Abstract:  The influences of sucrose, boric acid, calcium and GABA on the pollen germination of N. alata, N. tabacum L. cv. K326, N. repanda and N. stocktonii were studied with in vitro culture method. The result showed that the optimal concentration of sucrose, boric acid, calcium and GABA promoted pollen germination, while too high concentrations had disadvantage influence. For 4 Nicotiana species, the optimal boric acid and calcium ion concentrations were all 0.05 g/L. The suitable sucrose gradiant for N. alata and N. tabacum L. cv. K326 is 10%, and 12% for N. repanda and N. stocktonii. On 10% sucrose+0.05 g/L H3BO3+0.05 g/L Ca2+medium, the pollen germination ratio was 92% and 90% for N. alata and N. tabacum L. cv. K326, respectively; the pollen germination ratios were 85% and 87% for N. repanda and N. stocktonii， respectively, on 12% sucrose+0.05 g/L H3BO3+0.05 g/L Ca2+medium. By adding 0.7-1 mmol/L GABA into the above medium, the pollen germination rates of N. tabacum L. cv. K326, N. repanda and N. stocktonii differed insignificantly compared with the control, while it was restrained by adding GABA higher than 1 mmol/L. It was noteworthy that N. alata pollen germination was inhibited by adding GABA higher than 0.7 mmol/L, and the pollen germination ratio dropped down to 81%. N. alata pollen was further cultured in 10% sucrose+0.05 g/L H3BO3+1 mmol/L GABA medium, and the pollen germination rate was up to 89%, which showed that optimal GABA could promote pollen germination, and GABA and Ca2+ might have synergetic effects on promoting pollen germination.

Key words: tobacco, pollen germination, sucrose, boric acid, calcium ions, gamma-aminobutyric acid