Document Type : Research Article


1 Department of Horticultural Sciences, Faculty of Agriculture, Ilam University, Ilam, Iran

2 Date Palm & Tropical Fruits Research Center, Ahvaz, Iran


The 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 Methods
In 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 15, 18, 21, 24, 27, 30, 33, 36 and 39 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 -18 °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 Discussion
The results showed that there was a significant difference among cultivars, temperature and interactions of them at the level of 1%. Among the studied temperatures, the highest germination of pollen grains in all cultivars occurred at 30 °C, followed by 33 °C and 27 °C, respectively, and the lowest germination percentage were obtained at 15 °C. Among cultivars, the percentage of pollen germination in ‘Ghanami Sorkh’ was quite high (92.45%), and ‘Nare Pakutah’ (87.33%), also, simultaneously ‘Sabz Parak’ (84.82%) and in the ‘Khareji’ cultivar was the lowest. However, the percentage of pollen germination in ‘Ghanami Sorkh’ cultivar was higher than 59% under a wide range of temperature from 21 to 39 °C. Furthermore, the percentage of Pollen germination was reduced rapidly at temperatures less than 21 Cº and reach 15.85% in 15 °C. The germination percentage of pollen grains in ‘Nare Pakutah’ cultivar in the temperature range of 21 to 39 degrees Celsius was higher than 57%. The germination percentage of pollen grains in ‘Sabz Parak’ cultivar decreased with less acceleration than ‘Ghanami Sorkh’ at lower and upper temperatures of 30 °C, so that at 36 and 39 °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 57% in the wide temperature range from 21 to 39 °C.
According 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 30°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.


Main Subjects

©2023 The author(s). This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source.

