Table 4.

Effects of elevated temperatures on hybrid lethality observed in hybrid seedlings between N. tabacum and seven species of section Suaveolentes

			No. of hybrids showing lethal symptoms
Cross combination	Temperature (°C)	No. of hybrids cultured	By 30 DAG	After transfer to 28 °C*
N. africana × ‘Red Russian’	34	10	6	4
	36	10	0	10
‘Red Russian’ × N. africana	34	16	16	–
	36	10	0	10
N. excelsior × ‘Red Russian’	34	10	0	10
‘Red Russian’ × N. excelsior	34	10	0	10
‘Samsun NN’ × N. excelsior	34	10	0	10
N. goodspeedii × ‘Red Russian’	34	10	0	10
N. gossei × ‘Red Russian’	34	10	0	10
‘Red Russian’ × N. gossei	34	3	0	3
‘Samsun NN’ × N. gossei	34	6	0	6
N. maritima × ‘Red Russian’	34	10	0	10
N. megalosiphon × ‘Red Russian’	34	10	0	10
‘Red Russian’ × N. megalosiphon	34	5	0	5
‘Samsun NN’ × N. megalosiphon	34	8	0	8
N. velutina × ‘Red Russian’	34	10	0	10

*Hybrid seedlings that did not show lethal symptoms at 30 DAG were transferred from the elevated temperature to 28 °C.