Temperature requirements of Alnus pollen in Spain and Italy (1994-1998)

Abstract

Woody plants in temperate regions, in order to prevent the water in their cells from freezing, interrupt their growth entering into a physiological state called``dormancy''. Trees also have a heat requirement that must be full® lled before actual growth is resumed and pollination occurs. The objective of this study is to ascertain the in¯uence that a climatic parameter such as temperature exerts on Alnus, in order to identify the start of the dormancy period, its duration and the consequent heat requirement that triggers¯owering in three European regions located at the same latitude. In this regard, we chose two areas in Spain (Vigo and Santiago de Compostela) and one in Italy (Perugia), since they have diVerent temperature patterns, ranging from mild in the case of Vigo to cold in that of Perugia, including an intermediate temperature pattern (Santiago). Monitoring in the three stations was carried out by means of a 7-day Lanzoni VPPS 2000 pollen trap. Alnus began its pollen season between the second and third week of January in Spain, while in Italy it began during the ® rst week of February. During the four years under study, in order to overcome the dormancy period, Perugia needed an average of 962 chilling hours (CH), Santiago 622 CH, and Vigo had the smallest chilling accumulation with only 460 CH. In the case of heat accumulation, we found that Perugia had the smallest requirement and Vigo the largest, thus Perugia needed an average of 42 (growth degree days) GDD, Santiago around 50 GDD and Vigo 62 GDD.

The analysis of the Corylus, Alnus and Betula pollen seasons in Toruń in 2014 and 2016

“…Other year-on-year differences in the pollen season start date may be due to high temperatures during the freezing period and low temperatures during heat accumulation (Jato et al, 2000). The course of the alder pollen season during the both years compared differed.…”

May the definition of pollen season influence aerobiological results?

“…Pollen data can be used as a phenological indicator of flowering, and many phenological studies using pollen data have been conducted in order to determine the chilling and heat requirements for flowering in various species and geographical areas (Garcia-Mozo et al, 2000;Jato et al, 2000;Fornaciari, et al, 2000a;Gala´n et al, 2001;Laaidi, 2001). Meteorological data are usually supplied by local weather stations to enable calculation of thermic phenological indexes; accurate determination of the start of the Gala´n et al (1995) and Lejoly-Gabriel and Leuschner (1983) in 2002 and according to the criteria of Gala´n et al (1995) and Spieksma et al (1995) Feher and Ja`rai-Komlo´di (1997) and Lejoly-Gabriel and Leuschner (1983) in 2002 and according to the criteria of Feher and Ja`rai-Komlo´di (1997) and Spieksma et al (1995Spieksma et al ( ) in 2003 pollen season according to local flowering is therefore essential.…”

Airborne olive pollen in Vigo (Northwest Spain): a survey to forecast the onset and daily concentrations of the pollen season

“…Knowledge of the chilling and heat needs required by plants to overcome the period of dormancy enables us to determine the onset of pollination, which is of great importance to allergy sufferers (Richardson et al 1974, Faust 1989, Frenguelli & Bricchi 1998, Galá n et al 2001. Since the presence of pollen in the air is the result of flowering, aerobiological data have been used in recent years as phenological information in order to calculate the beginning of the pollination period (Recio et al 1997, Fornaciari et al 2000, Jato et al 2000, Frenguelli & Bricchi 1998, Galá n et al 2001.…”