Reação de cultivares de Phaseolus vulgaris L. aos fitonematóides de importância primária

Abstract

Phytosanitary problems, among other factors, are the main cause of low productivity in the common beans crop. The presence of nematodes in the crop is a direct cause of low yield. The reproduction of the nematodes Heterodera glycines race 3, Melodogyne incognita, M. javanica and Pratylenchus brachyurus was evaluated in eleven bean cultivars under greenhouse conditions. A completely randomized design with six replicates was used in this study. Ten days after sowing, seedlings were transplanted and inoculated with 4000, 5000, 2000 and 110 eggs/seedling, with H. glycines, M. incognita, M. javanica and P. brachyurus, respectively. Evaluation occurred 35, 60, 60, and 45 days for the nematodes, in the sequence previously presented. The number of H. glycines females in the root system was counted and the cultivars presented values ranging from 2.50 ( Diamante Negro ) to 15.17 ( Emgopa 201-Ouro ). The soybean cultivar Conquista , used as control, presented 30.50 females per root system, differing significantly from the other bean cultivars. Only the cultivars Diamante Negro , FT-Nobre , and Iapar-80 , showed reproduction factors above 1.0 for Meloidogyne javanica. The tomato plant Santa Clara, also used as control, presented reproduction factor (RF) of 9.85. All bean cultivars were considered bad hosts for M. incognita, with RFs smaller than 1.0. The Santa Clara tomato presented RF of 6.18. Pratylenchus brachyurus presented reproduction factors near zero for all bean cultivars as well as for the control treatments tomato Santa Clara and maize 30F33. The low multiplication rates of the phytonematodes found in this study, in comparison with literature results of similar plants, could be explained by the inoculum source for the two Meloidogyne species and by the low level of inoculum used for Pratylenchus brachyurus.