Genotype difference and heterosis of nutrient characteristics of fluecured tobacco in seedling stage

Six hybrids and 13 genotypes of fluecured tobacco were used to study the genotype difference, parentoffspring correlation and heterosis of F1 generation in their nutrient characteristics. The results showed a significant difference in biomass, root/shoot ratio, contents and absorptions of nitrogen (N), phosphorus (P) and potassium (K), chlorophyll concentration, nitrate reductase (NR) activity and root activity among different genotypes of fluecured tobaccos in seedling stage. The contents of N, P and K in roots and N and K in shoot, dry matter accumulation, root activity and root/shoot ratio showed no significant correlations between F1 generation and the parents. There was a significant negative correlation between P content in shoots of F1 generation and midparent, while NR activity of F1 generation had significant positive correlation with female parent. The chlorophyll concentration of F1 generation correlated significantly with male parent, midparent and lowparent. The P and K contents in root, N content in shoot, NR activity, chlorophyll concentration, root activity, root/shoot ratio, dry matter accumulation of fluecured tobacco in seedling stage had midparent heterosis. The P content in root, NR activity, root activity, root/shoot ratio, dry matter accumulation had over highparent heterosis. The N content in root and P, K contents in shoots had no significant heterosis, but some cross combinations had midparent heterosis and over highparent heterosis.