BIOFERTILIZER BASED ON SILICATE SOLUBILIZING BACTERIA IMPROVES PHOTOSYNTHETIC FUNCTION OF BRASSICA JUNCEA

Abstract

Usage of biofertilizers is one of the important components of integrated nutrientmanagement, as they are renewable source of plant nutrients, ecologically safecompared to chemical fertilizers and cost effective. Silicate solubilizing bacteria(SSB) can play an efficient role not only in solubilizing insoluble forms of silicatesbut also potassium and phosphates, hence increasing soil fertility and therebyenhancing plant productivity. The aim of this study was to investigate the influenceof SSB-enriched biofertilizer on the structural and functional parameters ofphotosynthetic apparatus of Brassica juncea (L.) Czern. The pure culture of SSBwas isolated from the clay substrate, cultivated on Zak–Alexandrov medium andidentified as Bacillus sp. To obtain the biofertilizer, SSB culture (0.6*108 cfu mL-1)was mixed with steriled peat (1:1, v/w) and dried at 35–40°C. Plants were grownfrom seeds during two months in the pots with adding SSB-enriched biofertilizer tothe mixture of clay and soil (1:10, w/w). The clay substrate plus peat without SSBwas used as a control. It was found that addition of SSB-enriched biofertilizer toclay substrate significantly increased the content of total nitrogen, phosphorus andpotassium in the leaves of B. juncea. The thickness of mesophyllic layer and thenumber of mesophyll cells were increased on average by 24 %. It was correlatedwith a sharp increase of photosynthetic pigment content and CO2 uptake (1.5–2.0times). We can conclude that SSB-enriched biofertilizer improves thephotosynthetic function of B. juncea.