光照强度对金钗石斛吸收氮素的影响

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

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× 1 0 4 Lx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× 1 0 3 Lx处理高 2 6 .5 4% ,5 0 .0 7% ,31 .1 1 %和 2 2 .2 2 % ;吸收木屑培养基质中的氮量分别提高 32 .84% ,43.41 % ,2 1 .85 %和 1 9.0 1 % ;吸收总氮量分别提高 2 9.1 9% ,46 .44 % ,2 6 .0 1 %和 2 0 .5 1 %。在石斛生长的四个阶段 ,光照强度为 2×1 0 4 Lx处理 ,植株干物重分别比 5× 1 0 3 Lx处理提高 1 2 .40 % ,2 2 .2 2 % ,1 7.0 8%和 1 5 .0 0 % ;但是 ,光照强度为 5× 1 0 3 Lx处理根干物重较光强为 2× 1 0 4 Lx处理高 1 8.2 1 % ,9.6 3% ,1 0 .0 4%和 1 8.45 %。

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.