Linkage between a panicle factor and the pearly-chalky mesocarp factor (Zz) in sorghum

Abstract

In the group of sorghum S.dochna (Forsk.) Snowden two types of panicles have been met with. In the loose-eonical type the panicle branches are long and the earhead is conical in appearance owing to their decreasing length from base to tip. In the compact-spindle type this conical disposition is also there, the cone being narrower; but the panicle branches are considerably shorter in length and due to the absence of the pulvinus-like structure in the axil of the panicle branches, they are adpressed to the central rachis giving the earhead a spindle-shaped look. In these spindle-shaped earheads, the rachis is slightly reduced in length, the number of side branches decreases and the number of fertile spikelets (grains) also decreases. The leaves also make a slightly narrower angle with the stem. A factor Pa1 produces loose conical earheads: factor pa1 results in compact spindle-shaped earheads. These factors Pa1 pa1 affecting the panicle shape are closely linked to the factors Zz governing the thickness of mesocarp and the deposit of starch in it, with a cross-over value of 1.07 per cent.