Gas Exchange, Water Status, and Growth of Pepper Seedlings Exposed to Transient Water Deficit Stress are Differentially Altered by Antitranspirants

Abstract

<jats:p>Successful field establishment of vegetable transplants often depends on the ability of young seedlings to tolerate various biotic and abiotic stresses after transplanting. Treatments that limit transpirational water loss could improve plant survival and stand establishment. In this study we evaluated growth and physiological responses of pepper (<jats:italic>Capsicum annuum</jats:italic> L.) seedlings to foliar application of chemical plant regulators [abscisic acid (ABA) and aminoethoxyvinylglycine (AVG)] or physical film-forming barriers [AntiStress (AS), Transfilm (TF), and Vapor Gard (VG)] during transient 4-day water deficit cycles. During two 4-day water deficit cycles, stomatal conductance (<jats:italic>g</jats:italic> <jats:sub>s</jats:sub>) and net CO<jats:sub>2</jats:sub> assimilation rate (A<jats:sub>CO2</jats:sub>) were unaffected by the application of physical materials, but differed for ABA and AVG. Compared with untreated control plants, ABA reduced <jats:italic>g</jats:italic> <jats:sub>s</jats:sub> (47% to 69%) and A<jats:sub>CO2</jats:sub> (37% to 57%) by the end of the second water deficit cycle, whereas AVG increased g<jats:sub>s</jats:sub> (27% to 60%) during the first desiccation cycle. Leaf (ψ<jats:sub>lf</jats:sub>) and stem (ψ<jats:sub>st</jats:sub>) xylem water potential of plants treated with film-forming materials generally decreased at the same rate as those of untreated plants, whereas application of AVG caused earlier and more pronounced decline of ψ<jats:sub>lf</jats:sub>. Application of ABA enabled the maintenance of ψ<jats:sub>lf</jats:sub> and ψ<jats:sub>st</jats:sub> during two desiccation cycles, and thus prevented an increase of electrolyte leakage and leaf abscission. Growth rates of all plant components were reduced after ABA applications. However, allometric relationships showed similar patterns of dry matter allocation in leaves and shoots among ABA, TF, VG, and untreated control plants. Application of AS reduced allocation of dry matter to leaves, whereas AVG enhanced it at the expense of roots. These data indicate that water deficit tolerance of pepper seedlings only occurred with foliar application of ABA. This effect was associated with improved plant water relations, increased cell membrane stability, reduced leaf abscission, and a transient reduction in plant growth rates.</jats:p>

Effect of foliar application of antitranspirant on photosynthesis and water relations of pepper plants under different levels of CO2 and water stress

“…However, 8 d of drought was excessive and photosynthesis was negligible. Goreta et al (2007) found that AT did not significantly influence leaf gas exchange or water relations of pepper seedlings exposed to water deficit. However, in agreement with our results, Plaut et al (2004) found that acrylic film application decreased gs and A CO 2 of greenhouse-grown pepper plants.…”

“…In addition to the effect of [CO 2 ] on stomatal behavior, foliar application of antitranspirants is a promising tool for regulating transpiration to maintain a favorable plant water status (Goreta et al, 2007). The formation of thin films can also minimize the escape of water from the plant by decreasing stomatal conductance, thus reducing transpirational losses, improving plant water status and reducing wilting and leaf abscission (Gu et al, 1998).…”

Preplant Application of 1-Methylcyclopropene Improves Postplanting Performance of Tomato Transplants by Suppressing Ethylene-induced Stress Responses

“…This mode of action proposes a new stress-management approach to reducing transplant shock. Most stress-management techniques reported in previous studies aim to reduce postplanting water stress by limiting transpiration (Berkowitz and Rabin, 1988;del Amor et al, 2010;Goreta et al, 2007;Iriti et al, 2009;Moftah and Al-Humaid, 2005) or by activating defense mechanisms in molecular processes (Tuteja and Sarvajeet, 2012). The main drawback of these techniques is that their beneficial stress control effects are limited under optimum field conditions (Agehara and Leskovar, 2012;Berkowitz and Rabin, 1988;Moftah and Al-Humaid, 2005).…”

“…Other negative side effects of abscisic acid include leaf chlorosis, leaf abscission, and excessive inhibition in leaf expansion and stem elongation (Agehara and Leskovar, 2014aLeskovar, , 2014bLeskovar, , 2015Leskovar, , 2017Park et al, 2016). In addition, the performance of film-forming antitranspirants is limited primarily on the adaxial leaf surface and is dependent highly on spray coverage (Goreta et al, 2007). By contrast, preplant 1-MCP treatment can improve postplanting performance of vegetable seedlings even when postplanting stress is minimal in the field, and it has no negative side effects.…”

“…Many chemical compounds have been evaluated for their effectiveness in reducing transplant shock (Berkowitz and Rabin, 1988;del Amor et al, 2010;Goreta et al, 2007;Iriti et al, 2009;Moftah and Al-Humaid, 2005). Antitranspirants can reduce plant water loss by limiting transpiration physically or physiologically (Park et al, 2016).…”