光照强度对金钗石斛吸收氮素的影响

应用15N 研究光强度对金钗石斛吸收氮素的影响，结果表明光强度为 2×104Lx 处理，在石斛生长的四个阶段吸收营养液中氮量分别比光强度为 5×10Lx 处理高 26．54％，50．07％，31．11％和 22．22％；吸收木屑培养基质中的氮量分别提高 32．84％，43．41％，21．85％和 19．01％；吸收总氮量分别提高 29．19％，46．44％，26．01％和 20．51％。在石斛生长的四个阶段，光照强度为 2×104Lx 处理，植株干物重分别比 5×103Lx 处理提高 12．40％，22．22％，17．08％和 15．00％；但是，光照强度为 5×103Lx 处理根干物重较光强为 2×104Lx 处理高 18．21％，9．63％，10．04％和18．45％。

EFFECTS OF LIGHT INTENSITY ON NITROGEN UPTAKE BY DENDROBE (DENDROBIUM NOBILE LINDL)

In an experiment with dendrobe (Dendrobium nobile Lindl) , the plants were grown on a wood chip medium under 2X10 4 Lx and 5X10 3 Lx and were irrigated with a 15 N-labelled nutrient solution at 8-day intervals from March 2,1998. Samples were taken on May, 19, July 22,September 24 and December 19 to study the effects of light intensity on N uptake by the plants. Analysis of the samples at the four dates showed that as compared with the treatment of low light intensity (5X10 3 Lx),N absorded from the nutrient solution by the plants increased by 26.54%,50.07%,31.11% and 22.22%, N uptake from the wood chip medium by 32.84%,43.41%,21.85% and 19.01%, total N uptake by 29.19%, 46.44%, 26.01% and 20.51%, and dry weight of the plant by 12.40%, 22.22%, 17.08% and 15.00%, respectively in the high light intensity treatment. However, dry weight of the root was greater in the low light intensity treatment, being 18.21%, 9.63%, 10.04% and 18.45% greater than that in the high light intensity treatment as measured at the four dates.