Effects of Recurrent Phenotypic Selection for High and Low Photosynthesis on Agronomic Traits in Two Maize Populations1

Abstract

Selection for high or low photosynthetic rate in plant populations may influence important agronomic traits. We studied the effects on agronomic traits of five cycles of recurrent phenotypic selection (RPS) for high CO2‐exchange rate (CER) in two maize (Zea mays L.) populations and three cycles of selection for low CER in one population.Estimates of the weighted‐average change in allelic frequency (Δpα) showed significant reductions in plant and ear heights and significant increases for percentages of plants not root and stalk lodged after five cycles of RPS for high CER in BSULl(RPH). Estimates of Δpα after RPS for high CER in BSUL2(RPH) were significant only for percentage dropped ears, which increased slightly across five cycles of selection. Estimates of Δpα for RPS for low CER in BSUL2(RPL) indicated that days to 50% pollen shed had increased significantly across cycles. Changes in grain yield were not significant for any population, but Δpα for low CER selection in BSUL2(RPL) was significantly greater than Δpα for high CER selection in either BSULl(RPH) or BSUL2(RPH). Estimates of Δpα for grain yield of both BSULl(RPH) or BSUL2(RPH) were negative, but not statistically significant at the 5% probability level.