Quantification of Critical Temperature Thresholds and Thermal Time Required for Seedling Emergence of Spring Rapeseed

Research On Crop Ecophysiology

دوره 16، شماره 2، شهریور 2021، صفحه 100-108   

شناسه دیجیتال (DOI): 10.30486/roce.2021.707788

نویسندگان

MANDANA MIRBAKHSH¹؛ MEHDI HAYATI²؛ MOHAMMAD ROOZKHOSH³

¹Department Agronomy, Purdue University, West Lafayette, IN 47907, USA

²Department of Agronomy and Plant Breeding, College of Agriculture, Islamic Azad University, Ilam Branch, Ilam, Iran.

³Department of Agrotechnology, College of Agriculture, Ferdowsi University of Mashhad, Iran and Department of Crop Protection, Faculty of Agriculture, University of Jiroft, Iran

چکیده

Quantification of Critical Temperature Thresholds and Thermal Time Required for Seedling Emergence of Spring Rapeseed
 
 
Mandana Mirbakhsh ¹, Mehdi Hayati ², Mohammad Roozkhosh ³, Fakher Kardoni ^4*
1- Department Agronomy, Purdue University, West Lafayette, IN 47907, USA
2- Department of Agronomy and Plant Breeding, College of Agriculture, Islamic Azad University, Ilam Branch, Ilam, Iran.
3- Department of Agrotechnology, College of Agriculture, Ferdowsi University of Mashhad, Iran and Department of Crop Protection, Faculty of Agriculture, University of Jiroft, Iran
4- Department of Agronomy, College of Agriculture, Birjand University, Birjand, Iran.
 
 
*Corresponding Author: Email: [e-mail]
 
Received: 8 April 2021                                                                               Accepted: 10 June  2021
 
 
Abstract
 
Quantitative knowledge about temperature T effect on seedling emergence in spring rapeseed (Brassica napus L.) is rare. Therefore, the main purpose of the present study was to determine the critical T thresholds and thermal time required for seedling emergence of spring rapeseed. To do this, two field trials, each with 15 different planting dates, were performed to evaluate the seedling emergence responses of five spring rapeseed cultivars to a wide range of T environments. A Normal-based thermal time model was used to describe the relationship between time-to-emergence and T. In this model, a Normal distribution of both sub-optimal thermal time θ_T(e) and maximum temperature T_m(e) was assumed while base temperature T_b and supra-optimal thermal time  remained constant for all emergence fractions. The model correctly explained the emergence dynamics of various cultivars in response to T over sub- and supra-optimal ranges. The thermal thresholds for seedling emergence, T_b, sub-optimal thermal time to reach 50% emergence (θ_T(50)), maximum emergence T for induction of 50% thermoinhibition in seeds (T_m(50)), and  depended on the rapeseed cultivar studied. The values of T_b, θ_T(50), T_m(50) and  ranged from 3.90 to 5.94 °C, 71.44 to 76.67 °C d, 32.90 to 33.48 °C and 4.76 to 6.67 °C d, respectively. Within each cultivar, optimum T (T_o(e)) exhibited a slight variation among various emergence fractions. The value of T_o(50) varied between 30.96 and 31.22 °C, depending on the cultivar. The outputs obtained from this work may be readily used in crop simulation models.
 
 

کلیدواژه‌ها

Keywords: Emergence rate؛ Modeling؛ Normal distribution؛ Temperature response؛ Time to emergence

سایر فایل های مرتبط با مقاله

Fakher Kardoni .3..doc