Cytological observation of anther structure and genetic investigation of a thermo-sensitive genic male sterile line 373S in Brassica napus L

Table 2 The calculated critical temperature of line 373S based on experiment results of four different environments

Environments	E1	E2	E3	E4
Days before flowering	23~27	19~23	23~26	18~23
r	−0.48~ − 0.52	− 0.77~ − 0.87	−0.81~ − 0.86	−0.70~ − 0.77
Tm_C (MFI = 0)	12.18~12.94	12.32~12.97	9.07~9.10	13.15~13.34

E1, pot cultivation (flower period 11/3/2017–30/3/2017), Yangling, Shaanxi; E2, field condition in 2016 (flower period 30/3/2016–15/4/2016), Yangling, Shaanxi; E3, field condition in 2017 (flower period 2/4/2017–17/4/2017), Yangling, Shaanxi; E4, greenhouse (flower period 19/2/2017–7/3/2017, 12 h/d in the temperature regimes of 28.5 °C (day) -10 °C (night)). The term ‘days before flowering’ means that temperature data at this time correlated significantly to the MFI (male fertility index) of the line 373S. r, Pearson correlation coefficient between MFI and the day mean temperature indicated by days before flowering. Tm_C, the calculated critical temperature when MFI = 0. * Significantly at 95% confidence level; ** Significantly at 99% confidence level

ISSN: 1471-2229