A study of the planting pattern and density effects on yield and physiological growth parameters in two corn cultivars (Zea mays L.)

摘要

Changing canopy structure in order to provide condition, in which the canopy of plant could absorb maximum light required for photosynthesis, is one of the most important ways to increase yield of crops. For this reason and also to study the effects of planting pattern and density on yield, yield components and physiological indices of two corn cultivars; an experiment was performed in 2001 at Dashte Naz, Sari. This research was done using Strip-Split-Plot design with three replications. Horizontal factor was planting pattern (conventional single row and double row), Vertical factor was density (65000, 75000 and 90000 PI/ha) and reciprocal factor was cultivar (SC 704 and TWC 647), which were randornizely placed in experiment plots. Results showed that only dry weight of ear and grain yield were affected by planting pattern, so that double row planting pattern had higher ear dry weight and grain yield. The effects of increase in density by 90000 Pl/ha on stem diameter, number of rows in ear and harvest index, were not significant, but on other traits were significant. In cultivars, stem diameter, ear length and the weights of 1000 seeds also were significant. Although grain yield and total dry weight were not significant between cultivars, but grain yield of SC 704 and TDM, TWC 647 were higher. Interaction effect of planting pattern and density, density and cultivar, in weight of 1000 seeds was significant. In study of physiological parameters, the curve of Leaf Area Index (LAI) crop growth rate and total dry weight in double row were higher. At the early growth stages, density of 90000 (PI/ ha) had higher relative growth rate, but with continuation in growth, this factor decreased with more gradients. In this density, net assimilation rate was less because of high shading. In SC 704 cultivar, the constants of LAI and NAR were more.