Table 5. Viability of hybrid seedlings generated from crosses between N. occidentalis and two progenitors of N. tabacum at different temperatures.
| No. of hybrids | |||||
| Cross combination | Temperature (°C) | Total | Viable | Inviable | Lethality typea |
| N. occidentalis ♀×N. sylvestris ♂ | 24 | 58 | 0 | 58 | II |
| 28 | 61 | 0 | 61 | II | |
| N. occidentalis ♀×N. tomentosiformis ♂ | 24 | 71 | 0 | 71 | V |
| 28 | 69 | 0 | 69 | V | |
| N. sylvestris | 24 | 59 | 59 | 0 | – |
| 28 | 58 | 58 | 0 | – | |
| N. tomentosiformis | 24 | 58 | 58 | 0 | – |
| 28 | 56 | 56 | 0 | – | |
a
Type II, browning of hypocotyl and roots; Type V, fading of shoot color.