A influência dos fatôres irrigação e estação do ano sôbre a fineza e a resistência da fibra do rami

Inglés. A study concerning the quality of ramie fiber of the Murakami variet, grown under conditions or not of irrigation, combined or not with chemical fertilizing, and coming from four consecutive urowth periods (summer autunm. winter, and spring) is here reported by the authors. This study was made on samples of chemically degummad fibers obtained from mechanically decorticated crude fiber ribbons. Qualily determinations weremade for fineness and tensile strength of fibers corresponding to the base, middle, and tip sections of the ramie stalks. Concerning the loss of weight by the degumming process, it was found that the lowest occurred in the crude fiber ribbons from the base section of the stalk, and that there was in any case a progressive increase in loss from base to up. Differences in loss for the three fiber positions were highly significant. As regards the treatments and growing seasons, the differences in the loss of weight of the crude fiber ribbons were significantly higher only for not irrigated plot and for autunm and spring plant growths. In relation to fineness, a highly significant difference was found for fiber positions in the stalk, the fiber of the tip section being significantly finer than that of the other two stalk sections. Considering the fiber of the irrigated plot against that of the not-irrigated plot there was a barely significant difference, the fiber of the last treatment being a little finer. The fiber from the winter growth was significantly finer than that of the summer growth, but only a little finer as compared to those of the autunm and spring growths. Tensile strenght differences were highly significant for fibers from the lip and base sections of the stalks, while for growing seasons they were barely significant. Fibers of the tips sections were significantly stronger than those of the base section, but a little stronger when compared with those of the middle section. No difference was found between the fibers of the base and middle sections of the stalk regarding tensile strength. Concerning the season of growth it was found that the fibers from the summer growth were significantly weaker for tensile strength than those of the other growing seasons, mainly as compared to those of the winter growth. Irrigation and fertilizing treatments had no effect on fiber tensile strength. To conclude, it may be stated that if fine and strong fibers were in demand by any ramie mill, it might be practical before degumming to divide at middle the bundles of crude fiber, and to handle the superior half separately, or besides this, to work only with crude fiber ribbons from plant winter growth. These facts must be considered by breeders and fiber technologists in any ramie breeding and selection program or technological studies concerning tiic sampling for comparing fiber characteristics between ramie varieties or fibers coming from distinet producing countries.

Portugués. Os autores analisam e discutem os resultados dos estudos sôbre os efeitos da irrigação e estação do ano nas características de resistência à tração e de fineza das fibras do rami Murakami, em amostras de fibras desgomadas químicamente e correspondentes às posições base, centro e poiila dos caules.