Morphological and physiological responses of Heteropogon contortus to drought stress in a dry-hot valley

Abstract

Background Heteropogon contortus is a valuable pasture species that is widely used for vegetation restoration in dry-hot valleys of China. However, to date, its morphological and physiological responses to drought, and the underlying mechanisms are not well understood. This study was aimed to investigate the morphological and physiological changes of H. contortus under drought stress during the dry-hot season. Heteropogon contortus was planted in pots and subjected to four levels of soil water treatments: above 85 % (control), 70–75 % (light stress), 55–60 % (moderate stress) or 35–40 % (severe stress) of field capacity.ResultsWithin the total stress period (0–29 days), H. contortus grew rapidly in the light stress, whereas severe stress had a negative impact on growth. Aboveground biomass decreased together with increasing drought stress, whereas root biomass increased. Consequently, the root/shoot ratio of the severe stress treatment increased by 80 % compared to that of the control treatment. The ratio of bound water/free water (BW/FW) was the most sensitive parameter to drought and showed a value under severe stress that was 152.83 % more than that in the control treatment. Although leaf water potential (LWP) and leaf relative water content (RWC) decreased with progressive water stress, H. contortus managed to maintain a relatively high RWC (nearly 70 %) in the severe stress condition. We also detected a significant reduction (below 0.6) in the ratio of variable fluorescence/maximum fluorescence (Fv/Fm) in the severe stress treatment.ConclusionsOur results show that H. contortus adapts to drought mainly by avoidance mechanisms, and its morphological and physiological characteristics are inhibited under severe stress, but can recover at a certain time after re-watering. These findings might help limited water resources to be fully used for vegetation management in the studied region.

Complex evolutionary history of two ecologically significant grass genera,ThemedaandHeteropogon(Poaceae: Panicoideae: Andropogoneae)

“…and Themeda triandra Forssk. are distributed throughout the tropics, and from Africa to East Asia, respectively, and are keystone species in many grasslands where they are found (Goergen & Daehler, 2001;Wang et al, 2016). The remaining species have variable range distributions from restricted to regionally widespread, mainly distributed throughout South Asia, Southeast Asia and Australia (Deshpande, 1988;Veldkamp, 2016;POWO, 2019).…”

Effects of Nitrogen Rates on the Productivity and Nutritive Value of Forage Grass Grown under Extreme Climatic Conditions

“…The results of this study showed that red clover and timothy were more susceptible to drought and excess moisture stress when heavily fertilized with N. Bahrani et al [23] and Wang et al [24] have indicated that drought treatments cause a reduction in plant height. According to Chai et al [25] post-drought recovery of perennial grasses depended on the recovery of existing leaf tissue and the regeneration of new tissue from crowns, stolons and roots.…”

The response of litter decomposition to extreme drought modified by plant species, plant part, and soil depth in a temperate grassland

“…Each of these changes may be related to altered biomass or nutrient allocation within a species in response to drought, and/or a drought‐induced change in species dominance. Within species, plants that experience water stress often have greater root‐to‐shoot ratios or deeper roots than well‐watered plants (Fernández & Reynolds, 2000; Huang, 1999; Skinner & Comas, 2010; Wang et al, 2016). In semi‐arid environments, drought also tends to increase the C:N ratio in leaves, thus decreasing litter quality (Sardans et al, 2012).…”

“…Within species, plants that experience water stress often have greater root-to-shoot ratios or deeper roots than well-watered plants (Fernández & Reynolds, 2000;Huang, 1999;Skinner & Comas, 2010;Wang et al, 2016). In semi-arid environments, drought also tends to increase the C:N ratio in leaves, thus decreasing litter quality (Sardans et al, 2012).…”

“…Just as litter quality, these factors can also change at species and community levels, due to altered biomass allocation within a species and shift in species abundances, respectively. An increase in root‐to‐shoot ratio within a species is a well‐documented response to drought, which allows plants to enhance water uptake from drier soils (Fernández & Reynolds, 2000; Skinner & Comas, 2010; Wang et al, 2016). As an example of changes at a community level, experimental drought in a mesic alpine grassland increased the relative abundance of deep‐rooted grasses, and decreased that of shallow‐rooted sedges and forbs, which contributed to a shift toward higher belowground net primary productivity compared to control, particularly in the deeper soil layer (Liu et al, 2018).…”