Effects of phosphorous fertilizer and mycorrhizal fungi on yield and yield components of durum wheat (Triticum turgidum var. durum) under rainfed condition

wheat is the most important crop in the world that human consumes 90% of its products directly. In Iran, wheat is the main crop grown in both irrigated and rainfed forms. According to available statistics, the average area under wheat cultivation is 6 million hectares, of which 3.8 million hectares have been allocated to dry lands. In these lands, water scarcity is the most important factor in reducing wheat yield. On the other hand, the use of chemical fertilizers in such areas to provide the nutrients needed by plants always causes environmental destructive effects. Therefore, it is necessary to study and apply renewable resources and inputs that maximize crop productivity and reduce environmental hazards. Arbuscular-Mycorrhizal (AM) fungi is one of the beneficial microorganisms that are able to activate symbiotic relationships with the majority of land plants. AM symbiosis has a positive influence on plant growth, which is mainly attributable to the ability of AM fungi to take up from the soil both water and nutrients especially phosphorous (P), and to a lesser extent nitrogen (N) and deliver them to the roots of its host, and also to enhance the health of its host by protecting it from pathogens, pests, and parasitic plants. Therefore, this study was conducted to investigate the effect of phosphorous chemical fertilizer and symbiosis with mycorrhizal fungi on yield and yield components of different cultivars of durum wheat under rainfed conditions of Ilam.

This experiment was carried out as factorial based on a randomized complete block design with three replications at Sarableh Agricultural Research station (33° 45´ N latitude, 34° 46´ E longitude, and around 975 m above sea level) during growing season 2018-2019. Experiment factors consisted of four cultivars of durum wheat (Dehdasht, Zahab, Savarz and Saji) and five levels of fertilizer source (control, 25 and 50 kg.ha-1 P, mycorrhizal fungi (GM), mycorrhizal fungi + 25 kg.ha-1 P). Studied traits were plant height, spike length, spike weight, spikes.m-2, no. of spikelet per spike, no. of grain per spike, 1000-grain weight, grain yield, biomass yield and harvest index. For statistical analysis, analysis of variance (ANOVA) and Duncan’s multiple range test (DMRT) were performed using SAS version 9.1.

The results indicated that the simple effect of fertilizer sources on all of traits including plant height, spike length, spike weight, spikes.m-2, no. of spikelet per spike, no. of grain per spike, 1000-grain weight, grain yield, biomass yield and harvest index was significantly. So that, treatment of mycorrhizal fungi + 25 kg.ha-1 P had the highest influence at increasing studied traits among other treatments. The results also showed that Saji and Zahab cultivars showed more resistance to drought stress than other cultivars and had the better yield. The interaction effect of cultivars and fertilizer sources revealed that the combined use of phosphorous fertilizer and mycorrhizal fungi had better results compared to their use alone. So that, the highest yield of durum wheat with 4238 kg.ha-1 was obtained at Saji cultivar along with application of mycorrhizal fungi + 25 kg.ha-1 P. Generally, it is concluded that application of mycorrhizal and phosphorous fertilizer increased yield and yield components due to their roles in root growth and phosphorous uptake.

The use of biofertilizer technology is especially important for the management of soil phosphorous in soils with a lack of phosphorous and soil moisture. The results of this study showed that in rainfed cultivation, the use of phosphorous fertilizer and mycorrhizal fungi can have a positive effect on increasing the yield of durum wheat due to their role in increasing the plant root system and thus more water absorption and nutrients. However, the results of this study clearly indicated that the combined use of phosphorous fertilizer and mycorrhizal fungi had better results compared to their use alone. So that, the highest of spike weight, no. of grain per spike, 1000-grain weight, grain yield and biomass yield obtained at Saji cultivar along with application of mycorrhizal fungi + 25 kg.ha-1 P and the lowest value these traits recorded in Savarz cultivar along with control treatment.