Effect of plant-growth regulators and nutrient levels on productivity and nutrient uptake of soybean (Glycine max)

A field experiment was conducted during the rainy (kharif) season of 2017 at Dharwad, Karnataka, to study the influence of plant-growth regulators and nutrient levels on yield and nutrient uptake of soybean [Glycine max (L.) Merrill]. The experiment was laid out using randomized complete-block design with 14 factorial combinations of treatments including control treatments and replicated thrice. The treatments consisted of 2 nutrient levels, viz. 125% recommended dose of fertilizer (RDF) [50-45-25 NPK kg/ha] and 100% RDF (40-35-20 NPK kg/ha), with 6 levels of plant-growth regulators (PGR), viz. salicylic acid @ 50 and 100 ppm, ethrel @ 100 and 200 ppm, chlormequat chloride (CCC) @ 250 and 500 ppm and the control. Recommended package of practice (RPP)-without PGR spray and RPP + KNO₃ @ 1%. Results indicated that, foliar application of 125% RDF + CCC @ 500 ppm at 25 and 40 days after sowing (DAS) resulted in significantly higher seed yield (2.63 t/ha) over the other treatments but it was at par with 125% RDF + ethrel @ 200 ppm (2.37 t/ha). The increment in seed yield owing to these treatments over the control was to the tune of 35.3% and 27.8% respectively. Number of pods/plant, seed weight/plant, total uptake of nitrogen, phosphorus and potassium, protein content and oil content were found higher in soybean when combined application of 125% RDF + CCC @ 500 ppm was done.