Plant density and leaf morphology affects yield, fiber quality, and nutrition of cotton/Densidade de plantas e morfologia foliar afetam a produtividade, qualidade e nutricao do algodoeiro

HIGHLIGHTS: High plant density does not improve cotton yield. The highest yield is obtained with the conventional leaf cultivar, regardless of plant density. Fiber strength and length are higher in conventional leaf cultivar. In sandy soils with frequent drought events, the choice of cultivar and plant density is crucial to improve water use eficiency and avoid losses in cotton yield and fiber quality. Tis study aimed to evaluate cotton cultivars' yield and fiber quality at different plant densities. Te study was carried out during two growing seasons (2017/2018 and 2018/2019) on sandy soil in southeastern Brazil. Te cultivar TMG 47B2RF showed 27 and 29% higher yields under low and medium plant density, respectively, when compared with the highest plant density. Te higher yield was due to the higher number of bolls in relation to the cultivar DBB 509B2RF. Te boll weight of cultivar DBB 509B2RF was 23 and 22% higher under low and medium plant density, respectively. Fiber length and strength were higher in TMG 47B2RF compared to DBB 509B2RF. The leaf nutrient content was higher in DBB 509B2RF, except for Ca and Mg. When there is a regular rainfall, the low plant density results in higher yields, but intermediate plant density is the best option in cropping seasons with severe drought. Te high density of plants in sandy soil environments was never a better option for none of the cultivars. Key words: leaf morphology, cultivars, plant nutrition, fiber strength Em solos arenosos com secas frequentes, a escolha da cultivar e densidade de plantas e fundamental para melhorar a eficiencia do uso da agua e evitar perdas na produtividade e qualidade da fibra do algodao. Objetivou-se avaliar a produtividade e a qualidade da fibra de cultivares de algodao em diferentes densidades de plantas. O estudo foi realizado em duas safras (2017/2018 e 2018/2019) em solo arenoso no sudeste do Brasil. A cultivar TMG 47B2RF teve produtividade 27 e 29% maiores sob baixa e media densidade de plantas, respectivamente, em comparacao com a maior densidade de plantas. A maior produtividade deveu-se ao maior numero de capulhos em relacao a cultivar DBB 509B2RF. O peso dos capulhos da cultivar DBB 509B2RF foi 23 e 22% maior em baixa e media densidade, respectivamente. O comprimento e a resistencia da fibra foram maiores com a cultivar TMG 47B2RF comparado com a cultivar DBB 509B2RF. O teor de nutrientes nas folhas foi maior no DBB 509B2RF, exceto Ca e Mg. Quando ha chuvas regulares, a baix