Temperaturas cardinais para a fase plantio-emergência de gladíolo

Abstract

The objective of this study was to determine the cardinal temperatures for planting-emergence phase of gladiolus corms. The experiment was conducted in a controlled environment in a growth chamber with temperature and humidity control. The experimental design was completely randomized with the treatments consisting of 12 thermal levels (5°C, 7°C, 10°C, 13°C, 16°C, 18°C, 20°C, 22°C, 25°C, 30°C, 33°C, 35°C), with ten replicates. The cultivar used was Amsterdam, with the planting of corms performed at 10 cm depth. After planting, was observed daily the date of gladiolus plants emergency. The emergence rate for each treatment was calculated as the inverse of the duration of the sprouting phase, with the estimated data obtained by a nonlinear simulation model proposed by Wang & Engel, called WE. When the function presented zero as response, it was defined as lower base temperature and higher base temperature. To determine the optimum temperature, was used the root mean square error (RMSE). In the temperature range of 22ºC to 25ºC planting-emergence phase is completed in a shorter time, but the smallest RMSE was obtained at 22.5ºC temperature where the relationship between the estimated and observed data are closer. The cardinal temperatures for planting-emergence phase of gladiolus are defined as lower base temperature of 5°C, optimum temperature of 22.5°C and higher base temperature of 35°C.