Table 1.
Changes in projected concentrations of Zn in leaf tissues of tomato and citrus to which droplets of either Zn(NO3)2 or ZnHN were applied to the abaxial or adaxial surface (for the control there was no foliar-applied Zn). Plants were grown in the presence (Zn-sufficient) or absence (Zn-deficient) of Zn in the rooting medium, and the leaves examined were either the youngest fully expanded leaf (YFEL) or a mature leaf. Using µ-XRF analysis, average concentrations of Zn were determined either in the tissues underneath where the droplet was applied or in tissues at least 5 mm from where the droplet was applied. For the strength coefficient (c), eqn 1 was fitted for projected concentrations along the length of a vein. Concentrations are reported on a fresh mass basis
| Zn(NO3)2 |
ZnHN |
||||||||
|---|---|---|---|---|---|---|---|---|---|
| Concentration under droplet (µg cm−3), mean ± s.d. | Baseline leaf concentration (µg cm−3), mean ± s.d. | c (95 % confidence interval) | Concentration under droplet (µg cm−3), mean ± s.d. | Baseline leaf concentration (µg cm−3), mean ± s.d. | c (95 % confidence interval) | ||||
| Tomato | Zn-sufficient | YFEL | Abaxial | 560 ± 150 | 0·88 ± 0·22 | 0·81 (0·71, 0·91) | 220 ± 17 | 0·81 ± 0·22 | 0·67 (0·62, 0·71) |
| Zn-sufficient | YFEL | Adaxial | 230 ± 200 | 0·88 ± 0·18 | 0·49 (0·46, 0·51) | 87 ± 41 | 0·96 ± 0·07 | 0·45 (0·43, 0·46) | |
| Zn-deficient | YFEL | Adaxial | 310 ± 150 | <0·5 | 5·4 (4·3, 6·6) | 180 ± 64 | < 0·5 | 1·6 (1·5, 1·7) | |
| Zn-sufficient | Mature | Adaxial | 320 ± 110 | <0·5 | 3·2 (2·8, 3·6) | 220 ± 24 | < 0·5 | 0·38 (0·32, 0·44) | |
| Citrus | Zn-sufficient | YFEL | Abaxial | 6·0 ± 8·7 | 1·1 ± 0·27 | – | 1·7 ± 0·50 | 1·0 ± 0·29 | – |
| Zn-sufficient | YFEL | Adaxial | 3·7 ± 0·40 | 0·57 ± 0·14 | – | 2·1 ± 0·87 | 0·90 ± 0·39 | – | |