PLANT-POPULATION DENSITY EFFECTS ON MAIZE INBRED LINES GROWN IN SHORT-SEASON ENVIRONMENTS

Development of maize (Zea mays L.) types that produce leaf area quickl y and tolerate high plant densities could enhance yields in mid-to sho rt-season environments. The leafy and reduced-stature traits each make contributions to this end, but have not previously been combined. Our objective was to evaluate the effect of plant densities on leafy norm al-stature (LNS), non-leafy normal-stature (NLNS), leafy reduced-statu re (LRS), and non-leafy reduced-stature (NLRS) inbreds. Twenty-one inb reds were held-grown over 2 yr at low (65000 plant ha(-1)) and high (9 0000 plant ha(-1)) densities. Above-ear leaf number, above-ear leaf ar ea, and single plant grain yield were lower For LNS and NLNS at the hi gh, as compared with the low, plant density, but were not affected for LRS or NLRS. The corn heat unit (CHU) requirements from planting to t asseling, and from planting to silking, as well as days between tassel ing and silking, were greater under high plant density for LNS and NLN S, but were not affected for LRS or NLRS. Grain yield increased to a g reater extent under high density compared with low density for LRS and NLRS than for LNS or NLNS. The LRS inbreds had a shorter vegetative p eriod, longer grain-filling period, highest yields, and were more tole rant of high plant density than the normal stature genotypes. These ch aracteristics indicate potential both for increased yields and product ion in areas with lower CHU availability. These advantages are expecte d to be conferred to LRS hybrids.