Genetic analysis of chlorophyll content in flue-cured tobacco leaf

Mixed major-gene plus polygene inheritance model was used to analyze inheritance of SPAD reading with six generations(P1,P2,F1,B1,B2,and F2) of flue-cured tobacco(N.tobacum L.) cross between Wanye and Coker319.Results showed that SPAD reading was controlled by a single gene with additive-dominance effect plus polygenes with additive-dominance-epistatic effect(D0 model).The additive effect of major gene was-5.89,and dominant effect of major gene was3.47.The major gene heritabilities in B1,B2 and F2 were 3.61%,46.11% and 48.94% respectively,and the corresponding polygenic heritabilities were 52.04%,8.25% and 0.00% respectively.These results indicated that major gene in F2 was a key factor and environmental factor was also relatively important.This implies that major-gene is a main factor in genetic improvement of SPAD reading whereas environmental effect should also be taken into consideration.