ISHS Acta Horticulturae 494: II International Symposium on Chestnut
EFFECT OF LEAF TO FRUIT RATIOS ON FRUIT GROWTH IN CHESTNUT |
| Authors: | F. Famiani, P. Proietti, A. Palliotti, E. Antognozzi, F. Ferranti |
| Keywords: | Castanea sativa Mill., source-sink relationships, photosynthesis, fruit size |
| Abstract:
In 1997 a trial was carried out to evaluate the influence of different leaf-to-husk ratios on fruit growth in Castanea sativa Mill. cv. Santa Restituta. Ten days after full bloom, defoliation was performed on girdled and ungirdled shoots fully exposed to the sun to give leaf-to-husk ratios of 2/1, 4/1, 7/1, 10/1 and 14/1. The number of fruits per husk was not affected by the treatments. The different leaf-to-husk ratio did not affect the fruit/husk+fruits ratio and fruit growth in ungirdled shoots. Conversely it affected these parameters in girdled shoots; the fruit/husk+fruits ratio and fruit growth were positively correlated to the leaf-to-husk ratio, with the 10/1 showing values similar to those of the ungirdled shoots. The different fruit sizes in girdled shoots with a different leaf-to-husk ratio corresponded to a different endosperm cell number and size. The different leaf-to-husk ratio did not influence the shoot dry matter and carbohydrate content in the ungirdled shoots, whereas it affected these parameters in the girdled ones. The leaf photosynthetic rate, stomatal conductance and intercellular CO2 concentration were similar in all the ungirdled shoots and in the girdled ones with a low leaf-to-husk ratio, whereas the girdled shoots with a high ratio had lower photosynthesis and stomatal conductance and a higher intercellular CO2 concentration. The results show that assimilates can be easily translocated and that it is necessary to have about 5 leaves per fruit well exposed to light (about 10 leaves per husk) to ensure normal fruit development and dry matter accumulation in the shoots. Fruit is stronger sink than shoot reserve tissues. Leaves have a quite high efficiency in producing assimilates which are allocated in the fruit and a feedback inhibition of photosynthesis at high leaf-to-husk ratios is suggested. | |
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