Twenty‐Four Cycles of Phenotypic Recurrent Selection for Percent Oil in Maize. I. Per Se and Test‐Cross Performance

Responses and limits to selection are found to differ in various maize ( Zea mays L.) populations and traits. Twenty‐four cycles of recurrent selection for high oil concentration have been completed in maize population Alexho Synthetic. The objectives of this study were to determine the response of oil concentration direct selection and correlated responses of fatty acid concentration, grain yield, and other agronomic traits. Cycles 0, 3, 5, 9, 11, 15, 18, 21, and 24 per se, the same cycles crossed to inbreds B73 and R802A, and hybrid check B73 ✕ Mo17, were evaluated in six environments at Yugoslavia and at Urbana, IL in 1985 and 1986. Selection was effective in increasing oil concentration. Total oil concentration increased by 118, 51, and 57 g kg −1 of dry matter in cycles per se B73 and R802A testcrosses, respectively. The rate of response in oil concentration was 4.9, 2.1, and 2.4 g kg −1 cycle −1 for the cycles per se for B73 and R802A testcrosses, respectively. The quadratic response was significant in testcrosses, but not in cycles per se. Thus, oil concentration has not yet shown evidence of plateauing. Oleic and linoleic acid concentration changed with selection for oil concentration in cycles per se −1.39 and 1.39 g kg −1 cycle −1 , respectively. Total grain yield of the cycles per se decreased by 1718 kg ha −1 , which corresponds to a response of −71.6 kg ha −1 cycle −1 . Yield of the testcrosses to inbreds B73 and R802 decreased 19.7 and 15.2 kg ha −1 cycle −1 , respectively. Plant height, ear height, 500 kernel weight, ear length, and lodging decreased, while grain moisture and ear row number increased with selection for oil concentration. No change was found in days to silk.