Resumo

RAMIREZ-SEANEZ, Ana Rosa et al. Cotton  biomass  production  as  affected  by  ultranarrow rows and population density. Agron. Mesoam [online]. 2012, vol.23, n.2, pp.259-267. ISSN 2215-3608.

The objective of this work was to study the performance  of cotton crops under ultra narrow row spacing in  comparison to the traditional planting system. Two production systems in rows spaced at 0.50 y 0.35 m (ultra narrow-rows) were evaluated in 2008 and 2009, with population densities of 90 000 and 110 000 plants/ha respectively, and rows spaced  at 0,75 m with a density of 70 000 plants/ha were used as a control. The seedcotton, lint-cotton yield and total dry matter were evaluated in both years. Crop growth rate (CGR), net assimilation rate (NAR), leaf area index (LAI), leaf area ratio (LAR), specific leaf area (SLA), and leaf weight ratio (LWR) we evaluated in 2009 only. For the estimation of these  indicators, three destructive sampling protocols were conducted at 59, 79 and 100 days after sowing (DAS). Two plants were collected per plot and were analyzed for total dry weight, total dry weight of vegetative and  reproductive organs and plant leaf area. For rows spaced at 0.35 m and a density of 110 000 plants/ ha the seed cotton yield was 16 and 43% higher than 0.50-90 000 and 0.75-70 000 plants/ha respectively. Row spacing and plant population density did not affect the relative foliar size according with the LAR, SLA and LWR estimates.

Palavras-chave : Gossypium hirsutum L.; dry matter; crop growth rate; net assimilation rate; leaf area index.

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