A experimentação do sisal: parte I - experiências de espaçamento

Abstract

<abstract language="eng">Sisal (Agave sisalana Perrine) accounts for about one half of the world's production of hard fibers. In spite os its economic importance pratically no research work has been carried out on this plant. Very little is known about the agronomic problems of its cultivation, while the physiological and genetic problems are nearly unknown. This is perhaps due to the fact that A. sisalana is a perennial plant with a life cycle of 5-8 years and the carrying out of field research work requires a great deal of time and is very expensive. This paper, the first of a series to be published on the agronomic problems of sisal cultivation, presents the data obtained from field trials on distance of planting and its relation to weight and number of leaves produced. The experiments were carried out at the Ribeirão Preto and Pindorama Experiment Stations of the Instituto Agronômico de Campinas. Sisal bulbils about one year old were planted in the latter part of 1939 in 4 randomized blocks of 9 plots each where different distances between and within the rows were used. Production data were obtained by cutting the leaves at one year intervals begining 2 ½ years from date of planting in the field. Only those leaves that were attached to the plant at an angle greater than 45.° in relation to the main axis of the plant were cut each year. Only in the trial at Ribeirão Preto the leaves were counted and weighted by plants. In the poling plants all leaves than existing were taken off, even the youngest ones adjacent to the pole (flower stalk). Descorticator machine for fiber extraction was not available, so that reliable data on fiber yield could not be obtained. A "probable" fiber yield was obtained by using 3% of leaf w r eight as a basis for calculations. This percentage is recognised as an average fiber content usually obtained from sisal leaves. From the data obtained from the spacing trials described in this paper the following conclusions can be drawn : 1. The life cycle from date of field planting to poling stage of most of the sisal plants in these trials varied from 5 to 8 years. A very small number of plants however had not poled even after 8 years when the present experiments were ended. 2. The life cycle of the sisal plants showed a close relationship to planting distances. At the greater planting distances the plants tended to pole much earlier than at closer planting distances. 3. It was observed that there was a marked seasonal incidente of poling. The flower stalk of almost all plants have appeared during the period of January to March. 4. A marked effect to the distance os planting on plot yields, as measured by total leaf weight, was observed. The greater the density of plants per unit area the greater the leaf production. 5. Under present leaf cutting practice, e. g., to cut yearly only the leaves at an angle greater than 45.° in relation to the main axis of the plant, the shorter distances between the rows are not recommended. The narrow spacing between rows not only restricts the passage of wo...