| Mentha spicata Linn is a perennial aromatic herb widely used in indoor ornamental and urban greening,with high medicinal,edible and economic value.Silicon and calcium are elements that are beneficial to plant growth and development,and can effectively promote plant growth and improve their yield and quality.This experiment used Mentha spicata cuttings as the test material to study the effects of different concentrations of silicon(500,1000,2000 mg/kg)and calcium(400,800,1200 mg/kg)on their growth,physiological characteristics and accumulation of mineral nutrients,which provided a reference for screening out the silicon and calcium concentrations suitable for the growth of Mentha spicata.The main findings are as follows:1.After 60 days of experimental treatment,the 1000 mg/kg silicon and 800 mg/kg calcium treatments had significant increases in plant height,leaf length and leaf width compared with the control(P<0.05),of which the plant height reached 1.11 and 1.15 times that of the control group,respectively.With the increase of silicon and calcium concentrations,the root configuration indexes showed a tendency to rise first and then fall,among which the total volume of roots after calcium treatment of 800 mg/kg reached 4.79 times that of the control group(P<0.05).After the calcium treatment of 800 mg/kg,the leaves,stems and roots were significantly higher than those of the control(P<0.05),reaching 4.18,4.84 and 3.58 times of the control group,and the 1000 mg/kg silicon treatment had the best effect on the increase in fresh weight of leaves and stems,reaching 2.33 and 3.95 times of the control group.2.The net photosynthetic rate of Mentha spicata leaves under different concentrations of silicon and calcium was increased compared with that of the control,and the net photosynthetic rate after the 1000 mg/kg silicon treatment was significantly increased by 72.77% compared with the control(P<0.05);The transpiration rate and intercellular carbon dioxide concentration after silicon treatment were reduced compared with the control,among which the transpiration rate after the 2000 mg/kg silicon treatment was significantly reduced by 42.25% compared with the control(P<0.05).After calcium treatment,the photosynthetic characteristics of leaves showed a law of first rising and then falling with the increase of calcium concentration.The contents of chlorophyll a,chlorophyll b and total chlorophyll increased with the increase of silicon and calcium concentrations,of which chlorophyll a and b after calcium treatment of 800 mg/kg reached 1.61 and 1.76 times of the control group.From the perspective of light response curve and light response parameters,the 1000 mg/kg silicon treatment and the 800 mg/kg calcium treatment were generally higher than the control,and the 2000 mg/kg silicon treatment was lower than the control.3.After the silicon treatment,the soluble sugar and soluble protein content,most defense enzyme activity and secondary metabolic substance content of the leaves of Mentha spicata incense increased first and then decreased with the increase of silicon concentration.After calcium treatment,only the enzyme activity and secondary metabolic substance content increased first and then decreased,and the malondialdehyde content and the relative permeability of the cell membrane decreased first and then increased.Under the 2000 mg/kg silicon treatment,the defense enzyme activity of Mentha spicata leaves was significantly increased compared with the control(P<0.05),and the POD enzyme activity increased by 24.74% compared with the control.The content of soluble sugars and soluble proteins is significantly reduced,and the degree of membrane lipid peroxidation is intensified.In the calcium treatment,800 mg/kg had the best effect on the content of osmotic regulatory substances and secondary metabolites,which was significantly higher than that of the control(P<0.05),and the content of secondary metabolites such as phenolic acid and flavonoids increased by 35.65% and 39.20%,respectively.4.In terms of the content of mineral nutrients in the whole plant,the N element after the 1000 mg/kg silicon treatment was significantly higher than that of the control(P<0.05),and the content of P,K,Mg,S and Ca under the 800 mg/kg calcium treatment was significantly increased compared with the control(P<0.05),reaching 1.34,1.69,1.53,1.36 and 1.48 times of the control group.In addition,the aboveground Si content after the 1000 mg/kg silicon treatment was significantly increased by 29.60%(P<0.05).The distribution of N,P,K,S and Ca elements in the aboveground and underground parts of the plant was manifested as the aboveground > the underground part.The Si element manifests itself as the underground part > the upper part of the ground. |
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