Parâmetros genéticos da resistência da soja ao nematóide de cisto Raça 1

Abstract

de freqüência e a análise de variância e, então, estimado o número de locos segregantes envolvidos na resistência das linhagens ao NCS (raça 1). Estimou-se o progresso de seleção (i = -2,154) entre as linhagens avaliadas (com diferentes números de repetições), bem como a herdabilidade em nível de média (h 2 ). Assim conclui-se que: a) A distribuição de normalidade das médias dos IF, bem como a estimativa da herdabilidade e a estimativa do número de locos segregantes indicam que a resposta das linhagens ao NCS (raça 1) tem caráter de herança poligênica; b) Foram encontradas linhagens promissoras para resistência ao NCS, porém, como este é de difícil avaliação recomenda-se utilizar maior número de linhagens F 6 na avaliação fenotípica e maior número de repetições para avaliação da reação ao NCS; c) A necessidade de se fazer correção para efeitos macroambientais aumentou o erro das estimativas.Palavras-chave: Heterodera glycines, resistência genética, Glycine max, ganho de seleção. ABSTRACT GENETIC PARAMETERS FOR SOYBEAN RESISTANCE TO RACE 1 CYST NEMATODEThis study aimed at verify the behavior of Recombinant Inbreed Lines, resulting of a cross between Hartwig (resistant parental) and EMGOPA-316 (susceptible parental) to NCS soybean nematode (race 1) and to estimate genetic parameters and those of selection progress. Estimated parameters used the mean female index (IF) obtained through the evaluation of 176 F 6 lines for NCS resistance. The genotypes were evaluated in greenhouse. The frequency distribution and the variance analyses were performed to estimate the number of segregating loci involved in the resistance to NCS. The selection progress was estimated (i = -2,154) among the lines evaluated using different numbers of repetitions, as well the herdability (h 2 ). It was concluded that: a) The normality distribution of the average IF, as well the estimated herdability and the number o segregation loci indicated the resistance to NCS (race 1) is poligenic; b) Promising NCS resistant lines were found. However, as the resistance test is difficult a larger number of F 6 lines and a larger number of repetitions should be evaluated; c) The necessity of correction due to macroenvironment effects increased the bias of the estimatives.

Genetic gain prediction in coffee progenies derived from the cross between Hbrido de Timor and Catua cultivars

“…Values of CV e ranged from 6.25% (PV) to 31.67% (NERG), revealing good experimental precision. High CV e values for the variables related to the nematode population in the roots were also found in other cultures by Moura et al (2008) and Silva et al (2011), and they may be explained by the complex methods used to evaluate this pathogen, especially under field conditions.…”

Genetic diversity in soybean genotypes with resistance to Heterodera glycines

“…The selection, identification and genetic studies of soybean cultivars with H. glycines-resistance have been conducted mainly in inoculated greenhouses , Moura et al 2008). However, according to Dias et al (2009a), the populations developed by Embrapa Soja, from the F 4 generation, whenever possible, are grown in areas infested with H. glycines, where the best plants are selected (in height, lodging resistance, cycle, disease resistance and yield potential).…”