Mycorrhizal fungi are effective in attracting food elements like phosphorus and nitrogen and the absorption of water in tension conditions, and in producing botanic hormones and harmonizing the environmental stress effect, increasing the plant’s resistance to abiotic stress (Portas and Taylor, 1975).
3.3. Oil content
Statistical analysis of data showed water stress had significant effect on oil content in sunflower (Table 1). The result of this study indicated that water stress treatments upto W2 increased the oil content but by increasing water stress from W2 to W3 the oil content decreased (Table 2). The oil content in sunflower seed depends on weather conditions, disease attacks during the season, and the hybrid’s characteristics. According to Škorić et al. (1994), oil synthesis ceases in sunflower seeds whenever the plant is exposed to any kind of stress. Škorić (1992), indicated that oil content in sunflower seed depends on mean daily air temperature, water supply at seed fill and the duration of the seed filling stage. Harris et al. (1978), noted that the oil content of sunflower seeds decreased with increasing air temperature.
Our results showed that the oil content of seeds in sunflower was significantly affected by mycorrhizal inoculation (Table 1). Results showed that the use of mycorrhiza increases the amount of oil content compared to the control treatment. In between two species of mycorrhiza, G. mossea had the highest effect of increasing oil content in seeds ( Table 2).
Data in this study indicated that interaction between water stress and mycorrhiza inoculation had significant effect on oil content (Table 1). The highest oil content of seeds was obtained at W2M2 treatment (Fig. 2).