July 15, 1915 Inheritance of Certain Characters of Grapes 319 



From a practical standpoint it is undesirable to grow self-sterile varieties. 

 They will not succeed in the large blocks of the commercial plantation, nor 

 are they always properly fertilized in the small home vineyard. Can we, 

 then, in our grape breeding eliminate self-sterility? Letting U stand for 

 upright stamens and R for reflex, the following table gives the results of 

 our crosses: 



UXUi =i8oU-f 47R RXR = 16U-I-16R RXU =207U-l-2o6R 

 Uselfed=69iU-|-i52R R selfed= 94U-f 73R Ratio iU:iR 



Total. . .871U4-199R Total. . . iioU-f89R 

 Ratio 4.3U:iR Ratio i.2U:iR 



UXR=? 



Of the varieties whose pure seedlings have entered into the ratio of 

 4.3 U to I R, only two, involving 18 seedlings, have given simply upright 

 stamens; consequently it may safely be said that no variety has proved 

 pure for upright stamens. In the remaining crosses of this class the 

 ratios have ranged from i U to 2 R up to 10 U to i R, with the greatest 

 frequency at 2 U to i R. The results with the crossed seedlings are 

 practically the same. Over a thousand seedlings from crosses of one 

 type would be expected to give some rather definite results; yet these 

 results are anything but definite, and apparently no conclusions can be 

 drawn from them except that the varieties are not homozygous for up- 

 rightness of stamens. 



The ratio of practically i to i in crosses of varieties with reflexed sta- 

 mens is perhaps best accounted for by the supposition that the gametic 

 composition of pollen and ovules is not alike. The ratio of i to i in 

 crosses of reflexed stamens by upright may be covered by the same 

 assumption. It should be noted that the pollen of the upright varieties 

 produces the same ratio as that of the reflexed varieties when both are 

 used on ovules of the reflexed kinds. 



Upright varieties have been crossed many times with reflexed sorts 

 and several hundred seedlings should have resulted from these, yet only 

 one plant has survived the vicissitudes of the seed bed and nursery to be 

 planted in the test vineyards. In the last five years 50 crosses have 

 yielded 600 seeds; yet from these there are now in the nurseries but 25 

 living seedlings. Many of the pollen parents used in these crosses were 

 the same as those used in the cross Rx R. In the two crosses RX R and 

 RxU, the pollen from upright and reflexed varieties produced the same 

 results; but comparing this last case, UxR, with the first one, UxU, 

 we see that the pollen of the upright and reflexed varieties has produced 

 quite different results when used on upright sorts. Why this should be 

 is not apparent. 



At present there does not seem to be any way of eliminating reflexed 

 stamens, but we can at least decrease the proportion by using for breed- 

 ing only varieties with upright stamens. 



^ The pollen parent is always placed last. 



