Adaptabilidade e estabilidade de genótipos de soja no Estado do Mato Grosso e reação de 111 genótipos à ferrugem asiática

Abstract

The major objectives of this study were to evaluate phenotypical adaptability and stability of soybean genotypes in the state of Mato Grosso, using different methodologies and to identify soybean genotypes with partial resistance to Asian rust (Phakopshora pachyrhizi) under artificial inoculation. Phenotypical adaptability and stability were evaluated in three subsequent years (2003/04, 2004/05, 2005/06), two trials, divided into culture cycle (semi-early/ medium and semi-late/late), in counties of the state of Mato Grosso, using as experimental design randomized blocks, with three repetitions. All genotypes belonged to the breeding program of UFU. Joint analyses were done with genotype x planting location and genotype x planting location x harvest, and the averages were compared by the Scott Knott and Tukey tests for subsequent computation of phenotypical adaptability and stability by seven different methods: multivariate method AMMI, reability index; bi-segmented linear regression method; simple linear regression; deviation of the ideal maximum method, variance components method, and method of ecovalence. The experiment to evaluate partial resistance to Phakopsora pachyrhizi was done in Uberlândia-MG, in a green-house, from December 2004 to February 2005 and consisted of three evaluation periods. he following resistance characteristics was evaluated: average latent period (PLM), average number of pustules per leaflet and rust severity. Based on the variables average number of pustules per leaflet and rust severity the area under the disease progress curve was calculated. Subsequently, analysis of variance was done and the averages compared by the Scott Knott test, at 5% probability. The methodologies studied for phenotypical adaptability and stability were similar and complemented each other for the results obtained. The environments differed in favorability as a function of agricultural year. In the early trials, harvest 2003/04, the most productive materials were genotypes UFU 01, Msoy 8400 and Emgopa 316; in 2004/05 was line UFU 19, while in 2005/06 was UFU 13, 18, 22, 23, 24, 27, 28, 29, 35, 36 and Msoy 8585. The lines UFU 23 (harvest 2004/05) and UFU 24 (harvest 2005/06) presented phenotypicial adaptability and stability in all methodologies evaluated. As for the semi-late/late cycle trial a greater performance was found for line UFU 21 (Confiança x Xingu) in the harvest 2004/05 and the materials UFU 18 (FT 50.268-M x Msoy 8400) and 28 (IAC 8-2 x IAC 100), in the harvest 2005/06. Partial resistance to Asian rust was found in genotypes P 5001 and Coodetec 78. The variables studied can be recommended for epidemiology studies of the pathosystem soybean x P. pachyrhizi. Cluster analysis allowed grouping genotypes with partial resistance to Asian rust.