Viability of Embryo Sacs and Fruit Set in Different Plum (Prunus domestica L.) Cultivars Grown under Norwegian Climatic Conditions.

Radosav Cerović,Milena Đorđević,Mekjell Meland,Milica Fotirić Akšić

doi:10.3390/plants11020219

Abstract

Compatibility and synchrony between specialized tissues of the pistil, female gametophytes and male gametophytes, are necessary for successful pollination, fertilization, and fruit set in angiosperms. The aim of the present work was to study the development and viability of embryo sacs, as well as fertilization success, in relation to the fruit set of the cultivars ‘Mallard’, ‘Edda’, ‘Jubileum’, and ‘Reeves’, under specific Norwegian climatic conditions. Emasculated, unpollinated, and open-pollinated flowers were collected at the beginning of flowering, and on the 3rd, 6th, 9th, and 12th days after flowering, from all four plum cultivars over two years (2018/2019). Ovaries were dehydrated, embedded in paraffin wax, sectioned, stained, and observed under a light microscope. Results showed the existence of synchronization between successive phases in the development of the embryo sac and individual phases of flowering. All plum cultivars had higher percentages of viable embryo sacs, fertilized embryo sacs, and fruit set in 2018 than in 2019. These differences may be related to the very low temperatures during the post-full-flowering period in 2019, and to the low adaptation of some studied cultivars to unfavorable conditions. In our study, the cultivar ‘Jubileum’ showed the highest percentage of viable embryo sacs, fertilized embryo sacs, and fruit set compared to other cultivars, i.e., the best low-temperature adaptation.

Highlights

Plum production in Norway is mainly located along the fjords in Western Norway, where winter and late-spring frosts rarely occur [1]
Our results show that the percentage of viable and fertilized embryo sacs and embryos was higher in all cultivars in 2018 compared to 2019
The functionality of embryo sacs, fertilization success, and fruit set were studied for two years in the plum cultivars ‘Mallard’, ‘Edda’, ‘Jubileum’, and ‘Reeves’, under the climatic conditions of Western Norway

Summary

Introduction

Plum production in Norway is mainly located along the fjords in Western Norway, where winter and late-spring frosts rarely occur [1]. In Norway, plum ranks second among commercial fruit crops, with a harvesting area of 424.3 ha and annual production of 1524.9 tons [3]. Unfavorable environmental conditions during plum pollination in spring contribute to a very negative effect on fruit set and yield quantity (year-to-year variations) in plum orchards [5]. For this reason, one of the most important objectives of plum breeding in Norway is the creation or introduction of cultivars suitable for these specific climatic conditions [6]

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Methods

Results

Discussion

Conclusion