Longevity and germination of Juniperus communis L. pollen after storage

Abstract

Pollen storage belongs among the most important activities associated with pollen handling. It overcomes the differences in pollen shedding and ovule receptivity during controlled pollination experiments. It is especially important for species like common juniper (Juniperus communis L.) with an extremely low quality of seeds due to pollination failure. Additionally, it is a substantial part of germplasm preservation programmes in pollen banks. In the present paper, the effect of short-term storage of pollen was studied using pollen samples from five shrubs in an in vitro germination test. Two temperature regimes were tested. The pollen viability of freshly collected pollen varied considerably between individual shrubs, exhibiting 67.3–88.6% germination rate and 248.0–367.3 µm of pollen tubes. Storage at + 4 °C for four months was accompanied by a profound decline in pollen viability. The germination percentage was reduced to 49.2–75.2% and the pollen tube length to 32.5–69.0%, depending on individual shrubs. The corresponding decline in pollen viability characteristics during storage at − 20 °C was only negligible in two of the tested shrubs. In the remaining three shrub samples, an increase in germination percentage was observed. Pollen tube growth responded more sensitively to freezing, but, on average, the decrease in length was lower than that at + 4 °C. The rate of reduction in pollen tube length varied between 11.5 and 45.4%. Cytological events accompanying in vitro germination of freezer-stored pollen exhibited some delay in releasing the exine from pollen grains during the early stages of germination as compared with freshly collected pollen. In conclusion, short-term storage of the common juniper pollen in a freezer is better for the preservation of its viability than storage at + 4 °C.

Pollen viability and longevity in Juniperus taxa native to Slovakia

“…Likewise, the pollen tube growth in J. sibirica was reduced by 61.7% compared to fresh pollen. Compared with the results of J. communis pollen storage at − 20 °C for four months, when only negligible differences in pollen viability of fresh and stored pollen were registered 20 , the storage at − 81 °C over one year represents a rather adverse figure. Different storage duration periods are not the only reason for such an unexpected outcome.…”

Pollen storage, viability and effect of growth hormones on in vitro pollen germination in two medicinal plants (Clerodendrum colebrookianum Walp. and Clerodendrum infortunatum L.) of the tropical moist forest of North-east India

“…Pollen grains of Juniperus communis (a tree with meager seed sets due to pollen limitation under natural conditions) can be stored suitably with significant pollen viability at − 20 °C as compared to -4°C. The stored pollens were valuable for pollen supplementation experiments to enhance seed sets in the tree species (Kormutak et al, 2021). Hence pollen storage is crucial in pollen handling that can act as a valuable tool for breeders to overcome problems associated with differences in flowering time, pollen shedding, stigma receptivity, and pollen limitation in controlled pollination experiments.…”

X-ray computed tomography (CT) and ESEM-EDS investigations of unusual subfossilized juniper cones

“…But it turns out that there are five chambers, but only three seeds 61 , 64 , 65 . Also, the seed quality of J. communis can be affected by the environment or forest ecology and nutrient, where the lower seed productivity can be a result of limited pollen availability or lower pollen quality and pollen growth rates 66 – 68 . In contrast, the opposite was observed in plants growing in nutrient-poor environments 67 .…”