Evaluation of Root and Grain Yield of Wheat Cultivars Affected by Phosphate Solubilizing Bacteria and Mycorrhizal Fungi under Dry land Conditions

Current estimates indicate that 25% of the world agricultural lands are affected by water stress. Iran, with an annual 228 mm of rainfall, is classified as a dry region in the word. Wheat is one of the main cereal crops, cultivated for human feeding. In order to increase crop yield per unit area, largely chemical fertilizers are used. The result of these activities in recent years has been the crisis of environmental pollution, especially water and soil pollution that threatens human society. Phosphorus is one of the limiting elements for crop production. It is essential for energy transfer, photosynthesis and other biochemical and genetic activities of plant. Biofertilizers have been used as source to improve plant nutrients in sustainable agriculture. Phosphorus Solubilizing Bacteria (PSB) plays an important role in phosphorus nutrition by enhancing its availability to plants through release from inorganic and organic soils phosphorus pools by solubilizing and mineralization. Mycorrhizal crops often have greater tolerance to drought than nonmycorrhizal crops. The use of arbuscular mycorrhizal fungi capable of forming symbiotic associations with most agricultural crops and has potential under such systems due to its higher binding capabilities and mineral nutrition. Therefore, the main of this study was to study the effect of phosphate solubilizing bacteria and mycorrhizal fungi on root characteristics and grain yield in dryland wheat cultivars. This experiment was carried out as factorial arrangement based on a randomized complete block design with three replications at the Agricultural Research Station of Ilam University (46*28' N, 33*37 E; elevation 1174 m) and Sarableh Agricultural Research, Recources Center (34*46 N, 33*45 E; elevation 975 m) during growing season 2013-2014. Experiment factors consisted of two dry land cultivars (Keras Sablan and Saji) and fertilizer sources including of 1: without application of phosphorious chemical fertilizer, 2: 50 kg.ha-1 phosphorous chemical fertilizer, 3: pseudomonas putida (PSB), 4: Glomus mosseae (GM), 5: PSB+GM, 6:PSB+GM+25 kg.ha-1phosphorous chemical fertilizer, 7: PSB+ 25 kg.ha-1 phosphorous chemical fertilizer and 8: GM+25 kg.ha-1phosphorous chemical fertilizer. At flowering stage root traits such as root volume, root area, root diameter, root length density and root surface area density were studied and measured. At full maturity, agronomic traits such as spikes.m-2, grains.spike-1, 1000-grain weight, grain yield and biomass yield were recorded using a sample of ten random guarded plants from the middle ridges of each plot. The data were analyzed statistically by SAS program and the data means were compared by Duncan's multiple range test (DMRT). Results indicated that interaction effect between cultivar× fertilizer sources had significant effect on root length total, root volume, root area, root diameter, root length density, root surface area density, spike.m-2, grains.spike-1, 1000-grain weight, grain yield and biomass yield. Using fertilizer sources had  positive and significant effect on root traits and grain yield in two dryland wheat under dry land condition, so that Saji cultivar ×GM+25 kg.ha-1 had the highest root volume (4.6 cm3), root area (70.9 cm-2), root length density (0.158 cm root length.cm-3 soil), root surface area density (84.3 cm2.cm-3), spike.m-2 (257.5 spikes), grains.spike-1 (42.7 grains), 1000-grain weight (39.7 g), grain yield (3571.6 kg.ha-1) and biomass yield (7840.6 kg.ha-1) and the lowest root traits and grain yield belonged to Keras Sabalan×check treatment. There was significant different between cultivars to response of Using of phosphate solubilizing bacteria and mycorrhizal fungi, so that Saji cultivars had the best response to mycorrhizal fungi. Therefore with regard to cultivation of wheat is facing to drought and heat stress indicated that Saji cultivar and using of mycorrhizal fungi can be the best result under dry land conditions. The results indicated phosphate solubilizing bacteria (PSB) and mycorrhizal fungi (GM) had positive effect on root system and grain yield, so that root traits and grain yield had the better status in presence of inoculation with GM. In fact PSB and GM could alleviate the partial of grain yield in presence of dry land farming. Recent studies indicated that symbiosis bio-fertilizers also improved soil physical and chemical traits and increaced organic matters content, root system and P available to coexistent plant.