EFFECTS OF POPULATION-DENSITY AND PLANTING PATTERN ON THE YIELD AND YIELD COMPONENTS OF LEAFY REDUCED-STATURE MAIZE IN A SHORT-SEASON AREA

Maize hybrids that yield well, mature earlier with low grain moisture contents, tolerate higher population densities and take advantage of n arrow row spacings better than the currently available hybrids would b e more suitable for production in short-season areas. Leafy reduced-st ature maize hybrids, which have only recently been developed, have tra its which address these criteria. The objective of this study was to e valuate the effects of different population densities (65 000 and 130 000 plants ha(-1)) and planting patterns (single rows 76 cm apart and paired rows with 20 cm between rows within a pair of 56 cm between row s of adjacent pairs) on the yield and yield components of two leafy re duced-stature (LRS1 and LRS2), one non-leafy reduced-stature (NLRS), a nd two conventional corn hybrids (Pioneer 3979, <2500 CHU; and Pioneer 3902, 2600-2700 CHU) at two locations. All hybrids had higher kernel numbers per row and single plant grain yields at the lower population densities when in paired rows. However, as plant density increased, th ese variables decreased more in the conventional hybrids than the LRS and NLRS hybrids, which demonstrates the greater tolerance of the latt er to the stresses associated with higher plant densities. Grain yield was higher for the two LRS hybrids and the NLRS hybrid at 130 000 pla nts ha(-1) than 65 000 plants ha(-1). Grain yield of conventional hybr ids was reduced at the higher population density. The LRS hybrids matu red before both conventional hybrids and out yielded Pioneer 3979 at t he higher plant population density in both row spacings at both sites. Harvest index was not affected by population density and this value w as not different among the NLRS and conventional hybrids. However, the harvest index of the LRS hybrids was greater than the others. LRS and NLRS hybrids had lower moisture contents and earlier maturities than conventional hybrids. Rapid growth of the first ear and higher harvest index values might are indications that LRS hybrids are more tolerant of higher population densities than the conventional hybrids.