Frost Resistance in Flax. 7 



Three more tests were conducted in the spring of 1922 with reselec- 

 tions from the more resistant of the tall fiber-flax selections. The 

 parent stocks of seed and the two commercial fiber-flax selections were 

 included for the sake of comparison. The accompanying diagram 

 (Fig. 3) shows that in each case improvement over the parent stock 

 lias been secured. One selection from Fiber Investigations No. 21003 

 was three times as resistant as Blue Blossom Dutch and nine times 

 as resistant as A^^iite Blossom Dutch. The data on the reselections 

 offer additional confirmation that frost resistance is a power that 

 varies with different flaxes and is inherited from one progeny to the 



Fig. 4. — Frost resistance in flax. A comparison between Saginaw and unselected fiber 

 flax. From right to left : Blue Blossom Dutch, 63 centimeters total height, resistant 

 to frost ; White Blossom Dutch, 69 centimeters total height, very suscentible to frost ; 

 and Saginaw, 82 centimeters total height, resistant to frost. (See Fig. 5, showing 

 drawings of individual plants.) 



next in a single plant selection. The reselections from Saginaw are 

 also more resistant to frost injury than Blue Blossom Dutch (Figs. 

 4 and 5). 



CONCLUSIONS. 



The temperature range for frost-resistance tests with flax is 21° 

 to 24° F. 



Frost injury is first noticeable in the flax hypocotyl, and unless the 

 temperature falls below the range of frost resistance the cotyledons 

 and root system are affected only indirectly. 



Seeds of low germinating quality produce plants very susceptible 

 to frost. 



