Abstract

The aim of this work is to study the role of the fruit controlling tree development in loquat (Eriobotrya japonica Lindl.). As approach, we established four levels of comparison: 1) two varieties, ‘Algerie’ y ‘Piera’, the former presenting a typical behaviour under Mediterranean Climate, the latter is an everflowering variety giving rise to several vegetative and floral flushes a year, which develop several fruit generations that develop and mature appropriately; 2) young trees (3 years old), growing in pots, capable of flowering and set suitably; 3) mature trees with their fruits and without fruits thinned by hand at early stage of development; and 4) flowering shoots, shoots with detached panicle and shoots with panicle isolated panicle by means of bark ringing. Sprouting and flowering intensity, root development, fruit development, both reducing and transport carbohydrates, starch, nitrogen fractions, N-NO3-, N-NH4+ y N-proteinaceous, and hormonal content, IAA, ABA, and zeatin, in different developing organs, were evaluated. Results suggest that sprouting takes place once the fruit is harvested, hence bud break and shoots development takes place in its absence and also flowering. In the same way, root growth and root activity are hardly reduced by fruit, thus reducing hormones transport to the canopy. Results also show a self-controlled fruit development through a nutritional competitive process among panicle-developing fruits and interacting with tree organs in active growth stage, thus harmonizing colour break and maturation. In brief: 1) fruit sink activity modulates photosynthesis since carbohydrates demand is largely depending on its development, mainly the seeds, and once the seeds complete the growth carbohydrates demand progressively cut off.; 2) Fruit reduces flowering by reducing premature bud break and number of flowers per panicle both of premature and current shoots; 3) Root growth and root activity slow down as fruit grows, giving rise to a shorter roots, a reduction in tubular outgrowths from trichloblast cells, a reduction of carbohydrates from the canopy, measured by a reduction of 13C transported after 13CO2 leaves exposure, and a reduced transport from the roots to the fruit, showed by root starch accumulation, and a reduced N-NH4+ and hormones concentrations; and 4) sugars accumulation and reduced concentration of N-NH4+ and zeatin make easy the maturation process, being, thus, self-controlled by fruit.