晚秋叶施尿素和生长调节剂对富士苹果幼树贮藏氮素的影响

EFFECTS OF AUTUMN FOLIAR APPLICATION OF ~(15)N-UREA AND SEVERAL PGR ON N STORAGE AND REUSE IN APPLE

Effects of autumn foliar application of ~(15)N-urea and several plant growth regulators ( PGR ) on N storage and reuse in young apple plants (Malus pumila Mill. ) were studied. Foliarly applied ~(15)N-urea (3.5%)or NAA ( 60ppm ) during autumn enhanced the retranslocation of leaf N to other plant parts and they also increased level of stored N, Either of them increased the pro-teolytic activity of the leaves; therefore, such activities appear to be a major mechanism of retranslocation of leaf N. GA ( l00ppm ) increased the proteolytic activity of the leaves ; yet it could not increase the level of stored N. There were no marked effects of autumn BA ( 100 ppm ) , or CEPA ( 200ppm ) , or ABA ( 20ppm ) sprays on the retranslocation of leaf N, and stored N in the plants. Above-ground parts and roots of apple during winter season possessed the approximate portion of stored N; protein-N is main form of stored N.Nitrogen retrans-located benefited growth in next spring and produced more growth during the following seasons. A considerable portion of the plant N during the following second and third year was attributable to the foliarly applied N during the first year.