Effect of Season on the Carnation (Dianthus Caryophyllus L.). III Flower Quality

Carnation flowers, cv White Sim, of three market grades from commercial-type beds were examined monthly to relate their grading to various quality parameters and to determine the extent of any seasonal changes in these values. Some showed small seasonal changes, e.g. percentage dry weights of flowers and stems, whereas others showed very large seasonal changes, e.g. flower diameter, stem strength and the proportion of the dry weight in the flower head relative to that in the stem. Regression analyses showed that flower fresh weight was related to the mean daily radiation and temperature integrals in the period from the early bud-visible stage to anthesis:

Fresh weight (g)=5.022+10.537 log_e cal cm-² day-¹-2.215 temp. °C.

Stem strength was also related to radiation and temperature in this period:

Stem strength (coded value)=34.825–9.027 log_e cal cm-² day-¹+1.214 temp. °C.

Unlike fresh weight and stem strength, in which solar radiation played a greater role than temperature, flower diameter was largely dependent upon temperature, high temperatures producing small flowers. Temperature and light integrals in the period from the early bud-visible stage to the bud reaching 1 cm diam. gave the best relationship to flower diameter at anthesis:

Diameter (cm)=9.361–0.1567 temp. °C+0.1353 log_e cal cm-² day-¹.

The environmental conditions required to produce good quality carnation flowers were found to be high solar radiation integrals coupled with low ambient temperatures.