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The long-term variation in yield of English apple orchards and of 2 main cultivars are examined. Three factors determining yield are specified: the weather, the alternate-year bearing character of apple trees, and the technology (the introduction of semi-dwarfing rootstocks, higher-density plantings and new management techniques) as represented by time. Time was the most significant factor in increasing yields in the long term. Weather, particularly during the pre-flowering period was shown markedly to affect the crop from season to season. The model developed can be used to predict current production up to 5 months before harvest.When yield varies widely from year to year, a decrease in the area cropped has little effect on production and hence policies aimed at marginally reducing orchard area would have little short-term effect on overall production. 相似文献
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The conditions prescribed in economic theory for “equilibrium” in an industry are “normal” earnings for those engaged. That best-known area of intensive horticulture, the Westland in South Holland, reached approximate economic equilibrium in 1971. Not all the constituent sectors of the industry were in mutual equilibrium, and to remain in overall equilibrium few additional resources will be permissible, although output must continue to increase relative to input.In the past such normal earnings are believed to have stimulated producers to further, unjustified expansion. Under current conditions Westland producers will be spared the consequences of unjustified response, because they will need to concentrate upon avoiding the trap of excess capacity. The purchasing power of their most important crop, tomatoes, being now seriously and progressively reduced, rationalization of production under glass is necessary and this is a difficult enough exercise in itself. 相似文献
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The problem of year-to-year variation in English apple crops was studied for the cultivar ‘Cox's Orange Pippin’ by analyzing data collected from similarly-managed commercial blocks of trees. In the period 1971–1975 yields, in each block of trees, moved in the same direction each successive year. In low-average yield years the variation in yield tended to be as extensive as in high-average yield years. Over the period studied, no relationships between climatic factors during the blossoming-period and subsequent yield could be determined. The most important factor linked with low-average yield was found to be above-normal temperatures in the pre-blossom stage.It was postulated that in order for a tree to carry a crop to its full potential, a decisive vernal temperature impulse is needed. If this dormancy break does not occur, because of above-normal temperatures, a full crop cannot be carried, even though subsequent weather conditions are optimum. Yield failures are attributed to some hormonal or other physiological imbalance occurring due to the lack of the normal decisive vernal dormancy break.It was shown that the alternate-year bearing pattern evident in apple crops in the United Kingdom, The Netherlands and Belgium between the years 1971 and 1975 could be explained by this hypothesis. 相似文献
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R.R.W. Folley 《Scientia Horticulturae》1973,1(1):43-55
Applying the economic concept of efficiency to the physiological behaviour of higher plants leads to a conclusion that deciduous fruiting trees in a Mediterranean location do not profit from their environment to the extent climatic parameters would suggest.The potential yield of commercial apple orchards in southern Europe is postulated to be less than 50% greater than on good sites in northern Europe, whereas some climatic parameters differ by 60 %.Given a constant proportional superiority for the south, the absolute gain over the north in physical yield will increase as the skill of the grower increases: it does not follow, however, that in practice as average levels of skill increase, southern growers will find their competitive advantage over northern growers thereby improved. 相似文献
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An economist's review on the choice of tree from and planting system for commercial apple production
R.R.W. Folley 《Scientia Horticulturae》1973,1(3):205-219
Desirable specifications for apple orchards are propounded, with reference to occupancy of the ground, mean volume of leaf canopy, light-interception properties, and labour productivity. It emerges that model high-yielding trees are relatively small and grow quickly, but are required not to take up more than a previously-allotted space and also to grow in an unnatural form.A conflict arises between the high-yield model and its associable labour productivity, both in old-fashioned and in new types of orchard. In the context of modern practice, the increasing cost of labour is likely to have more severe effects on labour-intensive systems than on tree-intensive systems notwithstanding the expectation of lower quality of crop where labour input is also lower. 相似文献
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