Chitosan is increasingly recognized as a promising biostimulant and potential biocontrol-related elicitor in forestry, yet its effectiveness under biotic stress remains underexplored. In this study, the effects of chitosan on photosynthetic pigments and secondary metabolites in pine (Pinus sylvestris L.) seedlings representing five genetic families were investigated, both in the absence of pathogens and following inoculation with Heterobasidion annosum (HA) or Lophodermium seditiosum (LS). Treatments varied by solvent formulation (water or acetic acid) and concentration (0, 2, or 10 g/L). In the absence of a pathogen, chitosan responses were strongly dependent on genotype and dose, with lower concentrations (2 g/L) often producing favourable changes in chlorophyll (e.g., in the 5J genetic family, chlorophyll concentration ranged from 154.49 mg/g (0 g/L) to 205.54 mg/g (2 g/L)) or secondary metabolite accumulation, while higher doses showed diminishing or genotype-specific returns. Solvent formulation had a secondary but detectable influence. Following pathogen inoculation, chitosan treatment altered pigment and secondary metabolite profiles relative to inoculated controls, with several genotype–treatment combinations showing higher chlorophyll, carotenoid, phenolic, or flavonoid concentrations. However, these responses were not uniform across families, pathogens, solvents, or concentrations. Overall, the findings indicate that Scots pine seedlings exhibit genotype-dependent physiological and biochemical responsiveness to chitosan under pathogen-associated stress. These results should be interpreted as evidence of treatment-associated physiological responses rather than confirmed disease protection. The strong influence of genotype and concentration in this pilot study highlights the need for further mechanistic and field-based studies before chitosan application strategies can be generalized.
Saba senegalensis is a multipurpose indigenous tropical liana of high ecological and socioeconomic importance in West Africa. Its declining natural populations, together with limitations of seed-based propagation, highlight the need for efficient vegetative propagation strategies. This study investigated the interactive effects of season and exogenous growth regulators on adventitious rooting and nursery establishment of air-layered S. senegalensis. A total of 450 air layers were established during cold (Temperature 24.93 ± 1.86 °C and Relative humidity 27.25 ± 6.33
Climate change is reshaping the climatic conditions that determine the spatial coincidence between forest parasites and their hosts by altering temperature and precipitation regimes across mountain ecosystems. However, although climate-driven shifts in individual species distributions have been widely investigated, comparatively little attention has been given to how climate change may reorganize the potential climatic co-distribution of interacting host–parasite systems. Recently, Pinus-dominated ecosystems in Mexico have become particularly at risk from dwarf mistletoes (Arceuthobium spp.), which constitute one of the most significant biotic agents undermining forest health and productivity. We evaluated how projected climate change may reorganize the potential climatic co-distribution between two dwarf mistletoes (Arceuthobium globosum and A. vaginatum) and five of their principal Pinus hosts in Mexico. Ecological niche models were developed using MaxEnt, and climatic suitability, environmental niche overlap, and climatic co-distribution were evaluated under current conditions and mid-century CMIP6 climate scenarios. Annual precipitation, mean annual temperature, and the mean temperature of the warmest quarter consistently contributed most to model performance. Current climatic suitability was concentrated across the Trans-Mexican Volcanic Belt and the principal mountain systems of Mexico. Niche overlap analyses (Schoener’s D = 0.34–0.56; p < 0.01) demonstrated a strong climatic alignment between dwarf mistletoes and their Pinus hosts, with spatial mismatches remaining relatively limited (25–30
The quality of tree seedlings is a critical determinant of survival and establishment in urban forestry greening programs, where trees are frequently exposed to stressful site conditions. Root architecture developed during nursery production strongly influences post-transplant performance, response to drought and post recovery of seedling. This study evaluated the effects of two container types, polybags and air-pots, on shoot growth, root architecture, post-transplant establishment, drought response and recovery of five landscape tree species (Koelreuteria paniculata Laxm., Putranjiva roxburghii Wall., Ficus benjamina L., Callistemon lanceolatus Sm., and Cassia fistula L.) Seedlings were raised in containers of identical dimensions (28 × 20 cm), placed in three replicates following completely randomized design. Seedlings grown in air-pots were found better in shoot and root growth, post establishment attributes, drought tolerance and recovery following rewatering, compared to those raised in polybags. The perforations at periphery of air-pots exposed growing root tips to outside air, thereby inducing natural air-pruning and stimulated multiple branching at root tips, while preventing root deformation and circling. The findings demonstrate that air-pots substantially improve post-transplant establishment, drought tolerance and recovery in tree seedlings. By promoting lateral root proliferation and reducing root deformities, air-pots support better seedling survival and establishment of urban trees, making them a promising alternative to conventional polybags for nursery production, intended for urban greening programs.
Forest plantations in Mexico face establishment limitations related to seedling quality. This study evaluated the effect of organic carrier materials (rice flour and coffee husk) in spore-based formulations of native ectomycorrhizal fungi (ECM), Laccaria spp. and Suillus decipiens, applied individually and in combination, on mycorrhizal colonization, growth, and quality of Pinus patula seedlings under nursery conditions. A completely randomized design with 10 treatments plus an uninoculated control was used, with 37 replicates per treatment. At 273 days after inoculation, seedling height, stem diameter, biomass, mycorrhizal colonization percentage, and quality indices were evaluated. Rice flour treatments significantly improved seedling survival (80–100
