Gilmara Moreira de Oliveira

Onion Seedlings Emergence and Initial Growth Under Increased Temperature and CO2

Climate change, especially atmosphere temperature and concentration of greenhouse gases increase, will affect plant growth and development . The aim of this study was to evaluate the effect of increased temperature and CO2 concentration in emergence of seedlings of onion cultivars Alfa San Francisco, Franciscan IPA 10, Valley IPA 11 Gold and Serena. The experiment was conducted in growth chambers with humidity, light, temperature and CO2 control during 12 days. The experimental design was completely randomized in a 4x4x2 factorial scheme, with four onion cultivars , four temperatures (25 °C; 28 °C, 31 °C and 34 °C and two concentrations of CO2 (380 to 770 ppm), with four replications and 36 seeds per treatment. Seeds of onion cultivars Alfa São Francisco, Franciscana IPA 10, Vale Ouro IPA 11 and Serena were sown in plastic trays with 36 cells containing commercial substrate and placed in different CO2 concentrations and temperature. Emergence percentage, average time of emergence, emergence speed, emergence speed index, shoot length and root length was evaluated. The data were submitted to variance analysis and the averages compared by Scott Knott test at 5% probability. The CO2 concentrations and different temperatures produced different effects among cultivars for most of the variables. The increase of CO2 and temperature influence the emergence onion seedlings process. Key-words: climate change, impacts, agriculture Revista Brasileira de Geografia Física v.08, número especial IV SMUD (2015) 471-483. Costa; D. C. C. da.; Pinheiro; G. de S.; Oliveira; G. M. de.; Santos; A. T. N. dos.; Santana; C. V. da S.; Angelotti; F..; Dantas, B. F.