Effect of growing site, plant density and year on the yield components of maize hybrids

Changes in the yield components of twelve single cross maize hybrids were studied for two years at three plant densities (45, 65 and 85 thousand plants/ha) at five locations: The total car mass per plant of the hybrids depended to the greatest extent on the size of the growing area and declined significantly with an increase in plant density. A positive correlation was found between the total ear mass per plant and the quantity of rainfall in July. The value of the correlation coefficient was 0.957 in 1997 and 0.947 in 1998. The location also had an influence on the yield components. This effect was greatest for the kernel mass and thousand kernel mass, while the effect of the location on the number of kernel rows was not significant. The year had the greatest effect on the total ear mass per plant and the kernel mass. The effect of the year on the number of kernel rows was smaller, but still significant. In the present experiment the greatest individual plant yields were given by hybrids Mv 8, Mv 1, Mv 4 and Mv 5. In these hybrids the development of secondary ears contributed to the better results. The smallest plant yields were recorded for hybrids My 7, My 10 and My 11. Stability analysis on the yield components revealed that the total ear mass per plant (CV = 9.3-42.4%), the kernel mass (CV = 17.5-30.0%) and the thousand kernel mass (CV = 11.1-20.3 %) were the most variable traits. Moderate variability was recorded for the length of the main ear (CV = 7.1-13.3 %), while the most constant yield component, which was least influenced by the environment, was the number of kernel rows (CV = 6.6-9.2 %).