Efeito de manipueira no controle do nematóide de cisto da soja Heterodera glycines Ichinohe

Abstract

The objective of this study was to evaluate the effect of liquid waste, produced by the cassava industry in Western Paraná, on the soybean cyst nematode Heterodera glycines Ichinohe through in vitro and in vivo essays. In vitro and in vivo essays were performed in randomized experimental designs with 5 replications for each treatment as follows: water (positive control), nematicide (negative control) and cassava waste at 5%, 10%, 15%, 20%, 25%, 50%, 75% and 100% for the in vitro test and cassava waste at 10%, 25%, 50%, 75% and 100% for the in vivo test. The in vitro tests were performed with eggs, J2 and cysts of H. glycines, which were immersed into each solution for 24 hours and then inoculated into pots containing soybean plants with two mature leaves. The evaluation occurred 30 days after inoculation (dai). The in vivo essays were carried out with one application and two applications of cassava waste. The in vivo essays started with the inoculation of 5,000 eggs and/or J2 of H. glycines on soybean plants. Forty five dai, liquid waste was applied in the pots and soybean plants had their shoot cut. Twenty four hours after the first application, new soybean plants were transplanted to the pots. To the essay with two applications of liquid waste, the second one was run 75 dai but keeping the same plants after application. The evaluation for the in vivo essays occurred 60 days after the transplanting. The variables assessed were plant height, shoot length, root length, number of cysts, number of females and eggs per root system, fresh weight and dry weight of plants and the reproduction factor of H. glycines on soybean plants. The cyanide content for the cassava waste was determined as 40 mg.L-1 in manipueira 100%, using the kit Microquant (Merck). The in vitro essays showed that the number of J2 decreased significantly and progressively (R2=0,82) from cassava waste 15% to 100%. For eggs and cysts, the cassava waste treatments from 10% to 100% were more efficient than the control water. Moreover, cassava waste at 25% concentration showed the lowest values for number of eggs and cysts for the in vitro essays. For the in vivo essays, two applications of cassava residue allowed a better development of soybean plants, allied to a decrease on the number of females and cysts of H. glycines, when compared to one application alone. The treatments cassava waste at 50%, 75% and 100% were superior to the others but cassava waste at 50% showed the lowest values for the number of females and cysts