23 research outputs found
Water deficit-induced changes in mesocarp cellular processes and the relationship between mesocarp and endocarp during olive fruit development
A field experiment was conducted during two
consecutive growing seasons to determine and quantify
the growth response of the olive (Olea europaea L. cv.
Leccino) fruit and of its component tissues to tree water
status. Pre-dawn leaf water potential (Ww) and fruit
volume were measured at about weekly intervals, and
fresh weight (FW) and dry weight (DW) of the fruit
tissues at 15, 20 and 21 weeks after full bloom (AFB).
Fruit anatomical sections were prepared at 8, 15 and 21
weeks AFB for area determinations and cell counts. Fruit
volume of the well-watered trees (average Ww = 0.97
MPa) increased rapidly and reached the greatest final size,
that from the most stressed (average Ww = 2.81 MPa)
grew most slowly and were smallest. In general, equatorial
transverse areas of the mesocarp increased with
increasing Ww, and this response was more evident at 21
than at 15 weeks AFB. By 21 weeks AFB, the mesocarp
of the well-watered trees reached values more than three
times higher than those measured at 8 weeks AFB. The
endocarp FW and DW did not increase between 15 and
21 weeks AFB. Within each sampling date the endocarp
area, FW and DW responded weakly to Ww. The
mesocarp-to-endocarp ratio (FW and DW) increased
from 15 to 21 weeks AFB regardless of water status,
mainly due to the mesocarp growth. In both years at 20
and 21 weeks AFB, low values of the mesocarp-toendocarp
ratio were found with Ww below 2.5 MPa.
Within the mesocarp, cell size was more responsive to
water deficit than to cell number. At 8 weeks AFB, the
number of cells in the mesocarp was unaffected by tree
water deficit, whereas cell size decreased, although
slightly, in fruits sampled from trees in which Ww was
< 3.0 MPa. At 21 weeks AFB, cell size showed a linear
decrease with increasing level of water deficit, whereas the
number of cells at 21 weeks AFB decreased as the Ww
decreased below 2.5 MPa and seemed unaffected above
that range. Overall, the results clarify the complexity of
the water-induced response of mesocarp and endocarp
growth and cellular processes of olive fruits
Interaction of crop load and water status on growth of olive fruit tissues and mesocarp cells
Trabajo presentado en el XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Plant Physiology from Cell to Fruit Production System, celebrado en Lisboa (Portugal) del 22 al 27 de agosto de 2010.Field-grown olive trees (Olea europaea L. ‘Leccino’) were hand-thinned at 5-6 weeks after full bloom (AFB) to establish heavy or low crop loads, and then were subjected to three irrigation regimes: a) FI, fully-irrigated with pre-dawn leaf water potential (LPWP) greater than -1.1 MPa; b) DI, deficit irrigated (LPWP between -1 and -3.3 MPa; c) SI, water stressed (LPWP higher than -4.2 MPa). Fruits were sampled at pit hardening and harvest, the mesocarp separated from the endocarp, and their fresh weight and dry weight determined. Additional fruits were fixed in FAE for anatomical studies, their mesocarp and endocarp area measured on transverse slices with an image analysis system connected to a stereo microscope. Mesocarp cell size and number were then determined by microscope after standard paraffin processing. The effect of crop load on the growth of fruit tissues was significantly influenced by the irrigation regime. Within the FI or DI treatments the mesocarp dry weight was higher at low than at high crop load. In the SI treatment, mesocarp dry and fresh weights were 180 and 200% respectively those for trees bearing high crop loads. The pulp-pit ratio was decreased by high cropping for both DI and SI treatments, but was unaffected for the fully-irrigated trees. Overall, there was a notable interaction of crop load and water status on fruit growth processes at multiple morphogenetic levels, including the absolute and relative growth of pulp and pit, mesocarp cell division and enlargement.Peer reviewe