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Abstract
Recently, the USDA/ARS announced a policy on cultivar development which calls for a reduction of 2 million dollars for breeding of horticultural crops (1). It has been indicated that this reduction will take place “upfront,” early in the proposed 6-year readjustment period. A significant decline in the number of public vegetable breeders also is projected in the State Agricultural Experiment Stations (SAES) by the year 1990 (unpublished data, H. Brooks and G. Vest, 1983 National Survey of Horticulture Administrators). Many believe that this decline in numbers has begun already. Coupled with the loss of ARS breeding programs, this reduction by SAES could signal the end of significant public investment in genetic improvement of important vegetable crops. There has not been a corresponding increase in private plant breeding activity for most vegetable crops to compensate for the reduction in the public sector.
Abstract
Onion (Allium cepa L.) bulbs exposed to light during all or a half of a 6-month storage period produced plants that flowered 2 to 4 days earlier than those kept in continuous dark. Bulb storage at 7°C resulted in earlier flowering than did a temperature regime of 2° the first half and 7°C the last half of the storage period.
Abstract
A questionnaire on genetics and breeding of horticultural crops, in conjunction with our responsibilities to the National Plant Genetics Resources Board (an advisory board to the Secretary of Agriculture under authority of Secretary’s Memorandum 1875 Revised dated 23 Feb. 1978), was sent to appropriate department chairmen or program leaders in Land Grant Universities, 1890 institutions, and the USD A Agricultural Research Service (ARS). The purpose of the questionnaire was to survey past, present, and anticipated programs on breeding and genetics of horticultural crops and to solicit views on national needs for germplasm of horticultural crops. Responses on the status of programs were received from all 98 questionnaires, and 74 respondents made comments on national needs.
Abstract
‘Jersey Centennial’ asparagus (Asparagus officinalis L.), tested under the designation Rutgers-Michigan Hybrid 202, is a new cultivar that is more vigorous, rust resistant, and productive than the ‘Mary Washington’ strain when grown on the fusarium-infested soils of New Jersey. It was also the most productive asparagus cultivar in a Michigan yield trial on noninfested soil.
A national trade model of the fresh onion (Allium cepa L.) market is used to identify the capability of Texas to compete with other production areas in dry onion sales throughout the United States. The analysis shows Texas and western U.S. producers to be major competitors in the spring and summer seasons. While Texas producers' proximity to major eastern markets yields a cost advantage, their market share is vulnerable to cost reductions by western U.S. shippers. Thus, both cost-reducing innovations (production) and quality improvements are important in maintaining the competitiveness of Texas producers.
Abstract
The peroxidase activity in bulbs of 3 onion (Allium cepa L.) genotypes known to differ in their dormancy characteristics was investigated at 2 stages of bulb development. Peroxidase activity was estimated by the oxidation of p-phenylenediamine, and peroxidase isozymes were studied by acrylamide gel electrophoresis. The peroxidase activity of all 3 genotypes was the same in young bulbs (1.5 – 2 cm, diam), but in mature bulbs peroxidase activity differed with genotype. Bulbs with short dormancy had higher activity, and a greater no. of isozymes than bulbs with long dormancy. A commercial preharvest spray of maleic hydrazide (MH) did not affect peroxidase activity in bulbs of either dormancy type.
Abstract
The diallel cross technique was used to evaluate the performance of onion (Allium cepa L.) inbred lines in F1 combinations and to estimate combining ability of several traits. All possible crosses, including reciprocals, among 10 inbred lines of diverse origin and known horticultural performance were tested at 3 locations in 1973. Cytoplasmic male-sterility was used to insure that all seed from maternal plants was hybrid. Cross variances were highly significant for all traits at all locations. General combining ability effects accounted for most of these differences. Specific combining ability effects were significant at all locations for yield, weight/bulb, firmness, and percent of storage loss. In all instances variance components of general combining ability were larger than those of specific combining ability. Specific rankings of the best and poorest lines for the traits measured according to the effects of their general combining ability were not identical at each location, but the same inbreds were generally in the same positive or negative grouping. Inbreds M728 and M2399 transmitted substantial yield and bulb weight to their progeny, while la163 consistently depressed these traits in the F1's. These results confirm the contribution that inbreds M728, M2399, and la163 make to a hybrid. Significant mean squares for reciprocal effects were apparent at all locations for only yield and maturity. Maternal effects per se influenced reciprocal variation, but were, generally, less important than nonmaternal reciprocal causes.
Abstract
A diallel analysis was used to estimate combining ability of several traits in onion (Allium cepa L.) and evaluate the importance of interactions of general combining ability (GCA) and specific combining ability (SCA) with locations and years. All possible crosses among 7 inbred lines of diverse origin and known horticultural performance were tested for 2 years at the same 3 locations for yield, maturity, bulb traits, and storage quality. Highly significant differences among crosses were detected for all traits. The partitioning of among-cross variation showed that all GCA main effects were highly significant, and SCA main effects were significant for all traits but ring thickness. Cross × environment interactions were primarily due to the interactions of GCA effects with environments. The GCA × year interaction was significant for bulb firmness and centers/bulb, and the GCA × location interaction was significant for yield. While first-order interactions involved only GCA effects, all traits showed significant second-order interactions of both GCA and SCA with years and locations. Variance components of GCA were predominant for all characters, and ratios of GCA to SCA ranged from 2:1 for centers/bulb to 13:1 for % of storage loss. Variance components of GCA × environmental interactions at all levels and for all traits were always smaller than those for GCA main-effect components. For the traits maturity and % of storage loss, the SCA × year × location component was larger than the SCA component. Correlations of GCA effects between environments suggested that significant interactions of GCA were sometimes due to a 1) change in rank of effects from environment to environment and 2) a change in rank and change in variance.
Abstract
Nine inbred onion (Allium cepa L.) lines of diverse origin and known horticultural performance were crossed in diallel to measure the extent of heterosis for yield and 6 other traits and to evaluate the types of gene action involved in character expression. Parents and the 36 F1 hybrids were compared at 2 locations (Michigan and Wisconsin) in 1975. Average performance of the parents and hybrids showed good agreement between environments for yield and several other traits. The mean performance of F1 hybrids fell within the range of parents for all characters. Although not always significant, F1’s on the average yielded more, were earlier to mature, had greater bulb weights, more centers, fewer rings, and were less firm than the average of the better parents in crosses. Heterosis was significant and favorable at both locations for yield, maturity, and bulb weight, but unfavorable for centers/bulb. Yield heterosis of the hybrids over the mid- and high parent, respectively, were 39 and 20% at Palmyra, Wisconsin and 27 and 12% at East Lansing, Michigan. In general, high F1 yields were associated with crosses involving high yielding parents. Variances of general combining ability (GCA) predominated for all traits. Small but significant specific combining ability (SCA) effects were noted for maturity, bulb firmness, and % of storage loss.