Abstract: A method for screening tobacco resistance against root-knot nematode based on intensive seedling production is provided. The method has two biological properties: inducing and stimulating the hatching of nematode eggs by host root exudates, and easily infecting the root cap elongation zone by hatched second-instar larvae. The second-instar larvae hatched by the root-knot nematode eggs are continuously inoculated. After that, under cultivating the infected tobacco seedlings in shallow water infiltrating and humidifying substrate, the created temperature, humidity and air permeability conditions are suitable for disease induction. After disease investigation, disease index is calculated, and the resistance of tested cultivars is evaluated according to the disease index. The method features simple operation, high selection efficiency, and high accuracy and reproducibility.

Abstract: A tobacco arsenic transport gene NtNIP7-1 and a cloning method and application thereof are disclosed. A nucleotide sequence of the tobacco arsenic transport gene NtNIP7-1 is shown as SEQ ID: No. 1, and an encoded amino acid sequence thereof is shown as SEQ ID: No. 2. The cloning method of the tobacco arsenic transport gene NtNIP7-1 includes (S1) extracting RNA in tobacco, performing reverse transcription, and obtaining a first-strand cDNA; and (S2) taking the first-strand cDNA obtained by the reverse transcription as a template, synthesizing a specific primer according to sequences of the NtNIP7-1 gene, performing PCR amplification, recovering and purifying a product of the PCR amplification, and sequencing. In the present invention, inhibition of the expression of the tobacco endogenous gene NtNIP7-1 in tobacco plants is able to significantly reduce the arsenic content of tobacco leaves, and has broad application prospects in the field of low arsenic content breeding.

Abstract: The disclosure provides a method of screening tobacco germplasm for resistance to Alternaria alternata by ripening seedling leaves. The method includes ripening seedling leaves, spray inoculation, disease induction, and evaluation of disease resistance. Dense planting, fertilizer control, and potassium increment were used to forcibly ripening seedling leaves. A hospitable environment was simulated to induce disease in the ripened leaves. These treatments reduce differences in leaf maturity and avoid environmental changes. The technique of the disclosure provides greater accuracy and repeatability than the current technique of screening brown spot resistance, and offers the advantages of simple operation, reduced cost, space requirement, and labor intensity, high selection efficiency, and an accurate screening of tobacco phenotypes with resistance to brown spot, etc., used for large-scale screening of tobacco varieties with resistance to brown spot.

Abstract: The disclosure provides a method of screening tobacco germplasm for resistance to Alternaria alternata by ripening seedling leaves. The method includes ripening seedling leaves, spray inoculation, disease induction, and evaluation of disease resistance. Dense planting, fertilizer control, and potassium increment were used to forcibly ripening seedling leaves. A hospitable environment was simulated to induce disease in the ripened leaves. These treatments reduce differences in leaf maturity and avoid environmental changes. The technique of the disclosure provides greater accuracy and repeatability than the current technique of screening brown spot resistance, and offers the advantages of simple operation, reduced cost, space requirement, and labor intensity, high selection efficiency, and an accurate screening of tobacco phenotypes with resistance to brown spot, etc., used for large-scale screening of tobacco varieties with resistance to brown spot.

Abstract: A tobacco arsenic transport gene NtNIP7-1 and a cloning method and application thereof are disclosed. A nucleotide sequence of the tobacco arsenic transport gene NtNIP7-1 is shown as SEQ ID: No. 1, and an encoded amino acid sequence thereof is shown as SEQ ID: No. 2. The cloning method of the tobacco arsenic transport gene NtNIP7-1 includes (S1) extracting RNA in tobacco, performing reverse transcription, and obtaining a first-strand cDNA; and (S2) taking the first-strand cDNA obtained by the reverse transcription as a template, synthesizing a specific primer according to sequences of the NtNIP7-1 gene, performing PCR amplification, recovering and purifying a product of the PCR amplification, and sequencing. In the present invention, inhibition of the expression of the tobacco endogenous gene NtNIP7-1 in tobacco plants is able to significantly reduce the arsenic content of tobacco leaves, and has broad application prospects in the field of low arsenic content breeding.

Abstract: A device and a method for removing impurities in an aluminum melt are provided, in which the device includes an upper furnace body, a lower furnace body, an intermediate partition plate, a crucible, heating elements and a charging opening. The intermediate partition plate is mounted between the upper furnace body and the lower furnace body. The upper furnace body, a mixing chamber and a heating element are above the intermediate partition plate. The crucible is mounted in the lower furnace body. A heating element is provided around the lower furnace body. The mixing chamber and the crucible are connected by a jet pipe passing through the intermediate partition plate. For the device and the method, impurity removal is quick, efficiency is high and the process is closed, so there is no environmental pollution, and the aluminum melt after impurity removal may be directly cast.

Abstract: A device and method for removing impurities in aluminum melt. The device comprises an upper furnace body, a lower furnace body, an intermediate partition plate, a crucible, heating elements and a charging opening. The intermediate partition plate is mounted between the upper furnace body and the lower furnace body. The upper furnace body, a mixing chamber and the heating element are above the intermediate partition plate. The crucible is amounted in the lower furnace body. The heating element is provided around the lower furnace body. The lower furnace body is provided with the charging opening and a pipeline. The upper furnace body is provided with an inlet valve and an exhaust valve. The mixing chamber and the crucible are connected by a jet pipe passing through the intermediate partition plate. A ceramic seal pad is used for sealing between the mixing chamber and the jet pipe.