Influence of soybean genotype on rate of seed maturation and its impact on seedborne fungi.

PLOPER, L.D.; ABNEY, T.S.; ROY, K.W.

PLANT DISEASE

AMER PHYTOPATHOLOGICAL SOC

Año: 1992 vol. 76 p. 287 - 292

0191-2917

Soybean (Glycine max) maturation rate, measured as the length or duration of late-season growth satge intervals and rate of moisture loss, was studied in a diverse group of soybean genotypes (plant introductions and adapted cultivars) to determine the role of plant and seed dry down on Phomopsis spp. and Cercospora kikuchii. A modified scale for late-season growth stages was developed and used to identified pod and seed maturation intervals after physiological maturity (R71, R72 and R73, identified by 1, 25, and 50% of all pods with mature pod color respectively). Length of the R71-R8 period during major pod and seed dry down was associated consistently with the incidence of seed infection. Among genotypes with nearly identical maturities, soybeans resistant to seedborne diseases had shorter R71-R8 intervals and a greater rate of moisture loss than susceptible soybeans. Incidence of pod infection by Phomopsis spp. or Cercospora kikuchii was similar for soybean entries that matured under similar environmental conditions, regardless of their seed susceptibility under natural field conditions or to inoculation with P. sojae or C. kikuchii. Only susceptible genotypes showed a rapid increase in seed infection between R71 and R8, when pod and seed moisture decreased from 30-35% to 15-18%.