The effect of salinity and bio-fertilizers on yield and yield components of isabgol (Plantago ovata Forsk.) under field conditions

Introduction Water and soil salinity are the most fundamental agricultural problems in arid and semi-arid area. There are some microorganisms in soil that helps plants in nutrients absorption in many ways. Mycorrhizal fungi are capable of establishing symbiosis with the roots of most plants. This symbiosis has several advantages for the host plants, including increased tolerance to environmental stresses and diseases. Pseudomonas is one of the main Mineral phosphate-solubilizing bacteria, due to the wide range of stimulating plant growth traits are improved plant growth. Isabgol (Plantago ovata Forsk.) is a plant from (Plantaginaceae) family. Currently, production of this plant is one of the 15 species medicinal plant that have economic priority. To find out the effect of arbuscular mycorrhizal fungi, Mineral phosphate-solubilizing bacteria in salinity condition on yield and yield components Isabgol (Plantago ovata Forsk.), this experiment designed and implemented. Materials and Methods The field experiment was conducted at the research farm of national salinity research center in Hosein Abad, Yazd in 2015. A split-factorial experiment based on randomized complete block with three replications. Three levels of salinity 2.5 (control), 5 and 10 dS.m-1 was as the main plot and mycorrhizal fungi and PSB were as sub plots. Arbuscular mycorrhizal fungi include two levels (Glomus intraradices and control) and PSB also includes two levels (Pseudomonas fluorescens bacteria control). After field preparation planting with 100 plants per square meter and 30 cm rows, was taken. Weed control was with hand weeding and herbicide was not used. Salinity stress started at 3-4 leaf stage with water mixture of different salinity level wells. To ensure the same level of irrigation in salinity factor, irrigation was done in a controlled manner. To determine the yield components, five plants of each plot were harvested and plots harvested at end to determine yield traits. Statistical analysis was performed with SAS software. Comparison of mean also was conducted by protected LSD test at five percent probability level. Results and discussion Analysis of variance showed salinity had a significant effect at 5% level on tillers numbers per plant and significant effect at 1% level on spike numbers per plant, seeds numbers per spike, 1000 seed weight, harvest index, biological yield and seed yield. The effect of arbuscular mycorrhizal fungi and Mineral phosphate-solubilizing bacteria on spike numbers per plant, seeds numbers per spike, 1000 seed weight, biological yield and seed yield was significant at 1% level and the effect of PSB on tiller numbers per plant and harvest index was significant at the 5% level. Also salinity, AMF and PBS interaction was significant at 5% level on biological and seed yield. Comparison of means showed that the highest spike numbers per plant, seeds numbers per spike, 1000 seed weight, harvest index, biological yield, seed yield, were 18.3 number, 43.4 number, 1.5 gr, 27.9 %, 3805 and 1063 kg.h-1 at 2.5 dS.m-1 salinity and the minimum number of these traits were 12.4 number, 31.2 number, 1.35 grams, 22.3%, 2164 and 485 kg.h-1 at 10 dS.m-1 salinity respectively. Also interaction results showed that maximum biological and seed yield was 4539 and 1310 kg.h-1 at 2.5 dS.m-1 salinity, Glomus intraradices and Pseudomonas fluorescens and minimum biological and seed yield was 1817 and 368 kg.h-1 at 10 dS.m-1, non inoculated and no bacteria respectively. Conclusions Totally the results of this study showed that water salinity can have a negative effect on yield of Isabgol, but utilizing of some soil microorganisms can compensate these negative effects. Therefore, utilizing bio-fertilizers can improve water and nutrients availability, moreover increase yield traits and effective in safe medicinal plant production.