Material segregating for a recessive barren-stalk was provided by C.R. Burnham. Expression in segregating progenies is variable for barren-stalk, most plants having neither an ear nor the characteristic "ear notch" in the culm, but occasional ears do develop and produce seed. The ear shanks are modified, having a lengthened internode between the node and the prophyll and a vertical, flattened shank that is often fused with the accompanying internode. The internode tends to curve into a distorted arc and often cracks horizontally. The tassels remain bundled vertically, the branches failing to drop to a horizontal position; the branches show elongated, spindly form reminiscent of broom corn sorghums; the pulvinus does not develop or does not expand, leaving the bundle of branches unspread. The symbol baf, barren-stalk-fastigiate, is assigned.

TB-9Sb uncovers this factor (listed as ba*-s in MNL 59:40), so it is distal to wx and w11. An F1 of sh bz wx/baf was testcrossed to sh bz wx, and recombinants were selected, self-pollinated and progeny tested for baf. Six + + wx individuals did not segregate for baf (the numbers of plants observed, however, were very small, totalling 30 plants for all six progenies; nonetheless this shows that recombination with bz is higher than with wx). Seven sh bz + individuals segregated for baf, and one did not (among 11 progeny). Two sh + + individuals both segregated for baf. Since baf is distal to wx, the order is clear: sh bz baf w11 wx. If the one sh bz + individual that did not segregate is correctly classified, it is the only crossover between baf and wx in this small experiment, suggesting that baf may be very close to w11.

Ed Coe and J.B. Beckett
 
 

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