Table 1.
Night-time acid accumulation (ΔH+, µequivalents g–1) derived from difference in dusk and dawn titratable acidity measurements, averaged across samples for all three species with standard error
Averages for plants kept well watered for the duration of the experiment or under drought stress (which began on day 3, not sampled, and ended after day 7). Significance values (Sig) indicate species by treatment measurements that are significantly different from zero by Student’s t-test: ***P< 0.001, **P<0.01, *P<0.05, n.s., not significant.
| Species and conditions | Day 1 | Day 5 | Day 7 | Day 9 | ||||
|---|---|---|---|---|---|---|---|---|
| ΔH + | Sig | ΔH + | Sig | ΔH + | Sig | ΔH + | Sig | |
| Y. aloifolia | ||||||||
| Well watered | 144.2±16.0 | *** | 106.7±16.2 | *** | 133.5±14.6 | *** | 125.5±7.3 | *** |
| Drought stressed | 135.1±6.9 | *** | 119.8±6.7 | *** | 48.0±14.2 | ** | 99.5±9.1 | *** |
| Y. gloriosa | ||||||||
| Well watered | 2.4±0.97 | * | 0.44±0.26 | n.s. | 2.0±0.71 | * | 1.6±0.67 | * |
| Drought stressed | 3.7±1.4 | * | 1.79±0.87 | n.s. | 1.7±1.0 | n.s. | 2.4±0.77 | ** |
| Y. filamentosa | ||||||||
| Well watered | 0±0 | n.s. | 0±0 | n.s. | 0±0 | n.s. | 0±0 | n.s. |
| Drought stressed | 0±0 | n.s. | 0±0 | n.s. | 0±0 | n.s. | 0±0 | n.s. |