Nitrogen availability, leaf life span and nitrogen conservation mechanisms in leaves of tropical trees

Abstract

Evergreen species of temperate regions are dominant in low-nutrient soils. This feature is attributed to more efficient mechanisms of nutrient economy. Nevertheless, the cashew (Anacardium occidentale-Anacardiaceae), a deciduous species, is native to regions in Brazil with sandy soil, whilst the annatto (Bixa orellana-Bixaceae), classified as an evergreen species native to tropical America, grows spontaneously in regions with more humid soils. Evergreens contain robust leaves that can resist adverse conditions for longer. The physical aspects of the leaves and mechanisms of nutrient economy between the two species were compared, in order to verify whether the deciduous species had more efficient mechanisms that might explain its occurrence in regions of low soil fertility. The mechanisms of nitrogen economy were also compared for the two species at available concentrations of this nutrient. The following were analysed: (i) leaf life span, (ii) physical leaf characteristics (leaf mass per area, and rupture strain), (iii) nitrogenous compounds (nitrogen, chlorophyll, and protein), (iv) nitrogen conservation mechanisms (nitrogen resorption efficiency, resorption proficiency, and use efficiency), and (v) nitrogen conservation mechanisms under different availability of this mineral. The higher values of leaf mass per area and leaf rupture strain found in A. occidentale were related to its longer leaf life span. A. occidentale showed lower concentrations of nitrogen and protein in the leaves than B. orellana. Under lower nitrogen availability, A. occidentale had higher nitrogen resorption proficiency, nitrogen use efficiency and leaf life span than B. orellana. These characteristics may contribute to the adaptation of this species to sandy soils with low nitrogen content.

Fitness of Mango for Colonization in Low Fertility Soils and Dry Lands: Examination of Leaf Life-Span, Leaf Nutrient Resorption, and Nutrient Use Efficiency in Elite Mango Varieties

“…Species with longer LLS have lower leaf mass per unit area [6], lower chlorophyll content [31, 12,22], and lower soluble protein [12,36,22]. However, there is no information about the intra-species plasticity of these parameters.…”

“…It is generally assumed that a long LLS permits a longer utilization of nutrients in the leaf biomass and this contributes to improving the nutrient use efficiency [13,24,6]. This is partly because a longer duration of leaf biomass can compensate for a smaller instantaneous productivity and thereby may help to increase nutrient use efficiency following longer period of storage of nutrient pools in leaf Leaf longevity is optimized to maximize plant carbon gain and thus determines the productivity of the trees [19].…”

“…LLS was estimated following the procedure described by Lima et al [22] and Corte et al [6]. Briefly, in 2006 very young whorls of leaves were selected in each tree and dated plastic tapes were placed around the petioles.…”

Foliar nitrogen and phosphorus resorption in an undisturbed and a Pinus pinaster Ait. planted forests in northern Turkey

“…High resorption proficiency implies low concentrations because a low N and P concentration in senesced leaves is the evidence of high proficiency, and vice versa (Yuan et al, 2005, Kilic et al, 2010. Corte et al (2009) stated that low RP indicates higher potential for conserving of a nutrient. V. arctostaphyllos had a higher potential for conserving N and P because it had the lowest mass-and area-based NRP and PRP in undisturbed forest.…”

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“…The N and P are the most limiting nutrients for plant growth, and their resorption is important for plant nutrient conservation [16][17][18]. Nitrogen is mobilized from senescing leaves to other plant parts, and this N resorption enable plants to reuse and conserve this nutrient for supporting spring budbreak and new leaf crop formation, and vegetative shoot extension thus reducing the dependence on external nutrient supply [19][20][21][22]. Nutrient resorption may occur throughout the life of a leaf but most of the resorption occurs shortly before leaf abscission.…”