6 research outputs found
A regulated deficit irrigation strategy for hedgerow olive orchards with high plant density
Background & Aims
There is not a consensus on the best irrigation approach for super-high density (SHD) olive orchards. Our aim was to design and test a regulated deficit irrigation (RDI) strategy for a sustainable balance between water saving, tree vigour and oil production.
Methods
We tested our RDI strategy for 3 years in an ‘Arbequina’ orchard with 1,667 trees ha−1. Two levels of irrigation reduction were applied, 60RDI and 30RDI, scaled to replacing 60 % and 30 %, respectively, of the of irrigation needs (IN). We also had a full irrigation (FI) treatment as control, with IN totalling 4,701 m3 ha−1
Results
The 30RDI treatment showed the best balance between water saving, tree vigour and oil production. With a yearly irrigation amount (IA) of 1,366 m3 ha−1, which meant 72 % water saving as compared to FI, the reduction in oil yield was 26 % only.
Conclusions
Our results, together with recent knowledge on the effect of water stress on fruit development, allowed us to suggest a potentially improved RDI strategy for which a total IA of ca. 2,100 m3 ha−1 was calculated. Both some management details and the benefits of this suggested RDI strategy are still to be tested
Advances in olive fruit cell and tissue development
The physiology of fruit development is closely related to the cellular processes
in the fruit tissues-cell division, expansion and differentiation. We have been carrying
out microscopy and image analysis studies on olives to quantify these processes and
provide a more comprehensive view of their role, timing, interaction, and the
influencing factors. Ovary size and cell number at bloom are highly correlated with
cultivar fruit size at maturity. The highest rate and amount of mesocarp cell division
occurs immediately following bloom, and it continues throughout fruit development,
although at a reduced rate. The differences in fruit size among cultivars are due to cell
number and water status tends to impact cell size rather than number. Pit hardening
requires the initiation and completion of individual cell sclerification, which is
composed of a series of processes, which vary among cells but are coordinated for the
endocarp tissue. Endocarp sclerification is affected by both water and assimilate
availability, and it seems to drive the end of endocarp expansion rather than vice
versa. These results provide new information for interpreting and managing olive
fruit growth, and for choosing breeding criteria
Effects of tetraploidy on olive floral and fruit biology
Floral biology and fruit development were studied in Leccino Compact (LC), a polyploid olive mutant of cultivar Leccino (L). This mutant, considered a mixoploid with both diploid and tetraploid cells, has thicker leaves and fruit size similar to the diploid cultivar. So far, no information is available on its floral biology. In this study,the ploidy level ofthe LC fruit epicarp, analyzed by flow cytometry, was determined to be tetraploid. Pollen size distribution confirmed that most flowers were tetraploid. Morphological and histological measurements of various floral structures and fruits were carried out on the two genotypes, and LC showed larger floral structures (i.e. rachis, flower and ovary) and slightly higher pistil abortion rates. The total number of flowers per inflorescence was not significantly different between L and LC. The large difference (about 2 fold) in ovary cross sectional area between LC and L ovaries was mainly due to increased cell size. LC had slightly larger fruit cross-sectional area (but not greater fruit volume, since LC fruits were less elongated), with much larger cells. Therefore tetraploidy resulted in larger floral structures, as normally occurs in tetraploid plants, but had little effect on fruit size, despite much larger cell size