Evaluation of phosphate-solubilizing bacteria on the growth and grain yield of rice (Oryza sativa L.) cropped in northern Iran

Abstract

Aims: This study aimed to evaluate the efficiency of four phosphate-solubilizing bacteria (PSB) on the growth and yield of rice under different soil conditions. Methods: Bacterial strains were Rahnella aquatillis (KM977991), Enterobacter sp. (KM977992), Pseudomonas fluorescens and Pseudomonas putida. These studies were conducted on different rice cultivars ('Shiroodi', 'Tarom' and 'Tarom Hashemi') in both pot and field experiments. Measurements started from transplanting and continued throughout the growing season in field experiments. Results: Single PSB inoculations in field trials increased grain yield, biological yield, total number of stems hill-1, number of panicles hill-1 and plant height by 8·50-26·9%, 12·4-30·9%, 20·3-38·7%, 22·1-36·1% and 0·85-3·35% in experiment 1, by 7·74-14·7%, 4·22-12·6%, 6·67-16·7%, 4·0-15·4% and 3·15-4·20% in experiment 2 and by 23·4-37%, 16·1-36·4%, 30·2-39·1%, 28·8-34% and 2·11-4·55% in experiment 3, respectively, compared to the control. Our results indicate that the application of triple super phosphate together with PSB inoculations resulted in reducing the use of chemical fertilizers (about 67%) and increasing fertilizer use efficiency. Conclusions: This study clearly indicates that these PSBs can be used as biofertilizers in ecological rice agricultural systems. Significance and Impact of the Study: To the best of our knowledge, this is first report on the association of Rahnella aquatilis with rice and also the application of a mathematical model to evaluate the effect of PSBs on rice growth.