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Parthenium avoids drought: understanding the morphological and physiological responses of the invasive herb Parthenium hysterophorus to progressive water stress
Environmental and Experimental Botany ( IF 5.7 ) Pub Date : 2020-03-01 , DOI: 10.1016/j.envexpbot.2019.103945
Blair W. Cowie , Marcus J. Byrne , Ed T.F. Witkowski , Lorraine W. Strathie , Jeremy M. Goodall , Nic Venter

Abstract Parthenium hysterophorus L. is a noxious annual invasive herb which threatens biodiversity, food security and human and animal health in various tropical and sub-tropical regions globally. Given that these regions, including South Africa, experience frequent drought events, it is important that the invasive potential of this weed be better understood in the context of water stress. This study aimed to assess the physiological and morphological responses of P. hysterophorus to water stress. To elicit these responses, juvenile and adult plants were progressively water stressed over a six-week period. Despite significant reductions in leaf water potential, relative leaf water content and stomatal conductance from severe soil water stress, plants maintained positive net photosynthesis, albeit at a severely reduced rate. Concomitantly, water-use efficiency of P. hysterophorus increased by more than 300 %. Morphologically, water-stressed plants exhibited reductions in leaf area and leaf number, with adults accelerating flower production when compared to well-watered plants. Linked to this, were alterations in biomass, with juveniles and adults reducing above-ground biomass by 75 % and 35 %, respectively. Overall, many of the physiological and morphological responses are indicative of a largely drought avoidance strategy, allowing P. hysterophorus to persist during periods of water-stress as leafy basal rosettes (juveniles) or as reproductive herbs (adults). This research yielded valuable insights into the underlying water relations of P. hysterophorus, and how these may relate to the potential spread, detriment and management of the weed in various sub-tropical environments.

中文翻译:

Parthenium 避免干旱:了解侵入性草本 Parthenium hysterophorus 对渐进式水分胁迫的形态和生理反应

摘要 Parthenium hysterophorus L. 是一种有害的一年生入侵草本植物,威胁着全球热带和亚热带地区的生物多样性、粮食安全以及人类和动物健康。鉴于包括南非在内的这些地区经常发生干旱事件,因此在缺水的背景下更好地了解这种杂草的入侵潜力非常重要。本研究旨在评估 P. hysterophorus 对水分胁迫的生理和形态反应。为了引起这些反应,在六周的时间里,幼苗和成年植物逐渐受到水分胁迫。尽管严重土壤水分胁迫导致叶水势、相对叶水含量和气孔导度显着降低,但植物仍保持正净光合作用,尽管速率严重降低。同时,P. hysterophorus 的水分利用效率提高了 300% 以上。在形态学上,与水分充足的植物相比,水分胁迫的植物表现出叶面积和叶数的减少,成年植物加速开花。与此相关的是生物量的改变,幼鱼和成鱼的地上生物量分别减少了 75% 和 35%。总体而言,许多生理和形态反应表明主要是避免干旱的策略,允许 P. hysterophorus 在水分胁迫期间作为叶状基底玫瑰花结(幼虫)或生殖草本植物(成虫)持续存在。这项研究为 P. hysterophorus 的潜在水关系提供了宝贵的见解,以及这些可能与各种亚热带环境中杂草的潜在传播、危害和管理之间的关系。
更新日期:2020-03-01
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