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This article in CS

  1. Vol. 22 No. 2, p. 310-314
    Received: Apr 28, 1981

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Duration of Developmental Stages of 10 Milo Maturity Genotypes1

  1. M. E. Sorrells and
  2. Oval Myers2



Duration of the vegetative, panicle development, and seed-filling stages of 10 milo sorghum [Sorghum bicolor (L.) Moench] maturity genotypes was studied at Santa Maria, Rio Grande do Sul, Brazil (30° S Lat), Carbondale, IL (37.5° N Lat), and Madison, WI (43° N Lat). Eight of the geneotypes represented the homozygous combinations of dominant and recessive alleles at maturity loci Mal, Ma2, and Ma3. Two additional genotypes had a third allele (ma3R) from ‘Ryer’ milo. A factorial analysis of variance for the eight homozygous combinations indicated that the number of days to floral initiation was significantly affected by the location × maturity-loci interaction. Most of this interaction variance was accounted for by locations × Mal × Ma2, and a location × Ma2 × Ma3 interaction was significant only at Santa Maria.

The photoperiod at all locations was longer than the 12 hours required to cause the maturity loci to initiate floral meristems at different times. Variation in days to floral initiation among locations for the eight maturity genotypes was not consistent with changes in photoperiod. Time to floral initiation of the daylength-sensitive genotypes 90M and 100M correlated well with the average minimum temperature or the average daily temperature while for the insensitive genotypes, days to floral initiation correlated best with the day/night difference in temperature. The two genotypes with the ma3R allele from Ryer reacted to changes in location as expected for a quantitative short-day plant, i.e., floral initiation was successively delayed under longer photoperiods. Thus, the time to floral initiation of the maturity genotypes was affected by a photoperiod-temperature interaction.

There were differences among genotypes in the length of the panicle development period and in the seed-filling period suggesting that the maturity loci also affect the duration of these stages.

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