Effect of nitrogen fixating, and potassium and phosphorus solubilizing bacteria on Mungbean (Vigna radiata) yield and components yield

Economic problems caused by increasing consumption of fertilizers from one side and environmental issues related to non-normative consumption of such fertilizers such as pollution of water and soil, loss of soil fertility and depreciation of plant products from on the other hand, it has provided more fields of attention to biological fertilizers. In order to reduce environmental pollution and ecological damage caused by the use of chemical fertilizers, resources and inputs should be used which, in addition to meeting the current plant's requirements, will also lead to the sustainability of agricultural systems in the long run (Karmakar et al., 2015). Beans are used not only as a human diet but also for improving soil fertility through biological nitrogen fixating (Rahimi et al., 2014). The purpose of this study was to reduce the harmful effects of chemical substances in agricultural products and reduce the cost of production by biofertilizer treatments (including Nitro Power Bacteria (NPB), Phosphate Power Bacteria (PhPB), Potassium Power Bacteria) and their effect on mungbean yield.

In order to investigate the effect of nitrogen stabilizing bacteria, potassium and phosphorus solubilizing bacteria on mungbean yield, a field experiment was carried out as a randomized complete block design with factorial arrangement of treatments. Two mungbean landraces (Dezfouli & Indian) were planted under six fertilization systems at the Agricultural Research Station of Ferdowsi University of Mashhad, Iran in 2017. Fertilization treatments were Nitro Power Bacteria (NPB), Phosphate Power Bacteria (PhPB), Potassium Power Bacteria (PPB), NPB+PhPB+PPB 5) chemical nitrogen fertilizer (N) and 6) no fertilizer application as control (C). Before planting, a soil depth of 0-30 cm was obtained from soil samples and the soil physico-chemical properties were measured according to the standard method. At the end of growing season, an area of 1 m2 from middle of each plot was selected and then plants were harvested for further analysis. The grain and biological yield, and yield components including plant height, number of branches in Plant, number of pods per plant, number of seeds per pod, number of seeds per plant and 100 seed weight were measured.

The results showed a significant difference between yield and yield components of mungbean and in different biological treatments (p<0.05). The highest biomass (6555 kg ha-1) and grain yield (1558 kg ha-1) were obtained for Dezfouli landrace under NPB+PhPB+PPB treatment. The lowest biomass and grain yield were observed for Hendi landrace under control treatment with 3518 and 1393 kg ha-1 respectively. The results showed that mixing of nitrogen stabilizing bacteria and potassium and phosphate release bacteria not only improves crop yields, but also reduces the negative aspects of the application of chemical fertilizers in crop production systems. It seems that weaker vegetative growth is one of the factors of reduction in the production of reproductive growth components, so inoculation with these fertilizers improves conditions for growth due to increasing access to nutrients that is an effective factor in stimulating the growth and photosynthesis of plants Production of photosynthetic materials and, consequently, increased yield in mungbean plants (Mehraban and GHasemi., 2015).

It was revealed that mixed application biological bacteria not only improve yield of mungbean but also reduce negative aspects of chemical fertilizer application in crop production systems. The necessity of attention to biological fertilizers as ecological agricultural methods to prevent soil and water pollution, in this regard, the use of environmental approaches to ecological agricultural goals. As final recommendation, the experiment should be repeated in plants under different abiotic stress such as salinity and water deficit.