Effect Of Selenium And Sulfur On The Physiological Characteristic And Quality 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 SOD) in plant tissues, promoting the synthesis of protein, increasing crop yields and improving crop quality. 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 protein synthesis, respiration, photosynthesis, biological nitrogen fixation, lipid synthesis, 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. Therefore the study on the interaction of selenium and sulfur in garlic has important theoretical and practical significance for the production of selenium enriched garlic. This experiment tries the material by ’jin suan3hao’, taking the sodium selenite and sodium sulfate as selenium source and sulfur source, through field test and solid medium culture, to investigate the effect of selenium and sulfur on biological characteristic, photosynthesis, yield and nutritional quality of garlic and green garlic sprouts.1. Effects of applicating selenium and sulfur on growth and physiological characteristics of green garlic sprouts.Green garlic sprouts were planted in nursery substrate, while watering nutrient solution with different selenium and sulfur based on Hoagland nutrient. Two selenium concentrations at10(Se10),20(Se20) μmol·L-1were designed, while three sulfur concentrations at2(S2),4(S4),6(S6) mmol·L-1were designed. There were totally7treatments plus CK. Investigating the effect of selenium and sulfur on growth, physiological characteristics and nutritional quality of green garlic sprouts. The test results indicated that:1) Watering appropriate selenium and sulfur could promote growth and development of green garlic sprout. The plant height, weight, leaf width, stem diameter, root activity and root-shoot ratio were all significantly improved by watering nutrient solution with10μmol·L-1selenium and6mmol·L-1sulfur. Meanwhile, the contents of chlorophyll a, chlorophyll b, carotenoid and chlorophyll (a+b) increased by25.9%,23.7%,20.5%and24.6%compared, respectively. Watering nutrient solution with20μmol·L-1selenium and2mmol·L-1sulfur, were most conducive to dry matter accumulation in leaves and pseudo stems of green garlic sprout. 2) Watering appropriate selenium and sulfur could enhance antioxidant enzyme activity of green garlic sprout and delay leaf senescence. CAT, POD and SOD activity in green garlic sprout leaves was improved effectively by watering nutrient solution with10μmol·L-1selenium and6mmol·L-1sulfur,65.1%,35.1%and47.9%higher than CK, respectively. The results also indicated that, low concentration selenium with sulfur has better effect on improve enzyme activity than high concentration selenium with sulfur.3) Watering appropriate selenium and sulfur could improve the nutrition quality of green garlic sprout. Soluble sugar, vitamin C, and allicin contents in leaves and pseudo stems of green garlic sprout were improved significantly by watering nutrient solution with10μmol·L-1selenium and6mmol·L-1sulfur,52.7%and59.6%,7.2%and5.6%,32.7%and19.5%higher than CK, respectively. And that decreased nitrate content in leaves and pseudo stems of green garlic sprout,17.8%and29.4%lower than CK, respectively.2. Effects of spraying selenium and sulfur on photosynthetic characteristics, yield and quality of garlicGarlic planted on field, spraying nutrient solution with selenium and sulfur. Five selenium concentrations at0(Se0),10(Sel),20(Se2),30(Se3),40(Se4) mg·L-1were designed. While four sulfur concentrations at0(SO),100(S1),200(S2),300(S3) mg·L-1were designed. There were20treatments totally. Investigating the effect of selenium and sulfur on photosynthetic characteristics, the yield and nutritional quality of bulb and garlic. The test results indicated that:1) Spraying appropriate selenium and sulfur could improve photosynthetic characteristics on garlic leaves. Compared with CK, photosynthetic pigment content in garlic leaves, transpiration rate, stomatal conductance and net photosynthetic rate increased effectively by spaying nutrient solution with200mg·L-1selenium and30mg·L-1sulfur, while intercellular CO2concentration declined.2) Spraying appropriate selenium and sulfur could promote the growth and development of garlic bulb and bolt. The fresh weight of bulb, transverse diameter of bulb, the fresh weight of bolt and length of bolt increased dramatically by spraying nutrient solution with100mg·L-1selenium and20mg·L-1sulfur. Spaying high concentration of selenium and sulfur had strong development inhibition to garlic.3) Spraying appropriate selenium and sulfur could improve the nutrition quality of bolt and bulb. The contents of allicin, soluble protein, free amino acid, vitamin C, and soluble sugar in bolt and bulb could be significantly improved by spraying nutrient solution with200mg·L-1 selenium and10～30mg·L-1sulfur.Compared with CK,those indexes increased by54.4%and27.9%,51.1%and39.7%,50.1%and16.5%,45.9%and11.8%,38.9%and36.9%, respectively.