Petunia grandiflora Juss. and
Nicotiana alata
Link & Otto are two of the most widely spread plants on the market for
annual potted ornamental plants. In order to identify the most adequate substrate formula we analyzed the effects of
different potting growing media used for
P. hybrida grandiflora ‘Bravo’ and
N. alata ‘Dinamo’ on their photosynthetic
capacity, leaf area, and flowering potential. Optimization of growing media formula for petunia and ornamental tobacco
was performed by preparing four growing media mixing fallow soil (FS), Biolan peat (BP), acid peat (AP), leaf compost
(C), and perlite (P) in different proportions. The physiological potential of petunia and ornamental tobacco was investigated
by photosynthesis and respiration rate and chlorophyll pigments in leaves, while the vegetative and flowering phenological
stages were evaluated by number of leaves per plant, leaf area, number of flowers per plant and leaf area/flowers ratio.
These measurements were significantly influenced by the different potting growing media used in this study. In the
flowering stage, the highest photosynthesis rates (8.612
μmol CO
2 m
-2 s
-1) as well as leaf area (1.766 dm
2) of petunias were
obtained on growing media with 60% biolan peat, 30% acid peat and 10% perlite (BP60-AP30-P10). Flowering responses
to growing conditions vary greatly among plants and the biggest number of ornamental tobacco flowers (22 flowers plant
-1)
was registered as an effect of BP60-AP30-P10 media. Growing media with the BP60-AP30-P10 formula seem to be the
most adequate growth substrate to develop profitable crops for petunias and ornamental tobacco with high decorative value.
