1972 



ENCYCLOPEDIA OP PRACTICAL HORTICULTURE 



be expected to run 1 roni live to twelve tons 

 per acre. Occasionally a good tomato 

 grower secures even a higher yield than 

 this. 



It is assumed that the commercial 

 tomato grower will fertilize his ground 

 each year with well-rotted stable manure 

 or its equivalent. This should increase 

 his yield each year very materially. The 

 tomato responds readily to fertilization. 

 An excess of nitrogen causes a rank 

 growth of the plant at the expense of the 

 fruit. A study of the amount of fruit and 

 vine on each plant will aid the grower in 

 the question of handling the fertilization. 



rROSSI>G TOM.VTOES TO INCKEASE 

 THK YIELD 



"New Blood (Jives New Vigor" 



Stock breeders have long recognized the 

 principle that mating animals of differ- 

 ent strains, races or varieties of the same 

 or closely allied species usually gives off- 

 spring of great vigor and frequently of 

 larger size than the parents. This view 

 had received some recognition from scien- 

 tists even before the time of Darwin; but 

 he collected so many illustrations of its 

 truth among both animals and plants that 

 biologists generally accepted the principle 

 as one of nature's laws, though it is a 

 law with exceptions. Other students and 

 investigators since Darwin's time have 

 tested this law in many fields, and, among 

 others, have proven it true with corn, 

 beans, sorghum, cotton, tobacco, peas and 

 other farm crops. 



In order to test this law in the case of 

 tomatoes, Richard Wellington, of the 

 Geneva station. New York, undertook an 

 experiment covering four years, which re- 

 sulted in first generation crosses from 

 standard parents giving more ripe fruit 

 and larger total yield by 2V2 tons of ripe 

 fruit and iVj tons total yield. 



It is only in the first generation that 

 this favorable influence is likely to be 

 profitable. 



Why Does Crossing Increase Yield? 



The fact that crossing parents not too 

 closely nor too distantly related increases 

 the vigor, size and productivity of the off- 

 spring is apparently well established; but 



only recently has any plausible explana- 

 tion for this effect of cross-breeding been 

 given. Now, however, Mendel's experi- 

 ments and observations on heredity have 

 given at least a workable theory to ac- 

 count for this increase in size or vigor in 

 the first generation of descendants from 

 parents of diverse characteristics, and the 

 rapid disappearance or reversal of this 

 favorable effect in subsequent generations. 



Practical Suggestions for Seed Growing 



High-yielding mother plants should be 

 chosen two or three generations pre- 

 viously. This can easily be done, and 

 the strain kept pure, since tomatoes are 

 readily self-fertilized. These high-yield- 

 ing strains should be continued and new 

 crosses made as new seed is needed. The 

 crossing need not be done every year, 

 since tomato seed retains its vitality for 

 at least three years, so that enough 

 crossed seed could be secured in one sea- 

 son to grow the crop for three years to 

 follow. But the tomato grower who does 

 not regularly raise his own seed must buy 

 the crossed seed each year unless he 

 wishes to find his second-season crop run- 

 ning down in yield. The improvement in 

 yield is not inherent in the strain; it is 

 merely the result of the crossing. 



Too violent crossing must not be at- 

 tempted, else sterility will result, as in 

 the well-known case of the mule. In 

 crossing the tomato and Jerusalem cherry 

 total sterility resulted. 



The best results can probably be se- 

 cured by keeping within the species and 

 crossing the distinct varieties and the 

 distinct strains; and in selecting these, 

 regard must be paid to the inheritance of 

 such qualities as smoothness, color, shape, 

 size and earliness. To obtain smooth 

 fruits only varieties producing smooth, 

 even-surfaced fruits should be used, since 

 roughness appears in the first generation. 

 If (lark red tomatoes are desired, one of 

 the parents at least must be dark red; but 

 the other may be red, pink or yellow, since 

 the red is a stronger character than the 

 pink or yellow, and will hide them in the 

 first generation. If pink is desired the 

 red must be avoided and two pink varie- 



