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New Opportunities in Breeding


Long before the days of modern plant breeding, farmers and gardeners had selected improved forms of wild plant species and had established, for many crops, productive cultivars giving goodquality produce. For example, most of the fruits and vegetables now grown in England, including the introduced species, have been established items of diet for at least several centuries. Many of the cultivars of fruits and vegetables that are grown today have changed little from the forms that were cultivated a hundred or more years ago. Where there have been substantial changes, often these have been made to adapt cultivars to make them suitable for new agronomic practices; to improve the uniformity of size, shape, color, and time of maturity; and to increase resistance to pests and diseases. Some of these improvements have increased marketable yields and economic returns to the grower, but there is little evidence that there have been genetic increases in total biological productivity. However, substantial increases in biological yields have been achieved by improved cultural practices, including the use of herbicides and crop protection chemicals and of more fertilizer, although in recent years there has been an increasingly vociferous environmental lobby to reduce the use of agrochemicals.