Influence of sulphur on protein quality of developing soybean [Glycine max (L.) Merrill] seed

The accumulation pattern of various protein fractions in soybean seeds harvested at different stages of development from plants grown under different treatments of sulphur i.e. gypsum and single superphosphate (SSP) @ 10, 20 and 30 kg S ha⁻¹ were investigated. The contents of various protein fractions viz. albumin, globulin and glutelin increased under the effect of various treatments from 30 DAP to maturity with maximum accumulation during mid-maturation stage i.e. 45 to 60 DAP. Sulphur fertilization significantly affected the accumulation of globulin sub-fractions viz., glycinin and â-conglycinin. Both acidic and basic polypeptides of glycinins increased with sulphur treatments at all growth stages with maximum accumulation observed with gypsum @ 10 kg S ha⁻¹ as revealed by densitometric analysis of electrophoretic gels. Thus, sulphur nutrition specifically influenced the accumulation of sulphur rich proteins relative to sulphur poor proteins of soybean. The increase in 11S/7S ratio in mature seeds due to various levels of sulphur fertilization as compared to control indicated improvement of soybean seed quality.