RELATIONSHIP BETWEEN MAIZE GRAIN YIELD AND THE NORMALIZED PRECIPITATION INDEX IN AZUERO

Abstract

A study was carried out to determine the Standard Precipitation Index (SPI) of six localities of the Azuero Region to characterize the rainfall of the region and to relate the SPI to the historical yields of the Regional Test of maize from a locality (El Ejido). For this, was utilized the historical data provided by the Department of Hydrometeorology of the Electric Transmission Company SA. The SPI was calculated on three time scales with a short-term objective (5 months or SPI-5) and long-term (12 and 24 months or SPI-12 and SPI-24). The Standardized Precipitation Evapotranspiration Index (SPEI-12) was also calculated from La Villa locality and compared to the SPI of the same locality in the period 2003-2015. In order to estimate the relationship between SPI and maize crop grain yields, the SPI-5 of December was correlated with data from the Regional Maize Test planted at the El Ejido Experimental Station. The results of this work indicate that over time there has been variability, encouraging dry and wet periods in the six localities. It was also observed that the localities located to the North of the Region (Parita, La Villa and El Ejido) are drier and have undergone more intense and prolonged periods of drought in the last 15 years. A high relationship between the grain yield potential and the SPI-5 of the month of December was obtained with a value of Pearson correlation coefficient of 0,87. In conclusion, both SPI and SPEI characterized drought satisfactorily in the Region and its use is recommended for this purpose.