Effect of environmental conditions and genotype on nectar secretion in sunflower (Helianthus annuus L.)

Autor: Chabert Stan, Sénéchal Christopher, Fougeroux André, Pousse Jérémy, Richard Fabien, Nozières Emma, Geist Olivier, Guillemard Vincent, Leylavergne Solenne, Malard Constance, Benoist Alexandre, Carré Gabriel, Caumes Édith, Cenier Charlotte, Treil Alain, Danflous Sébastien, Vaissière Bernard E.
Jazyk: English<br />French
Rok vydání: 2020
Předmět:
Zdroj: Oilseeds and fats, crops and lipids, Vol 27, p 51 (2020)
Druh dokumentu: article
ISSN: 2272-6977
2257-6614
DOI: 10.1051/ocl/2020040
Popis: The sunflower crop provides an important honey flow for beekeepers. In France, beekeepers observed a decrease in honey yield from this crop these past years compared to the 1980s–1990s. They suspect the new cultivars to be less productive in nectar compared to the older ones, but no data is available to support this, and it is known that climate conditions have a strong impact on nectar secretion. This study aimed to explore the effect of abiotic environmental conditions on nectar secretion in sunflower, as well the range of variation of this secretion in a sample of current cultivars. Thirty-four current sunflower hybrid cultivars were sampled in test plots for their nectar secretion under varying conditions of temperature, air humidity and soil moisture. Air humidity controlled the sugar concentration of nectar, and thus its volume. To study nectar secretion independently from this effect, analyses subsequently focused on nectar sugar mass per floret. The nectar sugar mass increased with temperature up to an optimum of 32 °C, while the variation range of soil water tension was not sufficient to detect an effect on nectar sugar mass. This varied by up to 100% among the 34 cultivars (from 101 to 216 μg sugar per staminate floret in average), with a similar range to those reported in the literature for older cultivars. Likewise, oleic cultivars, a new type introduced since the early 2000s, were found to secrete the same amounts of nectar as linoleic cultivars, an older conventional type. The more self-fertile cultivars also showed no reduction in nectar secretion. Finally, we tested the method that measures the nectar gross secretion rate in one hybrid, and we observed that this hybrid secreted in average 28 μg sugar per hour per staminate floret. The potential benefits of this method were discussed.
Databáze: Directory of Open Access Journals
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