Photosynthesis and biomass accumulation in young sugarcane plants grown under increasing ammonium supply in nutrient solution

Autor(es)

Pissolato, Maria D. ^[1] ; Silveira, Neidiquele M. ^[2] ; Machado, Eduardo C. ^[2] ; Zambrosi, Fernando C. B. ^[3] ; Sodek, Ladaslav ^[1] ; Ribeiro, V, Rafael

Afiliação do(s) autor(es)

^[1] V, Univ Campinas UNICAMP, Inst Biol, Dept Plant Biol, POB 6109, BR-13083970 Campinas, SP - Brazil

^[2] Agron Inst IAC, Lab Plant Physiol Coaracy M Franco, Ctr Res & Dev Ecophysiol & Biophys, POB 28, BR-13012970 Campinas, SP - Brazil

^[3] Agron Inst IAC, Ctr Res & Dev Soils & Environm Resources, POB 28, BR-13012970 Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: THEORETICAL AND EXPERIMENTAL PLANT PHYSIOLOGY; v. 31, n. 3, p. 401-411, SEP 2019.
• Citações Web of Science: 0

Resumo

The aim of this study was to evaluate the sugarcane responses to varying ammonium:nitrate (NH4+:NO3-) ratio and to reveal how much NH4+ plants can tolerate before showing impairment of photosynthesis and growth. Sugarcane plants were grown in nutrient solution with the following NH4+:NO3- ratios (%): 20:80; 30:70; 40:60; 60:40; 70:30; and 80:20. The lowest photosynthetic rates, stomatal conductance, instantaneous carboxylation efficiency and leaf chlorophyll a content were found in plants supplied with higher than 60% NH4+. The leaf content of chlorophyll b proved to be more sensitive than chlorophyll a and decreases were found from 40% NH4+. We did not observe significant differences in leaf NO3- concentration under varying NH4+:NO3- ratio. However, plants that received 80% NH4+ showed the highest leaf NH4+ concentration and lowest leaf {[}NO3-]:{[}NH4+] ratio. The estimated leaf nitrogen content was higher in plants supplied with 20% and 30% NH4+. Taken together, our data revealed that sugarcane plants are sensitive to NH4+, with photosynthesis and plant growth being impaired when NH4+ supply was higher than 30% in nutrient solution. Root biomass was significantly reduced under high NH4+ supply, which explains decreases in stomatal conductance. Besides stomatal limitation, photosynthesis was also limited by low carboxylation efficiency under high NH4+ supply. Apparently, leaf NH4+ concentrations higher than 1.0 mu mol g(-1) were enough to impair photosynthesis. The balance between {[}NO3-] and {[}NH4+] in leaves was more correlated to photosynthesis than either {[}NO3-] or {[}NH4+] alone. (AU)

• Processo FAPESP: 17/11279-7 - Amenizando os efeitos do déficit hídrico em cana-de-açúcar com a nutrição nitrogenada
• Beneficiário: Maria Dolores Pissolato
• Modalidade de apoio: Bolsas no Brasil - Mestrado