moisture of the seed at harvest on the yield and quality of green-shelled beans. The most adapted genotypes produced more than 5000 kg/ha of whole pods and 2200 kg/ha of green-shelled beans at both locations and growing seasons. Genotypes having different seed types were found to produce acceptable green-shelled yields. Whole pod yields were lower when harvested at the semi-dry stage than at the stage of development recommended for harvesting green-shelled beans. However, bean yields were similar when harvested at the green-shelled and semi-dry stages of development.
Starch gel electrophoresis was employed to study inheritance and diversity of allozyme loci in a sour cherry (2n=4×=32) germplasm collection. Segregation data was collected for alcohol dehydrogenase (ADH), glucose phosphate isomerase (GPI), isocitrate dehydrogenase (IDH), leucine amino peptidase (LAP), malate dehydrogenase (MDH), peroxidase (PX) (cathodal activity), phosphoglucomutase (PGM), 6-phosphogluconic dehydrogenase (6-PGD), and shikimate dehydrogenase (s k d h).
Data suggest that alleles can be assigned to many of the enzyme systems being studied: ADH, GPI, IDH, LAP, PGM, and 6-PGD. Most loci are diallelic and often exhibit the unbalanced heterozygous condition. MDH, PX, and 6-PGD are highly polymorphic. Progeny segregation data fit disomic inheritance models, indicating that sour cherry is an allotetraploid.
Abstract
Field experiments were conducted at two locations in Puerto Rico to measure the effect of growth habit on the ability of bean (Phaseolus vulgaris L.) genotypes to compensate for variation in plant population in hill-plots. Five determinate and five indeterminate bean genotypes were grown in 1-m-diameter hill-plots ranging in population from two to 10 plants per hill-plot. The indeterminate genotypes produced a greater seed weight per hill-plot, a smaller 100-seed weight, a greater number of pods per plant, and a greater number of seeds per pod than the determinate genotypes. Number of seed per pod and 100-seed weight did not differ significantly as the number of plants decreased from 10 to two plants per hill-plot. Number of pods per plant and seed yield per hill-plot increased in a linear fashion as the number of plants per hill-plot decreased. A covariance analysis using number of plants per hill-plot as the cov-ariate would be appropriate for adjusting hill-plot yields for variation in plant population. The similarity of the seed yield response of determinate and indeterminate bean genotypes to varying population density would permit both habits to be analyzed in a single covariance analysis.
Heritability of length of the reproductive period and rate of seed mass accumulation in beans (Phaseolus vulgaris L.) was estimated using 170 randomly derived F6 and F7 lines from three populations evaluated in the field in Puerto Rico and Honduras during two growing seasons. Narrow-sense heritability for length of reproductive period ranged from moderate (0.43) to high (0.83), and transgressive segregation for shorter and longer reproductive period was observed for the three populations. Heritability of rate of seed mass accumulation was low (0.24) to intermediate (0.49). Lines with high yield potential, which matured 4 to 7 days earlier than the later parents L227-1 and `Catrachita', were selected. Most of the superior lines combined earlier maturity with high yield potential by having greater rates of seed mass accumulation than the early parents `Cuarentena' and `Cuarenteño'. Low to intermediate heritabilities for rate of seed mass accumulation suggest that selection for this trait would be more effective by evaluating advanced generation lines in replicated trials. Several lines yielded significantly more than L227-1 or `Catrachita' by combining long reproductive period with fast rate of seed mass accumulation.
Abstract
A study was conducted in Puerto Rico to estimate the outcrossing rate of six common bean (Phaseolus vulgaris L.) genotypes when planted in December or May. Two experiments were conducted for each date, one using indeterminate and the other determinate genotypes. In each experiment, homozygous dominant and recessive genotypes were planted in alternate rows to permit natural cross-pollination. Percent outcrossing was calculated based on the number of heterozygous individuals observed in the progeny of the homozygous recessive rows. Significant differences in the rate of outcrossing were observed between genotypes and between planting dates. The dwarf outcrossing (do) genotype had rates of 15.9% and 39.3% for the December and May planting dates, respectively. Outcrossing rates of stipelless lanceolate leaf (sl) and dark green savoy (dgs) genotypes did not differ significantly from the white-flowered (p) genotype, which was < 1% for both dates. Outcrossing rates < 1% were also observed for both planting dates for the determinate genotypes.
