Table 2.
Time course of the changes in leaf greenness of soybean plants in response to anaerobiosis, oxygen deficiency and elevated root‐zone CO2 treatments
| Treatment duration (d) | |||||||
| Treatment | 2 | 4 | 6 | 8 | 10 | 12 | 14 |
| SPAD unit | |||||||
| Aeration with air | 38·2 ± 4·0* | 37·3 ± 4·4 | 36·0 ±4·2 | 36·9 ± 4·6 | 35·8 ± 4·9 | 33·4 ± 4·9 | 32·7 ± 5·3 |
| Non‐aerated | 38·9 ± 3·8 | 36·0 ± 4·0 | 35·1 ± 3·9 | 35·6 ± 4·1 | 35·6 ± 4·8 | 33·7 ± 5·1 | 31·8 ± 4·8 |
| 100 % N2 gas | 34·1 ± 3·6 | 33·1 ± 3·8 | 35·7 ± 4·0 | 36·8 ± 4·5 | 36·0 ± 5·2 | 32·7 ± 4·6 | 30·5 ± 4·0 |
| 15 % CO2 gas + 85 % N2 gas | 32·3 ± 3·5 | 30·2 ± 3·0 | 29·5 ± 3·5 | 28·0 ± 3·7 | 26·2 ± 4·1 | 26·5 ± 4·5 | 27·2 ± 3·6 |
| 30 % CO2 gas + 70 % N2 gas | 30·8 ± 3·2 | 28·8 ± 3·2 | 27·3 ± 3·1 | 25·7 ± 3·0 | 25·5 ± 3·7 | 24·0 ± 4·2 | 23·8 ± 3·3 |
| 50 % CO2 gas + 50 % N2 gas | 28·6 ± 3·0 | 25·0 ± 3·2 | 12·2 ± 2·2 | 13·3 ± 2·9 | 15·1 ± 3·0 | 18·2 ± 3·5 | 19·3 ± 3·1 |
Three measurements were taken on each of the three uppermost fully expanded leaves and averaged to give individual plant readings. Mean values of each experiment were calculated from six plants. Values presented are means ± s.d. of two experiments on a total of 12 plants.
* Three measurements were taken on each of the three uppermost fully expanded leaves and averaged to give the plant reading.