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Response of spiny cocklebur (Xanthium spinosum L.) and common cocklebur (X. strumarium L.) seed germination to environmental and soil factors

Amir Ahmadi, Faezeh Zaefarian , Mohammad Rezvani , Irandokht Mansouri, Brian Sindel

Abstract

Context. Seed germination and seedling emergence are affected by many environmental factors. Knowledge regarding factors affecting seed germination of spiny cocklebur (Xanthium spinosum L.), and common cocklebur (X. strumarium L.) could help to determine their potential distribution and control strategies. Aims. The present study was conducted in order to investigate the effect of key environmental factors on seed germination and seedling emergence of spiny cocklebur and common cocklebur. Methods. Seed germination of spiny cocklebur and common cocklebur was tested at various constant and alternating temperatures, pH, salinity and moisture stress. The effect of flooding height, burial depth, and soil type on seedling emergence was also investigated. Key results. The optimum constant temperature for germination of spiny cocklebur was 25 °C, and 35 °C and higher for common cocklebur. Under alternating temperatures, maximal germination was at 25/15 °C and 35/15 °C for spiny cocklebur and common cocklebur, respectively. Maximum germination of both spiny cocklebur and common cocklebur was at neutral pH. Spiny cocklebur germination was not suppressed as much by lower and higher pH or by increasing salinity as common cocklebur. Conclusions. Common cocklebur appears better adapted to warmer environments than spiny cocklebur, but less so to a broad range of soil pH and salinity stress. Implications. The differential germination responses of common cocklebur and spiny cocklebur to the environmental factors of temperature, pH and salinity implies that the two species may occupy different niches across the landscape. Our knowledge of these responses can help in identifying potential areas for invasion for increased monitoring and management.

BT23094  Accepted 22 April 2024

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