Comparison of Seed Corn Single Crosses SC 704 and SC 770 Response to Different Plant Densities and Nitrogen Levels

An experiment was conducted at the Research Station of Gharakheil of Mazandaran Province, Iran, to evaluate the response of seed corn single crosses SC 704 and SC 770 to different plant densities and nitrogen levels during summer 2010. The soil at the site of the experiment had a loamy texture consisting of 48% sand, 35% silt, and 17% clay, with pH of 7.81, and electrical conductivity of 0.55 mmohs/cm. The experiment was performed in the form of factorial-split using the randomized complete block design. The main factor investigated was the two corn cultivars of Single Cross 704 and Single Cross 770. The sub-factors included three levels of applied nitrogen- the control treatment B1 receiving no nitrogen, treatment B2 receiving 250 Kg nitrogen per hectare and treatment B3 receiving 350 Kg of nitrogen per hectare, along with three plant density levels were C1, C2, and C3, with 75000, 85000, and 95000 plants per hectare, respectively. Results showed that the effect of the cultivar on the trait of grain yield was significant at the probability level of 5 percent. Comparison of the means showed that the cultivar Single Cross 704 with a yield of 12138 Kg.h was superior to the cultivar Single Cross 770 (which had a yield of 10877 Kg.h). Comparison of the means of nitrogen levels indicated that the highest yield (12310 kg.h) was achieved with the application of 350 kg.h of nitrogen and the lowest (10500 kg.h) was obtained in the control treatment. Comparison of the means of the cultivars with respect to the number of seed rows suggested that the cultivar Single Cross 704 with 15.28 seed rows was superior to the cultivar Single Cross 770 with 14.96 seed rows. The rate of nitrogen application had no significant effects on the number of seed rows. The maximum and the minimum numbers of seed rows of 15.74 and 14.48 were observed at densities of 75000 and 95000 plants per hectare, respectively. Results of individual correlation coefficients of the traits studied suggest that seed yield has the strongest positive and significant correlation with the trait of the 1000 – seed weight (0.539*), with the corn ear length (0.52*), and with the number of seed rows per corn ear (0.453*). It was also found that the 1000-seed weight had the strongest positive and significant correlation with the diameter of corn ears (0.700*), the length of corn ears (0.386*), and the number of seed rows per corn ear (0.367*). Furthermore, the number of seeds per corn ear had the strongest positive and significant correlation with the features of the number of seeds per seed row (0.882*), the length of the corn ears (0.737*), and the number of seed rows per ear corn (0.457*).