Effect Of Sulfur And Selenium Combination On The Growth,quality And Antioxidant Activity Of Garlic

The selenium is the essential trace element for plant growth and development. The main biological functions of selenium include changing activity of oxygen defensive enzymes(such as GSH-Px) in plant tissues, promoting the synthesis of protein, improving crop quality and increasing crop yields. Sulfur is one of the essential mineral nutrients for plant growth and development, which is secondary element only after nitrogen, phosphorus and potassium. It participates in respiration, photosynthesis, protein synthesis, lipid synthesis, biological nitrogen fixation, glycometabolism and other physiological activity in plants. Selenium and sulfur is the same group elements, they have very high similarities in chemical and physical properties, so they have assist function in plants.The interaction performances in the absorption, assimilation of selenium in plants, plant growth and development and so on. Garlic is selenium-rich plant, which also is sulfur required crop. The effects of sulfur and selenium combination on the growth, quality and antioxidant activity of garlic were studied to provide references for the rational fertilization, nutrition improvement and Se-enriched garlic production. “Jinxiang 3” were tested, selenite and sodium sulfate were taked the sodium as selenium source and sulfur source in this research. The experiment was carried out in a small shed under the condition of hydroponic culture, two sulfur levels(2 mmol?L-1 and 4 mmol?L-1) and three selenium levels(0μmol?L-1、3μmol?L-1 and 6μmol?L-1) were designed to study the effects of sulfur and selenium combination on growth and development, yield,quality, nutrient absorption and enzymes activities of garlic. The results are as follows;1. Suitable selenium with sulfur treatment can promote the shoot fresh and dry weight, plant height, leaf width, pseudostem length, pseudostem diameter, fresh weight and diameter of bulb. Selenium’s impact on plant growth is not only associated with selenium concentrations also closely associated with garlic growth period and sulfur concentration.2. Selenium can improve plant activity of antioxidant enzyme system. Treatment with appropriate concentration of selenium can significantly improve the activity of GSH-Px, but selenium decreased the activity of SOD, and the effect of selenium on CAT and POD activity is relatively complex, also affected by the growth period and the concentration of sulfur. Selenium treatment increased the GSH-Px activity by 33.6%-22.3 times, and with the increasing of growing days, the GSH-Px activity increased significantly.3. Application of selenium can effectively slow down the ageing process of garlic. Under the low concentration of sulfur, selenium treatment decreased leaf MDA content by 19.1%-43.4%; Under the high sulfur concentration, leaf MDA content decreased with the increase of selenium. Selenium significantly improved the Fv/Fm value by 19.9%. All selenium treatments reduce the proline content except under low sulfur concentration in 160 d. At later growth stage, selenium slows down the decomposition of pigment, even increase the content of chlorophyll b and carotenoid, reduce the decline of photosynthetic pigment.4. Selenium can improve the nutritional quality of green garlic sprout, and the quality indicators have almost the same change trend: under the low sulphur concentration, with the increase of selenium concentrations indicators decrease after rising first, high sulfur concentrations in contrast. Selenium improved Vc, allicin, soluble sugar, soluble protein content of blade and pseudostem by 5.5%, 3.7%, 36%, 22%, 20.2%, 20.1%, 64.8%, 57.4%. Under low sulphur concentration, selenium treatment decreased soluble protein content in the bulbs by 10.9%, and under high sulfur concentrations, soluble protein content change trend is the opposite of low sulfur concentrations. Under low sulphur concentration,low selenium treatment improve the soluble sugar content of bulb, high selenium treatment reduced its content. Under the high concentration of sulfur, selenium application reduced the soluble sugar content of bulbs.5. Sulfur, selenium can promote the absorption of garlic to sulfur, selenium, potassium, calcium, magnesium, and selenium content increased most obviously. Selenium content increases with the increase of selenium concentrations in both sulfur concentrations. Under low sulfur concentration,potassium, calcium, magnesium, sulfur content increased with selenium concentrations at first and lowered later,in high sulfur concentration they increased with selenium concentrations. Selenium not conducive to the accumulation of phosphorus under low concentration of sulfur and not conducive to the accumulation of nitrogen under high concentration of sulfur.