BREEDING OF VEGETABLES 251 



vegetables (Malte and Macoun, 1915). This fact may be utilized 

 in making planting plans. 



CULTIVATED VEGETABLES OF THE GENUS BRASSICA 



Cabbage and several other vegetables such as cauliflower, 

 brussels sprouts, kohl-rabi, and rutabagas, belong to the genus 

 Brassica. Few inheritance studies have been made with this 

 group of vegetables. Cabbage has received more attention from 

 a breeding standpoint than the others. 



Inheritance. The evidence so far accumulated indicates 

 that cabbage belongs to the cross-fertilization obligatory group. 

 Price (1911-1912) and Jones and Oilman (1915) were not 

 able to produce self-fertilized seed under a bag. Tschermak 

 (1916) maintains that many of the kinds of vegetables belonging 

 to the cabbage group freely intercross when in close proximity 

 at blooming time. The above facts are fundamental and show 

 the method of breeding which must be used. They may also aid 

 in explaining some unusual inheritance results. 



Price crossed varieties of crinkled-leaf and smooth-leaf cabbage, 

 obtaining dominance for crinkled leaf in FI with no segregation 

 of this character in F 2 ,i.e., all plants (419) had crinkled leaves. 

 With respect to size, shape, and solidity of heads, color of foliage, 

 and length and thickness of stem, considerable more variability 

 was obtained in F 2 than in FI. In a cross between a crinkled- 

 leaf cabbage and a cauliflower, the thick, leathery leaf of the 

 latter was dominant in FI and was the only apparent leaf char- 

 acteristic in P 2 . Head cabbage crossed with headless produced 

 nothing but headed forms both in the FI and F 2 generations. 

 As to type of head, the cabbage or leafy form was found to be 

 dominant over the type of head of the cauliflower. In F 2 the 

 cabbage head form was maintained without apparent segrega- 

 tion. Crosses between cabbage and brussels sprouts gave FI 

 and F 2 generations identical with respect to habit of growth, i.e., 

 all were determinate. Axillary buds were more common in the 

 hybrids than in ordinary cabbage. The thick stem of kohl- 

 rabi was found to be dominant in a kohl-rabi-cabbage cross 

 and a limited number of F 2 individuals showed no segregation 

 of this character. 



Button (1908) crossed reciprocally kohl-rabi and Drumhead 

 cabbage, obtaining, in F^ 3 non-kohl-rabi plants to 1 resembling 



