Ten Cycles of Full‐Sib Selection in Maize

Full‐sib selection is one method of intrapopulation improvement used in maize (Zea maysL.). This study was conducted to evaluate the progress from 10 cycles of full‐sib recurrent selection in the Nebraska Krug open‐pollinated maize population. A 2‐yr full‐sib selection cycle was applied to the Krug population beginning in 1966. The selection criterion was a multiplicative selection index consisting of yield (adjusted to 155 g kg−lmoisture), proportion of standing plants, and proportion of plants without dropped ears. Based on field evaluations across nine seasons, the selection index increased 0.17 Mg ha−lcycle−1(4.4% cycle−1), yield increased 0.07 Mg ha−lcycle−l(1.2% cycle−l), the proportion of standing plants increased 2.8% cycle−l, and the proportion of plants without dropped ears increased 0.1% cycle−l. Grain moisture at harvest decreased 3.0 g kg−lcycle−1(0.3% cycle−1). Changes in plant traits other than those involved in the selection index were also measured. The multiplicative selection index was successful in increasing the yield on standing plants when applied to a full‐sib breeding system. Data indicate that yield on standing plants has continued to increase through the tenth cycle of selection.