Abstract
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.
Highlights
Humans have been using resin since prehistoric times, but the system of resin extraction at an industrial level began at the beginning of 18th century
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
We did not observe any significant effect of the treatments on stomatal conductance and only a marginal significant effect (p
Summary
Five-year-old seedlings of P. pinaster growing in 3l pots with 70% peat and 30% sand (v:v) were used in the experiment. 19 pine seedlings were used honing the diameter and height between each one. New stimulants in resin tapping with a punch of 1 cm of diameter, except in control plants. A previously weighed test tube was placed and sealed with the same portion of Parafilm tape (Fig. 1b). In mid-September, all the test tubes were collected. In mid-September, needle stomatal conductance (gs) and water potential (Ψleaf) were measured at midday in 6 pines per treatment. At the end of the experiment, the preweighed test tubes were collected and reweighed with resin and Parafilm. The effect of wounding and the chemical stimulant on resin yield and physiological measurements was tested with a one-way ANOVA. Pearson’s correlation coefficients were obtained between internal, reForest Systems leased, total resin and seedling diameter.
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