1. Introduction
Italy is the major tomato producer in EU accounting for the 38% of the total EU.
In Sardinia tomatoes grown in greenhouses show an inter-annual yield variability that
could be linked with shift in temperatures. This problem is magnified by the fact that
farmers in winter avoid heating systems for economical reasons.
Certainly, yield reduction can be caused to mid-winter period and to sudden change in
temperatures. Nevertheless, it is unclear which are keys factors affecting production and if
they are linked with pollination quality or pollen viability. For this reason all parameters
related to pollination were considered in the present study.
Two common tomato cultivar were selected for the present study: “fragolino” (Fig. 6) and
“cupido” variety. The main selection criterium was the production's sensitivity to changes
in climate shown in previous years. Experiments were carried out in 10 greenhouses, five
for each cultivar
POLLINATION OF TWO TOMATO CULTIVAR IN UNHEATED GREEHOUSES:
FROM POLLEN TRANSFER TO FRUIT DEVELOPMENT AND BUMBLEBEES
FORAGING ACTIVITY
Pirodda E. & Siclari P.
Santa Margherita Terra e Sole soc. coop. Km. 32.000, Strada St. 195 Pula, Cagliari (Italy), email: e.pirodda@gmail.com
Preliminary results
Preliminary results shows that bumblebee foraging activity is crucial for both quantity and
quality of tomato production. More in detail: contrary to expectation the proportion of
visited flower did not prove to be significantly related to the number of foraged flowers in
both fruit size and proportion of ripened fruit (Tab 1). On the other hand, high degree of
bruising level are positively related to the proportion of fruit developed and fruit size.
This shows the importance of an high bumblebee activity in order to obtain commercially
rewarding yield.
These results highlight the importance of focusing on bumblebees hives quality and to
direct effort in improving their management in order to ensure pollination, especially
when unfavourable weather conditions occurs and high pollination standard is more
needed.
Acknowledgements
This communication is part of the research project “Studio delle fasi d'impollinazione di alcune cultivar di
pomodoro nelle serre sprovviste di riscaldamento: dal trasferimento del polline allo sviluppo dei frutti e l'attività
bottinatrice del Bombus Terrestris.” carried out at the “ Santa Margherita Terra e Sole Cooperative”, by a
research grant financed from the resources P.O.R. SARDEGNA F.S.E. 2007-2013 - Obiettivo competitività
regionale e occupazione, Asse IV Capitale umano, Linee di Attività I.1.1. e I.3.1.
Republica ItalianaUnione Europea
Fondo Sociale Europeo
REGIONE AUTÒNOMA DE SARDIGNA
REGIONE AUTONOMA DELLA SARDEGNA
II International Plant Science Conference
110° Congresso della Società Botanica Italiana
Pavia, 14 - 17 September 2015
Methods
Experiments were conducted as follows:
1) In pollination experiments natural pollination performed by commercial bumblebees
were compared to hand pollination (Fig. 1) . Thereafter, after ripening, fruit were counted,
fruit diameter measured (Fig 5) and these parameters were compared in the two pollination
test to assess pollination efficiency.
2) At the same time bumblebees foraging activity was recorded through standardized
counting of flower in order to assess the number of visits. In addition flowers with necrotic
discoloration in anthers cones (Fig. 2), which are result of buzzing pollination by
bumblebees, were counted. Bruising level were included in five categories (0-4)
3) Other parameters were considered as pollen germination, greenhouses micro-climate,
farm management, bumblebee hives management.
The study started in February 2014 and it is ongoing.
Tab 1 – Correlation between fruit quantity and quality and bumblebee activity:
ripened fruit and fruit size was related to the number of flowers visited by
bumblebees and the level of necrotic discoloration in flowers that is related to the
intensity of bumblebee visits. Analysis were run with Pearson Test.
Fig 5– Fruit diameter were measured with a calliper
Fig. 1 – Hand pollination was performed for the entire blooming period with a paint brush
previously carried with pollen. Fig. 2 – An example of different bruising level in tomato
flowers. Fig. 3 – Commercial bumblebees hives used for tomato pollination in greenhouses.
Fig. 4 – Bumblebee worker (Bombus terrestris L.) carrying tomato pollen load in their
corbicula.
Graph 2 – The relation between level of necrotic discoloration and the
proportion of ripened fruit were positively related
Graph 1 – The relation between level of necrotic discoloration (also called
bruising level) and the size of the ripened fruit were positively related
Fig 6 – Fragolino cultivar