Grain quality traits were analyzed in a diverse sorghum sample set which consisted of 174 sorghum lines (110 non-tannin lines and 64 tannin lines). These samples were previously grouped into five distinct genetic populations which made it possible to compare grain quality traits across the genetic groups. For the non-tannin samples, in-vitro protein digestibility (IPVD) was highest in the zerazera-caudatum (60.3%) and caudatum (60.1%) groups, though there was wide variability across all the groups. However, nine of the 20 lines with the highest IPVD were from the caudatum group (with the highest line ~80%). Within the non-tannin samples total phenolics were similar across genetic groups though average ORAC values varied. The durra genetic group had the highest ORAC (61.4 µM Trolox equivalents (TE) /g) with the guinea-caudatum having the lowest (46.0 µM TE/g). Starch granule size distribution also varied across the non-tannin genetic groups with the guinea-caudatum group having the highest proportion of A-granules (53.9%) and the caudatum group the lowest (45.9%). Within the tannin samples, IVPD varied from 37.5% (kafir group) to 55.5% (zerazera-caudatum) and tannin content highest in the durra group (14.1 g catechin equivalents (CE)/kg) and lowest in the zerazera-caudatum group (4.49g CE/kg). Interestingly, ORAC values were highest in the kafir group (118.4 µM TE/g) with the lowest in the zerazera-caudatum (70.4 µM TE/g). Tannin content and ORAC value were only loosely correlated (r=0.55) suggesting that tannin chemistry, not just content, is important in governing anti-oxidant capacity in tannin sorghum lines. The variation of grain quality traits across genetic groups provides information needed to identify sources of new genetic material for improving the end-use quality of sorghum.

Grain quality traits in a sorghum association mapping panel

249th National Meeting (2015)

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