TAILIEUCHUNG - Báo cáo lâm nghiệp: "in heating units pollination bags avoid damage to flowers by spring frost"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: in heating units pollination bags avoid damage to flowers by spring frost. | Ann. Sci. For. 1988 45 2 157-160 Electric heating units in pollination bags avoid damage to flowers by spring frost J. CH. FERRAND INRA Station d Amelioration des Arbres forestiers Centre de Recherches d Orleans Ardon F 45160 Olivet Summary An effective cheap and simple heating device was designed by INRA Orleans to prevent flower frost damages in outdoor controlled crosses. It consists of a small electrical resistance which is inserted in each individual pollination bag. A field experiment conducted on larch trees showed that not only the number of living flowers is significantly increased after a frost period but also the number of full seeds per cone. Key words Control pollination frost protection electric heating Larix. Controlled crosses are essential for forest tree breeding but spring frost can destroy the pollinated female strobili. For example at the INRA Forest Tree Breeding Station in Orleans France frost in March and April frequently damages flowers of larch Douglas fir walnut and wild cherry. It has been suggested that controlled crosses be done on grafted stocks in heated greenhouses. An effective and much less expensive method has been developed that increases seed yield from controlled crosses. It consists of a small heating device placed inside the pollination bag in the field. The device is constructed of mm diameter enamel coated Constantine wire sandwiched between strong adhesive tape and aluminium foil. The aluminium foil increases the heat radiation surface and avoids excessive temperature Experiments in a controlled temperature chamber showed that in still air a unit with dimensions of 25 X 10 cm could increase the temperature in a 50 X 15 X 12 cm paper pollination bag by l c per watt. In 1983 a field trial of the heating units was performed in the clone banks of hybrid larch Larix X eurolepis Henry and of European larch Larix decidua Mill. at Orleans. Household current 220VAC was brought to the clone bank and transformed to 24VAC. The .

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