Document Type : Research Paper
Authors
1
Former M. Sc. Studetn, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran
2
Professor, Department of Agronomy & Plant Breeding, College of Agriculture, Ferdowsi University of Mashhad, Iran
3
Professor, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran
4
Ph. D. Candidate, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran
Abstract
In spite of the fact that Tribulus terrestrisis known as a spring weed but it has a significant input in the medicinal industries, so studying its different developmental stages of the plant will be useful for management of fields to produce it. In order to study the cardinal temperatures, a laboratory study was conducted to investigate the effect of different temperatures on seed germination of Tribulus terrestrisin a completely randomized design with three replications. Various constant temperatures (5, 10, 15, 20, 25, 30, 35 and 40ºC) were considered. The germinated seeds were counted everyday and the rate of germination and germination percentage, normal seedling and cardinal temperatures of Tribulus terrestriswere measured. Cardinal temperatures of seed germination were estimated by using three regression models including dent-like, segmented and beta models. The effects of temperatures on rate and percentage of germination and normal seedling were significant. The highest germination rates were detected at 30 ºC and the highest germination percentage and normal seedling were detected at 20 and 25 ºC. The best model for estimating cardinal temperatures was dent-like mode. The base temperature, optimal temperatures and ceiling temperature were, 8, 25, 30.8 and 37 °C, respectively.
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