Effect of soybean plant density on leaf chlorophyll content, pod, and seed characteristics

The Rowing Spacing Experiments

An investigation was conducted on Sequatchie loam to determine how yield components were affected by row spacings of both drilled and hill dropped soybeans. Essex, Forrest, York, and Mitchell soybeans were drilled in rows of 46, 61, 76, and 91 cm. Essex, Forrest, and York soybeans were hill dropped in 46 and 91 cm rows with four, three, and two plants per hill. The plots were sampled in the middle of October after the first frost. All pods were taken from the fan and upper branches, counted, hulled, and weighed.

Significant yield increases were observed for the soybeans drilled in narrow rows. As plants per hill increased in the hill dropped soybeans significant differences in yield were observed only for Essex. The hill dropped soybeans showed significant differences in yield as the row spacing was decreased from 91 to 46 cm in all varieties, except Forrest. The yield increase could be attributed to a decrease in the percentage of beans produced on the fan branches which produced beans of a smaller weight than the upper branches. The upper branches also produced a higher percentage of three bean pods.

The Chlorophyll Experiment

A study was performed on Sequatchie loam to determine the effects of plant density on the quantity of chlorophyll in the different trifoliates on soybean plants arranged in a nested experimental design. Essex, Forrest, York, and Bedford soybeans were grown in a equidistant arrangement with a distance of 15 and 30 cm between hills and one, two, and three plants per hill. Trifoliate samples for chlorophyll determinations were taken from the plots when the plants were in the early bloom stage.

The results showed that the amount of chlorophyll varied with the height of trifoliate with the fourth trifoliate being the highest. Significant reduction in trifoliate chlorophyll content was also found as the plants per hill increased from one to two plants. No differences in chlorophyll content were found among the varieties or the distance between hills.