Histological description of Saxifraga paniculata leaves with special focus on structures that release CaCO3

[EN] Saxifraga paniculata is a subalpine succulent perennial plant arranged in a rosette that is usually found in shallow soil among limestone rocks. Stereoscopic, light and scanning electron microscopy were used to describe the anatomical structure of S. paniculata leaves, paying special attention to structures related to CaCO3 (calcium carbonate) release. Anomocytic stomata are unevenly distributed on each leaf face, being absent in the lower third. The basal leaf margin presents translucent pluricellular trichomes of variable length and width. Towards the apical margin, trichomes become teeth. Both trichomes and teeth are completely covered with whitish CaCO3 crystals. Each tooth has a circular cavity connected to a single hydathode through pores. Clearing treatment revealed camptodromous leaf venation. Anatomical structure shows a bifacial cross-section with spongy mesophyll cells at basal part, becoming heterogeneous at the apex with palisade mesophyll on the adaxial face. Hydathodes are epithematic and connected to outer cavities via two kidney-shaped guard cells showing large substomatal cavity. The epithem is surrounded by a thickened sheath and is formed of highly packed elongated cells with interspersed tracheary elements. CaCO3 deposits consist of microscopic crystals with varying geometries, of which the rhombus is the basic unitSIWe thank the Universidad de León (Spain) for providing the funds for performing this stud

El hombre y la resina de pino: desde su uso pasado hasta la actualidad con especial atención en España

La resina de pino es una sustancia viscosa y pegajosa, constituida por una mezcla compleja de diferentes tipos de terpenos. Se produce en las células resiníferas y, tras ser expulsada al exterior del árbol por un estrés biótico o abiótico, se endurece y protege al pino contra patógenos y fitófagos. La resina en condiciones anóxicas puede fosilizar formando el ámbar. El hombre conoce y utiliza las múltiples aplicaciones que tiene la resina desde tiempos bíblicos. España, que fue uno de los países con mayor importación de resina entre los siglos XVI y XIX, pasó a ser uno de los principales países productores y exportadores a partir del XIX. Sin embargo, a finales del siglo XX la resina española dejó de ser económicamente competitiva, lo que provocó la práctica desaparición de su aprovechamiento en favor de otros países emergentes como China. Con la llegada del siglo XX se está viviendo un nuevo resurgir del oficio como motor de desarrollo de zonas rurales, lo cual favorece además la protección de los extensos pinares españoles. Este resurgimiento está respaldado por la cada vez mayor demanda europea de productos derivados de la resina

Salicylic and citric acid as promising new stimulants for resin tapping in maritime pine (Pinus pinaster Ait.)

Aim of the study: We tested alternative active principles to the most widely used resin tapping stimulant which contains sulphuric acid. We also studied the effect of wounding in five-year-old Pinus pinaster seedlings with a microtapping method.Area of study: The experiment was carried out at the Universidad Politécnica de Madrid in Spain.Material and Methods: The experiment consisted of six treatments: control (no stimulant no wounding), wound (no stimulant), and pines stimulated with sulphuric acid, ethrel, salicylic acid and citric acid. We evaluated the resin yield differentiating between released resin and internal resin (resin retained within the xylem), and the physiological status of the tree.Main Results: Wounded plants produced on average three times more resin than control plants. Plants stimulated with salicylic and citric acids showed the highest resin yield and produced on average 15% more resin than those stimulated with sulphuric acid, mainly because the released resin was higher. Tree diameter affected resin yield and thicker trees produced more resin. We did not observe any significant effect of the treatments on stomatal conductance and only a marginal significant effect (p<0.10) on water potential.Research highlights: Salicylic acid and citric acid seem to be promising stimulants for the resin tapping activity to be further tested in field experiments with adult trees.Keywords: sulphuric acid; ethrel; pine resin; microtapping; wounding; water potential; stomatal conductance.Abbreviations used: TR: total resin content; RR: released resin; IR: internal resin; gs: stomatal conductance; Ψleaf: midday leaf water potential

Salicylic and citric acid as promising new stimulants for resin tapping in maritime pine (Pinus pinaster Ait.)

Aim of the study: We tested alternative active principles to the most widely used resin tapping stimulant which contains sulphuric acid. We also studied the effect of wounding in five-year-old Pinus pinaster seedlings with a microtapping method. Area of study: The experiment was carried out at the Universidad Politécnica de Madrid in Spain. Material and Methods: The experiment consisted of six treatments: control (no stimulant no wounding), wound (no stimulant), and pines stimulated with sulphuric acid, ethrel, salicylic acid and citric acid. We evaluated the resin yield differentiating between released resin and internal resin (resin retained within the xylem), and the physiological status of the tree. Main Results: Wounded plants produced on average three times more resin than control plants. Plants stimulated with salicylic and citric acids showed the highest resin yield and produced on average 15% more resin than those stimulated with sulphuric acid, mainly because the released resin was higher. Tree diameter affected resin yield and thicker trees produced more resin. We did not observe any significant effect of the treatments on stomatal conductance and only a marginal significant effect (p<0.10) on water potential. Research highlights: Salicylic acid and citric acid seem to be promising stimulants for the resin tapping activity to be further tested in field experiments with adult trees