STUDY THE CORRELATION, REGRESSION AND PATH COEFFICIENT ANALYSIS IN SWEET CORN (Zea mays var. saccharata) UNDER DIFFERENT LEVELS OF PLANT DENSITY AND NITROGEN RATE

In order to evaluate the effect of plant density and nitrogen rates on ear yield of sweet corn (Zea mays var. saccharata) cultivar KSC. 403, an experiment was conducted at research field of Tarbiat Modares University on summer 2008. The experiment was carried out in a split plot design based on randomized complete blocks with four replications. In this research plant density (60000, 80000 and 100000 plant/ha) and nitrogen rate (120, 180, 240 and 300 kg N/ha) were arranged in main plots and sub plots respectively. Seeds were sown on these plots on July 3 rd and were harvested at soft dough stage on September 24 th . Sweet corn yield components including ear number.m -2 , row number.ear -1 , grain number per row, 1000 grain weight and grain yield.m -2 were measured. Some morphological traits like as plant height, leaf area, ear length and diameter have also investigated. Correlation, regression and path coefficient analysis were used to better understanding the direct and indirect effects of plant density and nitrogen rate on sweet corn ear yield and yield components. The results revealed that the grain yield was affected by plant density but it was not affected significantly by different levels of nitrogen rate. However by increment of plant density, the ear number.m -2 and grain yield were increased in expense of ear weight. The higher ear length and ear number was obtained in the lowest plant density and nitrogen rate (D1N1). Highly significant and positive correlation was observed between grain yield with ear number, 1000grain weight and grain number per ear. In this respect D3N1 treatment (100000 plant.ha -1 and 120 kg N.ha -1 ) which produced more ears and grain yield are recommended for the sandy soil as superior treatment, in studied area. The results of regression analysis by stepwise method for grain yield showed that grain number and 1000 grain weight made 98 percent of the grain yield variation. It is concluded that sweet corn grain yield can be improved by increment of grain number per m 2 and 1000 grain weight through increasing of plant density.