Individual and mutual effects of macro and micronutrients on soybean (Glycine max Merrill) growth in second cropping after wheat (Triticum aestivum L.)

ABSTRACT: A study, in the form of split – factorial using the randomized complete block design in four replications, was conducted in Dashte – Naz in Sari, in the north of Iran, in the cropping year of 2011 – 2012. It aimed to compare the individual and mutual effects of plant nutrients on yield and yield components of the soybean cultivar Telar as second cropping after wheat (Triticum aestivum L.) harvest. The factors studied included three rates of phosphorous application (zero, 100, and 200 Kg/ha) as the main factor, and the application of the micronutrients manganese and zinc (each at the two rates of zero and 50 Kg/ha) as the minor factor. Results obtained indicated seed yield and yield components increased when a higher rate of phosphorous was applied. Comparison of the means of the data revealed that the number of seeds per pod slightly increased if only manganese and zinc were applied, and that the 100 – seed weight went up but the number of pods per plant did not show a rise when only manganese was added to the soil. Furthermore, it was observed that the number of pods per plant substantially decreased if only zinc was applied. Moreover, comparison of the means of the data related to the rates of zinc application showed that the 100 – seed weight increased if only zinc was added to the soil. Results of comparison of the means of the data concerning seed yield revealed that the minimum seed yield (99.74 g/m2) was obtained in the control treatment, that seed yield jumped to 114.2 g/m2 when 100 kg of phosphorous was applied per hectare, and that it rose to 116.9 g/m2 when 200 kg of phosphorous was applied per hectare. By application of manganese, seed yield increased from 103.23 g/m2 in the control treatment to 108.58 g/m2. By application of zinc seed yield exhibited a declining trend, so that seed yield decreased from 107.7 g/m2 in the control treatment to 104.11 g/m2 in the treatment in which zinc was applied. Under the mutual effects of phosphorous, manganese, and zinc, it was observed that the minimum seed yield (95.28 g/m2) was obtained in the control treatment of phosphorous, manganese, and zinc, and that the maximum seed yield (141.3 g/m2) was achieved in the treatment of applying the highest rates of phosphorous, manganese, and zinc.