| In order to improve the growth and quality of tobacco plants at low temperatures.The main plant variety "Yuyan No.10" in Henan tobacco area was used as the test material.The treatment was carried out at a low temperature of 11℃/8℃.Tobacco seedlings were regulated by the interaction of exogenous substancesβ-aminobutyric acid,calcium chloride and the two.The mode of administration of the exogenous substance capable of mitigating low temperature damage and the concentration of application are screened.Furthermore,by observing the phenotype,the relevant physiological and biochemical indicators were determined to be studied at physiological level.The main research results are as follows:1.The growth of tobacco seedlings was significantly restricted in low temperature environment.The agronomic traits of Yuyan No.10 were significantly different from those of CK treatment.The root length,maximum leaf length,leaf width and leaf area were significantly lower than CK.The regulation reduces the damage at low temperature,and the antioxidant enzyme activity,proline,soluble sugar and malondialdehyde content are improved.On the one hand,the degree of membrane lipidation caused by low temperature is increased.On the other hand,the formation of osmotic adjustment materials also mitigates some of the low temperature damage.The photosynthetic pigment content decreased at low temperature,and the photosynthesis rate parameters showed photosynthetic rate,stomatal conductance,transpiration rate,water use efficiency and stomatal limit decreased,and intercellular carbon dioxide concentration increased.NtLDC1,NtERD10B and NtERD10BD showed significant changes in expression levels associated with tobacco stress at low temperatures.The expression level of the NtLDCl gene was down-regulated at low temperature NtERD10B.The expression level of NtERD10BD was significantly upregulated.2.Under low temperature,β-aminobutyric acid could alleviate the damage of tobacco seedlings to some extent by chilling injury.With the increase of rooting concentration,the degree of remission showed a trend of increasing first and then decreasing.Agronomic traits,antioxidant enzyme activities and photosynthetic pigments were best treated with 0.05 mmol/L of roots and the lowest content of malondialdehyde in different root-concentration treatments.The relative expression levels of NtLDC1,NtERD10B and NtERD10BD were higher.The physiological indexes of 0.02 mmol/L were the second only to the root of 0.05 mmol/L,followed by the root irrigation of 0.1 mmol/L.Spraying β-aminobutyric acid at a low temperature also has a certain relief effect.The degree of remission showed a decreasing trend with the increase of rooting concentration.The spraying concentration of 0.2 mmol/Lβ-aminobutyric acid was the best at a relatively low temperature,followed by 0.5 mmol/L.Comparison of the two modes of administration and different concentrations can be found.The physiological and biochemical indexes of 0.2 mmol/L were better,followed by treatment with 0.05 mmol/L.Spraying 1 mmol/L of and filling 0.1 mmol/L of did not perform well.The treatment with 1 mmol/L and 0.1 mmol/L was not good,and there was no significant difference between all aspects and low temperature treatment.It is indicated that the exogenous application of β-aminobutyric acid has the effect of promoting concentration and inhibiting high concentration.3.Based on the application of 0.2 mmol/L β-aminobutyric acid,the interaction between β-aminobutyric acid and calcium ions and β-aminobutyric acid were investigated by complexing calcium chloride,calcium ion chelating agent and calmodulin inhibitor.The mechanism of regulating low temperature.It can be found that the application of 0.2 mmol/L β-aminobutyric acid,10 mmol/L calcium chloride and the interaction of the two in the treatment of fresh weight,antioxidant enzyme activity,ASA,GSH content compared with low temperature treatment,APX,GR activity and ZA,GA,IAA,ABA four major hormone levels have significantly improved.Significantly decreased in terms of relative conductivity,malondialdehyde and hydrogen peroxide superoxide anion.The tendency of treatment with P-aminobutyric acid and calcium ion chelating agents and calmodulin inhibitors at low temperatures is contrary to the results of the first three treatments.It is indicated that the interaction between β-aminobutyric acid and calcium ion can improve the cold tolerance of tobacco seedlings,and the cold tolerance of β-aminobutyric acid to regulate tobacco may be related to calcium ion signaling. |
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