The Effect of Intraspecific Competition on the Phenotypic Plasticity of Morphological and Agronomic Characters of Four Maize Hybrids

The plasticities of 16 characters were studied in four maize ( Zea mays , L.) hybrids grown at seven equidistant spacings and at four growth stages in 1 year. Plasticity was a measure of the extent to which the expression of a character was modified by changes in plant density. The hybrids differed in their plasticities for all characters studied. Furthermore, the characters of a hybrid showed different plasticities. The most plastic characters were grain yield per plant and yield per unit area, and the least plastic were ear row number and ear height. The hierarchy of plasticities was essentially identical in all hybrids. The double-cross hybrids showed non-significantly higher mean plasticities than the less heterogeneous genotypes M.C. 101 and Warwick SL209.