Cold-tolerant sorghum hybrids and parental lines. III: Quality of seeds harvested from plants infected with Fusarium verticillioides (Sacc.) Nirenberg.

摘要

In an experiment conducted during 2003 in Montecillo, Mexico, under irrigated field conditions, 24 cold-tolerant genotypes (hybrids, parental lines, and cv. VA-110) were subjected to 3 inoculation treatments: (1) injection of the pathogen (F. verticillioides [Gibberella moniliformis]) in suspension (5x104 conidia ml-1), (2) injection with sterile water, and (3) absolute control, without inoculum or injection. Harvested seeds were assessed based on physiological quality (germination of normal and abnormal seedlings, dead seeds, vigour, and seedling dry matter production), physical quality (100-seed weight, volumetric weight, and number of seeds per gram), and sanitary quality (frequency of diseased seedlings). Tests were conducted to confirm the presence of F. verticillioides as the source of inoculum and transmission by seeds. Seeds harvested from hybrids were superior in physical quality to those obtained from parents and VA-110, but not in terms of physiological or sanitary quality variables. The quality of seeds from hybrids was more similar to that of seeds from male parents relative to seeds from female parents. For an average of 24 genotypes, seeds harvested from plants inoculated artificially with F. verticillioides exhibited lower germination rate, vigour and 100-seed weight than those from the control plants. Infection had no significant effects on seedling dry matter production or percentage of diseased seedlings. Artificial inoculation and injection with water had similar effects on most of the characteristics related to seed quality. In the Central High Valleys of Mexico, F. verticillioides and F. oxysporum are the causal agents of this disease in sorghum..