Abstract
Norwegian pear production is low due to climatic limitations, a lack of well-adapted cultivars and suitable pollinizers. However, nowadays it is increasing as a result of newly introduced and bred pear cultivars. Since cross pollination is necessary for high yields and good fruit quality, the aim of this investigation was to find the most suitable pollinizers for the pear cultivars “Ingeborg” (“Conference” × “Bonne Louise”) and “Celina” (“Colorée de Juillet” × “Williams”). Self-pollination of “Ingeborg” and “Celina”, together with “Conference”, “Belle Lucrative”, “Anna”, “Clara Frijs”, “Herzogin Elsa”, “Kristina” and “Fritjof” as potential pollinizers, were studied in this experiment during the 2017 and 2018 seasons in Norway. The success rate of each pollinizer was tested under field conditions, while the monitoring of pollen tube growth was done using the fluorescence microscopy method. All reproductive parameters (pollen germination, number of pollen tubes in the upper part of the style, pollen tube number in the locule of the ovary, number of fertilized ovules, initial fruit set, and final fruit set) in all crossing combinations were higher in 2018 due to much warmer weather. Based on the flowering overlap and success rate of each individual pollinizer and fruit set, the cultivars “Anna” and “Clara Frijs” can be suggested as pollinizers for the cultivar “Ingeborg”, while “Fritjof”, “Anna”, “Kristina” and “Herzogin Elsa” for the cultivar “Celina”. An even distribution of two compatible pollinizers having overlapping flowering times with the main commercial pear cultivar is a general recommendation for commercial pear production.
Highlights
Pear (Pyrus communis L.) cultivation has a long tradition in Norway
Pear production has declined in recent decades, mainly due to climatic limitations, a lack of well-adapted cultivars and suitable pollinizers
The temperature registered during the month of May, when all the investigated pear cultivars flowered, was on average 4 ◦ C higher in 2018 (15 ◦ C compared to that of 2017 (11 ◦ C))
Summary
Pear (Pyrus communis L.) cultivation has a long tradition in Norway. In 2018, the total acreage was only 62 ha with an average yield of 9 tons per ha [1]. Pear production has declined in recent decades, mainly due to climatic limitations, a lack of well-adapted cultivars and suitable pollinizers. Unfavorable environmental conditions for pear pollination during the Nordic spring can have a very negative effect on yield quantity in the pear orchards [2,3]. “Bonne Louise”) was developed at Balsgård-SLU (Swedish University of Agricultural Sciences) and is currently the most important commercial pear variety grown in Norway in terms of yield tonnage. The cultivation of “Ingeborg” is mainly located in the Hardanger district, western Norway. “Ingeborg” possesses good pomological traits and is suited for cultivation under Nordic conditions, fruit set and subsequent yields of this cultivar tend to vary between orchards and can be significantly lower than for other pear varieties grown in Norway [3,4]
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