ISHS Acta Horticulturae 726: IV International Symposium on Pistachios and Almonds
INFLUENCE OF WASHING POLLINATED STIGMAS ON FERTILISATION IN ALMOND |
| Authors: | E. Ortega, F. Dicenta, J. Egea |
| Keywords: | pollen-stigma adhesion, fertilization, Prunus dulcis, pollen germination, washing effect, rainy weather, fruit set |
| Abstract:
The fact that rainy weather negatively affects production in almond is well known by growers. However, as far as we know, no previous study has been carried out in this species to determine if the rain may wash pollen grains from the stigma surface and consequently affect fertilisation efficiency. To answer this question, flowers of the self-compatible almond “Antoñeta” were emasculated on branches from adult trees in the field, pollinated by hand with pollen of “Marcona”, and sprayed with water to simulate the rain effect at 4, 8, 24 and 48 hours after pollination. Seven days after spraying the flowers, the number of germinated pollen grains on the stigma was recorded in 10 pistils for each treatment by fluorescence microscopic observation. In addition, for each branch the initial and final fruit set were determined at 30 and 60 days after pollination respectively. The following year additional assays were performed in the field and in the laboratory in order to complete the study with earlier treatment times. Thus, rain was simulated in the field at 0, 2 hours, and flowers of “Antoñeta” were immersed and shaken in a water container in the laboratory at 0, 30, 60, and 120 minutes after pollination. One more sample was immersed, shaken, then pollinated and again immersed and shaken. The results from field assays showed that adhesion of pollen grains was very quick and strong, and the treatments did not affect pollen adhesion and subsequent fruit set. On the other hand, laboratory results showed that all washing treatments decreased the number of germinated pollen grains on the stigma, mainly when the flowers were immersed before being pollinated. In conclusion, the results showed that the simulated rain was not able to wash pollinated stigmas, although it seems to affect pollen adhesion to the stigma in forthcoming pollinations. | |
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