Physiochemical transformation of waste of super phosphate industry into new generation silicate fertilizer and its uses for rice growth under saline environment

摘要

Rice ( OryzaSativa L.) is a major staple food of majority of people in different countries of the world. Rice is highly susceptible to salinity and its yield is severely limited under salt stress environment. However, one favourable character of rice is that it is a silicate accumulator plant. We investigated the effect of new generation Si (silicate) fertilizer (produced from the waste of the phosphate industry, which mainly consisted of amorphous silica, potassium hydroxide, pulverized coal and aluminium chloride) amendments on two contrasting rice varieties. The produced smart Si fertilizer materials were solidified, dried, granulated and calcined to remove toxic compounds and to enhance end product’s solubility. Two rice varieties IRRI-9 (coarse rice) and Basmatti-2000 (fine rice) were grown under saline environment. Twenty six days old uniform sized rice seedlings were transferred in glazed clay pots filled with non-saline (ECe = 1.66 dS ) and saline soil (induced ECe = 6 dS ) under flooded conditions. New generation Si-fertilizer was used @ 0, 75 and 150 mg Si kg -1 soil. Plants were grown until maturity stage and different physiochemical parameters were investigated. Both, biological and paddy yields of rice were reduced significantly ( p 0.05) due to induced salt stress; however less reduction was observed in coarse as par to fine rice variety. The Si fertilizer amendment in growth environment significantly ( p 0.01) enhanced plant dry biomass (4-folds) with reference to control treatment and similarly paddy produce of rice was also enhanced (3-folds) in both plant culture environments. Sodium concentrations in plant shoots were negatively correlated (r= -0.90, p 0.01) with shoot dry matter, but potassium concentrations depicted positive correlation (r=0.90, p 0.01) in rice plants. Induced Na concentration was significantly reduced in plants receiving Si in the growth medium. Shoot Si concentration was significantly correlated with shoot potassium uptake (r=0.66, p 0.05) and insignificantly with shoot Na uptake (r=0.23, p 0.05). Applied silicate fertilizer in the root environment significantly enhanced K to Na ratio in rice genotypes exposed to salinity however, impact on K: Na ratio was insignificant in normal soil. Increased selective K uptake and reduced Na uptake or translocation may be one of the possible strategies of induced salinity tolerance by silicate nutrition in rice.