Eficiência do método de multiplicação rápida da Embrapa em duas cultivares de mandioca (Manihot esculenta Crantz.) no Oeste do Pará: Um estudo de caso

Abstract

Cassava cultivation is of great national importance, but there are obstacles to its large-scale propagation, since it has a low multiplication rate, since from one plant, 5 to 10 manioc stems, each 20 cm long, can be obtained. In order to overcome these difficulties, Embrapa Mandioca e Fruticultura, based on a study developed by CIAT (1982), employed a simple and inexpensive method, adapted to brazilian conditions, which has shown positive results in the northeast region of Brazil. This method can increase the multiplication rate of cassava by up to 60 times, and is therefore considered a rapid multiplication method. In this context, the objective of this study was to evaluate the efficiency of the rapid propagation method in two cassava cultivars in the western region of Pará, through a case study. The experiment was carried out in greenhouse I of the Campus Universitário de Juruti (CJUR/UFOPA), using two cultivars: Coaraci, acquired in the Juruti region; and BRS Poti, developed by Embrapa and acquired in Vila Fátima - Tracuateua (PA). The experiment was conducted in three stages, as follows: 1st) Propagation chamber with mini-cuttings; 2nd) Rooting chamber with mini-stems; and 3rd) Seedling establishment and acclimatization. In the 1st stage, two beds were used, each filled with a different type of substrate: Bed 1 - soil 1 + 20% cattle manure; and Bed 2 - soil 2 + 20% cattle manure. Each bed was subdivided into 10 parts, with 50 mini-cuttings with 2 to 3 shoots distributed in each unit. The cultivars were randomly selected, and there were 5 spaces with each cultivar in the two beds implemented. In the 2nd stage, the stems were placed in boiled water for rooting, and in the 3rd stage, using the destructive methodology with 20 plants of each cultivar, the plant height, diameter, fresh mass, dry mass and root volume were measured. For stages 1 and 2, descriptive statistics were applied to evaluate the method. In the third stage, the Student's t-test was used, at 5% significance, to verify the difference between the cultivars. The Coaraci cultivar showed a higher quantity of mini-stems obtained, however, a lower number of rooted ones, and consequently, a lower number of acclimated plants. BRS Poti showed greater efficiency related to the mini-stems collected and acclimated plants. In general, regarding the acclimated plants, the cultivars did not show differences between the parameters dry weight, fresh weight and root volume. However, Coaraci showed a higher number of leaves; and BRS Poti, greater plant height.