Plant density and geometry in relation to varietal differences and seasonal variations in rainfall for increasing and stabilizing production levels of winter sorghum in drylands

In field trials in 1971-5 winter-grown sorghum cv. CSH 3 and M 35-1 were sown at 36 000-180 000 plants/ha in a Bleasdale semi-circular pattern, single rows 45-95 cm apart or in paired rows 60-100 or 20-40 cm apart. Opt. plant population was low when moisture was limited in 1972-3 when a population density of 36 000 plants/ha gave the highest grain yields. In dry yr, CSH 3 gave higher yields and late types failed. At favourable moisture levels cv. CSV 7R responded to higher plant densities than M 35-1. Plant density rather than plant rectangularity tended to be more critical for successful grain production. When post-sowing rains failed, thinning of plants at the age of 30-35 days proved beneficial