Hazelnut cultivation is rapidly expanding in regions outside its native range. New hazelnut plantations in South Africa are facing adverse environmental conditions which threaten the pollination process and hamper nut yield. Artificial pollination can increase fruit yield and fill pollination gaps in some fruit crops, but its application on hazelnut is still not well explored. This study investigated biological factors and technical procedures in the first artificial pollination experiment on hazelnut in South Africa. A suspension media for artificial application composed of 10% sucrose, 0,1% agar and 0,02% boric acid was used. In addition, alternative low-cost suspension media containing other forms of sugar were also evaluated. Moreover, a novel and practical approach to assess pollen conditions in liquid solutions was designed. Pollen viability was tested in the different suspension media. This varied greatly among the examined cultivars. Wild hazelnut produced the pollen with the highest viability, while Tonda Gentile delle Langhe (TGL) and Barcelona the lowest. Sterile grains were very abundant, especially in cultivated varieties (up to 65% in TGL). Preliminary data on nut yield were also collected. Altogether, this study indicated that artificial pollination is a promising approach for hazelnut cultivation in increasing the final yield. Further research is needed to develop integrated pollination strategies, especially in areas where the environmental conditions are adverse to the pollination process.

Hazelnut (Corylus avellana L.) is one of the most appreciated nut crops, which is motivating the cultivation outside its historical production areas. Despite that, there is still limited knowledge about the floral biology of the species and its developmental fruiting stages under different environments. Adverse climatic conditions can threaten the pollination process and fruit development. In South Africa, the deciduous fruit industry identified the net shading as a tool to mitigate the effects of unfavorable abiotic events. The objective of this work was to investigate the effects of photo-selective nets on the pollination process and nut development of C. avellana. Mature hazelnut trees were maintained under netting and compared with the ones in open field. Microscopic examination of female flower and developing nuts were conducted in order to observe the pollen tube growth and the pattern of disodium fluorescein transport into the funiculus and ovule. The results showed differences in pollen tubes growth and timing between the treatments. Generally, trees under nets showed higher rate in pollen tubes developing and reaching the base of the style. On the contrary, the tests carried out in open field showed a higher ratio of pollen tubes arrested in the style. The results also indicated differences in ovules abortion. Developing fruits that showed an interruption point at the funicle level or at junction point of the ovule were classified as aborting fruits (blank nuts at harvest time). A higher rate of abortion was detected in open field compared to the plants under netting. In conclusion, the shade nets influenced the pollen tube growth and the nut development, principally due to micro-climate modification. Therefore, further investigations are needed to analyze the influence of light spectra and to determine the sustainability of photo-selective nets over several years.