Mitigation of salt stress in radish (Raphanus Sativus l.) by plant growth promoting rhizobacteria

Abstract

The effects of Staphylococcus kloosii EY37  and Kocuria  erythromyxa  EY43  on some agro­  physical properties such as shoot­root fresh weight, shoot­root dry weight, emergence percent (EP), chlorophyll content, leaf number per plant (LNPP), leaf relative water content (LRWC), electrolyteleakage (EL) and ionic composition  of leaves of radish were tested  under saline conditions. Seeds were soaked in the bacterial suspension incubated at 27 0C for 2 h. After incubation the seeds were air­dried before use. Salinity treatments were established by adding 0 and 80 mM of NaCl to a base complete nutrient solution. In control, salt treatment significantly decreased shoot and root fresh­dry weight, EP, LNPP, LRWC, chlorophyll and mineral content, but increased EL. However, EY37 and EY43 treatments under saline conditions significantly increased shoot fresh weight (79.5%, 56.2%), root fresh  weight (100.0%­52.2%), shoot dry weight (108.1%­97.0%), root dry weight (150.6%­  157.4%), LNPP (34.1­12.8), LRWC  (37.0%­20.6%), EP (17.2%­14.1%)  and  chlorophyll content (21.2%­24.9%), but decrease EL (19.5%­26.9%)  compared  to  the control (without plant growth promoting  rhizobial bacteria  (PGPR)). Ionic compositions of the leaves of radish  plants were significantly affected by salinity and bacterial inoculations. All nutrient element contents investigated were significantly decreased  except for Na  and  Cl under salt stress, which  were significantly increased  by salt treatment. Bacterial inoculation  under salinity conditions usually increased  plantnutrient element (PNE) contents of the leaves. It can be concluded from the study that treatment with EY37 and EY43 strains can ameliorate the deleterious ef ects of salt stress on nutrition and on thegrowth  parameters of radish  plants under salinity conditions;  PGRB treatment could  offer an economical and  simple application  technology to  alleviate the moderately salt sensitive radish production problems in arid soil caused by high salinity.