Changes in the content of pigments in croton (Codiaeum variegatum (L.) Blume) leaves caused by spider mite feeding
1999
Pilko, A. | Tomczyk, A. (Warsaw Agricultural Univ. (Poland). Dept. of Applied Entomology)
The research was carried out on three croton varieties: Excellent, Norma and Golden Sun. The plant material was taken for pigment analyses after five weeks of mites infestation when Tetranychus urticae population density exceeded 25 specimens per leaf. Content of chlorophyll a and b as well as carotenoids were estimated in the fresh plant material in control and infested plants of each tested variety. The lowest concentration of chlorophyll content was noticed in the healthy leaves of Excellent variety in comparison with varieties Golden Sun and Norma. No significant differences were found in the total level of carotenoids between all studied varieties. However, differences were observed in the content of four main carotenoids separated by chromatographic method: beta-carotene, lutein, violaxanthin and neoxanthin. For example in the leaves of variety Norma, concentration of violaxanthin was 3 times lower as compared to other varieties. Spider mite feeding caused the reduction in the level of all plant pigments. The highest decrease was observed in the injured leaves of variety Excellent as compared to control leaves. The content of chlorophyll as well as carotenoids in the infested plants was lower by more than 66/ than in uninfested leaves. The mite feeding had the strongest influence on the content of beta-carotene. The level of this carotenoid decreased almost 5 times as a result of mite infestation in the case of variety Excellent. The injuries caused by T. urticae feeding lowered strongly the decorative value of all croton varieties.
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