عنوان مقاله [English]
Current estimates indicate that 25% of the world's agricultural lands are affected by water stress. Iran, with an annual 240 mm of rainfall, is classified as a dry region of the world. Wheat is one of the main cereal crops, cultivated to the demands of the population for human feeding. Winter wheat, the most important food grain produced in Iran, is grown on some 6 million ha. Production of wheat typically requires intensive use of chemical fertilizers. In addition to nitrogen (N) and potassium (K), phosphorous (P) is also one of the essential macronutrients required for the growth and development of wheat. P is usually applied to the soil in the form of phosphate fertilizers. However, a large portion of soluble inorganic phosphate applied to the soil as chemical fertilizer is immobilized rapidly and becomes unavailable to plants. Soil microorganisms can contribute to the enhanced availability of soil P through mineralization of organic P or solubilization of inorganic P resulting in the reduction of P fertilization. Beneficial free-living rhizobacteria, which have been shown to improve plant health or increase yield, are usually referred to as plant growth-promoting rhizobacteria (PGPR). Mycorrhiza, which is a symbiotic fungus, has been under research for more than a century. Inoculation of plant roots with arbuscular mycorrhizal (AM) fungi may be effective in improving crop production under drought conditions. Improved productivity of AM plants was attributed to enhanced uptake of immobile nutrients such as phosphorus, zinc, and copper. In addition, other factors associated with AM fungal colonization may influence plant resistance to drought. These include changes in leaf elasticity, improved leaf water, and turgor potentials, maintenance of stomatal opening and transpiration, increased root length and depth, and development of external hyphae. Therefore the main goal of this study was to find the effect of phosphate solubilizing bacteria and Mycorrhizal fungi on yield, yield components, and its association in two dryland wheat cultivars.
Materials and Methods
In order to find the effects of the phosphorous deficiency and phosphate solubilizing bacteria (PSB) and Mycorrhiza fungi on grain yield and associated traits, an experiment was carried out in factorial arrangement using 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) during 2013-2014 cropping season. Experiment factors consisted of two dryland wheat cultivars (bread (Keras Sabalan) and durum wheat (Saji)) and phosphorous deficiency, phosphate solubilizing bacteria, and Mycorrhiza fungi treatment including (without application of phosphorous, 100% consumption of phosphorous fertilizer, phosphate solubilizing bacteria, Mycorrhiza fungi, phosphate solubilizing bacteria + Mycorrhiza fungi, 50% of phosphorous fertilizer + phosphate solubilizing bacteria + Mycorrhiza fungi, 50% of phosphorous fertilizer + phosphate solubilizing bacteria, 50% of phosphorious fertilizer + Mycorrhiza fungi). At full maturity, agronomic traits such as spik.m-2, spikelet.spike-1, grain.spike-1, 1000-grain weight, grain yield, biological yield, harvest index, spike length, spike weight, and plant height were recorded using a sample of ten random guarded plants from the middle ridges of each plot. The data were analyzed statistically by the SAS program, and the data means were compared by Duncan's multiple range test (DMRT).
Results and Discussion
Results indicated that the interaction effect between cultivar×bio-fertilizer had a significant effect on the spike.m-2, spikelet.spike-1, grains.spike-1, 1000-grain weight, grain yield, biological yield, harvest index, spike length, spike weight, and plant height. The use of bio-fertilizer had a positive and significant effect on total studied traits in two dryland wheat under dryland conditions so that Saji cultivar and Using of bio-fertilizer had the highest grain yield with 62% to check treatment (without using of phosphorous chemical fertilizer and f bio-fertilizer) and also Increasing of 36% observed to 100% of using of phosphorous chemical fertilizer. There was a significant difference between cultivars to the response of Using phosphate solubilizing bacteria and mycorrhizal fungi so Sji cultivars had the best response to mycorrhizal fungi. Therefore with, regard to the cultivation of wheat is facing terminal stresses (drought and heat), indicating that the Saji cultivar and Using of mycorrhizal fungi can be the best result under dryland conditions.
This study indicated that phosphate solubilizing bacteria (HSB) and Mycorrhizal fungi had a positive effect on grain yield and associated traits and grain yield was higher in the presence of inoculation with Mycorrhizal fungi and HSB. In general, using bio-fertilizers and managing integrated nourishment quantitatively and qualitatively is one the efficient ways to improve plant production, and the environment would have a better condition if chemical fertilizers consumption reduce. Recent studies indicated that using bio-fertilizers also improves soil physiological structure and also increases organic matter content and P available to the coexistent plant. Of course, before it is recommended for massive production and wide application, it is necessary to implement and replicate this experiment in different regions.