268 



The Journal of Heredity 



tion of one night when a temperature 

 of 15°C. was recorded. 



Comparative Germination of Parents 

 and Hybrids 



The data for the germination test of 

 Victory, A. sativa. Garton 748, A. sati- 

 va orient alls, and two varieties of A. 

 fatua as well as the second generation 

 seed of certain crosses, are shown in 

 Table I. One of the fatua forms had 

 a brown hairv lemma and the other 

 had a yellow glabrous lemma. 



In a few cases, seeds which showed 

 no signs of germination at the expira- 

 tion of six days and at that time were 

 not treated by searing or cutting 

 through the seed coats, showed weak 

 germination at the end of thirteen days 

 (Table II). The data in Table I are 

 made up from the number of untreated 

 seeds per plant which showed germina- 

 tion during the thirteen-day period. 



Each of the fourteen Victory plants 

 and five Garton 748 j^lants germinated 

 95 per cent or above. The eleven plants 

 of the Yellow wild oat ranged from 

 to 55 per cent germination, whereas the 

 eight plants of the Brown Hairy wild 

 oat ranged from to 25 per cent germ- 

 ination. Although the number of 

 plants involved is somewhat small, the 

 data indicate that the brown hairy wild 

 oat shows a somewhat greater degree 

 of delayed germination than the gla- 

 brous yellow wild oat. Data previously 

 collected corroborate the above state- 

 ment. 



The individual plants of each second 

 generation progeny tested show a wide 

 range in percentage of germination. 

 The only apparent exception is the 

 cross Yellow Wild oat X Victory in 

 which the range of germination is from 

 G(j to 100 per cent. The reciprocal 

 cross, however, shows a range in germ- 

 ination of Hi to 100 ])er cent. In the 

 generations of all the other crosses, 

 namely. Brown Hairy wild oat X Vic- 

 tory and the reciprocal, Garton 748 X 

 Brown Hairy wild oat, and Garton 748 

 X Yellow wild oat. tbe range in germ- 



ination is from 31 or below to 100 per 

 cent. The data in Table I, comprising 

 tests of seed-samples from 437 second 

 generation plants, show that delayed 

 germination is an inherited character 

 and that in general the range in per- 

 centage of germination in the second 

 generation is from the fatua parent to 

 the sativa parent. The second genera- 

 tion individuals show a distinct piling 

 up at the upper limit of the frequency 

 distribution. In other words, delayed 

 germination behaves as a recessive 

 character in these fatua-sativa crosses. 



The Test for Delayed Germination 



In order to determine whether de- 

 layed germination was the main cause 

 of seeds failing to grow during the first 

 six-day period of the test, the ungerm- 

 inated seeds of each of a larger number 

 of plants were divided into two ai)prox- 

 imately equal lots. Before returning 

 the seeds to the germinator one lot was 

 treated either by cutting through or 

 searing the seed coats and the other lot 

 was untreated. After the treated and 

 untreated seed had been in the germ- 

 ination chamber for an additional 

 seven-day period, the number of seeds 

 which had germinated was determined. 

 The results are tabulated in Table II. 



It will be noted from Table II that 

 the germination of the Brown Hairy 

 wild oat was less affected by treatment 

 of the seed coats than was the germ- 

 ination of the Yellow wild oat or the 

 second generation hybrid plants. Both 

 the seared and cut seed of the second 

 generation plants germinated approxi- 

 mately forty-five per cent while only 

 one per cent of the untreated seed 

 germinated. The data presented in 

 Table II show that the seed treatment 

 appreciably increased the percentage of 

 germination. 



When the germination test was com- 

 pleted it was found that the untreated 

 seeds exhibiting delayed germination 

 were still firm whereas seeds which 

 failed to grow for other reasons were 

 sf)ft and ])artially decayed. 



