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- Author or Editor: David H. Byrne x
Abstract
I would like to clarify the difference between two words that are frequently misused in our publications. I suppose the words “pollenizer” and “pollinator” have been confused since their invention, given their consistent misuse in at least one major pomology text (Tree Fruit Production by Tesky and Shoemaker). A pollinator is the agent of pollen transfer, which, in many species, are bees or some other insects; a pollenizer is the source of pollen, which is usually a flowerproducing plant. One recent paper talks of “planting of pollinators”, which brings up visions of planting bees in the orchard, and of “pollinator frequencies”, which indicates the author is referring to bee hive density, when the author was really referring to the density of trees as pollen sources. Another author was describing parentage of some tree fruits and said that cultivar A “was the progeny of unrelated unknown pollinators of” cultivar B. How fruit trees can be the progeny of fruit insects is beyond me! Of course, the authors meant to use the word “pollenizer”, not “pollinator”. Similar mistakes have been made throughout the literature equally by professionals in a range of disciplines.
Abstract
Genetic analysis of five presumptive isozyme loci in apricot (Prunus armeniaca L. and related species) revealed that the variation observed was controlled by two or three alleles in a simple Mendelian manner. This increases the number of known simply inherited traits in apricot from one to six. Linkage was not detected between MDH-1 and MDH-2.
Abstract
The mean inbreeding and coancestry coefficients of Japanese-type plums grown in California and the southeastern United States were one-half or less of those calculated for peach. The three most important founding clones for the major California cultivars were ‘Santa Rosa’, ‘Eldorado’, and ‘Gaviota’; for the plums of the southeastern United States they were ‘Methley’, ‘Santa Rosa’, and ‘Mariposa’. The species background of both groups of plums was ≈50% P. salicina, although the sources of P. salicina differed between groups. For the California cultivars, the other half was composed of P. simonii and P. americana, whereas, for the southeastern group, the major contributing species was P. cerasifera, with lesser contributions from P. simonii, P. americana, P. angustifolia, and P. munsoniana.
Despite the hundreds of existing stone fruit (Prunus spp.) cultivars used for fresh market, there is a continuing need to develop new stone fruit cultivars as the requirements of the industry change. Over the last 20 years there has been a shift toward private breeding as the public sector decreases its support of these long-range programs. As a result there are fewer public breeding programs and many of those still operating protect their releases and partially fund their programs with royalty payments. Other trends that are shaping the development of new stone fruit cultivars are a need for smaller or more easily managed tree architecture, a trend toward the use of fewer agricultural chemicals, the expansion of production zones into the milder winter zones to allow year-round availability of stone fruit, a general diversification of fruit types being marketed, the increased awareness of the health benefits of fruit consumption, the need for better and more consistent quality, and given the global marketing of these fruit the increased need for enhanced postharvest qualities. The breeding programs of the world are responding to these trends and working toward developing the cultivars for the world markets of the future.
Poor germination in Rosa spp. has hindered breeding programs for years. Several methods exist to increase germination of rose seed. Unfortunately no consensus exists on the best method, or if any one method is best for all rose types. Rose seeds from a R. wichuraiana × Old Blush hybrid were broken into 3 replications with an average of 400 seeds per replication. Seeds were leached at room temperature with tap water for a period of 0, 3, 7, or 14 days. Constant filtration and aeration were supplied. After leaching, seeds were placed on either moist milled sphagnum moss or agar. Seeds were then placed in a cold stratification (≈2.8 °C) treatment for 8 to 12 weeks. Individual seedlings were planted when a root was visible. The combination of no leaching plus the moist milled sphagnum moss treatment significantly increased germination over leaching for 3 or more days and agar.
Mild winter weather conditions reduce fruit yield and quality of many peach cultivars grown in the Medium Chill Region of the United States. Peach fruit shape instability limits marketing options for growers in this region. The Stonefruit Breeding Program at Texas A&M University evaluated a wide range of peach cultivars and breeder selections from throughout the world during the mild winters of 1988-198 9 and 1989-1990. Fruit shape response was highly variable among genotypes with similar chilling requirements. The implication of this is that the potential is high for eliminating fruit shape instability due to highly variable winter conditions in the Medium Chill Peach Production Region.
The Thai Tiger series of low-chill peaches are being released for use in subtropical or tropical highland regions and particularly for use in the northern highlands of Thailand to expand the harvest season of the present low-chill variety grown, ‘EarliGrande’. The Thai Tiger series are yellow-fleshed acid-sweet peach varieties that produce excellent yields of firm peaches and will allow a continuous harvest from early April until early May in the northern highlands of Thailand.
Six controlled crosses of cultivated and advanced selection Japanese-type plums adapted to southeast and southwest regions of the United States were made in 1990 and 1991. Over 800 seedlings from these crosses along with open pollinated seedlings of the parents were established in Suiting nurseries. The long range objective of this study is to determine linkage relationships between RAPD markers and commercially important traits (soluble solid, resistance to bacterial leaf spot, chilling requirement, fruit development period). The first step in the projects to characterize RAPD genotypes in the progenies. Eighty oligodecamers have been screened and 57 yielded successful reactions with an average of two to three bands per primer. The variability and inheritance of the RAPD markers in these plum populations will be described.