ISHS Acta Horticulturae 387: III International Protea Research Symposium
PRELIMINARY RESULTS ON FACTORS AFFECTING IN VITRO GERMINATION AND STORAGE OF PROTEA POLLEN |
| Authors: | I.D. van der Walt, G.M. Littlejohn |
| Abstract:
The effects of pH, sucrose, boric acid and temperature upon in vitro germination of Protea repens (L.) L. cv. Embers pollen were investigated in hanging-drop culture to optimize conditions for germination. The basal medium consisted of 300 ppm Ca(NO3)2.4H2O, 200 ppm MgSO4.7H2O and 100 ppm KNO3 in distilled water. The following ranges of the variables tested were found to be optimal for fresh pollen: pH (5–8), sucrose concentration (0.4 to 0.7M), boric acid concentration (50 to 500 ppm) and incubation temperature (5 – 30 °C). There were no significant differences in germination percentage or pollen tube length within these ranges, but a sharp drop in germination occurred beyond these ranges. In all cases pollen tubes did not reach a length of more than 120 μm. The influence of storage temperature and humidity on pollen viability were studied in two Protea clones. Pollen was stored at a range of temperatures and relative humidities (r.h.) for up to 6 months and tested for ability to germinate in vitro following a period of hydration at high humidity. Pollen stored at -196 °C in liquid nitrogen and at -14 to -18 °C in a deep freezer, retained a germination percentage as high as that of fresh pollen (> 90%). Pollen stored at 2 to 7 °C and 22 to 27 °C maintained a moderate (> 50%) germination percentage for 75 and 30 days respectively at the 10 and 30% r.h., while the germination percentages dropped much quicker at the 60% r.h. | |
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