Growth, productivity and quality of soybean (Glycine max (l) Merrill) under different levels and sources of phosphorus and plant growth regulators in sub humid Rajasthan

In India, soybean is the third largest oilseed crop but its productivity is lower and that can mainly be related to low fertilizer phosphorus usage, poor phosphorus use efficiency and flower and bud drop. In this backdrop, to achieve sustained higher soybean productivity, twenty seven treatments [three doses: 20, 30 and 40 kg P2O5 ha-1; three sources: single super phosphate (SSP), phosphorus rich organic manure (PROM) and di-ammonium phosphate (DAP) and three plant growth regulators (PGRs): water spray, benzyl adenine 50 ppm and naphthalene acetic acid (NAA) 100 ppm] were evaluated in a split plot design having three replications on medium clay loam soils of Udaipur (India) during rainy seasons of 2009 and 2010. Results conclude that 40 kg P2O5 ha-1, SSP and NAA  recorded significantly higher pooled plant height (51.65, 50.82 and 51.17 cm), branches plant-1 (4.56, 4.43 and 4.48), oil content (21.40, 20.91 and 21.20%), oil yield (558.89, 528.75 and 521.79 kg ha-1), seed protein yield (1111.56, 1039.96 and 1045.60 kg ha-1), grain yield (25.95, 25.12 and 24.23 q ha-1) and stover yield (37.37, 36.23 and 35.73 q ha-1) over their corresponding treatments. Use of NAA and benzyl adenine were statistically indifferent, however, they recorded significantly early setting of 50% flowering and substantially extended the crop maturity period over water spray. However, various levels and sources of phosphorus were indifferent in periods of 50% flowering and maturity. Use of 40 kg P2O5 ha-1 and NAA recorded significantly higher pooled seed protein content over their corresponding counterparts but phosphorus sources were indifferent.     Key words: Oil content, phosphorus levels, phosphorus sources, plant growth regulators (PGRs), protein content, soybean productivity.