光强和光质对野外栽培高山红景天生物量和红景天甙含量的影响

Effects of field light intensity and quality on biomass and salidroside content in roots of Rhodiola sachalinensis

为探讨野外条件下光强及光质对高山红景天 (Rhodiola sachalinensis)生物量和红景天甙含量的影响 ,于 2 0 0 1年 5月 8日至 9月 16日在大兴安岭加格达奇的高山红景天种植圃地 ,利用纱布及红色、蓝色和绿色的滤光膜遮光处理 ,对生长 3a和 4 a的高山红景天进行了光强、光质控制实验。与温室实验类似 ,遮荫显著抑制高山红景天根的生长 ,并使红景天甙的含量略有提高。红膜处理使光强大约降低一半 ,但仅从光质的角度而言 ,红膜处理对根的生长影响不大 ,却显著增加了根中的红景天甙含量和产量 ,不过效果不如温室实验明显。绿膜处理未表现出对红景天甙积累的促进作用 ,这与温室实验结果不同。红膜处理不同天数的结果表明 ,处理时间对红景天甙含量提高的程度影响很小。这意味着在野外种植的情况下 ,可以在临近收获的最后一段时间用红膜对高山红景天进行处理 ,这样既可避免红膜处理对高山红景天根生长的抑制 (由于减弱了光照 ) ,又可显著提高根的红景天甙含量 ,从而达到大幅度提高红景天甙产量的目的。

Rhodiola sachalinensis A. Bor, a perennial herb, belonging to the family Crassulaceae, is mainly distributed at mountains of 1700～2500 m above sea level. It is a very important medicinal plant with high activities of anti-fatigue, anti-senescence and anti-radiation, due to the secondary product salidroside in its roots. Our previous research in a greenhouse has testified that shading can reduce biomass, salidroside content and yield in roots of Rh. sachalinensis , and shading with red film promotes salidroside content observably with a little negative effect on biomass, thereby results in a higher yield of salidroside in roots of Rh. sachalinensis . In the present paper, the effects of light intensity and light quality on plant growth and salidroside content in roots of Rh. sachalinensis in the field were investigated. Controlled experiments were performed on 3- and 4-year-old Rh. sachalinensis in 2001 at a nursery of Daxinganling Mountain (124°02′E, 50°30′N). Herbs were treated under red, blue and green films (relative light intensities were 51.76%, 26.96% and 24.80% of full sunlight, respectively), together with a control (CK) of no shading. All experiments started on May 8 and stopped on September 16, 2001 and Rh. sachalinensis roots were cropped on September. In treatment Ⅰ, Rh. sachalinensis plants were shaded by neutral cloth to achieve a same intensity as red-film-shading did during the experimental process. In Treatment Ⅱ, Red-film-shading was conducted all the time. In treatment Ⅲ, Ⅳ, Ⅴ or Ⅵ, plants were covered with neutral shading cloth from May 8, and then changed to red film on June 3, July 4, August 4 and September 2 (for 105, 74, 43 and 14 days of red-film-shading) respectively. In treatment Ⅶ or Ⅷ, blue- and green-film-shading were performed from the beginning to the end. In treatment Ⅸ, shading materials were shifted from neutral cloth to green film on September 2. Biomass and salidroside content were measured at the end of experiment, and salidroside yield (the product of salidroside content and biomass of root) was calculated. Shaded by neutral cloth positively affected salidroside content, but negatively did root biomass of 3- and 4-year-old Rh. sachalinensis (treatment Ⅰ) in the field, and synthetically resulted in a negative effect on salidroside yield in both 3- and 4-year-old Rh. sachalinensis with no significant difference to CK, which were similar to those results in a greenhouse. In the field, red film slightly decreased root biomass of 3- and 4-year-old Rh. sachalinensis (treatment Ⅱ, Ⅲ, Ⅳ, Ⅴ and Ⅵ) to their relative control of treatment Ⅰ, and a little severer biomass losses were showed while the treatment time prolonged. Similar to the results in a greenhouse, salidroside contents in roots of Rh. sachalinensis were improved significantly by red film, which were 57.13%～67.57% and 45.45%～55.27% higher than did neutral cloth in 3- and 4-year-old plants, respectively, and as a result, the enhancement of salidroside yields of 43.90%～73.02% in 3-year-old plants, and of 43.84%～47.46% in 4-year-old plants were observed. The difference among treatment Ⅱ~Ⅵ was of no significance which implied that the improvement of the accumulation of salidroside induced by red film did not depend on the spell of time, suggesting that we could treat Rh. sachalinensis plants under red film for a couple of days before harvest to yield more salidroside and less biomass losses. Long-term treatments (for 131 days) under blue and green films (treatment Ⅶ, Ⅷ) observably inhibited the growth of Rh. sachalinensis roots, whereas short-term treatment (14 days) with green film (treatment Ⅸ) affected root growth insignificantly. Though the results in a green house suggested that green film would also do favor to the production of salidroside in roots of Rh. sachalinensis as did red film, it did not show a corresponding result in the field. The content and yield of salidroside in roots of Rh. sachalinensis with short-term green light treatment were comparable to their control of treatment Ⅰ.