In crosses between stringless and stringy podded pea cultivars, all plants of the F1 and backcross to the stringy parent had stringy pods. F2 ratios varied widely among crosses, and populations always had more stringy plants than expected, based on a single locus. The ratio of nonsegregating (stringy): segregating F3 families derived from stringy F2 plants fit a single-gene hypothesis in half of the crosses. Backcrosses of F1 to the stringless parent fit the expected 1:1 ratio when the pollen parent was stringless, but the reciprocal backcrosses showed a deficiency of stringless plants, suggesting that poor competitive ability of pollen bearing the stringless factor was the reason for deficiencies of stringless plants. It is concluded that stringlessness is controlled by a single recessive gene for which the designation sin-2 is proposed. A reduction in pod size, plant height, and number of wrinkled seed segregates was associated with stringlessness.
There was no difference in percentage in vitro germination of pollen from stringless pea (Pisum sativum L.) cv. Sugar Daddy and stringy `Oregon Sugarpod II' (OSP) and `OSU 705' (705). However, pollen tubes of `Sugar Daddy' grew more slowly in vitro than those of OSP or 705. Differences in pollen tube growth rate were demonstrated in vivo following time-course pollinations involving reciprocal crosses of `Sugar Daddy' with OSP and 705, along with the selfed parents. After 8 hours, pollen tubes from stringless peas (“stringless” pollen) had entered 13% of the ovules compared with 51% for those from stringy peas (“stringy” pollen). Stringless pollen tubes entered 29% and stringy pollen tubes 66% of the ovules after 10 hours. The slower growth of stringless compared with stringy pollen tubes is a plausible explanation for previously observed deficiencies of stringless plants in segregating populations.
cultivar may be adapted to other temperate regions of the world having similar climatic conditions. Origin Early maturity and dwarf growth habit with attractive stringless green tender pods were the major breeding objectives for the development of the
Abstract
Bean plants (Phaseolus vulgaris L. cvs. Provider and Stringless Black Valentine) were exposed to 395 µg/m3 (0.08 ppm) peroxyacetyl nitrate (PAN) for 0.5 hr and subjected to drought stress following exposure. PAN influenced the plant water potential of ΡAN-sensitive ‘Provider’ resulting in visible wilting and reduced soil moisture content. There was no effect of PAN on the water relations of the PAN-tolerant ‘Stringless Black Valentine’.
Abstract
Eighteen bean cultivars were grown from seed in a growth chamber and exposed to 140 pphm ozone for 1 hr. ‘Sanilac,’ ‘Tenderette,’ ‘Blue Lake Stringless,’ ‘Bush Blue Lake 290,’ and ‘Spurt’ were the most sensitive to ozone; ‘Pinto 111’ was moderately sensitive; and ‘Black Turtle Soup’ and ‘French’s Horticultural’ were the most resistant. Necrotic flecking, dispersed over most of the leaf, characteristically developed on the cultivars ‘Spurt,’ ‘Early Gallatin,’ ‘Orbit,’ and ‘French’s Horticultural.’Necrotic patching, restricted to certain areas of the leaf, characteristically developed on ‘Sanilac,’ ‘Blue Lake Stringless,’ ‘Bush Blue Lake 290,’ ‘Bush Blue Lake 274,’ ‘Apollo,’ ‘Coloma,’ ‘Tempo,’ and ‘Black Turtle Soup.’ Pigmented lesions on adaxial surfaces developed on all ‘Sanilac’ plants and on some ‘Resistant Asgrow Valentine’ and ‘Pinto 111’ plants. A generalized chlorosis was observed on some plants of all cultivars. Cultivar sensitivity was evaluated by determination of chlorophyll concentration and visual observations. For most cultivars, similar estimates of injury were obtained by the 2 methods. Injury assessments differed the most for cultivars that developed the necrotic patching symptom.
