Pollen study of two Juniperus L. species in Goinik Jargalan habitat of North Khorasan province

Vegetation has undeniable environmental and economic benefits. sustainable management of natural plant ecosystems requires knowledge of species and their habitats, therefore, one of the important priorities of researchers and executives active in the fields of environment and natural resources, is paying attention to plant species capable of adapting to harsh climatic conditions; Juniperus L. species are important in habitats. Goinik Jargalan region in North Khorasan is one of the important habitats of two Juniper species, including J. excelsa and J. polycarpos. This study investigates the pollen characteristics of these two species. this study was conducted, from February ۲۰۱۸ to April ۲۰۱۹, the cones of the studied species were collected from the habitat area and the pollens were separated from the cones and studied. Pollen was examined by light microscope (LM) and electron microscope (SEM). Analysis of ۱۰ pollen grains data from each of the studied species were observed that most of the pollen grains contain granular elements. In the LM, the general design of the pollens is circular but in the SEM they are irregular. According to the ratio (P/E); the pollens of both species are Prolatespheroidal in both study habitats. In all samples, the pollens are in the group of small pollens (۱۰-۲۵ microns) in terms of size. In the study of pollens, Exin layer thickness was measured in LM images in J. excelsa, ۰.۹۹ microns and in J. polycarpos, ۱.۴۱ microns. according to the data, it was found that J. polycarpos has a better establishment than another species, which may be due to the thickness of the exin and the resistance of the pollen to natural factors; however, there is a risk of extinction for J. excelsa in this area and it needs special attention.

Keywords:

Conifera , Archa , Pollination , Exin , Pollen grain