Sweet Clovers, a Source of Fibers Adapted for Growth on Wet and Saline Soils

ABSTRACT

Sweet clovers are legumes able to grow on most soils, and two sweet clover species, Melilotus albus and Melilotus officinalis have been introduced and are now cultivated on estuary land. We characterized the composition and morphology of sweet clover stems collected after the seeds had reached maturity. We also carried out histochemical analyses on transverse sections. The two species had similar morphological structures, which two fiber fractions: flexible long fibers and stiff, dense shives, accounting for about 12% and 88% of stem dry matter, respectively. Histological analysis revealed the presence of bundles of highly cellulosic bast fibers (lignocellulosic material: 71–78% of dry matter). The shives are a natural mesoporous material composed of 85–90% lignocellulosic fibers. Both fiber fractions displayed good thermal resistance to temperatures up to 225°C and a moderate affinity for water. These two types of fibers are similar to those of flax and hemp, suggesting their possible use for the same types of applications. Sweet clovers therefore constitute a new source of fibers that can be cultivated on wet and saline soils not otherwise suitable for agriculture.

摘要

草木樨是适宜在大部分土壤中生长的一种豆科植物，目前引入的有白花草木樨和黄香草木樨两个品种，现已在河口土地上栽培。本文主要研究草木樨在种子成熟后其茎部的特点和形态。我们还对其横截面进行了组织学分析。这两个品种有类似的形态结构，其纤维有两个组成部分：柔软的长纤维和粗硬的密植物性杂质，在干物质中分别约占 12％ 和 88％。组织学分析表明存在高纤维质韧皮纤维束（木质纤维材料：占干物质的 71–78％）。植物性杂质是一种天然孔状材料，包含 85–90％ 的木质纤维。这两种纤维成分都表现出良好的耐热性（高达 225℃），对水具有中等亲和力。这两种类型的纤维类似于亚麻和大麻纤维，表明它们可用于与后者相同类型的用途。因此，草木樨可作为不适合其他农作物种植的潮湿和盐碱土壤上的新纤维来源。

KEYWORDS:

• Bast fiber
• fiber crops
• Melilotus alba
• Melilotus officinalis
• natural fiber
• saline wet soil

关键词:

• 麻类纤维
• 纤维作物
• 白花草木樨
• 黄香草木樨
• 天然纤维
• 潮湿盐渍土壤

Acknowledgments

The authors want to thank Aurélie Le Ru and Alain Jauneau from the imagery platform Toulouse Réseau Imagerie of the INRA (France) for histological preparations and their valuable assistance in the interpretation of biological structures.

Funding

Authors would like to thank the ANR for his financial support CIFRE and the community of common “Coeur d’Estuaire” for the logistical support.