Seedling emergence response to temperature in safflower: measurements and modeling

Document Type : Research Paper

Authors

1 Department of Agronomy and Plant Breeding, Agriculture College, Vali-e-Asr University of Rafsanjan, Iran.

2 Department of Agronomy and Plant Breeding, Agriculture College, Vali-e-Asr University of Rafsanjan, Iran

Abstract

Quantitative information about the response of seedling emergence to
temperature for safflower (Carthamus tinctorius L.) is rare. The main objective of
the present study was to develop a model for predicting days to emergence for
safflower as influenced by the temperature. In this regard, a field experiment with a
range of sowing dates and four safflower cultivars were conducted to describe the
response of seedling emergence to temperature and determine cardinal
temperatures and biological days required for emergence (number of days to
emergence under optimum temperatures). The segmented, dent-like and beta
functions were used to describe the response of seedling emergence to temperature.
Results showed that the segmented function described well the seedling emergence
response to temperature with the cardinal temperatures of 3.4, 22 and 35 °C for
base, optimum and ceiling temperatures, respectively. The biological days required
for seedling emergence was estimated 8.6 days. Based on the findings, a seedling
emergence model was conducted which can estimate time to 50% of emergence
under variable temperature conditions. Model evaluation by using the some
independent data showed that the model predicted time to 50% of emergence
accurately (RMSD=1.3 days and R2=0.92).

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