Improved drought tolerance in Festuca ovina L.using plant growth promoting bacteria

Numerous ecological factors influence a plant’s ability to live and grow,in which dryness is a substantial constraint on plant growth in arid and semi-arid areas.In response to a specific environmental stress,plants can use the most effective bacteria to support and facilitate their growth and development.Today,plant growth promoting rhizobacteria(PGPR)is widely used to reduce drought stress on plant growth.In this study,the effects of drought on Festuca ovina L.germination,growth,and nutrient absorption were investigated using PGPR in a factorial test with a completely random design under four water regimes.Soil water content was kept at 100%FC(field capacity),70%FC(FC),50%FC,and 30%FC.The treatments were inoculated with Azotobacter vinelandii,Pantoea agglomerans+Pseudomonas putida,and a mixture of bio-fertilizers.Results showed that the effects of drought stress were significantly reduced(P<0.05)when A.vinelandii and P.agglomerans+P.putida were used separately,however,the combined treatment of bio-fertilizers had a greater influence on seed germination than the single application.P.agglomerans+P.putida under 30%FC condition resulted in higher increases in stem,root length,and plant dry biomass.The highest uptake of nutrients was observed for the combined treatment of bio-fertilizers under 30%FC condition.Therefore,the use of A.vinelandii and P.agglomerans+P.putida,applied separately or combined,increased tolerance to drought stress in F.ovina by increased germination indices,dry weight,stem length,and root length.Because of the beneficial effects of PGPR on the growth characteristics of plants under drought conditions and the reduction of negative effects of drought stress,inoculating F.ovina seeds with Azotobacter and Pseudomonas is recommended to improve their growth and development characteristics under drought conditions.PGPR,as an affordable and environmentally friendly method,can improve the production of forage in water-stress rangelands.

Effects of Haloxylon spp. of Different Age Classes on Vegetation Cover and Soil Properties on an Arid Desert Steppe in Iran

In arid regions,afforestation has been considered as a method for ecological revival in terms of vegetation enrichment and soil amelioration.In this study,the effects of afforestation with Haloxylon spp.on vegetation cover and soil properties were measured<3,3,6,and 25 years after planting in an arid desert in Iran.Soil samples were collected at two depths(0-30 and 30-60 cm)under and between shrub canopies.Afforestation succession significantly affected plant community characteristics.In total,16 species from 8families and 15 genera were observed along the afforestation successional gradient.Plant species richness and diversity and vegetation cover increased slowly during the succession,and reached the maximum values in the area where Haloxylon had been planted for25 years.Soil nutrient values gradually increased during the succession,and the levels of organic matter,total nitrogen,available potassium,and available phosphorus were significantly higher under Haloxylon canopies than between them.Afforestation reduced soil pH under and between Haloxylon canopies during the succession,while soil electrical conductivity followed an opposite pattern.Haloxylon planting increased the silt content in the 0-30 cm soil layer.Our results suggest that Haloxylon establishment plays an important role in the reestablishment of desertified ecosystems in arid regions.