The effect of genetic constitution and processing methods on the ability of maize seed to germinate in cold soil

Abstract

<p>In samples of commercial hybrid seed a highly significant negative correlation (r = -.81) was found between cold-test germination percentages and percentages of the kernels with pericarp injuries over the germ. Highly significant correlations of field stands with cold-test germination percentages were found, indicating that pericarp injuries over the germ are an important cause of poor stands;Pericarp injury was found to occur in shelling and in other steps in processing which involve an impact between the kernels and a hard surface. The moisture content of the seed during shelling and handling was a very important factor in determining the amount of damage. Handling treatments which caused practically no injury at 13--14 percent moisture, injured 60--80 percent of the kernels when they contained only 8 percent moisture;In these tests treatment of seed with New Improved Semesan Jr. fungicidal dust was not an adequate means of preventing stand reduction by pathogens in the field;Reciprocals of single crosses differed in their ability to germinate under cold-test conditions. Parental inbreds in nearly all instances germinated less well than the single crosses indicating either a relation between vigor and resistance to pathogens responsible for poor germination or a complementary or supplementary action of genes for resistance from the parents. No evidence was found for a relation between vigor and resistance;Germination in cold-test of inbreds and of crosses involving the inbred as the seed parent was determined to a large extent by seed borne infection and seed-coat condition both of which are related to the maternal parent. In tests of seed produced on inbred plants, maternal influences were so important that genetic differences in resistance of the zygotes to the pathogens involved could not be detected with certainty;Cold-tests of 3-way crosses, produced by using pollen of the inbreds R4 and I234 on six tester single crosses, indicated that R4 transmitted more resistance to the pathogens responsible for reduced germination than did I234. The use of 3-way crosses is suggested as a means of locating genetic resistance.</p>