Physiological responses of two tropical weeds to shade: II. Leaf gas exchange and nitrogen content

Resumo

Ipomoea asarifolia (Desr.) Roem. & Schultz (Convolvulaceae) and Stachytarpheta cayennensis (Rich) Vahl. (Verbenaceae), two weeds found in pastures and crop areas in the Brazilian Amazonia, Brazil, were grown in controlled environment cabinets under high (800-1000 µmol m-² s-¹) and low (200-350 µmol m-² s-¹) light regimes during a 40-day period. The objective was to determine the effect of shade on photosynthetic features and leaf nitrogen content of I. asarifolia and S. cayennensis. High-irradiance grown I. asarifolia leaves had significantly higher dark respiration and light saturated rates of photosynthesis than low-irradiance leaves. No significant differences for these traits, between treatments, were observed in S. cayennensis. Low-irradiance leaves of both species displayed higher CO2 assimilation rates under low irradiance. High-irradiance grown leaves of both species had less nitrogen per unit of weight. Low-irradiance S. cayennensis had more nitrogen per unit of leaf area than high-irradiance plants; however, I. asarifolia showed no consistent pattern for this variable through time. For S. cayennensis, leaf nitrogen content and CO2 assimilation were inversely correlated to the amount of biomass allocated to developing reproductive structures. These results are discussed in relation to their ecological and weed management implications.

Resumo conforme Crossref.

Palavras-chave

• Ipomoea asarifolia
• Stachytarpheta cayennensis
• shade tolerance
• light irradiance
• leaf gas exchange
• photosynthesis
• dark respiration
• carbon assimilation
• leaf nitrogen content
• reproductive investment
• weed control
• tropical weeds

Termos atribuídos por OpenAlex.

Fontes bibliográficas

Esta publicação está registrada em 3 fontes de metadados.

• CrossrefDOI 10.1590/s0100-204x1999000600005 · ISSN 0100-204XAbrir registro em Crossref (nova aba)
• Currículo LattesISSN 0100204XAbrir registro em Currículo Lattes (nova aba)
• OpenAlexW2146633849 · DOI 10.1590/s0100-204x1999000600005 · ISSN 0100-204X · ISSN 1678-3921Abrir registro em OpenAlex (nova aba)