Determination of the Cardinal Temperatures of Cashew Tree Using a Nonlinear Development Model

Abstract The aim of this study was to determine the cardinal temperatures of three cashew tree clones using a nonlinear development model for estimate the phenological stage of ripening of their fruits. Between August 2010 and August 2012, up to ten young fruits per clone were identified weekly, accompanying them until they ripened. Fruit development rate was obtained with the Wang and Engel model, using three approximations of the air temperature of Santo Antônio de Leverger / MT (15° 51’ S and 56°04’ W, 140 m). Fruits marked from May to July required a greater time, nearly 44 days to reach maturity due to lower air temperature values during this period, with a compensated average of 23 °C. However, fruits marked between August and October, the period with the largest average compensated air, of approximately 26.6 °C required a shorter time, 37 days. Cardinal temperatures ranged from 14.0 to 17 °C, 27.5 to 32.5 °C and 33.0 to 41.5 °C for the minimum, optimal and maximum base temperatures, respectively.