Progress from Mass Selection for Field Emergence and Seed Weight in a sh2 Population of Maize1

Abstract

The objective of this study was to evaluate progress from 11 cycles of mass selection for increased field seedling emergence and higher seed weight in a shrunken‐2 (sh2) maize (Zea mays L.) population. Evaluation trials included the 11 cycles of mass selection and four commercial checks homozygous for sh2. The evaluation included field tests, and cold and warm laboratory germination tests of the 15 entries. Field tests were done in nine environments with four replications in each environment. All entries were planted in two‐row plots arranged in a randomized complete block design. Selection for increased field emergence among the 11 cycles of the sh2 population resulted in a significant linear gain of 3.3% per cycle, based on cycle zero. Plant and ear height measurements demonstrated significant correlated increases, while date of flowering showed no significant change. Laboratory germination tests included three replications of 100 seeds for both the cold and warm tests performed in 2 years. The cycles of selection showed significant linear increases in germination percentages for both tests. The phenotypic correlation between field emergence and test weight entry means was highly significant [r = 0.86** (**Significant at the 0.01 level.)]. Phenotypic correlations between field emergence and test weight, and laboratory germination test performance were also significant.