Bean common mosaic necrosis virus (BCMNV) includes four African strains, BCMNV-NL3, -NL-5, -NL8, and -TN1, previously considered to be members of the bean common mosaic virus (BCMV) group. Many bean cultivars resistant to BCMNV-NL8 were found to be susceptible to the other strains of the virus. `California Light Red Kidney' (CLRK) and `Carbon', resistant to BCMNV-NL8, were crossed with the susceptible cultivars Sanilac or Black Turtle 2 (BT-2). In plants of F1, F2, and reciprocal backcross populations involving CLRK × `Sanilac' or BT-2 × `Carbon', the resistance to BCMVN-NL8 was determined to be conferred by a single dominant factor. The same factor was detected in BCMNV-NL8-resistant `Great Northern 1140' and `IVT-7214, when crossed with the susceptible cultivar Stringless Refugee or BT-2.
Abstract
Mosaic-like crinkled-leaved variegated rogues were found in the ‘Stringless Green Refugee’ snap bean variety. Grafting experiments suggested that this condition was not due to an infectious virus. The degree of expression of the symptoms was influenced by temperature and the symptoms appeared almost completely masked at 80°F. This suggests that effective selection against the rogue should be done in cool climates. Differences in the expression of the character was observed between field and greenhouse grown plants.
Segregation in the F2 ‘G.N. 1140’ X variegated rogue indicated that this character was controlled by a major gene with variegation being recessive. In reciprocal crosses between 2 ‘Bush Blue Lake’ lines X variegated rogue, almost complete elimination of the variegated plants was noted in segregating generations. The similarity of some of these results to serotype mechanisms and/or virus tolerance is discussed.
Abstract
The ozone-sensitive bean cultivars ‘Spurt’ and ‘Blue Lake Stringless’ and the ozone-resistant cultivars ‘Black Turtle Soup’ and ‘French’s Horticultural’ were grown from seed in a growth chamber. The resistant cultivars had 25% fewer stomata per mm2 leaf area than the sensitive cultivars and exhibited partial stomatal closure following exposure to 134 pphm ozone for 1 hr, while the sensitive cultivars did not. Stomatal closure was determined to be more important than reduced stomatal frequency in providing resistance to ozone. On the basis of previously established ozone dose-response data for P. vulgaris, the stomatal mechanisms appeared to account for the difference in ozone sensitivity between the sensitive and resistant cultivars. Neither leaf area nor leaf expansion rate were correlated with genetic resistance to ozone in these cultivars.
Abstract
The past quarter century has been a “Golden Era” for the development of a multitude of vegetable cultivars. We have seen the development of tomatoes that can be mechanically harvested with only slight injury to the fruit; sweet corn that is “super-sweet” with an extremely tender pericarp; green beans that are stringless and peas tha-t are very determinate and adaptable to mechanical harvesting. Countless other breeding achievements have been made in vegetable quality and adaptability, not to mention the broad spectrum of disease and insect resistance that has been bred into nearly every vegetable species. We can be thankful for our highly competitive system for bringing about so many of these advances in such a short time.
Abstract
Ozone sensitivity was compared in F1 and F2 populations from crosses between 2 ozone-sensitive bean cultivars, ‘Spurt’ and ‘Blue Lake Stringless’, and 2 ozone-resistant cultivars, ‘Black Turtle Soup’ and ‘French’s Horticultural’, under controlled environmental conditions. F1 plants were as sensitive as the sensitive parent. About 10% of the F2 progeny obtained by selfing F1 plants appeared to be as resistant as the resistant parent and 90% of the progeny could be divided equally between a group as sensitive as the sensitive parent and a group intermediate in sensitivity between the parent plants. However, precise separation of F2 progeny was not possible because of the variability in injury expression. The average injury on the F2 plants was greater than the parental midpoint value and the variance in injury on the F2 plants was about 3.5x greater than that for the parents. The heritability of resistance to ozone was estimated to be 0.83. It was concluded that ozone resistance is recessive in P. vulgaris and appears to be regulated by a few major genes.