In Vitro Germination of Different Date Palm (Phoenix Dactylifera L.) Pollen Sources from Southern Tunisia under the Effect of Three Storage Temperatures

Abstract

Date palm pollen storage is becoming more and more necessary due to the asynchronous maturation of male and female flowers that, frequently, occurs, during the last years in Tunisia. However, little information is available on the pollen viability and favorable storage conditions. The present study aims to compare date palm pollen storage at three temperatures (25 ± 2°C, 4°C and −20°C) and to evaluate the aptitude of pollens from different geographical origins to conserve their in vitro germinative potency. Results revealed that, after the fresh pollen, the overall pollen in vitro germinations were significantly improved with storage at −20°C (41.04 ± 23.84%) and 4°C (20.07 ± 22.19%) compared with storage at 25 ± 2°C (4.27 ± 4.39%). For each used temperature, the in vitro germination was not affected by the pollen origins. In fact, almost similar reactions were observed for fresh and stored pollen at 25 ± 2°C and 4°C. On the other hand, pollen stored at −20°C had reacted independently from the origin. However, the aptitude of pollens from similar origins to preserve their in vitro germination potencies under the three storage temperatures reveals some similarities. Physiologic characteristics of pollens were not related to the geographic origins and did not significantly affect their aptitude for storage.