Benefits from using maize density-independent hybrids

Density-independent varieties were defined as those whose maximum grain yield per unit area is attained in a wide range of plant densities. The study was conducted to assess possible benefits, derived from the development of density-independent maize (Zea mays L.) hybrids. Six recycled hybrids, found to be less density dependent than their original hybrid (PR,318 3) due to their improved yield potential per plant, were evaluated along with their original hybrid at three densities (2.5, 4.2, 8.3 plants/m(2)) in two locations (Technological Education Institute farm of Florina, Greece, and University farm of Thessaloniki, Greece), for two years (1998, 1999). The results showed that number of tillers and ears per plant, ear length, and grain protein concentration increased with decreasing plant density. Number of clays from sowing to pollen shedding and ear silking, pollen-to-silking interval, and grain moisture at harvest decreased with decreasing plant density. In comparison to their original hybrid, the recycled hybrids formed more tillers and ears and their grain yield decreased less at lower densities. Decreased plant density was associated with decreased plant-to-plant variability for plant height, ear height, and ear length. The development of density-in dependent maize hybrids may contribute to increase protein production, to decrease kernel drying cost, to reduce field loss as result of earlier maturity, and to reduce barrenness resulting from the improved synchronization of pollen shedding and silking. Moreover, the improved crop stand uniformity under lower densities is essential for higher and stable grain yield per unit area.