Artificial pollination on hazelnut in South Africa: preliminary data and perspectives

Abstract

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.

Effect of Photo-Selective Shade Nets on Pollination Process and Nut Development of Corylus avellana L.

“…Artificial pollination was carried out utilizing a suspension media. This method showed to be more effective than dry-pollen applications, especially when warm and dry winter conditions threaten the pollen viability (Ascari et al, 2018). In accordance with other authors, the augmented stigma receptivity, pollen germination, tube growth, and nut development under some of the nets could be probably associated to the decreased air/canopy temperature and increased RH (Germanà et al, 2003;Zilkah et al, 2013).…”

“…For the suspension, the procedure followed the method described by Ascari et al (2018) . The pollen was suspended at 0.1% (w/v) in a liquid media containing: 10% (w/v) sucrose mixed with 0.5% (w/v) xanthan gum and 0.02% boric acid.…”

“…In South Africa, the predominant nut crops grown are macadamias (world’s largest exporter) and pecans ( Brits, 2018 ; Sikuka, 2020 ). However, other nuts such as walnut, almond, pistachio, and hazelnut, relatively new in South Africa, are slowly emerging, where research institutes, private companies, and farmers are working on finding appropriate agronomic procedures, cultivars, and to demonstrate the sustainability of the crop ( Swart and Blodgett, 1998 ; Chen and Swart, 2000 ; Ascari et al, 2018 ; Kriel, 2019 ). Although recent reports from the International Nut and Dried Fruit Council [INC] (2020) point out that traditional hazelnut growing countries like Turkey, Italy, Azerbaijan, and Georgia source 88% of the global production, the increasing interest toward hazelnut has driven the search for new areas of cultivation outside its native range.…”

Hazelnut Pollen Phenotyping Using Label-Free Impedance Flow Cytometry

“…To deepen the knowledge about pollination dynamics and improve crop yield, basic and applied research was recently carried out. In particular, the effect of temperature on hazelnut pollen storage (Ellena et al, 2014;Novara et al, 2017), the influence of spermidine and temperature on pollen performance (Çetinbaş-Genç et al, 2019(Çetinbaş-Genç et al, , 2020, and the efficacy of artificial pollination in constrained growth conditions (Ascari et al, 2018) were investigated.…”

“…The increased economic interest toward hazelnut has brought its cultivation in new areas, where plants are often subjected to different environmental conditions if compared with those found in the native range. Besides, the lack of wild hazelnuts in these areas can hinder fertilization and cropping without the adoption of proper pollination strategies ( Ascari et al, 2018 ).…”