Objective To study the low temperature tolerability of different photo-thermo sensitive genic male sterile (PTGMS) lines in rice so as to provide a basis for breeding and utilizing of the PTGMS lines with stable male sterility.

Method At the temperature sensitive stages, the PTGMS lines of XianS, N28S, AnnongS, Peiai64S, N9S and N2S were treated at 21 and 23 ℃ for 3, 7 and 10 d in the plant growth chambers, respectively. The pollen fertilities of these PTGMS lines were investigated for 30 d after they were transferred to the outside of plant growth chamber to analyze their low temperature tolerability.

Result The low temperature tolerability order of these PTGMS lines was XianS, N28S > AnnongS > Peiai64S > N9S, N2S. The non-pollen type PTGMS lines of XianS, N28S and AnnongS produced no fertile pollens after treated at 21 and 23 ℃ for 3 d. XianS and N28S were still completely sterile, while AnnongS produced some fertile pollens after treated at 21 and 23 ℃for 7 d. After treated at 21 and 23 ℃ for 10 d, XianS and N28S produced some fertile pollens, and AnnongS produced more fertile pollens compared with that for 7 d. However, the typical abortion type PTGMS lines of Peiai64S, N9S and N2S produced some fertile pollens after treated at 21 and 23 ℃ for 3, 7 and 10 d respectively, except for Peiai64S after treated at 23 ℃ for 3 d. The percentage of fertile pollen increased with the continuous extension of time and the temperature dropping.

Conclusion The low temperature tolerability of the PTGMS line relates to the type of pollen abortion besides the critical temperature inducing sterility (CTIS), and the non-pollen type PTGMS line with low CTIS shows stable male sterility. It should be paid more attentions to the non-pollen type PTGMS lines with low CTIS in the breeding process of the practical PTGMS lines.