In MNL 59:40, observations were reported on browning of silks at the tips, 5-10 minutes after they are cut. Red-cob, P-WR lines show silk browning, while most white-cob, P-WW lines do not--i.e., the cut silks remain green. We have conducted tests to determine the relationship of determinants for browning silks in white-cob lines to the P locus. Whitecob inbred lines were crossed to a hybrid between W23 and K55, P-WR/P-WW W23 is red-cob browning (WRB), while K55 is white-cob green (WWW). The F1 plants were selfed, and F2s from red-cob and white-cob F1 plants were grown from each line for classification of silk browning and cob color.

White-cob green (WWW) inbreds segregated, from F1s with red cobs, approximately 3 red-cob browning to 1 white-cob green in F2 (3 WRB:1 WWW). From the F1s with white cobs, all F2s were white-cob green (WWW). The WWW inbreds we have tested are A619, C166, FR29, FR35, FR802W, FR805W, FR806W, FR807W, FR808W, FR809W, FR810W, K41, K61, K63, K150, K155, K302, K306, K814, K816, Mo15W and Mo16W,

White-cob browning (WWB) inbreds segregated, from F1s with red cobs, about 3 red-cob browning to 1 white-cob browning (3 WRB:1 WWB). From the F1s with white cobs, segregation was around 3 white-cob browning to 1 white-cob green (3 WWB:1 WWW). The WWB inbreds we have tested are K44, K166, Ky228, Mo1W and Mo14W. Results with one additional inbred were ambiguous and need to be tested further.

Evidently browning of silks in white-cob inbred lines is due to particular alleles, P-WWB, in contrast to the red-cob browning (P-WRB) and white-cob green (P-WWW). The evidence does not favor a silk-browning factor separate from P in WWB lines, nor a green-silk factor separate from P in WWW lines.

E. H. Coe and Chang-deok Han
 
 

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