The Garden Magazine, September, 1921 



41 



on the market year after year and may also 

 have an appeal of interest to the experi- 

 mental home vegetable grower. As Tomato 

 seed remains fertile three to seven years, it 

 would not be necessary to make crosses 

 oftener than once in three years. The seeds- 

 man as well as the farmer can profitably 

 raise hybrid seed, provided a guarantee for 

 the quality and quantity of the crop is not 

 given for more than one generation; since 

 the grower will have to use original first gen- 

 eration hybrid seed every year. The vigor 

 secured in the first generation is reduced in 



iecd Variety 



]<* y ear 



the second and 

 same cross. 



later generations from the 



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 1 



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Definite Products 



THE best results of crossing can be ob- 

 tained by keeping within a species and 

 crossing the distinct varieties and the distinct 

 strains. To insure a desirable commercial 

 Tomato, the hybrid seed producer must keep 

 in mind the inheritance of such qualities as 

 smoothness, color, size, shape, and earliness. 

 For smooth fruits cross only varieties with 

 smooth and even surfaces, as roughness will 

 appear as a "dominant" character in the first 

 generation. (See article in this series in last month's Garden 

 Magazine). Plants that have shown a tendency to sterility 

 must be avoided as that factor may cause irregular development 

 of the shape. 



The inheritance of color in Tomatoes has been carefully 

 studied, and it is now known that the dark red is dominant to 

 the pink and the yellow, and that the pink is dominant to the 

 yellow color. Thus, to obtain a red fruit it is necessary to have 

 one parent red; to secure a pink fruit one parent must be pink, 

 the other may be pink or yellow, but not red; and to obtain a 

 yellow hybrid both parents must be yellow. 



Size is inherited as if blended into an intermediate condition. 

 Thus crossing large fruits results in large fruits; crossing small 

 fruits results in small ones; and crossing a large with a small 

 fruit will produce one slightly smaller than the larger parent. 

 The fruit of a hybrid from two large fruits is often larger than 

 either of the parents. 



Shape is inherited in much the same fashion as size, and the 

 same considerations need be given to this character. 



Earliness is somewhat increased by crossing; but a marked 

 increase in early maturity is noticed when crossing strains that 

 themselves are very early maturing. 



Facts of Increased Yield 



THE first generation hybrid of the two Cucumber varieties, 

 White Spine and London Long Green, exceeded the higher 

 yielding parent by 24 per cent., and that of Fordhook Famous 

 and White Spine exceeded the better parent by 39 per cent. 

 The character in which increased vigor in Cucumber crosses is 

 mostly evident is in the number of fruits per plant. All the 



fold crop 



from 



hybrid seed 



Z*£ year 



3d year 



THIS SHOWS HOW IT IS DONE WITH 

 CORN 



Diagram illustrating a method of producing 

 hybrid seed corn. By alternating the variety 

 detasseled each year and carrying over seed 

 of the pure variety for two years, no extra 

 seed plots are needed for keeping the pure 

 strains going. Crosses indicate detasseled 

 rows producing hybrid seed 



hybrids tested exceeded the more prolific 

 parent from 6 to 27 per cent. 



Plants of this family (which includes 

 Watermelons, Canteloupes, Squashes, and 

 Pumpkins) are monoecious — i.e. pistillate 

 and staminate flowers are separate but on 

 same plants — and produce a large number of 

 seeds per fruit. Although definite knowl- 

 edge of the heredity is available for only a 

 few of these there is reason to believe this 

 principle of hybrid vigor will be of value in 

 all of them. 



In Corn, which is a dioecious plant in prac- 

 tice^ — because the tassel (stamens) and silk 

 (pistils) on the same plant ripen at different 

 times — and wind pollinated, the method 

 employed to secure hybrid seed is very simple 

 and easy. The two varieties to be crossed 

 are planted in alternate rows, and all the 

 tassels of one variety are removed. This 

 requires going over the rows about three 

 times at intervals of several days in order 

 to detassel all the plants. The silks on 

 the detasseled plants will receive pollen 

 from the variety not detasseled and the 

 resulting Corn will be hybrid. Seed for the 

 next year's crop could be selected from these 

 detasseled rows. As the corn on the rows not detasseled will 

 be pure for that variety, enough should be collected for planting 

 the crossing plot for the next two seasons. By holding over 

 enough of the pure variety for planting the second year, and by 

 alternating each year the variety to be detasseled no extra plot 

 of the pure strains need be grown at all. 



Fifty first generation hybrids have been tested by Dr. D. F. 

 Jones who found that 88 per cent, yielded more than the average 

 of their parents and that high yielding parents produced high 

 yielding hybrids. Naturally, crossing of different colors of corn 

 is to be avoided, as the corn ears produced on the first gen- 

 eration hybrid plants would contain a mixture of the colors of 

 the parents. 



HETEROSIS is no longer a hazard as a commercial asset. 

 Experiments have demonstrated beyond peradventure 

 that the grower who puts it into practice will be amply re- 

 warded. Nor is it being neglected by commercial seed com- 

 panies. In the spring of this year Dr. H.J. Webber, a leading 

 man in plant breeding work for 30 years, first as plant breeder 

 for the U. S. Department of Agriculture, then professor of 

 plant breeding at Cornell University, and but recently Director 

 of the Agricultural Experiment Station of the University of 

 California, left that institution to become the director of a 

 new department for the production of tested hybrid seeds of a 

 commercial concern at Hartford, North Carolina. It would seem 

 that it will be but a short time before other seed companies will 

 establish similar departments for the production of hybrid seed 

 for market and garden and field with the certain result that the 

 crops of the country will reflect a greater annual production. 