  1. Abdul-Baki, A.A. (1992). Determination of pollen viability in tomatoes. Journal of American Society for Horticultural Science, 117, 473-476.
  2. Al-Halal, A.A., Basalah, M.O., & Mohammad, S. (1988). Effect of storage and temperature on pollen germination and rate of pollen elongation of date palm. Phyton, 48, 119-12.
  3. Aly, H.S. (2018). Evaluation of pollen grains germination, viability and chemical composition of some date palm males. Middle East Journal of Agriculture Research7(7), 235-247.
  4. Araújo de Oliveira, A.C., da Silva Lédo, A., Polek, M., Krueger, R., Shepherd, A., & Volk, G.M. (2021). Optimization of in vitro germination and cryopreservation conditions for preserving date palm pollen in the USDA National Plant Germplasm System. Plant Cell, Tissue and Organ Culture (PCTOC),144(1), 223-232.
  5. Asif, M.I., Al-Tahir, O.A., & Farah, A.F. (1983). The effects of some chemicals and growth substances on pollen germination and tube growth of date pollen. HortScience, 18, 476-480.
  6. Baliga, M.S., Baliga, B.R.V., Kandathil, S.M., Bhat, H.P., & Vayalil, P.K. (2011). A review of the chemistry and pharmacology of the date fruits (Phoenix dactylifera L.). Food Research International, 44(7), 1812-1822.
  7. Beltrán, R., Valls, A., Cebrián, N., Zornoza, C., Breijo, F.G., Armiñana, J.R., & Merle, H. (2019). Effect of temperature on pollen germination for several Rosaceae species: Influence of freezing conservation time on germination patterns. PeerJ, 7, e8195.
  8. Brown, G.K., Perkins, R.M., & Vis, E.G. (1969). Temperature and heat unit occurrences during date pollination in the Coachella Valley of California. Date Growers' Inst. Report, 46, 21-24.
  9. Furr, I.R., & Ream, C.L. (1986). The influence of temperature on germination of date pollen. Report of Date Growers Institute, 45, 7-9.
  10. Galeb, H.A., Mawlood, E.A., & Hamood, H.H. (1988). The influence of bagging on fruit set and fruit characteristics in date palm CV. Hallawi. Date Palm Journal, 6, 238-254.
  12. Kadri, K., Ahmed, O., Souhaila, M., Mohamed, S.C., Abdelhamid, C., & Amani, T. (2019). Contribution to the study of the effect of pollination mode on fruit set rate and yield in the date palm (Phoenix dactylifera) in the Oases of Tozeur (Tunisia). International Journal of Agriculture Innovations and Research7, 533-537.
  13. Koyuncu, F., & Güçlü, F. (2009). Effect of temperature on in vitro pollen germination and tube growth in sweet cherries. American-Eurasian Journal of Agricultural and Environmental Science6(5), 520-525.
  14. Maryam, M., Fatima, B.I.L.Q.U.E.S., Haider, M.S., Abbas, S.U.M.M.A.R., Naqvi, M., Ahmad, R.A.S.H.I.D., & Khan, I.A. (2015). Evaluation of pollen viability in date palm cultivars under different storage temperatures. Pakistan Journal of Botany,47(1), 377-381.
  15. Mesnoua, M., Roumani, M., & Salem, A. (2018b). The effect of pollen storage temperatures on pollen viability, fruit set and fruit quality of six date palm cultivars. Scientia Horticulturae236, 279-283.
  16. Mesnoua, M., Roumani, M., Bensalah, M.K., Salem, A., & Benaziza, A. (2018a). Optimization of conditions for in vitro pollen germination and pollen tube growth of date palm (Phoenix dactylifera). Journal of Fundamental and Applied Sciences,10(1), 158-167.
  17. Moafi, S.F., Sharafi Y., Rezaei, A., & Fotokian, M.H. (2019). Microscopic study of the effect of boron spraying on the pollen tube penetration in apple crosses. Journal of Horticultural Science, 33, 207-218. (In Persian with English abstract).
  18. Monselise, S.P. (2018). Handbook of fruit set and development. CRC press.
  19. Moosavi Nazhad, S., Hajilou, J., & Rahnamoon, H. (2014). Effect of different temperatures on germination and pollen tube growth dynamics with different time of flowering in almond cultivars. Plant Productions37(1), 49-58. (In Persian with English abstract).
  20. Mortazavi, S.M.H., Arzani, K., & Moini, A. (2010). Optimizing storage and in vitro germination of date palm (Phoenix dactylivera) pollen. Journal of Agricultural Science and Technology, 12, 181-189.
  21. Myint, K.A., Rafii, M.Y., Sheikh-Abdullah, S.A., Lwin, N.M., Mohd Din, A., & Latif, M.A. (2012). Determination of the optimum pollen germination medium for different fruit forms of oil palm (Elaeis guineensis). Journal of Animal & Plant Sciences, 14, 1855-1865.
  22. Pfahler, P.L., Pereira, M.J., & Barnett, R.D. (1997). Genetic variation for in vitro sesame pollen germination and tube growth. Theoretical and Applied Genetics, 95, 1218-1222.
  23. Rastegar, S., & Rahemi, M. (2015). Comparision of physicochemical characterristic of pollinated and unpollinated Piarom and Shahani date palm during fruit growth and development. Journal of Plant Productions, 38(1), 65-74. (In Persian with English abstract).
  24. Reuveni, O., Abu, S., & Golobovitz, S. (1986). Date palm Pollen germination and tube elongation on pistillate flowers cultured at different temperatures. Acta horticulture, 175, 91-95.
  25. Rezazadeh, R., Hassanzadeh, H., Hosseini, Y., Karami, Y., & Williams, R.R. (2013). Influence of pollen source on fruit production of date palm (Phoenix dactylifera) cv. Barhi in humid coastal regions of southern Iran. Scientia Horticulturae160, 182-188.
  26. Salomon-Torres, R., Krueger, R., Garcia-Vazquez, J.P., Villa-Angulo, R., Villa-Angulo, C., Ortiz-Uribe, N., & Samaniego-Sandoval, L. (2021). Date palm pollen: Features, production, extraction and pollination methods. Agronomy11(3), 504.
  27. Shekofteh, H., & Nick-Pour, M. (2016). Study on the effect of calcium and potassium spray on date bunch fading disorder. Journal of Horticultural Science, 30, 358-365. (In Persian with English abstract).
  28. Volk, G.M. (2011). Collecting pollen for genetic resources conservation. In: Guarino, L., Ramanatha, V.R., Goldberg, E. (eds) Collecting plant genetic diversity: technical guidelines. Bioversity International, Rome.
  29. Zaid, A. (1999). Date Palm Cultivation. FAO Technical Bulletin, 156, FAO Pulications, Rome.