Seleção de genótipos de soja resistentes a raças de Heterodera glycines e a Pratylenchus brachyurus

Abstract

The nematodes are among the factors that contribute for decrease in of soybean production mainly in the central region of the country. Although the culture is attacked by various nematodes Heterodera glycines e Pratylenchus brachyurus worth mentioning, by difficulty in finding resistant cultivars P. brachyurus by the various existing physiological races of H. glycines. Faced of this scenario the objective with the present study select soybean genotypes resistant to races 1, 2, 4, 5, 6 and 14 H. glycines and P. brachyurus. The experiments were conducted in a greenhouse in a completely randomized design. The first in a factorial design 18 x 6 corresponding to soybean genotypes and races of soybean cyst nematode and the second with 12 soybean genotypes for resistance to P. brachyurus, both with five replications. The genetic material consisted of promising breeding genetic lineage of soybean, University Federal of Uberlândia program. Were included the differential cultivars Peking, Pickett, PI 88788, PI 90763, Lee Hartwig and 74 were included for characterization of races and Pintado, Conquista and crotalaria as patterns of susceptibility and resistance of P. brachyurus. Each experimental drive has been represented by two plants grown in a vase with a capacity of 1.5 dm3 of soil, containing a mixture of soil and sand in the proportion (2: 1). After seven days after sowing the seedlings were inoculated with their suspensions of 5 mL containing 3000 eggs and juveniles of H. glycines in the first experiment and 600 specimens of P. brachyurus second experiment in the root 2 cm hypocotyl. Were analyzed: plant height, stem diameter, chlorophyll index Falker and dry weight of shoot for H. glycines. After 30 days of inoculation with H. glycines, the roots were carefully removed from the vases for counting females and estimate the resistance index based on females. For P. brachyurus at 90 to days after inoculation the root system was removed for recovery nematode and calculated the reproduction factor calculated for each genotype. The genotypes UFUS 6901 and UFUS Mineira were moderately resistant to race 5 and 6, respectively .In relation to the nematode Genotypes UFUS 119, UFUS Guará, UFUS 6901, UFUS Tapajós, UFUS 8401, UFUS 7401, Villa Rica, UFUS 32 and UFUS 37 were statistically equal to the standard Crotalaria of the nematode resistance, and unfavorable or poorly suited to playing Pratylenchus spp.