Agronomic potential of Reseda luteola L. as new crop for natural dyes in textiles production

Six weld genotypes (Reseda luteola L.) were evaluated for their agronomic characteristics in a 4-year field study carried out under rainfed condition in Central Italy in order to point out productive potential and the best harvest time to maximise yield of dye. Good agronomic performances were observed with an overall dry yield of about 40 g per plant and an estimated dry yield per hectare of 2.8 tons. Differences were found among the six accessions and some of them withstanded well to drought conditions experienced in drier growing seasons. The harvest of plants during flowering or during beginning of fruit ripening did not affect overall dry yield (40 and 45 g per plant at flowering and fruit maturity, respectively). The luteolin amount (expressed in mg g(-1) dry weight) was affected by climatic conditions as experienced in two different growing seasons (1993 and 1994) and by the plant phenological stages at harvest being luteolin most abundant in the dryest year and in plants harvested during flowering. Genetic variability existed for the luteolin content in leaves plus reproductive structures (inflorescences and fruits) that varied from 13.6 to 28.7 mg g(-1) dry weight in the six accessions tested in 1994. The dry powder from leaves and reproductive structures was used in the dyeing of cotton, wool and silk yarns. Good and bright yellow colours were observed using a ratio 30:100 (weight/weight) of weld on the textile materials. Separated weld organs showed different dyeing capacities being the leaves, inflorescences and fruits the most effective ones. Weld showed a progressive decrease in resistance to fading going from cotton, to the other kind of yarns. Finally, all dyed specimens exhibited good resistance to light and wash fastness making the use of weld a viable alternative to synthetic yellow dyes. (C) 2003 Elsevier Science B.V. All rights reserved.