No escape? Costs and benefits of leaf de-submergence in the pasture grass Chloris gayana under different flooding regimes

Abstract

Elongation-induced leaf emergence is one way for plants to deal with complete submergence by ‘escaping’ from water. This growth strategy is hypothesised to be more beneficial under single long-term submergence than under repeated short-term submergence events (i.e. fluctuating environment), as costs of repeated plant ‘adjustment’ would exceed the initial benefits of shoot elongation. To test this idea, 2-week-old plants of Chloris gayana Kunth. cv. Fine Cut (a submergence-tolerant cultivar first selected by a screening experiment) were grown for 4 weeks under (i) control conditions, (ii) two 1-week submergence cycles, or (iii) one 2-week submergence cycle. Additionally, a set of plants were placed below nettings to assess the cost of remaining forcedly submerged. Impeding leaves emergence through nettings did not compromise survival when submergence was 1-week long, but determined the death of all plants when extended to 2 weeks. Growth as affected by flooding regime revealed that under one 2-week submergence event, plants accumulated a 2.9-fold higher dry mass than when they experienced the same submergence duration in separate events along 1week. The ‘escape’ strategy in the grass C. gayana, by which leaf contact with air is re-established, is essential for its survival, and it is more beneficial for plant growth under long-term submergence than under repeated short-term submergence cycles.

The hypoxia–reoxygenation stress in plants

“…The regulation of hydraulic conductivity in roots seems to be exerted by a protein kinase that links O 2 and potassium sensing in soils, thus modulating tolerance to hypoxia ( Shahzad et al , 2016 ). The potential reduction in hydraulic conductivity during post-submergence remains to be demonstrated in different plants but it certainly would lead to dehydration and leaf wilting in shoots ( Striker et al , 2017 ; Yeung et al , 2018 ), symptoms that are likely to be due to the inability to efficiently close the stomata ( Postiglione and Muday, 2020 ). Although stomata closure can prevent water loss by transpiration, it also limits carbon dioxide uptake and thus photosynthesis, so this process should be tightly regulated during the post-hypoxia recovery ( Fig.…”

Eco-Physiological Traits Related to Recovery from Complete Submergence in the Model Legume Lotus japonicus

“…It is alleged that shoot growth and increased shoot to root ratio (S:R) during submergence can induce a better balance between gas transport capacity (oxygen source) and root oxygen consumption (oxygen sink) when plants are able to succeed in the process of emerging leaves above water ("escape strategy"; [34,35]). However, an increased S:R can also constrain plant recovery after de-submergence if water loss by transpiration cannot be replenished by root water uptake, regardless of whether leaf emergence was achieved, as seen in the forage grass Chloris gayana subjected to 1 week of full submergence [24]. In our experiment, S:R ratio upon de-submergence was negatively related to the RGR during the recovery phase across L. japonicus genotypes.…”

Екологічні Функції Та Переваги Щодо Середовища Існування У Прибережній Зоні Водосховища

“…The elongation induction strategy of leaf blade of Chloris gayana Kunth. under different water flooding time and mode, and found that long-term water flooding is more beneficial to plant growth than repeated water flooding was studied in detail Striker et al, 2017). The changes of biomass, photosynthesis and other physiological and biochemical characteristics of Alternanthera philoxeroides (Mart.)…”