Table 1.
Morphological parameters of the different hierarchical levels of the coconut fruit. Given are mean values ± standard deviation. From hierarchical level H3, only the endocarp was considered. Abbreviations: number (n), thin to thick ratio (t:t ratio), vascular bundles (vb), sclereid cell matrix (scm), resolution (res), tracheids (t), sclereid cells (sc), mesocarp side (ms), centre (c), testa side (ts), cell wall (cw), width to length ratio (w:l ratio), primary cell wall layer (l1), secondary cell wall layers (l2), pits (p).
| Hierarchical Level | Structure | n | Length | Width | Thickness | Others | Evaluated Data |
|---|---|---|---|---|---|---|---|
| H0 | fruit | 161 | up to 25 [cm] 1 | up to 20 [cm] 1 | − | “ellipsoidal to broadly ovoid, indistinctly 3-angled” [Dransfield and Cooke, 1999] |
|
| H1 | − | − | − | − | − | “almost always 1 only, very large, with a narrow layer of homogeneous endosperm, and a large central cavity partially filled with fluid; embryo basal, opposite one of the endocarp pores” [Dransfield and Cooke, 1999] | |
| pericarp | − | − | − | − | − | ||
| H2 | exocarp | − | − | − | 0.015 [mm] 2 | “smooth” [Dransfield and Cooke, 1999]; “a smooth, tough coat, of a brownish or grayish color” [Winton, 1901] |
|
| mesocarp | − | − | − | 3–4 [cm] 2 | “very thick and fibrous, dry” [Dransfield and Cooke, 1999]; “consists of a hard outer coat, but a few mm thick and a soft portion usually 3–4 cm thick on the sides and much thicker on the base. Imbedded in the mesocarp are numerous longitudinally arranged fibers, varying in size from slender hairs to large […] forms, 2–3 mm broad.” [Winton, 1901] | ||
| endocarp | 10 | 116.5 ± 9.2 [mm] | 92.8 ± 5.2 [mm] | thin: 2.5 ± 0.5 thick: 4.7 ± 0.6 [mm] | Shell with a prolate, spheroidal shape and varying thickness | digital calliper | |
| H3-1 | vb | − | − | − | − | diameter: 0.22 ± 0.14 [mm] | CT data (res: 42 µm) + CT Analyser |
| H3-2 | scm | porosity: 0.033 | CT data (res: 42 µm) + CT Analyser | ||||
| H4-1 | t | − | 424.3 ± 263.3 [µm] (n = 6) | 11.5 ± 3.6 [µm] (n = 80) | − | − | LM images (macerated cells) + ImageJ |
| H4-2 | sc-ms | 60 | 100.3 ± 21.5 [µm] | 40.7 ± 9.2 [µm] | − | w:l ratio 0.42 ± 0.10 | LM images (macerated cells) + ImageJ |
| sc-c | 60 | 115.6 ± 29.4 [µm] | 31.3 ± 6.5 [µm] | − | w:l ratio 0.29 ± 0.09 | LM images (macerated cells) + ImageJ | |
| sc-ts | 60 | 125.2 ± 38.8 [µm] | 25.4 ± 5.4 [µm] | − | w:l ratio 0.22 ± 0.09 | LM images (macerated cells) + ImageJ | |
| H5-1 | cw (t) | 30 | − | − | 1.7 ± 0.4 [µm] | scalariform pitting | SEM images + ImageJ |
| H5-2 | cw (sc) | 30 | − | − | 13.8 ± 2.9 [µm] | thickness in relation to cell radius 89.2 ± 4.3 [%] | SEM images + ImageJ |
| H6-2 | l1 (sc) | 24 | − | − | 2.0 ± 0.5 [µm] 3 | − | SEM images + ImageJ |
| l2 (sc) | 145 | − | − | 253 ± 74 [nm] | − | SEM images + ImageJ | |
| p (sc) | 414 | 2.5 ± 0.6 [µm] | 1.8 ± 0.4 [µm] | − | bordered, ramiform pits | SEM images + ImageJ |