avo flower

FLOWER QUALITY AND REPRODUCTIVE BIOLOGY IN AVOCADO


M.Librada Alcaraz1, J.I. Hormaza1 and J. Rodrigo2
1Estacion Experimental la Mayora - CSIC. 29750 Algarrobo-Costa, Malaga Espana,
2Unidad de Fruticultura. CITA de Aragon. Apdo. 727. 50080 Zaragoza. Espana

In avocado, only a very small fraction of flowers produced at anthesis are able to set fruits.
However, information is elusive to explain why most flowers prematurely abscise while some of
them remain in the tree. The term "flower quality" is used to express something inherent to the
flower that has a reflection on the subsequent fruit set. In order to gain insight in the causes that
produce this low fruit set in avocado, in this work we have studied different aspects of flower quality
such as the influence of the nutrient reserves of the flower and several morphological flower
parameters on fruit set. With this purpose, flowers from different panicles of the cultivar Hass were
individually tagged, recording the date of anthesis and the position in the panicle. Each flower was
collected at anthesis and histochemically processed for analysis under the microscope after staining
with I2KI for starch reserves. Starch content in individual flowers was measured with the help of an
image analysis system attached to the microscope. Style length, ovary size and stigmatic surface
were also measured for each flower. Differences in both starch content and morphological
parameters were found among flowers at anthesis, suggesting a possible relationship among starch
content of the flower, the size of the floral structures and the capacity of each flower to set a fruit.
The results are discussed in terms of the possible implications of the nutritional status of the flower
in the reproductive success and fruit set in avocado.

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