Study of biofertilizers and nano zinc oxide application on remobilization and leaf area index of triticale (Triticosecale Witt.) under soil salinity

Introduction Salinity is one of the major abiotic environmental stresses, which affect almost every aspect of plant life and significantly reduces crop yield in affected areas. Thus it is a serious threat to agricultural productivity especially in arid and semiarid regions. Several strategies have been developed in order to decrease the toxic effects caused by high salinity on plant growth, among them use of bio fertilizers such as mycorrhiza and plant growth promoting rhizobacteria (PGPR) plays important role in yield improvement of plants. PGPR can facilitate plant growth indirectly by reducing plant pathogens, or directly by facilitating the uptake of nutrients from the environment, by influencing phytohormone production (e.g. auxin, cytokinin and gibberellins) and production of siderophores. Mycorrhiza is a symbiotic association between plant roots and fungi. Arbuscular mycorrhizal fungi promote salinity tolerance by utilizing various mechanisms such as accumulation of compatible solutes and production of higher antioxidant enzymes. Zinc is an essential micronutrient for humans, animals and plants, which act either as the metal component of enzymes or as a regulatory co-factor of a large number of enzymes. A number of researchers have reported the essentiality and role of zinc for plant growth and yield. Zinc is required for chlorophyll production and plays an important role in biomass production. The aim of this study was to investigate the effects of bio fertilizers and zinc on grain yield, remobilization and leaf area index of triticale in response to biofertilizers and nano zinc oxide under soilsalinitycondition.  Material and method A factorial experiment was conducted based on randomized complete block design with three replications in research greenhouse of faculty of Agricultural and Natural Resources, University of Mohaghegh Ardabili. Factors experiment were included soil salinity in four levels (non-salinity, salinity 20, 40 and 60 mM NaCl), biofertilizers in four levels (no application of biofertilizers, application of mycorrhiza, application of Azotobacter + Psedomunas, co-inoculation with PGPR+mycorrhiza) and nano zinc oxide in three levels (without nano zinc oxide, application of 0.4 and 0.8 g L-1). Mycorrhiza fungi (mosseae) was purchased from the Zist Fanavar Turan corporation and soils were treated based on method of Gianinazzi et al. (2001). Psedomunas putida strain 186 and Azotobacter chrocoococum strain 5 were isolated from the rhizospheres of wheat by Research Institute of Soil and Water, Tehran, Iran. Result and conclusion Results showed with increasing salinity decreased yield and leaf area index but remobilization from shoot organs and stem increased. Means comparison showed that the highest of grain yield and leaf area index were obtained at co-inoculation with PGPR+mycorrhiza, foliar application with 0.8 g L-1 nano zinc oxide and non-salinity. The highest remobilization from stem and shoot organs were obtained in salinity of 60 mM, no application of biofertilizers and nano zinc oxide. Results showed that salinity 20, 40 and 60 mM, respectively 8.9%, 22.1% and 32.3% reduced from grain yield and use of biofertilizers and nano zinc oxide compensated 40.1%, 49.7% and 40% respectively from yield reduction. Conclusion Based on the results, it was concluded that bio fertilizers and nano zinc oxide application can be recommended for profitable triticale production under salinity condition.