Threshold Capacity of Strawberry Cultivars to Salinity and Rhizosphere Bacterial Population for Tolerance

Abstract

An experiment was conducted on seven strawberry cultivars and the wild species Fragaria vesca L., during two consecutive rabi seasons (November to April) at Sam Higginbottom University of Agriculture, Technology & Sciences, Allahabad, India to investigate the effect of NaCl stress on growth and antioxidant enzymes for salt tolerance. The cultivars viz., Adina, Belrubi, Chandler, Dana, Etna, Pajaro, Selva and wild species Fragaria vesca L., were used to identify salt tolerant cultivars for sub-tropical zones with of commercial importance. The effect of rising salinity levels above 28.89 and 43.34 dS m-had negative effect on growth parameters like plant height, leaf area, and plant spread in all the cultivars except the cultivars selva and belrubi. The SOD activity of selva and belrubi exhibited high induced levels even at high salinity levels (up to 28.89dSm-1showed relatively tolerance). APOX also linearly increased up to 31.596 μmol−1xg Fw x min−1 at 1.5% NaCl in wild Fragaria vesca L but cultivars selva (30.849μmol−1xg Fw x min−1 at 1.5% NaCl) and belrubi have shown at par with wild berry, which attributes to efficient function of these enzymes to decompose oxidants such as O2 and H2O2. The catalase activity was increased with increase in the salinity levels. The rhizosphere bacterial population viz., Bacillus, Pseudomonas, Enterobacter, Azatobacter and Rhizobium under salinity showed the reclamation effect on salinity where Rhizobium population at 43.4 dSm−1 (i.e., 3.0%). The effect of longer period NaCl treatments on fruiting period caused the higher leaf tissue electrolyte leakage and exhibited lesser LT50 than short period of NaCl treatments i.e up to pre-flowering in all seven cultivars and wild berry. Among all cultivars, wild berry F. vesca L. and cultivar selva exhibited high threshold capacity (28.9 dSm-1) followed by belrubi (25.16 dSm-1). These results indicate that strawberry cultivars like selva and belrubi could withstand to high salinity at par with wild type due to efficient antioxidant machinery. Salt stress effects in rhizosphere were minimized by inhabitant root colonizing bacterial population developed an induced tolerance to salinity for strawberry cultivars.