Rol del servicio de la polinización en el cultivo de soja
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La polinización entomófila es un servicio ecosistémico de regulación clave para el desarrollo
de semillas en muchas plantas con flor. Estudios previos demuestran que la acción de
polinizadores aumenta la producción de frutos y semillas incluso en especies autógamas como
lo es la soja. En esta tesina se abordó la diversidad específica de insectos polinizadores y de
patógenos en semillas posiblemente asociados a la polinización. Se capturaron insectos por
medio de trampas pan traps y se realizaron muestreos de visitas en flores. Se aplicaron
tratamientos de exclusión de polinizadores, y se evaluó la influencia en variables de
productividad (peso de frutos, número de frutos y peso de semillas), cantidad de semillas
normales y vanas, la calidad de las semillas (cantidad de proteínas y lípidos), peso de plantas,
y la presencia de patógenos en semillas provenientes de ambos tratamientos de polinización.
Fueron capturadas 12 morfoespecies de polinizadores dentro del cultivo. De las
morfoespecies de abejas halladas seis son potenciales polinizadores de la soja según
bibliografía, y entre ellas la familia Halictidae fue la más abundante. No se registraron visitas
a las flores durante los periodos de muestreo, lo que sugiere una tasa de visitas muy baja. Las
diferencias halladas no fueron estadísticamente significativas en ninguna de las variables de
productividad ni de calidad de semillas entre tratamientos. Fueron hallados 12 patógenos
fúngicos, dentro de los cuatro más abundantes, los géneros Phomopsis, Alternaria, y
Cercospora tuvieron una abundancia levemente mayor en las plantas a las cuales los
polinizadores no tuvieron acceso, mientras que Cladosporium fue mayor en plantas expuestas
(p=0,009). El hecho que la mayoría de los patógenos fúngicos se encuentren en plantas a las
que no tuvieron acceso los polinizadores indica que éstos no estarían actuando como agentes
dispersores de esporas de la mayoría de ellos.
La fauna polinizadora está presente como lo demuestran las capturas en las trampas pero la
tasa de visitas a las flores fue muy baja, lo que puede explicar la falta de significancia
estadística en los tratamientos de polinización.
Entomophilous pollination is a key regulatory ecosystem service for seed development in many flowering plants. Previous studies show that the action of pollinators increases fruits and seed production even in self-pollinated species such as soybean. This study focused on the diversity of insect pollinators and seed pathogens possibly associated with pollination. Insects were registered on soybean flowers and were captured using pan traps. Pollinator exclusion treatments were applied, and the influence on productivity variables (fruit weight, fruits number and seeds weight), total normal seeds and total empty seeds, and seed quality (amount of proteins and lipids), plant weight, and the presence of pathogens in seeds from both pollination treatments were evaluated. Twelve morphospecies of pollinators were captured in the crop. Six of found bees are potential soybean pollinators according to the literature, and the family Halictidae was the most abundant. No flower visits were recorded during the sampling periods, suggesting a very low visitation rate. The differences found were not statistically significant in any of the productivity or seed quality variables between treatments. Twelve fungal pathogens were found. Among the four most abundant the genera Phomopsis, Alternaria, and Cercospora were slightly more abundant on plants without pollinators, while Cladosporium was more abundant on plants with pollinators (p=0.009). The fact that more fungal pathogens were found on plants without pollinators indicates that pollinators would not be acting as spore dispersing agents for most of them. The pollinator fauna was present as evidenced by trap captures but the rate of flower visits was very low, which may explain the lack of statistical significance in the pollination treatments.
Entomophilous pollination is a key regulatory ecosystem service for seed development in many flowering plants. Previous studies show that the action of pollinators increases fruits and seed production even in self-pollinated species such as soybean. This study focused on the diversity of insect pollinators and seed pathogens possibly associated with pollination. Insects were registered on soybean flowers and were captured using pan traps. Pollinator exclusion treatments were applied, and the influence on productivity variables (fruit weight, fruits number and seeds weight), total normal seeds and total empty seeds, and seed quality (amount of proteins and lipids), plant weight, and the presence of pathogens in seeds from both pollination treatments were evaluated. Twelve morphospecies of pollinators were captured in the crop. Six of found bees are potential soybean pollinators according to the literature, and the family Halictidae was the most abundant. No flower visits were recorded during the sampling periods, suggesting a very low visitation rate. The differences found were not statistically significant in any of the productivity or seed quality variables between treatments. Twelve fungal pathogens were found. Among the four most abundant the genera Phomopsis, Alternaria, and Cercospora were slightly more abundant on plants without pollinators, while Cladosporium was more abundant on plants with pollinators (p=0.009). The fact that more fungal pathogens were found on plants without pollinators indicates that pollinators would not be acting as spore dispersing agents for most of them. The pollinator fauna was present as evidenced by trap captures but the rate of flower visits was very low, which may explain the lack of statistical significance in the pollination treatments.