[Show abstract][Hide abstract] ABSTRACT: Due to the high economic importance of Pinus pinaster Ait., there is considerable interest in developing, improving and extending the use of its families for mass clonal propagation and in breeding programmes. In the current study, we evaluated shoot growth, rooting ability and mini-cuttings production of P. pinaster in response to nitrogen fertilization and seasons. We compared eight half-sib families of P. pinaster from Asturias and Galicia (Northern Iberian Peninsula), searching for useful parameters and growing conditions to be included in a mass propagation program for clonal family forestry. We fertilized P. pinaster seedling mother plants kept in a greenhouse with three levels of nitrogen: high (HN), medium (MN) and low (LN) to evaluate rooting ability of mini-cuttings. In addition, we evaluated the maximal potential production of rooted mini-cuttings considering nine cycles of propagation over 1 year, also using three levels of nitrogen. The HN treatment significantly influenced the rooting process, with length, area and volume of roots all being positively affected. Spring was the most favourable season for mini-cuttings in the HN treatment. This study provides valuable new information to optimize the clonal propagation protocol for P. pinaster and shows that the mini-cuttings technique has great potential in mass scale cloning, providing high quality sprout production and well-formed new plants.
New Forests 01/2012; 43(5-6):651-663. · 1.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Environmental stresses come in many forms, yet the most prevalent stresses have in common their effect on water status. Under severe stress, a plant adapts its metabolism and alters its development. Cold and water stress are two clear examples of convergence and they have been used for cold acclimation in some species. With this in mind, we conducted an assay using five nine-month-old clones of Pinus pinaster Ait. from three different half-sibs families of Oria provenance (Almeria, Southern Spain). The plants were kept in a growth chamber under controlled conditions for 11 months, and two levels of watering were applied: control (90% of the field capacity) and stress (gradual stress down to 20% of field capacity). Various water, morphological and biochemical parameters were evaluated. After water stress treatment, needles were exposed gradually to freezing temperatures (ranged from -4°C to -24°C) to determine the injury index of each clone measured by electrolyte leakage method (ELM). In addition, we evaluated changes in cold hardiness of needles as measured by differential scanning calorimetry (DSC). Water stress modified most of the parameters quantified, reducing growth under the water stress treatment: predawn (Ψpd) and midday (Ψmd) water potential, and needle relative water content (RWC) decreased with water stress. All genotypes showed some degree of osmotic adjustment, although proline level increased only at midday. Abscisic acid (ABA) content showed an unclear relationship with the treatment, since only some clones showing higher levels in the stress treatment. Preliminary results provide support for chilling tolerance, measured both with ELM and DSC, has being induced by water stress. Water stress treatment induced dehydratation as shown by the lower values of RWC, although, interestingly, the amount of non-freezing water in water stress acclimated plants was less than in the control. This study of stress responses enhances current knowledge of basic plant biochemistry. By studying how plants respond to severe stress, we learn more about their metabolism, its flexibility, its limits, and its diversity.
[Show abstract][Hide abstract] ABSTRACT: Pinus pinaster Ait. is one of the main forest tree species planted in Spain, Portugal and France. Due to its high economic relevance, there
is considerable interest in developing techniques for vegetative breeding aimed at mass propagation. In this study we present
a mini-propagation protocol in order to define an efficient method to propagate families or clones of P. pinaster. We carried out three experiments using mini-cuttings of 3–5cm in length with the aim of evaluating the effects of temperature
(4°C vs. 25°C), plant growth regulator (IBA) and shoot age on rooting ability. Percentage of rooted cuttings and morphological
root variables were recorded. The percentage of rooted cuttings per treatment ranged from 68 to 97%. Treatment with IBA significantly
influenced the rooting process at 25°C but not at 4°C. The number of apexes, length, area and volume of roots were all positively
affected by temperature treatment. Shoot age also had a positive effect on rooting capacity of cuttings, with the cuttings
from the youngest shoots (70days after pruning) having higher rooting percentages, ranging from 84.7 to 98.3%. The use of
juvenile material, good environmental conditions and IBA all benefited the rooting of clonal material, resulting in high rooting
capacity. This study presents an innovative propagation protocol for P. pinaster that can be used as a tool in breeding programs.
KeywordsMaritime pine–Vegetative propagation–Rooting–Shoot age–Indolebutyric acid–Temperature
New Forests 01/2011; 41(3):399-412. · 1.64 Impact Factor