عنوان مقاله [English]
Most researchers believe that good management and proper use of biofertilizers are the ways for preparation of better nutritional conditions for the medicinal plant. Garlic is one of the most important medicinal crops. Allicin is the main active ingredient in this plant. Biofertilizers contain beneficial soil microorganisms or the metabolic products. Mycorrhizal symbiosis improves the soil physical, chemical and biological properties. Mycorrhizae increase crop resistance to pathogens, nutrient and water uptake, also reduce the negative effects of environmental stress and improve the quality of their host plants. Adding sulfur to the soil to improve the nutritional status of the plant by the release of nutrients will be effective when that the oxidation of sulfur in the soil is significant. For sulfur uptake by the plant, it is necessary that this element convert to sulfate by soil microorganisms. If elemental sulfur distribute in the soil and mix with the organic material, conversion of sulfur-oxidizing microorganisms be faster in wet conditions.
Materials and methods
The experiment was conducted as randomized complete block design with three replications in 2012. Treatments were included control plot, mycorrhizal inoculation (M), Thiobacillus (T), M + T, 75 kg sulfur per hectare (75S), 75S + M, 75S + T, 75S + M + T, 150 kg sulfur per hectare (150S), 150S + M, 150S + T, 150S + M + T. Each plot consisted of four rows with a spacing of 40 cm and row length of 10 m.
In treatments with 75 and 150 kg sulfur per hectare, 48 and 96 g of sulfur were used, respectively. Thiobacillus at the recommended dose was added to the soil a week before planting. Percent of fungal colonization obtained with Gridline Intersect Method. HPLC method was used to extract allicin content. Data were analyzed with the MSTAT-C software; the means were compared with LSD test at the 5% level of probability.
Results and discussion
The results showed that tuber dry weight increased significantly at 75s and 1505 in combination with Thiobacillus and mycorrhiza. Also the effects of 150S and150S + M, 150S + T were significant on tuber dry weight. The highest tuber dry weight was obtained in combination of 150S with Thiobacillus and mycorrhiza. The effect of 75s was not significant on tuber dry weight but application of 150S increased significantly dry tuber weight (about 50% over the control plots). Adding Thiobacillus to sulfur treatments (75s and 1505) had a significant effect on tuber dry weight and increased about 38 and 72 percent compared to the control, respectively. Chlorophylla content increased significantly in all treatments compare to the control. While the effects of 150S + M, 150S + T, 150S + M + T were significant on chlorophyllb.
The effects of 75S, 75S + M, 75S + T, 75S + M + T, 150S, 150S + M, 150S + T and 150S + M + T were significant on carotenoid. Allicin yield increased significantly in all treatments except mycorrhiza compared to the control. Application of 150 kg sulfur per hectare +Thiobacillus+mycorrhizas increased essential oil yield up to 3 times compare to the control. As a result the essential oil yield increased significantly in treatments of 75 and 150 kg sulfur per hectare compared to the control.
Tuber dry weight increased significantly with sulfur application in combination with Thiobacillus and mycorrhiza. Chlorophylla content increased significantly in all treatments. Allicin yield increased significantly in all treatments except mycorrhiza. Application of sulfur, increased essential oil yield.