Significance and Interaction of CaCl² treatments and genetic background in Primula greenhouse crop improvement efforts

Primula (Primrose) is an important horticultural crop grown in glass houses for its ornamental value in the NE US. Plants are prized that exhibit large, prolific flowers. The potential of several combinations or concentrations of CaCl² products and a control were tested in on several Primrose cultivars ("Donova Mix", Sakata) at UConn. The products tested were CalOxFT (Biosafe Systems, East Hartford, Connecticut), which is an 8-0-0 fertilizer with 10% mobilized calcium, and DowFlake (Occidental Chemical Corporation, Dallas, TX), which is fundamentally a road salt product adapted to horticulture research. Plant dry weight, number of flowers, and flower diameter were measured.

A Poisson regression model was carried out in R. Statistical analysis revealed that there was interaction between cultivar and CaCl² treatment (p<0.01), suggesting a high genetic variance in Primula response to CaCl². Flower color was associated with Total flower number, with the positively associated cultivars being Flower Color Pink 1, Flower Color Pink 3, and Flower Color White (p<0.05). For example, the Blue flower color was a mid-performer, with a mean of 62.9 total flowers, and Flower color Pink 1 produced an average of 99.45 total flowers.

In terms of CaCl² treatments, DowFlake1X and DowFlakePlusCalOx1/2 were positively associated with number of TotalFlowers (p<0.05). Using Tukey contrasts for multiple comparisons of means, we determined that DowFlake1X resulted in significantly more flowers than the control, and also DowFlakePlusCalOX1/2 produced significantly more flowers per plant than the control during the experiment (p<0.005). The mean number of the flowers for the control group was 72.35; the DowFlake1X group had an average flower number of 81, and DowFlakePlusCalOX1/2 had an average of 79.5 flowers per plant.

There was no honestly significant difference in average flower diameter from CaCl² treatments; this parameter was determined by the Flower Color or variety. The average flower diameters varied from 5.033- 5.2cm and were similar for the treatments and control. This research may be applicable to other flowering crops, and suggests that nursery operators may optimize production by selecting the top performers under CaCl² treatment.