TEE AGRICULTURAL NEWS. 



Januauv 11, 1919. 



NOTES ON INHERITANCE IN THE 

 COWPEA. 



A^TH0*:YAN1^' COlA>LRATUlN OK STEM ASl) LEAK >I'ALK, AND 

 NEW EKA FATTEKX OK THE .SEKIJ COAT. 



As the oulooTiie of work carried on at the Experiment 

 Station, Sr. Vincent, by Mr. .". C. Harlaud, B.Sc, a con- 

 siderable body of information has been acquired respecting 

 the mode of inheritance of certain genetic factors in the 

 cowpea. Mr. Harland now furnishes the following notes, 

 with a desire to place on record a summary of such facts as 

 hare come to light, reserving a detailed presentation of the 

 complete results for a later date. A paper embodying the 

 results of his inveslig^itions relating to the inheritance of 

 colour and pattern of the seed coat, and of flower colour, has 

 been contribu'ed to the /i'UJ'//'i/ "J Gi'/iei/cs by him, and will 

 probably appear in the near future. 



In many varieties of cowpea, the region near the 

 junction of the main stem and petioles is dark red in colour, 

 owing to the presence of anthocyanin pigment in the epider- 

 mal cells. The same pigment is also found at the junction of 

 the petioles with the leaflets. In other varieties pigmenta- 

 tion is totally absent. In crosses between pigmented and 

 Tlnpigmenied kinds, the following results were obtained : — 



/<■, j(ene?'jiion. 



Pigmentation present. 



J".^ j^tnerafion. 



Five families were grown, and segregation occurred into 

 the parental types in the following proportions: — 

 Plants. Pigmented. T'npigmented. 



171 132 39 



Expectation 137"'5 42 7.5 



This ratio is close to the expected 3:1, characteristic of a 

 single genetic diflFerence. Several families were grown in Y .. 



/<., gcticratiou. 



Of fifteen families grown from F.^ pigmented plants, four 

 families threw pigmented only. There were ninety-one plants 

 in all. The rtmaining eleven families segregated into pig- 

 mented and nnpigmented, the results being: — 



Plants. Pigmented. I'npigmented. 



.369 276 9.3 



Expectation l.'7" 7.5 92l'5 



The ratio of pigmented to nnpigmented plants in segre- 

 gating F.. families is thus close to 3:1. 



From F., unpigmented jilants four families were grown 

 in F ,. .Ml bred true to the nnpigmented condition, the 

 number of plants being 140. 



Cone/iis!o>i. 



From these reaulis it may be concluded that thi' presence 

 of anthocyanin colouration in the stem and leaf stalk of the 

 cowpea is due to a single unit factor, dominant to its 

 absence. 



THE .NKW EUA I'AITKRN ">K TUB seed COAI'. 



The variety New Era is one of the best known varieties 

 of oowpea, being highly valued by the farmers of the Southern 

 Htate.t as a forage crop. Tbesewls are thickly and uniformly 

 dotted with a dark blue anth'iryaoin pigment, Ih" ground 



colour being a medium brown which deepens with age. In pre- 

 vious investigations I Spillnian (1911), llarland (1918)] it has 

 been noted that the Solid type of pattern, i.e. that characteriz- 

 ing the basal colour of New Kra, is due to two factors. One 

 of these is the Watson factor (W), and the other is the Hol- 

 stein factor (H). The factor H is responsible for the type 

 of pattern known as Holstein, while the factor W produces 

 another type of pattern known as Watson. The factor 

 Watson deepens the colour of the flower, changing it from 

 the type known as Pale to the type known as Dark. Thus, 

 it may be assumed that New Era contains both W and H. 

 Crosses have made between New Era and a variety known 

 as Para, which was originally obtained from Brazil. A short 

 description of the parental types is as follows : — 



Xi-w lira. Pattern, solid brown, thickly dotted with 

 blue anthocyanin pigment producing the charicteristic 

 New Kra pattern. Flower, of type known as Dark, i e. 

 standard and wings both purple. Anthocyanin pigment 

 present in stem and leaf stalk. The same pigment is 

 also found in the young pod, particularly at th<- tip, 

 in the calyx, and at the top of the flower stalk. 

 Para. Seed, pale cream, almost white Flower and also 

 the vegetative parts of the plant devoid of antho- 

 cyanin pigment. Types with no anthocyanin pig- 

 mentation whatevLT are conveniently termed 

 'albino ' 



/', X' '"'■''/■'""• 



The seed p'lssesses the characteristic N^ew Era patterni 

 but the dotting is not so intense. The distribution of antho- 

 cyanin C'.ilour in t'le vegetative parts is like that of New 

 Era, as is also the flower colour. 



F.^ generation. 



Owing to the attacks of insect pests it was not possible 

 to grow a large number of plants in the F.^, but sutficient 

 data were obtained to render fairly clear the genetic constitu- 

 tion of the parental types. Three types appeared: — 



1. The New Era type (including plants like the F, ). 



■J. .\ new type, different in several respects from New 

 Era. The seed coat pattern is brown solid colour, no dotting 

 being jiresent. .\nthocyanin is present in stem and leaf stalk, 

 but not in the young pod, calyx, or peduncle. The flower 

 colour i.s dark. 



3. The Albino type 



The numerical results ot the 



Era. 



Brown. 



are as follows:- 

 -Vlbinok 



ihese 

 were 



New 

 10 



In the V .. three fainilie.s were grown. One oi 

 Wis from an albino, and bred true. The other tw< 

 from F.^ pants of the New Era type, and both showt-d seg- 

 regation into New l'>a, Brown, and Albino. The nuiiierical 

 results of these two families areas follows: — 



New Kra. Brown. Albino. 



Family 114 6 10 



2 II 4 9 



Total 2-5 10 19 



( "ombining these results with those of F.^, it will b( .seen 

 that the ratio of N'ew Era:Hrown:Albino is very close to 

 9:.3;4, thus: — 



New Era. I'.rown. Albino. 



Found If) 12 24 



Expected 39 9 133 ]7 8 



These results mity be explained by assuming that 

 independently Jnherivad genetic differences are conctrnod 

 this cro'-s : — 



two 



