三个种源侧柏一年生苗木对磷的吸收

ABSORPTION OF PHOSPHORUS BY ROOTS OF ONE-YEAR SEEDLINGS OF PLATYCLADUS ORIENTALIS(L.) FRANCO. FROM THREE PROVENANCES

用３２Ｐ示踪原子法研究了一年生侧柏根系吸收磷的规律和影响因素。结果表明，生长和适应有代表性的３个种源侧柏，山东泰安（ＳＴ）、贵州黎平（ＧＬ）、和内蒙包头（ＮＢ）吸收３２Ｐ的规律相同但数量不同。ＳＴ、ＧＬ和ＮＢ吸收３２Ｐ的速率遵从方程Ｖ＝Ｖ０Ｅｘｐ（Ｋｔ），外流速率遵从Ｅ＝Ｅ０／（Ｋｍ＋ｔ）２。种源侧柏的基因型差异、生理活性和环境条件都影响其对Ｐ的吸收。ＳＴ、ＧＬ和ＮＢ的半吸收期Ｔ１／２在营养液中分别是６．４、６．１和５．８ｈ，在土壤中分别是４０．７、１８．４和７．５ｈ；在营养液中的外流最大量一半所需的时间Ｋｍ分别是０．９、５３和１４ｍｉｎ。ＳＴ、ＧＬ根部褐色区吸收３２Ｐ中比ＮＢ多，黄褐区类似而根尖区相反。苗木吸收的Ｐ大部分积累在根部，其余的向地上部分运输，ＳＴ、ＧＬ和ＮＢ上运３２Ｐ的速度分别是３．０、４．０和２．２ｃｍ／ｈ，上运量ＧＬ＞ＳＴ＞ＮＢ。

The processes and the influence factors of phosphorus absorbed by one-year seedling roots of Platycladus orientalis from three provenances,Taian,Shandong (ST), Liping, Guizhou(GL), Baotou, Inner Mongolia (NB), were studied with isotope atom indicator, 33P. As a result, the patterns of the P uptaken in the three provenances were similar, while the quntities uptaken were different. The absorption rate of -H2PO4 (32P) varied according to V= V0exp (Kt). The efflux rate according to E=E0/ (Km +t)2,where V0, E0, K, Km are constants, t is time variable. The absorption of phosphorus is influenced by some factors, such as the genetic variation, the physiological activities and the surroundings of the provenances. The half-time (T1/2) of P(32P) absorption for ST,Gl and NB were 6. 4, 6. 1 and 5. 8h respectively when cultured in nutrient solution, but they are 40. 7, 18. 4 and 7. 5h, partyly when cultured in soil. The half-time for P(32P)maxium efflux (Km) are 0. 9, 53,and 14 min separately. When the parts of root from root-tip to upper 0- 0. 5cm, 0. 5-7. 5cm and 7. 5-14. 5cm Were determined to root-tip or white, yellow-brown and brown sections, respectivly, at the brown section of the root more P (32P) were uptaken by ST and GL than NB, at the yellow-brown were similar but at the root-tip zone, white section, less were uptaken by the formers than the latter. Most of P(32P) had entered the seedlings remained in the roots and less were transported up to the part above the ground. The speed of movementin ST, GL and NB were 3. 0,4. 0 and 2. 2cm/h and the mass removed were GL >ST>NB.