Impactos das mudanças climáticas na demanda hídrica e duração do ciclo do sorgo forrageiro e feijão-caupi no estado de Pernambuco (Impacts of climate change on water demand and duration forage sorghum and cowpea cycle in the state of Pernambuco)

O aumento na ocorrencia de eventos climaticos extremos nas ultimas decadas e uma forte evidencia das mudancas climaticas. Em regioes Semiaridas, onde a pressao de desertificacao tem se intensificado, sao esperadas diminuicao da disponibilidade de agua e maior ocorrencia de periodos seca, e, consequentemente, efeitos na resposta fisiologica das plantas. Assim, objetivou-se analisar os impactos dos cenarios de mudancas climaticas sobre a duracao do ciclo fenologico e a demanda de agua do sorgo forrageiro e do feijao-caupi cultivados no Estado de Pernambuco. Foram utilizados os valores mensais da normal climatologica brilho solar, temperatura do ar, umidade relativa do ar e velocidade do vento de dez municipios. Considerou-se um aumento de 1,8°C (Cenario B2) e 4,0°C (Cenario A1F1) na temperatura do ar e um decrescimo de 5,0% dos valores absolutos de umidade relativa do ar, alem do aumento de 22% na resistencia estomatica e de 4% no indice de area foliar. Com base nessas informacoes foram gerados tres cenarios: situacao atual e projecoes futuras para B2 e A1F1. Os resultados revelaram uma reducao media de 11% (B2) e 20% (A1F1), e de 10% (B2) e 17% (A1F1) na duracao do ciclo, e de 4% (B2) e 8% (A1F1), e 2% (B2) e 5% (A1F1) na demanda de agua acumulada para o sorgo forrageiro e feijao-caupi, respectivamente. Conclui-se que a magnitude das reducoes da duracao do ciclo e a demanda de agua simulada para as culturas do sorgo forrageiro e do feijao-caupi variaram espaco-temporalmente no Estado de Pernambuco com os cenarios de mudancas climaticas. 800x600 Normal 0 21 false false false PT-BR X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabela normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} The increase in the occurrence of extreme weather events in recent decades is a strong evidence of climate change. In semiarid regions, where the pressure of desertification has intensified, are expected to decrease in the availability of water and higher occurrence of drought periods, and, consequently, effects on physiological response of plants. Thus, the objective of analyzing the impacts of climate change scenarios on the duration of phenological cycle and water demand of forage sorghum and cowpea, grown in the State of Pernambuco. Monthly values were used normal climatological solar brightness, air temperature, relative humidity and wind speed of ten municipalities. It was considered an increase of 1.8° C (B2 Scenario) and 4.0° C (A1F1 Scenario) on air temperature and a decrease of 5.0% of the absolute values of relative humidity, in addition to the 22% increase in stomatal resistance and 4% in leaf area index. Based on this information were generated three scenarios: current situation and future projections for B2, A1F1. The results revealed an average reduction of 11% (B2) and 20% (A1F1), and 10% (B2) and 17% (A1F1) for the duration of the cycle, and 4% (B2) and 8% (A1F1), and 2% (B2) and 5% (A1F1) in accumulated water demand for forage sorghum and cowpea, respectively. It is concluded that the magnitude of the reductions in the duration of the cycle and the simulated water demand for crops of forage sorghum and cowpea ranged space-temporarily in the State of Pernambuco with climate change scenarios. Keywords: global heating, carbon dioxide, evapotranspiration, Sorghum bicolor (L.) Moench; Vigna unguiculata (L.) Walp.