Agro-climatic zoning for citriculture in the Agreste region of Pernambuco State, Brazil

The objective of this study was to accomplish an agro-climatic zoning for the Agreste region of Pernambuco State, Brazil, with the aim to identify agro-climatic zones for citrus cultivation. Monthly climatic data of 100 stations from over 20-year observation series (1911 to 1990) were selected within and close to the study area. From climatic data of mean air temperature and rainfall, we calculated the climatic water balances using available water capacity (AWC) of 50 and 100 mm. From data of both potential and estimated actual evapotranspiration, agro-climatic zones were established in agreement with the Water Requirement Satisfaction Index (WRSI). According to our study, the annual temperature variation in the Agreste mesoregion of Pernambuco State, with minimum temperature of 16.4°C and maximum of 33.4°C, is not a limiting factor for citrus production. Fifty municipalities in the region are located in the favorable agro-climatic zone for citrus cultivation, what represents an area of 12,000 km2 yet to be explored since less than 0.5% of it is being cultivated. Other 16 municipalities are located in the intermediate zone, with moderate risk, while five of them are in the adverse zone, presenting high climatic risk and water deficit.   Key words: Citrus production, temperature, water balance, orange, tropical region.