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- Author or Editor: Jim Hancock x
N.I. Vavilov, Academician of the V.I. Lenin All-Union Academy of Agricultural Sciences, takes his place as a founding pillar of knowledge in the cathedral of the origin and development of cultivated plants. Relying on the theories of his revered predecessors, Charles Darwin and Alphonse de Candolle, Vavilov developed the concept of centers of origin for agronomic crops. Vavilov’s astute hypotheses set the stage for the modern use of exotic germplasm in plant breeding. Vavilov, a devoted scientist, continued to revise and refine his theory of the centers of origin throughout his lifetime based on additional plant collections and data evaluation. Though he initially proposed three in 1924, and eight in 1935, his final papers of 1940, discussed seven major centers with some minor additions. His concept of specific centers of origin for crop plants was not an isolated aphorism but has directed breeders, on their study and reflection, to the continued improvement and economic development of plants for humanity. Inherent genetic plant variability is the basis of domestication and breeding into crops of economic importance with food, fuel, fiber, and industrial uses. The objective of this article is to present a summary of Vavilov’s plant explorations. His collection trips led to the development of his theory of the centers of origin of cultivated crops, the law of homologous variation, as well as his concept of genetic erosion. Further modification of his theories by other scientists and the impact of his ideas are mentioned. His influence on present day conservation of genetic resources are presented.
Most highbush blueberries (Vaccinium corymbosum L.) in Michigan are treated annually with fungicides and insecticides with several types of sprayers. The goal of this study was to determine how sprayer type, pruning severity, and canopy development interact to affect spray deposition patterns. Deposition was measured as the percentage of the surface area of card targets that was covered following applications of black dye. Light measurements indicated that the canopy of blueberry bushes, regardless of pruning treatment, closed by the middle of June, and light levels within the canopy changed little from then until fruit harvest in August. A standard airblast sprayer that pushed spray up and through bushes provided acceptable deposition in all parts of the canopy early in the season, but later in the season, coverage was poor in the top and sides furthest from the sprayer. An above-row sprayer with fan-driven micronozzles also provided acceptable coverage throughout the bushes early in the season, but once the canopy had closed, coverage was poor in the bottom of the bush. Both sprayers were operated in bushes receiving light, moderate, and heavy pruning. The more severe pruning regimes increased the amount of spray deposited from the above-row sprayer, but not from the airblast sprayer.
Controlled-atmosphere storage had little effect on the quality of fruit of eight cultivars held under 2 kPa oxygen (O2) and 8 kPa carbon dioxide (CO2) versus ambient air. ‘Elliott’ fruit harvested from bushes with only 30% ripe fruit had significantly better storage quality than fruit picked later; however, there was no significant difference in the storage life of fruit that was stored fully blue versus partially green. Fruit from the first harvest of four cultivars had superior storage quality to that of the second. In one comparison of the long-term storability of nine cultivars, ‘Bluegold’, ‘Brigitta’, and ‘Legacy’ performed the best, storing for 4 to 7 weeks. In another postharvest trial of 17 cultivars, ‘Brigitta’ stored the longest (8 weeks) followed by ‘Aurora’ and ‘Draper’ (7 weeks). The most resistant genotypes to Alternaria spp. were ‘Brigitta’, ‘Aurora’, ‘Elliott’, and ‘Draper’, whereas the most resistant genotypes to Colletotrichum spp. were ‘Elliott’, ‘Brigitta’, ‘Toro’, ‘Draper’, and ‘Bluejay’.
Fragaria species are in different plodiy levels (from 2n = 2x = 14 to 2n = 8x = 56) and distributed in almost all parts of the arable areas of the world. The flora of Turkey has wild strawberries, some of which are harvested for their small, but very aromatic berries. There are also old cultivars found in Turkey that are known for their aromatic fruits. We made collection trips to the Marmara and Black Sea areas to collect both wild strawberries and old cultivars in Summer 2004. During these trips, we sampled 50 populations from the altitudes of 6 to 2007 m, lat. 35°91'N to 41°76'N latitudes, and long. 26°81'E to 42°65'E. The samples were propagated in a greenhouse and evaluated in a replicated trail for both taxonomic and horticultural traits in an unheated greenhouse. The chromosome numbers of the genotypes were also determined. The results indicate that Turkish strawberry germplasm consists of both diploid and octoploid species. The principal components and cluster analysis separated the genotypes into three groups: octoploid cultivars and/or derivatives (e.g., `Madame Moutot'), and two diploid Fragaria species, vesca and viridis. Further relationships of the genotypes will be discussed.
Highbush blueberries (Vaccinium corymbosum L.) in Michigan are treated annually with fungicides to control fruit rots caused by Colletotrichum acutatum J.H. Simmonds, Alternaria sp., and Botrytis cinerea Pers.:Fr. Control with recommended fungicide programs is often inadequate. The goal of this study was to compare the effects of two spray treatments and three levels of pruning severity on fruit rot levels in mature `Jersey' bushes. Two spray treatments were tested for 3 years: 1) recommended fungicide rates applied with a conventional airblast sprayer; 2) 67% of recommended fungicide rates applied with a multifan/nozzle, above-row sprayer. Pruning treatments included light and heavy pruning (compared for 1 year), and light, moderate, and heavy pruning (compared for 3 years). Fruit rot incidence was determined after incubating individual fruit at 100% relative humidity and 21 °C for 7 to 11 days, and after exposing 0.24-L plastic clamshell containers of fruit to simulated commercial handling. The above-row sprayer provided fruit rot control at least equivalent to the airblast sprayer even though less chemical was applied. Anthracnose rot in berries from the top of the bush canopy were reduced by pruning, but those in the bottom of the bush, and levels of other diseases were not consistently affected. Pruning also reduced yields, although the study was too short in duration to determine the long-term impact on production.