Supplementary Calcium Restores Peanut (Arachis hypogaea) Growth and Photosynthetic Capacity Under Low Nocturnal Temperature

Abstract

Peanut (Arachis hypogaea L.) is a globally important oil crop, which often experiences poor growth and seedling necrosis under low nocturnal temperatures (LNT). This study assessed the effects of supplementary calcium (Ca 2+ ) and a calmodulin inhibitor on peanut growth and photosynthetic characteristics of plants exposed to LNT, followed by recovery at a higher temperature. We monitored key growth and photosynthetic parameters in a climate-controlled chamber in pots containing soil. LNT reduced peanut growth and dry matter accumulation, enhanced leaf nonstructural carbohydrates concentrations and non-photochemical quenching, decreased the electron transport rate, increased the transmembrane proton gradient, and decreased gas exchange rates. In peanuts subjected to LNT, foliar application of Ca 2+ restored growth, dry matter production and leaf photosynthetic capacity. In particular, the foliar Ca 2+ application restored temperature-dependent photosynthesis feedback inhibition due to improved growth/ sink demand. Foliar sprays of a calmodulin inhibitor further deteriorated the effects of LNT which validated the protective role of Ca 2+ in facilitating LNT tolerance of peanuts.

Exogenous Calcium Alleviates Nocturnal Chilling-Induced Feedback Inhibition of Photosynthesis by Improving Sink Demand in Peanut (Arachis hypogaea)

“…significant accumulation of nonstructural carbohydrates in photosynthetically active leaves (Figures 2, 4), which are consistent with studies on maize (Adams et al, 2013) and peanut (Song et al, 2020). This study showed that the negative impact of LNT stress on peanut photosynthesis was due to reduced export of nonstructural carbohydrates, as we only exposed plants to nocturnal chilling stress (Figures 1-4).…”

“…Specifically, chilling stress reduces leaf expansion rates and leaf area in sorghum (Sorghum bicolor), maize, and sunflower (Helianthus annuus; Tardieu et al, 1999). LNT stress can also reduce leaf growth, the concentration of photosynthetic pigments and shoot and root dry matter accumulation in tomato (Latef and He, 2011), melon (Hao et al, 2016), and peanut (Song et al, 2020). We demonstrated that even a short-term (11 HoL) overnight chilling stress significantly increased soluble sugar, starch, and total nonstructural carbohydrate concentrations in leaves (Figures 2A-C).…”

“…Restored Nocturnal Chilling-Dependent Feedback Inhibition of Photosynthesis Was Mainly Due to Improved Growth/Sink Demand Exogenous Ca 2+ reduced the accumulation of nonstructural carbohydrates and H 2 O 2 in leaves (sources) when undergoing overnight chilling stress (Figures 1, 2, 4). There are pieces of evidence that exogenous Ca 2+ can serve to maintain photosynthetic processes by improving chilling stress resilience (Brauer et al, 1990) in tomato (Zhang et al, 2014;Liu et al, 2015), wheat (You et al, 2002), Chinese crab apple (Li et al, 2017b), and peanut (Liu et al, 2013;Song et al, 2020). In particular, Ca 2+ is a critical essential element for peanut -a calciphilous legume crop -and directly connected to plant growth processes and responses to phytohormones (Wan, 2003;White and Broadley, 2003;Thor, 2019); and Ca 2+ is involved in regulating a series of cellular activities, including plant cell division and elongation, cytoplasmic flow, and photomorphogenesis (Kader and Lindberg, 2010).…”

“…Frontiers in Plant Science | www.frontiersin.org and during its recovery under normal temperature (Liu et al, 2013;Song et al, 2020); however, the underlying physiological mechanism how exogenous Ca 2+ alleviating inhibition of photosynthesis by nocturnal chilling in peanut remains poorly understood. Therefore, the present study examined the effects of exogenous Ca 2+ and a CaM inhibitor, trifluoperazine (TFP) on photosynthetic reactions and growth in peanut exposed to long-term (days) and short-term (hours) LNT stress.…”

Calcium Nutrition in Coffee and Its Influence on Growth, Stress Tolerance, Cations Uptake, and Productivity

“…A Ca 2+ deficit can interrupt the photosynthetic process and reduce carboxylation efficiency, stomatal behavior, photosynthesis capacity, and quantum yield (Atkinson et al, 1989;Ramalho et al, 1995;Eticha et al, 2017;Song et al, 2019). Ca 2+ signaling and cytosolic acidification in guard cells trigger auxin-induced stomatal opening.…”