2025-07-032025-07-032022-02-25https://repositorio.ifal.edu.br/handle/123456789/1019The study about the sorghum is of important relevance for farmers and ranchers, because it has great rusticity and is among the most cultivated cereals in the world, being widely used for animal feed in the form of silage, pasture and/or grains. Knowing which the cultivar and planting density in relation to the accumulated degree days allows the producer to carry out sowing at the most suitable times and with greater chances of obtaining high yields. Therefore, the objective of the present work was to determine the growth and accumulated degree days of sorghum cultivars under two planting densities in rainfed cultivation in Alto Sertão de Alagoas. The experiment was carried out in the rainy season of 2019 in the experimental field of the Instituto Federal de Alagoas, Campus Piranhas, under a randomized block, with installments subdivided in time, with four replications. The treatments referred to the combination of three forage sorghum cultivars (IPA 467, BRS Ponta Negra and Chopper) and one grain (IPA 1011), with two planting densities: 187.5 thousand plants ha-1 and 250 thousand plants ha-1 . The subplots were constituted by the accumulated degree days (AG) according to the days after planting (DAP), which were added to 39 DAP (568.86 °C), 53 DAP (762.53 °C), 66 DAP (941.56°C) and 81 DAP (1,158.27°C). The characteristics evaluated were: plant height, stem diameter and number of leaves per plant. The sorghum cultivars and planting densities showed similar plant heights, except for the Chopper cultivar, which obtained lower values in the two densities, with a statistical difference at 53 DAP (762.53 °C), 66 DAP (941.56 °C) and 81 DAP (1,158.27 °C), presenting a final average in the last evaluation of 73.20 cm and 80.86 cm, for the densities of 250 thousand plants ha-1 and 187.5 thousand plants ha-1 , respectively. The stem diameter had no significant difference at 39 DAP (568.86 °C) and 66 DAP (941.56 °C), however, at 81 DAP (1,158.27 °C), the cultivar IPA 467 at density of 250 thousand plants ha-1 had a diameter of 16.10 mm, surpassing IPA 1011 in the density of 250 thousand plants ha-1 (12.25 mm). For the number of leaves per plant, there was no statistical difference for the treatments when the GDA were 568.86 °C and 762.53 °C, but, in the last two evaluations at 66 DAP and 81 DAP there was a variation in the number of leaves , with the lowest average in the IPA 467 in the density of 250 thousand plants ha-1 (2.70 leaves per plant), when the GDA were of 1,158.27 °C, not differing statistically from the IPA 467 x 187.5 thousand plants ha-1 ( 3.05 leaves per plant), BRS Ponta Negra x 250 thousand plants ha-1 (4.22 leaves per plant) and IPA 1011 x 250 thousand plants ha-1 (3.80 leaves per plant). The sorghum cultivars and plant densities had the same growth behavior, obtaining a constant increase and subsequent decrease or stabilization. Between 66 DAP (941.56 °C) and 81 DAP (1,158.27 °C), there was a tendency for the number of leaves and stem diameter to decrease. Plant height had an initial constant increase, with subsequent stabilization when the GDA ranged from 941.56 °C (66 DAP) to 11158.27 °C (81 DAP).ptSorghum bicolarAgrometeorologiaEspaçamentoSequeiroAgrometeorology.SpacingDrylandTrabalho de Conclusão de CursoCIENCIAS AGRARIAS