عنوان مقاله [English]
Background and objectives: Garlic is one of the excellent medicinal plants, used thousands of years ago. In addition to essential oils and valuable secondary metabolites, this plant contains elements such as sulphur and silicon. These elements, in addition to creating favorable drug properties, cause the plant to resist biological and non-biological stresses. Therefore, the use of these elements can have beneficial effects on the yield and medicinal properties of this plant. In the present study, the effect of sulphur and silicon on yield, yield components, photosynthetic parameters, nutritional elements and some phytochemical parameters of garlic plant were investigated.
Materials and methods: This experiment was conducted as factorial based on randomized complete block design with two factors of sulphur (at three levels of zero (S0), 15 (S15) and 30 (S30) liters per hectare) and silicon (at three levels of zero (Si0), 2 (Si2) and 4 (Si4) liters per hectare) with three replications. The treatments were applied as fertigation with intervals of 7-day, three times. At the end of experiment, traits such as yield, single garlic bulb weight, clove weight, length and width of bulb and clove, number of cloves, photosynthetic parameters (includes percentage of leaf relative humidity, transpiration velocity, stomatal conductance, stomatal conductance versus water vapor, carbon dioxide uptake ratio, photosynthetic active radiation of below and above the leaf, and photosynthetic active radiation of the environment) were recorded. Also, phytochemical properties (including antioxidant activity, total phenol, total flavonoid and caffeic acid) were evaluated. Data analysis was performed using SAS software and mean comparisons were done through Duncan's multiple range test at 1 and 5 percent probability level.
The results showed that the use of fertilizer treatments (sulphur and silicon) in comparison to control (non-fertilizer application) increased in all studied traits. Application of S15Si0 treatment had a superiority in evaluating yield and yield components, or didn’t show significant differences with treatments having higher sulphur and silicon content. The highest amount of photosynthetic active radiation of the below the leaf, environment and above the leaf were obtained in S15Si4 treatment. The rate of carbon dioxide absorption in the S15Si0 treatment was highest, and at the same level with S30Si2, statistically. The highest rate of transpiration was achieved with application of S30Si2 treatment. Also, the use of S30Si4 treatment increased the amount of water vapor and relative humidity of the plant. In the case of nutrition elements, it can be concluded that the highest amount of nitrogen were obtained from S30Si2 treatment, the highest amount of phosphorus, potassium and calcium were obtained from S0Si4 treatment and the highest Sulphur and silicon concentrations in S0Si2. The application of S15Si4 treatment also resulted in the highest amounts of magnesium production, which was at a statistical level with S0Si4, S15Si0 and S30Si2 treatments. The highest level of antioxidant activity was related to S15Si2 treatment. Also, the highest total phenol was obtained by S0Si2 treatment. Maximum content of total flavonoid was observed in S30Si2 treatment. The highest amount of caffeic acid was obtained in S0Si0, S15Si0 and S30Si0 treatments with 20.9, 20.2 and 20.2 mg / kg dry weight, respectively; which had no significant difference with S0Si4 and S30Si2 treatments.
Conclusion: In order to produce the highest amount of dry matter, as well as producing the highest quality of garlic in terms of the amount of active substances in the pharmaceutical industry, the application of elements such as sulphur and silicon can be very important; so that the lack of these elements will reduce the qualitative and quantitative characteristics of this plant.