This study was carried out under natural conditions at College of Agriculture Experiment Base of Guangxi University in late June. The temperature was between 10˚C and 30˚C. Experimental plants Da107 used as the test group were derived from successive self-pollination for six generations after the hybridization of T-4 (a genic male sterile line from Okayama University) and stigma exsertion mutant type (WANYU), and the fertile line First was used as the control.

The experimental materials were treated with 3 steps as follow: 1) The seeds were disinfected in water solution with Trisodium phosphate dodecahydrate’s concentration of 10% for 20 minutes; flushed with water; and then soaked in normal temperature water for 12 hours; finally, accelerated germination with gauze in normal temperature, and each day during germination with water washing 1 - 2 times. 2) Culture of seedling was in seedling matrix with seedling-raising disk. 3) Transplanted when the seedlings were 25 days old in a glass greenhouse; and other management was according to the normal level. The experimental dates of the tomato trial were tabulated.

There were no significant difference in the pollen germination rate between Da107 and First grew at night temperature(NT) between 14˚C - 18˚C (Figure 1). On the contrary, the results showed significant difference between those grew at 20˚C - 28˚C (NT) (Figure 2). The two pictures (as below) indicated that temperature was a

major factor affecting the PGR of Da107.

The PGR of Da107 was low to 4.34% at 26.43˚C night temperature, but up to 56.21% at 16.42˚C. It can be seen that correlation coefficient between PGR and temperature was −0.97 (Table 1). It meant that RGR of Da107 was significantly negatively related to temperature. With the increase of temperature, the PGR of Da107 was decreased. The PGR of 56.21% of Da107 had no significant difference with First when the temperature was 16.42˚C. In other words, Da107 restored fertility under the conditions of low temperature. The T-4 mutant plant’s PGR was four times higher in autumn (low temperature) than that in spring (high temperature) and it was restored when exposed to low temperatures [10] . Masaharu Masuda reported that the fertility of T-4 mutant type was affected by night temperature and the male-sterile line which restored fertility could be propagated under low night temperature conditions (above 12˚C and below 18˚C) [11] . SPSS analysis test showed that the analysis of variance at 1% level of significance indicated that the differences of the PGR between Da107 and the control first were statistically significant. So the results manifested that with the environment conditions changed, Da107 was a perfect MSL whose sterility was up to 95% and maintenance line also.

Normal fertile line First (Figure 3.3) showed big corolla, full-fledged filament, full stylus and yellow plump anther, and tetradynamous stamen was as high as or slightly higher than the stylus. Compared with the First, small coralla, browning or whiting thin less anther, and tetradynamous stamen much higher than the stylus was characterized as Da107 (Figure 3.1 vs Figure 3.2).

In natural conditions, that the length of Da 107’ s stylus was about 75% longer than the stamen (Table 2) posed an obstacle to self-pollination, and the trait stood for a functional male sterile phenotype (FMSP) [12] . So Da107 was a double male sterility line. In other words, Da107 was not only the thermo-sensitivity male-sterile mentioned above, but also FMSP. Studies on the genetic variability of exserted stigma-sterility showed that this male-sterile was not to be evaluated based only on the length of the style that protruded from the anther cone, but also depended on the length of both style and anther, and all these were affected mainly by the temperature [13] [14] ). The length of the stylus and stamen increased with the temperature rising. That was to say, the sterility of Da107 increased with temperature rising. It could be concluded that Da107 was a perfect male sterile line under the condition of higher temperature. Furthermore, Da 107’ s stylus had the diameter almost one bigger than First’s (Table 2), which was in favor of the hand pollination immensely. In any case, Da107 was used as MSL at high temperature or maintenance line at low temperature

Table 3 showed that the F₁ hybrid-seed contamination rate with the selfed-seed was inapparent, so, Da107 was a valuable sterile material for breeding when taken as female parent.