Paez A, Gonzalez ME, Tschaplinski TJ
Laboratorio de Ecofisiologia. Dept. Biologia, Facultad de Ciencias, Universidad del Zulia, Maracaibo, Venezuela
Environ Exp Bot. 2000 Oct 1;44(2):133-139. doi: 10.1016/s0098-8472(00)00062-9.
Research was conducted on Aloe vera, a traditional medicinal plant, to investigate the effects of light on growth, carbon allocation, and the concentrations of organic solutes, including soluble carbohydrates and aloin. The plants were vegetatively propagated and grown under three irradiances: full sunlight, partial (30% full sunlight), and deep shade (10% full sunlight) for 12-18 months. After 1 year of growth, five plants from each treatment were harvested to determine total above- and below ground dry mass. Four plants from the full sunlight and the partial shade treatments were harvested after 18 months to assess the soluble carbohydrate, organic acid and aloin concentrations of the clear parenchyma gel and the yellow leaf exudate, separately. Plants grown under full sunlight produced more numerous and larger axillary shoots, resulting in twice the total dry mass than those grown under partial shade. The dry mass of the plants grown under deep shade was 8.6% that of plants grown under full sunlight. Partial shade increased the number and length of leaves produced on the primary shoot, but leaf dry mass was still reduced to 66% of that in full sunlight. In contrast, partial and deep shade reduced root dry mass to 28 and 13%, respectively, of that under full sunlight, indicating that carbon allocation to roots was restricted under low light conditions. When plants were sampled 6 months later, there were only minor treatment effects on the concentration of soluble carbohydrates and aloin in the leaf exudate and gel. Soluble carbohydrate concentrations were greater in the gel than in the exudate, with glucose the most abundant soluble carbohydrate. Aloin was present only in the leaf exudate and higher irradiance did not induce a higher concentration. Limitation in light availability primarily affected total dry mass production and allocation, without substantial effects on either primary or secondary carbon metabolites.
对传统药用植物库拉索芦荟进行了研究，以调查光照对其生长、碳分配以及包括可溶性碳水化合物和芦荟素在内的有机溶质浓度的影响。这些植物通过营养繁殖，并在三种光照强度下生长：全光照、部分光照（全光照的30%）和深度遮荫（全光照的10%），持续12 - 18个月。生长1年后，从每个处理中收获五株植物，以测定地上和地下总干质量。18个月后，从全光照和部分遮荫处理中各收获四株植物，分别评估透明薄壁组织凝胶和黄叶渗出物中的可溶性碳水化合物、有机酸和芦荟素浓度。在全光照下生长的植物产生的腋芽更多、更大，其总干质量是在部分遮荫下生长的植物的两倍。在深度遮荫下生长的植物的干质量是在全光照下生长的植物的8.6%。部分遮荫增加了主茎上叶片的数量和长度，但叶片干质量仍降至全光照下的66%。相比之下，部分遮荫和深度遮荫分别将根干质量降至全光照下的28%和13%，这表明在低光照条件下，分配到根中的碳受到限制。6个月后对植物进行采样时，光照处理对叶片渗出物和凝胶中可溶性碳水化合物和芦荟素浓度的影响较小。凝胶中的可溶性碳水化合物浓度高于渗出物，其中葡萄糖是最丰富的可溶性碳水化合物。芦荟素仅存在于叶片渗出物中，较高的光照强度并未导致其浓度升高。光照可利用性的限制主要影响总干质量的产生和分配，对初级或次级碳代谢产物均无实质性影响。
