مطالعه اثرات تداخلي جمعيت طبيعي علف هاي هرز بر شاخص هاي رشد ذرت دانه اي (Zea mays L.) در تراكم گياهي مختلف

The interference effects of natural weed population on growth indices of corn (Zea mays L.) at different plant densities

In order to evaluate the interference influence of natural weed population on growth indices of corn an experiment in Randomized Complete Block design with 4 replications was conducted in 2006 at Ramin Agricultural and Natural Resources University, Mollasani, Ahwaz. Treatments included weed-free control of corn at three densities (4, 7 and 10 plant/m2) and weed-infested period to v9, v13 in any of plant populations (4, 7 and 10 plant/m2). Somewhat weeds interfere from emergence to the aforementioned stages of corn growth. Then weeds were controlled to harvest time. Meanwhile, one additional treatment was arranged as control plots for weed-infested (full season competition) with density (7 plant/m2, common plant density in Khouzestan). Results showed that, weeds caused significant reduction in corn dry matter, leaf area index, crop growth rate and relative growth rate. Meanwhile, excluding the early season growth, the maximum dry matter, leaf area index, crop growth rate and relative growth rate observed in weed-free (pure stands) treatments in all densities(4, 7 and 10 plant/m2). The maximum reduction rate of dry matter and leaf area index of corn to weed-infested (full season competition) treatment was concerned in 7 plant/m2 density. The minimum reduction rate of dry matter and leaf area index to weed-free occurred in 10 plant/m2 density.