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- Author or Editor: Edward J. Ryder x
Abstract
Major reliance for protection of lettuce plantings from lettuce mosaic virus (LMV) in the United States is placed on a seed indexing procedure developed in California (1). The only major crisphead lettuce (Lactuca sativa L.) cultivar in the United States with resistance to lettuce mosaic has been ‘Vanguard 75’, released by the U.S. Dept. of Agriculture, cooperatively with the California Agricultural Experiment Station, in 1975 (3). ‘Vanguard 75’ is one of the important cultivars in the mid-February to early March harvest period in the desert districts of California and Arizona. It is also a major early cultivar in the spring season of the San Joaquin Valley. ‘Winterset’ is a new lettuce mosaic-resistant crisphead lettuce. It is suitable for the same periods and districts as ‘Vanguard 75’ and, in addition, is adapted for production in late winter in the desert.
Three chlorophyll deficiency traits in lettuce (Lactuca sativa) are reported. One, chlorophyll deficient-3 (cd-3), is quite yellow in the seedling stage, and controlled by a single recessive allele. Chlorophyll deficient-4 (cd-4) has sectors of yellow-green and green in the true leaves. It is inherited as a single recessive, and may be allelic to chlorophyll deficient-2 (cd-2). Sickly (si) is stunted, yellow, and partially necrotic, and is also controlled by a single allele. Virescent (vi) is epistatic to cd-4 and the latter is partially lethal. Linkage and additional epistatic relations with previously named chlorophyll deficient genes and other traits are discussed.
Abstract
The papers of this symposium will effectively illustrate the 2 most serious characteristics of the relationship between pollution and horticulture: there are innumerable problems to solve and there is little knowledge available to help solve them. An obvious conclusion is that there is a need for a massive research effort in the horticultural world to attack these problems. The ad hoc Committee on Environmental Pollution was formed over a year ago to alert horticulturists to this need and to help provide ideas, motivation, and means to develop appropriate research programs.
Abstract
It is said that environmental pollution is a cause that everybody can identify with, perhaps because it is so easy to blame others for it. Yet a little closer inquiry will show that nearly all of us contribute to pollution. The automobile emits polluting substances, but only when we drive it. High phosphate detergents cause eutrophication in our fresh waters, but only because we wash with them. We buy the products of the steel industry, and we use the electricity provided by the power companies.
Abstract
Since the publication of the list of lettuce lines and cultivars screened for resistance to common lettuce mosaic (2), many more materials have been screened. A second source of resistance was found and the screening technique was changed. This paper brings the list up to date and notes the changes.
Abstract
In the last 2 decades, 2 cultivars of lettuce (Lactuca sativa L.) have dominated the western U.S. lettuce industry. The first, ‘Calmar’ was released by the University of California in 1960. For several years in the mid-1960's, it was planted on nearly all the spring, summer and early fall acreage in the Salinas Valley and other coastal districts in California. It is a large, vigorous cultivar of the Great Lakes type. The second, ‘Vanguard’, was released by the USDA in 1958 and for many years has been the mainstay cultivar for early spring production in the Imperial Valley and other desert districts. Each cultivar has spawned a group of selections, a ‘Calmar’ group and a ‘Vanguard’ group, which have increased the adaptive range of the original cultivars.
Abstract
Lettuce mosaic virus (LMV), has been one of the most destructive diseases of lettuce (Lactuca sativa L.) in nearly all production areas of the world. One of the major goals of the USDA Lettuce Breeding Project in Salinas, California, has been to develop mosaic resistant cultivars. We began this program in 1959 with a search for sources of resistance. Three years later, we identified 3 resistant Plant Introductions from Egypt (3).
Abstract
Although plant breeding is very old, it has, at least during recorded history, seldom been short of new ideas and concepts that have made breeding procedures more and more powerful and effective. It is reasonable to speculate that the first act of plant breeding was the use of seeds from superior plants for the next year’s crop. Development of new technologies in the intervening years, has added to the power and versatility of the plant breeder’s art. Some of these changes have been spectacular, others rather modest.
Abstract
The Salinas River and the valley through which it flows are deceiving to the casual traveler driving through on a summer day. If he looks down while crossing one of the bridges over it, the river is quite unimpressive. The bed seems to be largely overgrown with weeds. The trickles and pools of water seem to have no movement. The traveler is likely to forego a second look and to relegate it to the far reaches of his mind with all the other dry streambeds of the West.