Physiological Responses of Dwarf Coconut Plants Under Water Deficit in Salt-Affected Soils

Abstract

-The objective of this study was to characterize the physiological acclimation responses of young plants of the dwarf coconut cultivar ‗Jiqui Green' associated with tolerance to conditions of multiple abiotic stresses (drought and soil salinity), acting either independently or in combination. The study was conducted under controlled conditions and evaluated the following parameters: leaf gas exchange, quantum yield of chlorophyll a fluorescence, and relative contents of total chlorophyll (SPAD index). The experiment was conducted under a randomized block experimental design, in a split plot arrangement. In the plots, plants were exposed to different levels of water stress, by imposing potential crop evapotranspiration replacement levels equivalent to 100%, 80%, 60%, 40%, and 20%, whereas in subplots, plants were exposed to different levels of soil salinity (1.72, 6.25, 25.80, and 40.70 dS m -1 ). Physiological mechanisms were effectively limited when water deficit and salinity acted separately and/or together. Compared with soil salinity, water stress was more effective in reducing the measured physiological parameters. The magnitudes of the responses of plants to water supply and salinity depended on the intensity of stress and evaluation period. The physiological acclimation responses of plants were mainly related to stomatal regulation. The coconut tree has a number of physiological adjustment mechanisms that give the species partial tolerance to drought stress and/or salt, thereby enabling it to revegetate salinated areas, provided that its water requirements are at least partially met.Keywords: Cocos nucifera L.. Water and salt stress. Physiology. RESPOSTAS FISIOLÓGICAS DE PLANTAS DE COQUEIRO ANÃO SOB DEFICIÊNCIA HÍDRICA, EM SOLOS AFETADOS POR SAISResumo -Objetivou-se, com este trabalho, caracterizar as repostas fisiológicas aclimatativas de plantas jovens de coqueiro Anão, cultivar -Verde do Jiqui‖, associadas com a sua tolerância às condições de múltiplos estresses abióticos (deficiência hídrica e salinidade do solo), atuando isolados e/ou combinados. O estudo foi realizado sob condições controladas e avaliaram-se: as trocas gasosas foliares, o rendimento quântico da fluorescência da clorofila a e os teores relativos de clorofila total (índice Spad). O experimento foi conduzido sob delineamento estatístico de blocos casualizados, no arranjo de parcelas subdivididas, sendo as parcelas constituídas por diferentes níveis de deficiência hídrica, mediante a imposição de cinco distintos percentuais de reposição das perdas de água por evapotranspiração potencial da cultura (100; 80; 60; 40 e 20%) e as subparcelas constituídas pelos crescentes níveis de salinidade do solo (1,72; 6,25; 25,80 e 40,70 dS m -1 ). Os mecanismos fisiológicos são efetivamente limitados quando a deficiência hídrica e a salinidade atuam isoladamente e/ou em conjunto. Os efeitos do estresse hídrico se mostram mais efetivos nos comprometimentos dos parâmetros fisiológicos, em detrimento à salinidade do solo. As magnitudes da...

Coconut genome assembly enables evolutionary analysis of palms and highlights signaling pathways involved in salt tolerance

“…S11 ), was downregulated at all stages, contrary to what is was observed in rice and Arabidopsis 75 . This is however consistent with the fact that the physiological response to salt in dwarf coconut seedlings is mainly mediated by stomatal regulation 76 . In fact, a decrease of PP2C could enhance ABA signaling which, in turn, triggers stomatal closure as well as the synthesis of protective molecules contributing to the osmotic homeostasis 7 .…”

Biochemical modulations in açaí palm (Euterpe oleracea Mart.) under vegetative stages in an agroforestry system of the Amazon

“…7) in the different tissues and organs of the plants indicate that the damages caused by the lower water availability were adequately avoided. This same behavior was observed in other plant species subject to different drought regimes ( Silva et al., 2017a, 2017b; Silvestre et al., 2017; Oliveira et al., 2016). Moreover, the accumulation of this amino acid is favored with the increase in the physiological maturity of E. oleracea .…”

“…The accumulation of this amino acid in plant tissue may be related mainly to the decrease of relative water content and protein degradation ( Kerbauer , 2008; Taiz and Zeiger , 2013). The literature suggests that a limited number of species of palm trees have mechanisms of water stress tolerance ( Oliveira et al., 2002; Gomes et al., 2008; Silva et al., 2017a, 2017b). The objective of this work was to analyze the biochemical responses of the açaí ( Euterpe oleracea Mart) to the dry season, in order to identify the potential and mechanisms of adaptation of the plant, guaranteeing its growth and development under conditions of water deficiency.…”

A flora of agricultural and horticultural crops : a quick scan of selected crops in the Mekong Delta

“…The coconut tree has a number of physiological adjustment mechanisms that give the species partial tolerance to drought stress and/or salt, thereby enabling it to re-vegetate salinated areas, provided that its water requirements are at least partially met [13]. Maize is generally planted through direct seeding, but in Vietnam a transplanting technique has been adopted.…”