Effects of relative humidity and temperature stress on pollen viability of Cistus incanus and Myrtus communis
Titel:
Effects of relative humidity and temperature stress on pollen viability of Cistus incanus and Myrtus communis
Auteur:
Aronne, Giovanna
Verschenen in:
Grana
Paginering:
Jaargang 38 (1999) nr. 6 pagina's 364-367
Jaar:
1999-11-01
Inhoud:
Cistus incanus and Myrtus communis are two species commonly found in Mediterranean shrublands, flowering respectively in spring and summer. Pollen of single flowers of C. incanus is available for dispersal for 8-10 hours, during which time viability decreases from 91% to 61%. Field measurements of the variation in the percent pollen viability during the anthesis of single flowers of M. communis shows that, immediately after anthesis, pollen viability is very high; by the end of the first day it significantly declines and 36 hours after anthesis almost all grains are unviable. Experiments carried out under controlled environment showed that, in C. incanus, the greatest loss of viability occurs at 100% humidity and high temperatures, while under dry conditions pollen viability remains high throughout a wide temperature range. Similarly, pollen viability of M. communis remains high for several hours at high temperature and dry conditions, while it rapidly decreases at high humidity. In conclusion, the temperature experiments indicate that in C. incanus and M. communis, pollen viability does not appear to be drastically reduced if the relative humidity of the environment is low. Therefore, humidity is a far more important factor determining pollen viability loss in both species.
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