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Pollination of fruit trees is required to produce seeds with surrounding fruit. It is the process of moving pollen from the anther to the stigma, either in the same flower or in another flower. Some tree species, including many fruit trees, do not produce fruit from self-pollination. The pollination process requires a carrier for the pollen, which can be animal, wind, or human intervention (by hand-pollination or by using a pollen sprayer). Cross pollination produces seeds with a different genetic makeup from the parent plants; such seeds may be created deliberately as part of a selective breeding program for fruit trees with desired attributes. ==Apple== Most apples are self-incompatible, that is, they do not produce fruit when pollinated from a tree of the same cultivar, and must be cross pollinated. A few are described as "self-fertile" and are capable of self-pollination, although even those tend to carry larger crops when cross pollinated from a suitable pollenizer. A relatively small number of cultivars are "triploid", meaning that they provide almost no viable pollen for themselves or other apple trees. Apples that can pollinate one another are grouped by the time they usually flower so cross-pollinators are in bloom at the same time. Pollination management is an important component of apple culture. Before planting, it is important to arrange for pollenizers - varieties of apple or crabapple that provide plentiful, viable and compatible pollen. Orchard blocks may alternate rows of compatible varieties, or may plant crabapple trees, or graft on limbs of crabapple. Some varieties produce very little pollen, or the pollen is sterile, so these are not good pollenizers. Good-quality nurseries have pollenizer compatibility lists. Growers with old orchard blocks of single varieties sometimes provide bouquets of crabapple blossoms in drums or pails in the orchard for pollenizers. Home growers with a single tree and no other variety in the neighborhood can do the same on a smaller scale. During the bloom each season, commercial apple growers usually provide pollinators to carry the pollen. Honeybee hives are most commonly used in the United States, and arrangements may be made with a commercial beekeeper who supplies hives for a fee. In Japan, orchard bees are more commonly used, one species providing 80% of the apple pollination.〔( The Role of Pollen Bees in Fruit Tree Pollination and Some New Cautions on Pesticide Use ) Orchard bees in the genus Osmia have been shown to be more effective at pollinating apples than honeybees. One species, known as the Japanese orchard bee (JOB), is used for pollinating over 80% of all apples in Japan, and is related to several other species used as commercial pollinators of apple and pear in Europe, and almond in the western U.S.〕 According to Christopher O'Toole's ''The Red Mason Bee'', ''Osmia rufa'' is a much more efficient pollinator of orchard crops than the honeybee.〔Christopher O'Toole, The Red Mason Bee, ISBN 0-9539906-8-0, page 26〕 Home growers may find these more acceptable in suburban locations because they do not sting. Some wild bees such as carpenter bees and other solitary bees may help. Bumble bee queens are sometimes present in orchards, but not usually in enough quantity to be significant pollinators. Yet another kind of bee cultivated for orchard pollination is the hornfaced bee. It is used in Japan, and increasingly in the US, because it is up to 100 times more efficient than the honeybee, a mere 600 hornfaced bees being required per hectare, as opposed to tens of thousands of honeybees.〔(Solitary Bees For Orchard Pollination ) For the past 15 years, in late winter, I have sent "starter kits" of hornfaced bees, including instructions and materials for nests, to growers, beekeepers, scientists, extension agents, schools, and nature study centers in many states. The bees have survived best in humid parts of USDA Plant Hardiness Zones 5 to 8. Because these bees are so efficient, only about 600 female bees are needed per hectare of orchard; this compares favorably with the usually recommended two hives of honey bees (with tens of thousand of workers) per hectare. Hornfaced bees strongly prefer the flowers of Rosaceae, and, unlike honey bees, they are not readily distracted by dandelions and other weeds. An individual hornfaced bee is 80 times more effective than an individual worker honey bee for pollination of apples (Maeta 1990).〕 Symptoms of inadequate pollination are small and misshapen apples, and slowness to ripen. The seeds can be counted to evaluate pollination. Well-pollinated apples have best quality, and will have seven to ten seeds. Apples with fewer than three seeds will usually not mature and will drop from the trees in the early summer. Inadequate pollination can result from either a lack of pollinators or pollenizers, or from poor pollinating weather at bloom time. Multiple bee visits are usually required to deliver sufficient grains of pollen to accomplish complete pollination. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fruit tree pollination」の詳細全文を読む スポンサード リンク
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