Contribution of cyanobacterization to rice growth and performance under different field stand densities and levels of combined nitrogen

Abstract

The Indica rice variety Giza 176 was transplanted regularly at 20 × 20 cm spacing (500 seedlings/20 m2) or irregularly (traditionally) at 372 ± 16 seedlings/20 m2. Regular transplanting along with cyanobacterization by a soil-based inoculum containing balanced colony-forming units (CFU) of the cyanobacteria, Anabaena oryzae, Aulosira fertilissima, Nostoc muscorum and Tolypothrix tenuis at 100 kg fresh material (90% moisture)/ha, 5 days after transplanting and increasing urea fertilizer from 48 to 96 or 144 kg N/ha enhanced plant height, productive tillering, grain and straw yields and N content, harvest index (% grain yield/grain and straw yields) and the agronomic fertilizer N-use efficiency (kg grain yield/kg N fertilizer). Cyanobacterization and urea at 48, 96 and 144 kg N/ha with irregular transplanting increased grain yield by 25.6, 26.3 and 20.3% compared with 22.7, 20.1 and 9.1% for the regular transplanting, respectively. Cyanobacterization and regular transplanting registered yield increases of 9.5, 13.8 and 11.8% over the irregularly transplanted counterparts.