Correlations between resistance of tobacco to Bemisia tabaci (Gennadius) and chemical components of tobacco leaves

With the aim for the resistance mechanism of tobacco to Bemisia tabaci, we determined the chlorophyll content of tobacco leaves, the chemical components and amino acid content in fresh or cured tobacco leaves, and analyzed the correlations between resistance of tobacco to Bemisia tabaci and chemical components of tobacco leaves. Results show that significantly negative correlation occurs between the chlorophyll content in middle tobacco leaves and the population amount of Bemisia tabaci. The ratio of K₂O to Cl, sugar to nicotine, nitrogen to nicotine, and the contents of reducing sugar, nicotine, protein in fresh leaves are correlated with the resistance of tobacco variety to Bemisia tabaci, yet with no significant level. Involving the chemical components of cured tobacco leaves, nicotine demonstrates the most evident and negative correlation to the amount of Bemisia tabaci, while the ratio of nitrogen to nicotine, the positive. The total amount of amino acid is significantly positive correlated to the amount of Bemisia tabaci. Six amino acids have greater effects on the resistance of tobacco variety, including serine, arginine, threonine, glutamic acid, leucine, lysine, with the correlation coefficient reaching significant level. We conclude that the contents of chlorophyll, nicotine, six amino acids, and the ratio of nitrogen to nicotine have more considerable effects on the resistance of tobacco variety to Bemisia tabaci.