Simulação da produtividade de tubérculos de batata em cenários de mudança climática

Abstract

Potato (Solanum tuberosum L.), Solanaceae, is ranked fourth in food amount production, exceeded only by wheat, rice and corn. Brazil has potential in climate and soil for growing potatoes, but with a growing concern of society with possible changes in global and regional climate because of anthropogenic increase in greenhouse gases, this crop may be affected in the future. This study had the following objectives: to calibrate for Santa Maria and evaluate simulation models of potato tuber yield for Santa Maria (subtropical climate and São Joaquim (temperate climate), and evaluate the potato tuber yield in scenarios with increasing concentration of carbon dioxide and temperature in Santa Maria, RS, in different sowing dates, considering symmetric and asymmetric increase in minimum and maximum daily air temperature. We evaluated six simulation models of potato tuber yield and the statistics used to evaluate the performance of the models was the root mean square error (RQME). In order to evaluate the effect of climate change on potato tuber yield, one of the six evaluated models (SPITTERS, 1987) was used. Seven climate scenarios (0ºC, 1ºC, 2ºC, 3ºC, 4ºC, 5ºC to 6ºC) for the next 100 years were generated with the Weather Generator LARS-WG using as base series observed meteorological data from 1969 to 2003 in Santa Maria, RS. Potato tuber yield was simulated throughout the 100-year period of each climate scenario in several planting dates for the Spring and Fall growing seasons. Models with the original coefficients showed similar performance in the simulation of tuber yield in Santa Maria and São Joaquin. The models of Hartz; Moore, Johnson, and Pereira simulated better the potato tuber yield. After calibration, the Sands. model was the one that best predicted the potato tuber yield, followed by the models of Pereira and MacKerron; Waister. For the Spring growing season, a symmetrical increase in temperature of 4ºC and an asymmetrical increase of 5ºC offset the beneficial effect of increasing concentration of carbon dioxide. For the Fall growing season, the increase in temperature affected little the potato tuber yield. An anticipation of 14 days in the emergence date in the Spring growing season and a delay of seven days in emergence date in the Fall growing season decrease the negative impact of increased air temperature on the tuber yield of potato grown in Santa Maria, RS.