Reasons for large annual yield fluctuations in wild arctic bramble (Rubus arcticus subsp. arcticus) in Finland

Abstract

Fluctuations in the yield of wild berries are markedly influenced by weather conditions. However, the cause–effect relationship is often poorly understood. Based on data spanning a 20-year period in Finland, we made an effort to elucidate the influence of different weather conditions on the yield of arctic bramble (Rubus arcticus L.). We analyzed the regression coefficients of various weather conditions in several regression models using the elaboration approach. Temperature accumulated in July had a positive effect on yield. Yield was negatively influenced by temperature accumulated during the previous summer, rainfall in the October of the previous year, and temperature accumulated in May of the same year. It is notable that the same weather conditions had a positive influence on yield of the same year whereas these conditions had a negative effect on the yield potential of the following year. Compared with traditional analysis methods, the elaboration approach provided a better understanding of the relationship between weather parameters and yield. The rarity of a good yield could be explained by the particular vulnerability of arctic bramble to the negative effects of weather conditions. Some of these factors could be controlled in field conditions when cultivating arctic bramble.

Sphagnum moss is a promising growth substrate in arctic bramble container cultivation

“…Overall, pollination success in arctic bramble is highly variable and low fruit set and incomplete fruit development are common problems (Vool et al 2009;Kokko et al 2012;Kostamo et al 2018). In this study, both fruit set (Table 2) and the number of drupelets in 'Alli' (Table 3) were considerably higher than we observed previously in a greenhouse (Tommila et al 2022), suggesting better pollination conditions.…”

The effect of relative humidity and the use of algae-based biostimulants on fruit set, yield and fruit size of arctic bramble (Rubus arcticus) arcticus)

“…The reasons for arctic bramble yield fluctuations remain poorly understood, although the likely main factors are weather conditions affecting flower bud development, pollination and fruit development (Kostamo et al 2018). The arctic bramble plants usually flower abundantly, but fruit set is often poor (Ryynänen 1973, Kostamo et al 2015 and many of the fruits that are set may dry up or otherwise spoil during development (Kokko et al 2012, Kostamo et al 2015.…”

“…On the other hand, flowering often continues concurrently with fruit development and ripening, where high RH or associated rain and dew could increase the risk of fruit spoilage due to mold infections. Kostamo et al (2018) note that rainy weather during harvest season often causes spoilage in the ripening fruits.…”