Understanding the importance of abiotic drivers in wind-pollinated species is a key issue to predict seed production. Researches on anemophilous species (e.g. olive, walnut, oak) highlighted the correlation between airborne pollen concentration and seed production. Moreover, recent phenological studies revealed the importance of humidity as a trigger for tree phenology. Despite the economic importance of Corylus avellana, few in-field studies on pollen dispersal have been produced on this species. Pollen concentration depends on pollen production and atmospheric stability at the lower layers of the atmosphere, i.e. low convective activity and low radiation). Thus, we tested the hypothesis that high air humidity and low wind velocity within the canopies favor high pollen concentration. To unravel these mechanisms, we monitored hazelnut reproductive phenology on 10 adult trees of C. avellana var. TGL in Piedmont (Italy), together with daily pollen concentrations, air and bud temperature, air humidity and wind, during winter 2016-2017. Our data set on meteorological parameters and daily pollen concentration of the five previous years indicates that pollen concentrations lasted on average 12 weeks from mid-December to mid-March involving multiple phenological phases from catkin elongation until its decay. The highest pollen concentration peaks always occurred with air vapor pressure deficit well below 5hPa and with no precipitation event. Also, catkins elongation resulted positively affected by higher absolute humidity between the 2nd and the 3rd phenological phase in 2016-2017. These findings disclose the importance of atmospheric stability within the canopy layer as explanatory parameters for hazelnut pollen emission.

METEOROLOGICAL CONDITIONS FAVORING HIGH POLLEN CONCENTRATION IN HAZELNUT ORCHARDS

PASQUALOTTO, GAIA;
2017

Abstract

Understanding the importance of abiotic drivers in wind-pollinated species is a key issue to predict seed production. Researches on anemophilous species (e.g. olive, walnut, oak) highlighted the correlation between airborne pollen concentration and seed production. Moreover, recent phenological studies revealed the importance of humidity as a trigger for tree phenology. Despite the economic importance of Corylus avellana, few in-field studies on pollen dispersal have been produced on this species. Pollen concentration depends on pollen production and atmospheric stability at the lower layers of the atmosphere, i.e. low convective activity and low radiation). Thus, we tested the hypothesis that high air humidity and low wind velocity within the canopies favor high pollen concentration. To unravel these mechanisms, we monitored hazelnut reproductive phenology on 10 adult trees of C. avellana var. TGL in Piedmont (Italy), together with daily pollen concentrations, air and bud temperature, air humidity and wind, during winter 2016-2017. Our data set on meteorological parameters and daily pollen concentration of the five previous years indicates that pollen concentrations lasted on average 12 weeks from mid-December to mid-March involving multiple phenological phases from catkin elongation until its decay. The highest pollen concentration peaks always occurred with air vapor pressure deficit well below 5hPa and with no precipitation event. Also, catkins elongation resulted positively affected by higher absolute humidity between the 2nd and the 3rd phenological phase in 2016-2017. These findings disclose the importance of atmospheric stability within the canopy layer as explanatory parameters for hazelnut pollen emission.
2017
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3240508
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