The effect of improved potential yield per plant on crop yield potential and optimum plant density in maize hybrids

Honeycomb selection in the F-2 generation of maize (Zea mays L.) hybrid PR 3183, based on line performance per se in the absence of competition, led t o recycled hybrids with improved potential yield per plant (mean yield per plant in the absence of competition). In the present study six S-6 X S-6 re cycled hybrids and two commercial single-cross hybrids (PR 3183 and B73 x M ol7) were tested at three plant densities (25 000, 41 667 and 83 333 plants /ha), in two locations (Technological Education Institute farm of Florina, Greece and University farm of Thessaloniki, Greece), for 2 years (1998, 199 9). The study was undertaken to assess indirectly the potential yield per p lant (p), the crop yield potential (Y-max), and the optimum plant density ( D-opt) of the hybrids. Estimate of p and Y-max were obtained through linear regression analysis of yield per plant (Y-p) on plant density (D), express ed by the equation Y-p = p - qD, with Y-max being equal to (1/4)p(2)q(-1). Optimum plant density was assessed through linear regression analysis of na tural logarithm of yield per plant on plant density, expressed by the equat ion ln(Y-p) = alpha -bD, with D-opt being equal to 1/b. The recycled hybrid s had higher estimated potential yield per plant (p), than the two check hy brids, with p values being positively correlated with yield per plant of hy brids obtained experimentally in the absence of competition. Results indica ted that the higher potential yield per plant decreases the optimum plant d ensity, and renders the hybrids less density-dependent.