The Effects Of Silicon In Nutrient Solution On The Growth And The Physiological-biochemical Characteristics Of Garlic

Silicon is the second most abundant element in soil and an important inorganic composition of higher plant. As a recognized beneficial element, silicon plays an important role in promoting crop yield, improving the product quatity and increasing crop resistance. For more than a decade, many scholars did a lot of silicon fertilizer experiment on the crops such as rice, wheat, sugarcane et al, and showed good results. However, in regard to the effects of silicon on physiological-biochemicial characteristics of garlic, there isn’t related research reports yet up to now. So in order to find out the demand law on silicon of garlic, and then provide a theoretical reference for resonalbe silicon fertilizer application,"Jinxiang white garlic" was taken and Five different silicon levels (0、0.75、1.5、2.25、3.0mmol·L-1) were designed to investigate the effects of silicon on growth, photosynthetic characteristics, yield, quality, activity of enzymes and absorption characteristic of N, P and K of garlic in nutrient sulution. The main results was as following:1. Applying with silicon in nutrient solution, the content of silicon of garlic roots, pseudo stems, leaves and bulbs significantly increased, and was positively related to the silicon contentation in nutrient solution. They reached the he biggest at Si3.0, and increased by2638.79%,177.28%,404.29%and141.80%compared to CK, respectivity. At the same time the distribution of SiO2at different organs is nonuniform, and the size order of SiO2concentation is:root> bulb> pseudo stem> leaf.2. Adding appropriate silicon concentration (1.5mmol·L-1) to nutrient solution significant promotes the growth and the activity of root, compared with the treatment without silicon, the fresh weight of root, length of root and number of root increased by74.35%,18.56%and17.85%, respectivity, the activity of root increased by32.90%. The plant fresh weight, plant height, pseudo stems length, pseudo stems diameter, leaf width and leaf area are also have different degrees of boost with the increase of silicon content from0to3.0mmol·L-1, and the effects is best while the silicon content is1.5mmol-L-1, however at the part of promoting the growth of garlic, silicon plays a positive role at early stage than later period of the birth. Bisedes, the yield of garlic bolts and bulbs also significantly boost. Compared with the treatment without silicon, the average fresh weight per bolt of garlic increased by13.12%-53.64%and the average fresh weight per bulb increased by20.16%～44.87%. Except for yield, the exterior quality of bulb is also enhanced, such as the diameter of bulb increases by3.62%～23.73%while the height of bulb increases by3.62%-23.73%.3. In the range of0-1.5mmol·L-1, the pigment content, net photosynthetic rate and stomatal conductance of garlic leaves rise with the increase of silicon concentation, but they decrease while the silicon content over1.5mmol·L-1. However, the change trend of transpiration rate is opposite, it falls first and then rises at the silicon content from0to3.0mmol·L-1, and reaches the minimum value at Si1.5, reduced by17.78%compared with CK. But the effect of silicon on intercellular CO2is unconspicuous. Besides, silicon also enhances the activity of NR in garlic leaves, promote the nitrogen oxidoreduction levels and the synthesis of organtic nitrogen compound. At the same time, silicon also reduces the content of MDA significantly, maintains the stability of cell membrane systems, and it must be have a very close relationship with that silicon can siginificantly enhance the activity of antioxidant enzymes such as SOD, POD and CAT.4. The content of soluble sugar, free amino acids and vitamin C in leaves, pseudo stems, bolts and bulbs of garlic rises first and then falls when the silicon content is in the range of0-3mmol·L-1. The content of soluble sugar was the highest while the silicon content was1.5mmol·L-1. Compared with the treatment without silicon, the content of soluble sugar in leaves and pseudo stems increased by21.28%-36.21%and27.53%-41.96%, respectivity, the content of soluble sugar in bolts and bulbs of gailic increased by21.89%and23.74%, respectivity. However the content of free amino acid and vitamin C reaches their maximum value at Si2.25. But the content of soluble protein in leaves is reduced while it is improved in pseudo stems, bolts and bulbs of garlic with the increase of silicon content. The reason may be that silicon promotes the synthesis of soluble protein in leaves and the transfer from leaves to pseudostems, bulbs and bolts. Besides, whatever the leaves and pseudo stems or the bulbs and bolts of garlic, the content of allicin all decreased, and the content of allicin in leaves and pseudo stems is lowest at Si2.25, while it was at1.5mmol·L-1in bolts and bulbs.5. The effect of silicon on the absorption of nitrogen, phosphorus and potassium of garlic is complicated. It is in favor of the absorption of nitrogen if using silicon at the period of seedlings while decreases the absorption of nitrogen using at later period of the birth. But at the whole progress of growth and development of garlic, the absorption of phosphorus is significantly promoted, and the content siginifantly increases than the treatment without silicon. The best contention of silicon for the absorption of phosphorus of garlic is1.5mmol·L-1. In this experiment, it promotes the absorption of potassium applying with a low concentration of silicon (0.75-1.5mmol·L-1), however it refrains that while the silicon conerntration in nutrient over1.5mmol·L-1.0.75～1.5mmol·L-1is the best silicon concent for the absorption of potassium of garlic.