Search Results
Abstract
Semi-hard seed (SHS) in beans is defined as dry seed which does not imbibe water during a 24 hour soak, but which will gain moisture rapidly at high relative humidity within 14 days and then germinate normally. The inheritance of SHS was found to involve several genes. Soft seed was incompletely dominant to SHS. Narrow sense heritability ranged from 20 to 50% in populations studied. SHS was associated with excellent seed quality resulting in unusually vigorous seedlings.
Abstract
Inheritance of resistance to Pythium, Fusarium, and Rhizoctonia in snap beans, Phaseolus vulgaris L., was studied for three populations involving a common resistant parent (Cornell 2114-12) and 3 different susceptible parents. Pythium resistance was strongly associated with colored seed but resistance was found in some white seeded segregants and was widely influenced by degree of susceptibility of white seeded parents. In contrast to the widely accepted theory that colored seed and resistance to Rhizoctonia are tightly linked, Rhizoctonia resistance seemed to be independent of seed color. Heritability for Rhizoctonia resistance was 0.75 and 0.65 for broad and 0.32 and 0.29 for narrow sense heritability. Resistance to all three diseases was independent and quantitatively inherited. Correlations for resistance to Pythium and Fusarium in F4 with F3 selections (r = 0.557**) were in line with heritability expectations. In the Rhizoctonia selections, generation to generation correlation was high (r = 90**) among those with the best resistance but only moderate among those with moderate resistance. In view of the low narrow sense heritability, selection for resistance in later rather than earlier generations should be more effective.
Abstract
The response of 20 lines of beans (Phaseolus vulgaris L.) was studied at 3 stages of development: germination, vegetative growth, and bloom. Emergence evaluation at 12°C was preferable to 8° or 10°. Radicles in cold-tolerant lines did not emerge except at 10° to 12°. Radicles in standard cultivars emerged at 8°, but the seed rotted. Growth at 16° identified early maturing lines under cold conditions. 25° (day)/8° (night) during bloom identified those lines able to set fruits at low temperatures. These screening parameters correlated well with field performance for percentage of emergence, plant vigor, and yield under cool growing conditions. PI 165426, NY 5-161, and NY 590 exhibited the best overall cold tolerance.
Abstract
Pollen germination in vivo in beans (Phaseolus vulgaris L.) was less at 8° and 12°C than at 18°. There were large cultivar differences, and germination at 9 am was no different from that at 3 pm. Pollen from bean flowers grown in the greenhouse at 21° Day/18°C Night (D/N) was transferred to plants in bloom at combinations of 8°, 10°, and 12° N, and 20°, 25°, and 30° D. Pollen from plants at the 9 temperature combinations also was used to pollinate plants in the greenhouse. Pollen from plants grown at 30° as compared to 20° and 25°, resulted in reduced seed yields. Conversely, viable pollen transferred to plants at 30° reduced set insignificantly. Thirty/8° D/N combinations resulted in the lowest yields. Low night temperatures appeared to inhibit ovule viability. In contrast, high temperatures reduced pollen viability. NY 5-161 and OSU 1604 were more stable than BBL 47, BBL 92, and PI 165426 at both high and low temperatures.
Abstract
Lines and cultivars resistant to mechanical damage with white and colored seeds germinated 60–80% compared to under 20% for several major cultivars. Seed damage resistance was associated with transverse cotyledon cracking (TVC) resistance, r = .649, seed coat shattering (SH) resistance, r = .488, and seed coat weight, r = .373. The SH test indicates whether the seed coat is tightly or loosely adhered to the cotyledons. If % seed coat as a proportion of seed weight exceeded 10% and TVC and SH were under 10%, then damage resistance was almost always good. Weakness in any one character resulted in damage susceptibility. Damage resistant lines produced more vigorous seedlings than susceptible lines following seed maltreatment. Damage resistance was correlated, r = .722, with seedling vigor following seed impaction.
Abstract
Colored and white seeded inbred bean lines resistant to mechanical damage (MD) and transverse cotyledon cracking (TVC) were crossed with 2 susceptible white seeded snap bean cultivars. Resistance to both MD and TVC was inherited quantitatively although colored segregants were more resistant than white-seeded segregants, MD and TVC resistant white-seeded selections were obtained. Broad-sense heritability varied from 55 to 79% for MD and 53 to 93% for TVC; narrow-sense heritability resistance varied from 22 to 73% for MD and from 22 to 58% for TVC. Severe selection pressure for MD resistance on bulked F3 seed was shown to be a simple and practical method to obtain resistance.
Abstract
Three populations of beans were screened for resistance to white mold using a mycelium/juvenile stem inoculation (JSI) method on 3-week-old plants and an ascospore/blossom test on plants in bloom was used to test resistance of survivors of the JSI test. There were few survivors in the JSI test: 0.8% in the 4-way cross of susceptible × susceptible, 2% in the intermediate × intermediate crosses and 3.8% in 10 P. coccineus lines with intermediate resistance. JSI tests of the progeny produced more survivors, 17% from the first 2 populations. There was good agreement between the JSI test on juvenile plants and the ascospore/blossom tests on blossoming plants respectively. The JSI test appears to he an efficient method with which to identify individual plants with moderate resistance.