The development of density-independent hybrids in maize

Intense selection across the production environments for tolerance to stres ses and responsiveness to inputs led to the development of highly productiv e maize (Zen mays L.) hybrids whose yield depends heavily on high plant den sities. The partition of crop yield into components (i.e., yield per plant assessed by the progeny mean, tolerance to stresses assessed by the progeny standardized mean, and responsiveness to inputs assessed by the progeny st andardized selection differential) revealed that density-independent maize hybrids can be produced by concurrent selection for genes controlling the t hree components of the crop yield. In the present study selection in the F, of the single-cross maize hybrid PR 3183 Far inbreds characterized by high yield per plant and high standardized mean led to recycled hybrids with eq ual performance to the original hybrid at higher plant densities and statis tically better performance at lower plant densities. The results showed tha t continuous recycling in the absence of competition for the three componen ts of crop yield across the production environments may lead to the develop ment of highly productive and stable inbreds that transmit their superior p erformance and render hybrids density-independent