Effects of phosphorous, manganese, and zinc on the morphological features and seed yield of soybean (Glycine max L. Merrill cv. Telar)

ABSTRACT: A study in the form of split – factorial using the randomized complete block design was carried out in four replications in Dashte - Naz in Sari in the cropping year 2011 – 2012 in order to investigate the effects of phosphorous and of the micronutrients zinc and manganese on the morphological features and seed yield of the soybean cultivar Telar. The factors studied included the three levels of 0, 100, and 200 Kg/ha of concentrated superphosphate (as the major factor), and the two levels of 0 and 50 Kg/ha of each of the two micronutrients manganese and zinc in the forms of manganese sulfate and zinc sulfate (as the minor factor). Results of the experiment showed that plant height and mowing height of the plants increased when phosphorous was applied, that plant height remained almost the same when zinc was added to the soil, and that plant height decreased but mowing height increased when manganese was applied. These results also confirmed that the number of axillary shoots increased when P, Zn and Mn singly or in combination were applied to the soil. With an increase in the application rates of phosphorous, manganese, and zinc, it was observed that seed yield, like other components of yield, exhibited a rising trend, so that comparison of the means revealed that the lowest seed yield (95.28 g/m2) was recorded when no phosphorous or manganese or zinc were applied, and that the largest seed yield (141.3 g/m2) was achieved when the maximum rates of phosphorous, manganese, and zinc were added to the soil.