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Soybean genotype analysis for cyst nematode resistance

Author(s): B.C.M. Juliatti, I.F. Beloti, L.C. Pena and F.C. Juliatti

Some species of soybean cultivars have the characteristic of resistance or alteration in survival skills, and perpetuation of nematodes (female index - FI), whose process is activated when the nematode parasitism starts and the development of new resistant cultivars is primordial to the preservation of plant productivity. The objective of this study was to identify the reaction of 101 soybean genotypes and two standards, one susceptible (M-SOY 8866) and the other resistant (BRSGO Raissa) of the Germplasm Laboratory of Federal University of Uberlândia (LAGER/UFU) improvement program, after inoculation of Heterodera glycines race 3 eggs. The evaluations 35 days after inoculation consisted of the fresh and dry weight of roots, root volume, the number of females (NF), and females index (FI). Genotypes 46 (F5: 6 BRSGO Caiapônia x 100 IAC) and 11 (Engopa 316 RR - Sel. 4) performed moderate resistance; the genotype 61 (F5: 6 Caiapônia x Potenza) had moderate susceptibility; and the rest of the genotypes presented susceptible. Between the genotypes, NF ranged from 9.5 to 159.7 and FI ranged from 17 to 214.8. The coefficient of genotypic determination (H2) was 70.28 (high) for NF, indicating genetic variation in the genotypes tested. Estimates of genotypic (rg), phenotypic (rf), and environmental (ra) correlation coefficients had lower magnitude values (<0.70). Analysis of the simple Pearson correlation was significant and positive between the variables dry weight (g) and root volume (cm3) but was not related to the resistance to the cyst nematode in the assay.