Field reaction of 25 red mottled bean (Phaseolus vulgaris L.) genotypes to common bacterial blight [Xanthomonas campestris pv. phaseoli (Smith) Dye] was evaluated in Puerto Rico over 2 years. The average disease severity (percent leaf area with symptoms) was similar over years. The determinate red mottled genotypes had almost twice as much disease as indeterminate genotypes. Eight of the indeterminate genotypes had significantly less disease than the mean of the field experiments. These genotypes may serve as useful sources of resistance to common bacterial blight. The size of the chlorotic zone around necrotic lesions varied between growing seasons, showing that environment can influence the expression of common bacterial blight symptoms.
Methods to improve the grain yield of red kidney bean without the addition of commercially fixed nitrogen will have significant benefits to farmers in Jamaica and other tropical regions. Red kidney beans provide a major portion of the dietary protein for most families in these regions. Our experimental objective was to evaluate the nitrogen fixing capabilities of several breeding lines of Phaseolus vulgaris when inoculated with Rhizobium strains isolated from Jamaican soils. Surface sterilized seeds of 11 Phaseolus lines were inoculated with inoculum prepared from 5 day old Rhizobium YEM mixture. Rhizobium used were T2 and B17 from Jamaica and UMR 1889. The greenhouse study was arranged as a completely randomized design. Bean lines 9056-101, 9056-98B, 8954-5 and 8954-4 showed improved nodulation and N2 fixation when inoculated with UMR 1899. The combination of breeding line 8954-5 and Rhizobium strain B17 produced the highest nodule number and shoot dry weight of 193 and 0.72 g, respectively. The Rhizobium strain B17showed some ability to compete successfully for nodule sites against known effective strains.
High levels of resistance to common bacterial blight caused by Xanthomonas campestris pv. phaseoli (Smith) Dye (Xcp) have been observed for tepary bean (Phaseolus acutifolius A. Gray var. latifolius Freeman). However, the inheritance of resistance from this source is unknown for many lines. The inheritance of common bacterial blight resistance was studied in four tepary bean lines crossed with the susceptible tepary bean MEX-114. Progenies were inoculated with a single Xcp strain 484a. Segregation ratios in the F2 generation suggested that resistance in Neb-T-6-s and PI 321637-s was governed by one dominant gene, and Neb T-8a-s had two dominant genes with complementary effects. These hypotheses for inheritance of resistance were supported by various combinations of F1, F3, BC1Pn segregation data in all lines except PI 321637-s where an additional minor-effect gene with recessive inheritance was indicated. Generation means analyses corroborated that multiple resistance genes were present in PI 321638-s. Lack of segregation for susceptibility among testcrosses for allelism between Neb-T-6-s/PI 321637-s, Neb-T-6-s/Neb-T-8a-s, PI 321637-s/Neb-T-8a-s, and PI 321637-s/PI 321638-s, suggested that one or more loci conditioning resistance to common bacterial blight were in common across the four tepary lines.
184 random F2 plants from a high temperature (HT) sensitive X HT tolerant snap bean cross were advanced to the F5 by single seed descent. At anthesis and after HT pre-treatment, all plants in each generation were evaluated in the laboratory for leaf ethylene evolution (EE), % viable pollen (VP), and leaf cell membrane thermostability (CMT). Population means among generations differed significantly for VP and CMT in a paired t-test, while EE means in the F3, F4, and F5 were similar. Correlations among traits were very low (≤.25) with a consistent negative correlation between VP and the others (high VP is a positive trait while low EE and CMT are considered positive). VP and total pollen were highly correlated (r≤.81). To determine if the 3 traits might predict HT tolerance in the field, F5-derived F6 lines were grown at Becker, MN (control), and Isabella, PR (HT environment). Yield component data were collected at both locations. Tolerance may be computed as % yield of the lines in the HT vs. the control environment for any or all of the yield components. Regression analysis showed a very low r2 (≤.16) when EE, VT, and CMT were used to predict tolerance as estimated by pod production. However, as expected, the F5 best predicted F6 performance. Further results from Minnesota field and greenhouse and from Puerto Rico field data will be discussed.
Genetic variation for abaxial leaf pubescence was detected among dry bean (Phaseolus vulgaris L.) cultivars/lines. Inheritance of pubescence (long, straight hairs) was studied in the dry bean crosses of pubescent `Pompadour Checa-50' (Dominican Republic) × eight glabrous cultivars/lines. Segregation for pubescence vs. glabrousness indicated that pubescence was determined by a single major gene or by duplicate recessive epistatic genes, depending on the cross involved. Trichome density (number trichomes per mm) was a quantitative trait. Thus, pubescence was a discrete trait, but trichome density ranged from low to high.