THE INFLUENCE OF VAPOUR PRESSURE DEFICIT ON LEAF WATER RELATIONS OF COCOS NUCIFERA IN NORTHEAST BRAZIL

Abstract

SUMMARYDaily courses of leaf gas exchange and leaf water potential (Ψleaf) of green dwarf coconut palm (Cocos nucifera) were measured in irrigated plantations on the wet coastal plateau and in a dry semi-arid area of northeast Brazil. At both sites, significant correlations were obtained between stomatal conductance (gs) and vapour pressure deficit (VPDair), Ψleaf and VPDair, leaf transpiration (E) and gs, and E-Ψleaf. Despite these similar relationships between sites, stronger correlations involving gs-VPDair and E-Ψleaf were found at the semi-arid site, where whole-plant hydraulic conductance (gp) was correlated significantly with VPDair. In addition, at the semi-arid site, only, the net photosynthesis (PN) was not correlated with E and Ψleaf, and the intrinsic water use efficiency (WUEi) was disconnected from VPDair and Ψleaf. The different behaviour of leaf gas exchange and Ψleaf between sites was probably caused by low gs in response to high VPDair at the semi-arid site. Our results indicate potential for significant alterations in the pattern of leaf gas exchange during future climatic changes with increasing temperature and concomitant increases in VPDair. The atmospheric water stress will probably reinforce the strength of connection among water relation variables (E, Ψleaf, gs, gp, and VPDair), but it will disrupt the linear relationship between net CO2 assimilation and leaf water relations such as PN-E, PN-Ψleaf, WUEi-VPDair and WUEi-Ψleaf.

Photosynthetic characterization of three dominant plant species in the saline–alkaline soil of the Yellow River Delta, China

“…Afterwards, the decrease in P N until late afternoon may be related to the higher afternoon T a and VPD. Similar pattern was shown by palms such as coconut (Passos et al 2009), as well as by other tree species such as citrus (Machado et al 2002). Temperature can influence enzymatic reactions, and the physiological and biochemical responses of cell membranes, and thus became the main factor to impact photosynthetic dynamics of the plant (Li et al 2011;Chen et al 2012;Oukarroum et al 2012;Suleman et al 2013).…”

Gas exchange in gariroba palms grown under subtropical conditions

“…It is known that climate elements mainly PPFD, temperature and air RH influence directly gas exchange of all plant species and its impact is of high importance to physiology of production, once productivity depends highly on the P N throughout the crop cycle (Taiz & Zeiger, 2009). Like all palms (Tucci et al, 2010;Prado et al 2001;Passos et al, 2009), gariroba palm presented diurnal variation of gas exchange with a performance consistent with that of photosynthetic metabolism of C3 plants (Larcher, 2000), both in May and in August (Figure 2 and 3).…”

“…On the other hand, Larcher (2000), suggested for C3 trees, maximum P N between 10 and 15 µmol m . Differently to what has been observed for palms of more economical importance like coconut (Gomes & Prado, 2007;Gomes et al, 2008;Passos et al, 2009), oil palm (Dufrêne & Saugier, 1993;Suresh et al, 2012) and lately the heart-of-palm producer palms (Tucci et al, 2007(Tucci et al, , 2010Lavinsky et al, 2014;Pereira et al, 2014), no references to gariroba palms gas exchange were found.…”

“…In irrigated peach palms under subtropical conditions of São Paulo State, Brazil, P N maximum reached 15 µmol m -2 s -1 in February (Tucci et al, 2010). In other palms of economic importance, like dwarf coconut, P N reached values of 14-17 µmol m -2 s -1 (Gomes & Prado, 2007;Gomes et al 2008;Passos et al 2009). …”

Mecanismos de transferência de água entre solo, planta e atmosfera e sua relação com o estresse hídrico vegetal

“…The efforts to correlate it with environmental parameters are not always successful. Stomatal conductance of sunlit leaves depends on air temperature and air CO 2 concentration, but the air vapor pressure deficit and the soil water status also play an important role (JARVIS, 1976;PASSOS et al, 2009). The following two parts of the soil-water-atmosphere system need special attention in mechanistic modeling of plant water stress:…”