Two complementary factors C and R for the production of flower colours have been found already by the former investigators. In plants lacking either any of them or both, the flower should be white in its corolla, though in the flower tubes or stems some white flowers may be coloured.
The author could ascertain through several crossing experiments the genetic relation of composition and the colouration as follows:-
CY……Colour-tubed white flower with green stem
cR……Light yellow-tubed white flower with coloured stem
cY……Light yell ow-tubed white flower with green stem
The factor
Cis connected to some extent with the colour of folower-tubes, and
R with that of stems.
The F
1 plant derived from the crossing between
Cr white type and
cR white type almost always segregates out in the next generation the coloured and the whites containing three types on the ratio 9:7. The results obtained by crossing the normal coloured flower with the third type white was not reported in this paper, and in this case the coloured F
1 plant was found to segregate the coloured and the whites on the same ratio as well as in the previous crossing, though the dihybrid ratio was somewhat disturbed on account of the occurrence of a coupling between the factor
c and
r.
There occurs another white group having yellow tubes and green stems just like the third type white, but producing white seeds. This is due to the lacking of the factor
Ca, which activates
C.
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