Document Type : Research Paper
Authors
Department of Plant Production and Genetics, Faculty of Agriculture, Agricultural Sciences and Natural Resources University of Khuzestan, Bavi, Mollasani, Khuzestan, Iran
Abstract
An experiment with 10 constant temperatures (5, 10, 15, 20, 25, 30, 35, 40, and 45°C), was conducted in 2019 at the Agricultural Sciences and Natural Resources University of Khuzestan based on completely randomized design (CRD) with 8 replications to investigate germination and determine the cardinal temperature of Physorhynchus chamaerapistrum (Boiss.) Boiss. The highest seed germination was 86% at 25°C. Germination percentages at temperatures of 10, 15, 20, 30, 35, and 40°C were 77%, 83%, 85%, 85%, 34%, and 13%, respectively. No germination was observed at 5 and 45°C. The relationship between imbibition time and cumulative germination percentage was described by a three-parameter sigmoid equation. According to this equation, the results indicated that the shortest time required to reach 50% germination (T50) was observed at 25 and 30°C (33 and 34 hours), and the longest at 10 and 40°C (106 and 141 hours). T50 for temperatures of 15, 20, and 35°C was predicted to be 76, 37, and 51 hours, respectively. According to the dent-like model, the base temperature, lower optimal temperature, upper optimal temperature, and ceiling temperature were predicted to be 16.5, 22.91, 29.52, and 43.45°C, respectively. The results of this study showed that this plant could have the highest germination percentage from November to January, considering the growth conditions. Therefore, during these months, plans for managing this rangeland plant (seed dispersal and rangeland restoration) and issues related to grazing management should be considered.
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