Abstract

GILL-LANGARICA, Homar René; MALDONADO-MORENO, Nicolás; PECINA-QUINTERO, Víctor  and  MAYEK-PEREZ, Netzahualcóyotl. Reaction of improved soybean [Glycine max (L.) Merr.] germplasm to Macrophomina phaseolina (Tassi) Goidanich and drought stress. Rev. mex. fitopatol [online]. 2008, vol.26, n.2, pp.105-113. ISSN 2007-8080.

The reaction of 73 experimental lines and ten soybean cultivars (four from Mexico and six from abroad) to a highly virulent isolate of Macrophomina phaseolina was evaluated in vitro (seed) and in the greenhouse (seedling), under irrigated drought-stress conditions in order to identify resistant germplasm to the fungus. Thirty seeds of each genotype were cultivated for five days in Petri dishes with cultures of M. phaseolina. The germplasm was established in the greenhouse using a split-split factorial arrangement, where the large plots were two humidity levels (irrigated: irrigation each third day; and drought stress: only one irrigation at sowing); intermediate plots corresponded to M. phaseolina levels (inoculated and control), and small plots were assigned to the 83 soybean genotypes. Mexican experimental lines H86-5030 and H98-1552, as well as Mexican cultivar Suaqui-86 were moderately resistant to M. phaseolina in vitro and under greenhouse conditions, while 96.5% of the soybean germplasm evaluated was susceptible in vitro and 85% under greenhouse conditions. In greenhouse, drought stress increased M. phaseolina infections and reduced seedling dry weight. The inoculation with M. phaseolina also reduced soybean growth and aggravated drought stress effects based on biomass accumulation.

Keywords : Charcoal rot; genetic resistance.

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