The influence of shading levels on foliage plant growth and quality

Ficus benjamina L. (weeping fig) and Codiaeum variegatum (L.) Bl. (croton) are very spread plants mostly used in the interior landscapes. These two foliage indoor pot plants have to be grown in a greenhouse under suitable conditions in order to enhance their adaptability to the interiors. Appropriate low light levels during cultivation are really important to improve plant quality but, in the same time, they can affect plant growth rate. This could be a problem for growers which have to produce high quality plants in a reasonable short period. With the aim to investigate the effect of shading levels and their period length on growth and quality of weeping fig and croton, plants were grown in pots for a three month period under 50, 70 and 90% shading level. After this period, half of the plants belonging to 50% and 70% shading levels were transferred to 90% shading level for two further months. Tested species showed different growth rates linked to plant morphology and leaf characteristics. Shading levels have modified plant growth and external quality. These variations were more significant in weeping fig than in croton plants. Our results showed the light reduction decreases plant growth but in the same time increases net photosynthesis under low PAR conditions (45 μmol m-2s-1). Plant visual quality was affected by the more light reduction during the experimental period; particularly, the colour of leaf variegation was positively influenced by the highest shading level.