Effects of shading treatments on pigmentation and inflorescence quality of Calathea crotalifera bracts

Abstract

The pigment composition and colouration of inflorescence bracts of Calathea crotalifera were evaluated in this study. The concentration of anthocyanin and chlorophyll were quantified during bract development in two selected cultivars (Red and Yellow). The results of this study indicate that the concentration of different pigments (chlorophyll a and b, carotenoids and anthocyanins) varied according to bract maturity stage. The photosynthetic pigments of chlorophylls were increased at the early stage of inflorescence development and significantly decreased during the fully pigmented stage simultaneous with an increase in either carotenoids or anthocyanins. The chlorophyll contents start to increase when the inflorescence showed a discolouration of red and yellow pigments in the bracts. The major pigments in the fully pigmented yellow bract were carotenoids while the main composition pigments in red bracts were anthocyanins and carotenoids. In the investigation of shading treatments, we found that shading significantly reduced chlorophylls, carotenoids and anthocyanins contents in the bracts. The highest pigment contents were recorded in the control treatment (without shading) followed by shading at 40% and 80%. Relatively, control treatment gave the best result for growth and development of C. crotalifera cv. 'Red' inflorescence in terms of colour, number and size of bract, and inflorescence yield. The inflorescence length, diameter and colouration decreased significantly in shading treatments (40% and 80%) as compared with control. Overall, these works highlight the positive effects of control treatments on the development and quality of cut flowers of C. crotalifera under tropical climate in Malaysia.