Salvia splendens `Top burgundy' was grown in pots of different sizes (5, 50, 150, and 450 mL) to assess the effect of rooting volume on the growth and development of salvia. Seeds were planted in a peat-lite growing medium and plants grown in a greenhouse during the winter and spring of 1996. Plants were spaced far enough apart to minimize mutual shading and interplant light competition. Plants were harvested at weekly intervals and shoot and root dry mass and leaf area were measured. Relative growth rate (RGR) and net assimilation rate were calculated from these data. Differences in plant size became evident at 25 days after seeding. A small pot size (5 mL) decreased root and shoot dry mass, RGR, and NAR, while increasing the root:shoot ratio. Differences between the pot sizes became more apparent during the course of the experiment. The observation that root: shoot ratio decreased with increasing pot volume suggests that the decreased plant size in smaller pots was not the direct effect of reduced root size. Growth most likely was limited by the ability of the roots to supply the shoots with sufficient water and/or nutrients. Pot volume did not only affect the growth, but also the development of the plants. Salvia flowered faster in bigger pots (about 50 days after seeding in 450-mL pots), while the plants in 5-mL cells did not flower during the 9-week period of the experiment.
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