Effect of Rhizobium trifolii, Pseudomonas fluorescens and Azotobacter chroococcum on Growth and Yield of Crismon Clover and Rice in a Rice-Clover Rotation

Cultivation of legume species as the second crop in rotation with rice and using plant growth promoting bacteria can be a good approach to improve rice production sustainability. This experiment was carried out to evaluate the effect of plant growth promoting bacteria on accelerating vegetative growth of crimson clover (Alborz 1) and rice (Hashemi) yield in a rice-based cropping system. A factorial experiment in randomized complete block design with three replications at Rice Research Institute of Iran was conducted during 2015-2017. Experimental factors included four inoculation levels of clover seeds with Rhizobium leguminosarum bv. trifolii and four inoculation levels of clover seeds with non-symbiotic plant growth promoting Rhizobacteria including control, Pseudomonas fluorescence, Azotobacter chroococcum and combined treatment of these bacteria. The combined treatment of symbiotic strains led to significant increase in plant height (68.3 cm), fresh forage yield (32704.4 kg/ha) and dry forage yield (7783.7 kg/ha) of clover compared to the control treatment (61.8 cm, 28248.2 and 6765 kg/ha, for plant height, fresh forage yield and dry forage yield, respectively). Assessing inoculation of clover seeds with non-symbiotic bacteria and subsequent rice cultivation showed that the combined treatment led to increase in number of filled grains (112.8) and paddy yield (3336.4 kg/ha) relative to the other treatments. The findings of this research showed that the application of plant growth promoting bacteria is potent to increase the cloverchr('39')s agronomic performance and rice yield in a rice-based cropping system.