بررسی دماهای مختلف آزمایشگاهی بر روی جوانه زنی دانه گرده و سرعت رشد لوله گرده در برخی ارقام خرما

IntroductionThe date palm (Phoenix dactylifera L.) belongs to the family Arecaceae is a dioecious trees. Due to the problems of non-overlapping flowering of some male and female palm trees, commercial date production requires artificial pollination. Temperature is an important environmental factor influencing the pollination, fertilization and fruit set of the date palm. Availability of efficient male pollinators are of great importance in date palm production chain and for regular yearly bearing as the quantity and quality of pollen is a yield determining factor. The flowering and pollination period of date palm varies upon cultivar, geographic location and climatic conditions. However, frequent asynchronous flowering of date palm male and female trees occur due to climatic changes and abiotic stress. In such cases, farmers may pollinate their trees with pollen of a known male conserved at ambient conditions from the previous season; however, this is mostly result in a low fruit set and yield.Materials and MethodsIn this study, a factorial test was performed based on a completely random design with three replications at the laboratory of the Horticulture department at Ilam University to determine the rate of germination in five male date palm cultivars. The first factor consisted of nine temperature levels of ۱۵, ۱۸, ۲۱, ۲۴, ۲۷, ۳۰, ۳۳, ۳۶ and ۳۹ and the second factor referred to the cultivar of the pollinator which had five levels of ‘Ghanami Sorkh’, ‘Ghanami Sabz’, ‘Sabz Parak’, ‘Nare Pakutah’ and ‘Khareji’. The pollen of the above-mentioned cultivars was obtained from the date palm Germplasm collection at the Date Palm and Iranian Tropical Fruits Institute in the city of Ahwaz. In the early days of the flowering season (March), the cultivars under study were identified and labeled. They were then checked on a daily basis and whenever the sheaths were ripe enough, they were picked and preserved in a sterile environment in room temperature. After the sheaths opened, the flower clusters were dried in the same environment and at the same temperature. Then, the cluster strings were separated and kept in a freezer at -۱۸ °C until it was time for the test. Viability and vitality of the pollen was specified through the dying method using Acetocarmine solution.Results and DiscussionThe results showed that there was a significant difference among cultivars, temperature and interactions of them at the level of ۱%. Among the studied temperatures, the highest germination of pollen grains in all cultivars occurred at ۳۰ °C, followed by ۳۳ °C and ۲۷ °C, respectively, and the lowest germination percentage were obtained at ۱۵ °C. Among cultivars, the percentage of pollen germination in ‘Ghanami Sorkh’ was quite high (۹۲.۴۵%), and ‘Nare Pakutah’ (۸۷.۳۳%), also, simultaneously ‘Sabz Parak’ (۸۴.۸۲%) and in the ‘Khareji’ cultivar was the lowest. However, the percentage of pollen germination in ‘Ghanami Sorkh’ cultivar was higher than ۵۹% under a wide range of temperature from ۲۱ to ۳۹ °C. Furthermore, the percentage of Pollen germination was reduced rapidly at temperatures less than ۲۱ Cº and reach ۱۵.۸۵% in ۱۵ °C. The germination percentage of pollen grains in ‘Nare Pakutah’ cultivar in the temperature range of ۲۱ to ۳۹ degrees Celsius was higher than ۵۷%. The germination percentage of pollen grains in ‘Sabz Parak’ cultivar decreased with less acceleration than ‘Ghanami Sorkh’ at lower and upper temperatures of ۳۰ °C, so that at ۳۶ and ۳۹ °C had the highest amount of germination compared to the other cultivars. Also, the germination rate of pollens in ‘Ghanami Sorkh’ cultivar were investigated above ۵۷% in the wide temperature range from ۲۱ to ۳۹ °C.ConclusionAccording to the findings of this study, the timing of pollination plays a crucial role in the fertility of male date palm cultivars, with the optimal temperature being around ۳۰°C. It is essential to select cultivars that exhibit a high rate of pollen germination and contribute positively to fruit properties. Male cultivars such as 'Ghanami Sorkh', 'Sabz Parak', and 'Nare Pakutah' demonstrated a broader range of optimum temperatures for pollen germination. Therefore, these cultivars are recommended for climates characterized by significant temperature fluctuations during the flowering period of female date palms.

کلیدواژه ها:

جوانه زنی ، خرما ، دانه گرده ، رقم ، غنامی سرخ