Figure 1.
Diagram of a Quercus fruit showing the pericarp components, hypocotyle-root axis (embryo axis) and cotyledons.
Figure is modified from [31].
Table 1.
Collection information and vegetation types in which the 9 Quercus species investigated in this study occur.
Figure 2.
Representative drying curves for fruits of 5 Quercus species.
The presented curves span the entire range of drying rates observed for the full 9 species. For each species, 37 fruits were desiccated at 15°C using silica gel. The slopes of the fitted lines (k) are given on the figure. Inset: the relationship between drying rates (k) and rates of water uptake for fresh fruits of the 9 Quercus species imbibed in water for 24 h.
Table 2.
Fruit dry mass, viability and drying rates (see also Figure 2) of the 9 Quercus species studied here.
Figure 3.
The routes of water flow into fresh Q. fleuryi fruits when imbibed in water.
(A) SEM photograph of apical end of fruit; (B) cross-section of the main pericarp area of the fruit following imbibition in 5‰ Methylene Blue for 8 h, showing that vascular bundles in vascularised inner pericarp layer stained blue; (C) SEM photograph of the surface of the scar, showing the open ends of the vascular bundles of the pericarpial vascular system; (D) longitudinal section through the apex, with Methylene Blue staining showing that water entered into the fruit at the point where the remains of the perianth segments are attached; (E) longitudinal section of the scar (to the left of the dashed line) and the main pericarp (to the right of the dashed line), with Methylene Blue staining showing that water enters from the scar directly into the pericarpial vascular system that penetrates the inner pericarp layer; (F) longitudinal section of the scar with Methylene Blue staining only the vascular bundles whereas the surrounding water-impermeable sclerenchymatous tissue remains unstained; m = micropylar area of the fruit (embryo missing in photograph); pe = perianth remains; pl = palisade layer; s = stylar remains; sc = seed coat; vb = vascular bundle; vi = vascularised inner pericarp layer; we = point of water entry. Arrows show the points of water entry.
Table 3.
Anatomical characteristics of the scar, the main pericarp and the apex of the 9 Quercus species studied here.
Figure 4.
Transverse sections of the main pericarp of Q. fleuryi (A) and Q. lamellosa (B) stained with Sudan which colours the cuticle red.
c = cuticle (stained red); pl = palisade cell layer; vb = vascular bundles; vi = vascularised inner layer.
Figure 5.
The increase in moisture contents for fruits of the 9 species following imbibition in water for 24 h.
The figure shows the moisture content increase of the whole fruit when different components of the pericarp were sealed with wax. Treatments were as follows: no part of the pericarp was sealed with wax (P, treatment 1); the entire pericarp, except for the scar, was sealed with wax (S, treatment 3);the entire pericarp, except for the non-scar area, was sealed with wax (NS, treatment 4); the entire pericarp, except for the apex, was sealed with wax(A, treatment 5). The final treatment (MP, C) represents water uptake through the main pericarp, i.e. assuming the scar and apex were sealed. This value was derived by subtracting the mean of the water uptake through the apex (A, treatment 5) from that through the non-scar area (NS, treatment 4). Bars (mean ±1SE) with the same letters (a-d) are not significantly within each species were not significantly different at p>0.05 (One-Way ANOVA with Fisher’s LSD post hoc analysis). The asterisk (*) above the bars showed the increase in moisture contents when only the main pericarp are unsealed (MP, C) were calculated by the mean values without standard errors. Data for the increase in moisture content were analyzed using 1 sample t-test to test for effects of the pericarp sealing treatments on water uptake.
Figure 6.
Rates of water uptake through the various pericarp components of 9 Quercus species after 24 h imbibition.
Fresh fruits were used in this experiment. Figure shows imbibition through the pericarp (A, treatment 1), the scar (B, treatment 3), the non scar area (C, treatment 4), the apex (D, treatment 5), and the main pericarp (E, by calculation); an = Q.annulata, fa = Q. fabri, fl = Q. fleuryi, fr = Q. franchetii, la = Q. lamellosa, mu = Q. multinervis, sc = Q. schottkyana, si = Q. sichourensis, va = Q. variabilis. Bars (mean ±1SE, in plot A, B, C, D) with the same letters (a-f) are not significantly different from each other (p≥0.05). Bars in plot E showed the mean rate of water uptake of the main pericarp which is calculated as the mean increase in moisture content relative to the surface area of the main pericarp. Bars are ordered according to increasing drying rates of the species. Note the different scales on the y-axes.
Table 4.
Final multiple regression analysis model for the effects of area of vascular bundles within the scar and the thickness of the vascularised inner layer of the main pericarp on the rate of water uptake for 9 species of Quercus.