Self-fertility in raspberries

To assess raspberry self-fertility, genetic markers and manual pollination methods are used, comparing performance data of isolated flowers with the results of cross-pollination. The primary criteria are the percentage of fruit set and the number of well-developed drupelets in the berry, as total fruit set does not always reflect the market quality of the produce.

Significant cultivar variability is observed within the species: from high self-fertility in modern commercial cultivars to partial self-incompatibility. In the latter, self-pollination leads to a sharp decrease in the number of drupelets, resulting in the formation of deformed, 'crumbling' fruit.

The degree of self-fertility is critically important when planning plantations and growing raspberries in greenhouses in the absence of natural pollinators. For cultivars with low self-fertility, which historically included such forms as Latham and Lloyd George, the inclusion of pollinator cultivars remains a mandatory condition for profitability.