Introduction

The use of fertilizers for forest plant production in nursery improves quality and favors field performance.

Objective

To identify the effects of fertilizer doses on the growth of Pinus patula Schiede ex Schltdl. & Cham. under nursery conditions, and survival and growth under field conditions.

Materials and methods

A total of eight fertilization treatments with eight (Multicote Agri®) and 12 months (Multicote®) nutrient release times were evaluated at the GUMAIR nursery in Acaxochitlán, Hidalgo. Plants were established in the field and fertilization treatments were incorporated to evaluate survival and growth (height and diameter) after a year.

Results and discussion

Under nursery conditions, plants with 8 g∙L^-1 of eight-month fertilizer in combination with 4 and 6 g∙L^-1 of 12-month fertilizer release had the highest values (P ≤ 0.0001) in all variables. The combination of 4 g∙L^-1 of eight-month fertilizer and 4 g∙L^-1 of 12-month fertilizer release had the same effect as these treatments in diameter, root and shoot dry weight and Dickson\'s quality index under nursery conditions, while under field conditions it caused higher survival (95 %) after a year of planting. The effect of these three treatments in the nursery agreed with the higher growth and N concentration in foliage under field conditions.

Conclusion

Plants with desired morphological characteristics and better field performance were obtained with 4 g∙L^-1 of eight-month fertilizer and 4 g∙L^-1 of 12-month release.

Introduction

Sustainable forest management focuses on securing environmental services while maintaining aboveground biomass (AGB) accumulation.

Objective

To evaluate the AGB along of a Chronosequence of temperate forest and to examine the role of forest management for timber production on patterns of AGB fixation, increment and allocation.

Materials and methods

A chronosequence of stands dominated by Pinus patula Schiede ex Schltdl. & Cham. was selected in a range from 7 to 30 years. AGB was estimated with allometric models and with parameterized models to infer the age at which the managed forest reaches its maximum production. AGB production, aboveground net primary productivity (ANPP), increments in AGB and their allocation to tree structural components were calculated and compared with those of a natural forest (NMF).

Results and discussion

AGB and ANPP increased with stand age throughout the chronosequence. The 30-year-old stand produced 79 % of the AGB observed in the NMF. These two sites had high AGB production, which corresponded to high ANPP with 87 % similarity. Stems were the tree structural component with the highest AGB allocation (70 %), mainly due to silvicultural practices such as thinning, which is part of the forest management program.

Conclusions

P. patula forests with forest management accelerated the accumulation of AGB in temperate forest stands along the chronosequence studied, reaching levels similar to those of a NMF in a shorter period.

Introduction

There is growing public awareness in Mexico concerning natural resources and, in particular, the threat they face due to the increase in the number of forest fires.

Objective

To reconstruct the fire records of a 66-year period (1945-2011) and analyze its relationship with climate conditions in the southeastern part of Jalisco.

Materials and methods

Pinus douglasiana Martínez samples were processed according to standard dendrochronological techniques. The statistical analysis and relationship of fires with climate were determined with the ‘burnr’ library of the R program. Winter precipitation and PDSI (Palmer Drought Severity Index) and PDO (Pacific Drought Oscillation) indices were used as proxies for climate.

Results and discussion

All scars (114) were in the zone of initial growth of earlywood; therefore, fires occurred during the spring (dry season). The mean fire frequency interval for the 100 % filter of scars was 5.1 years, for the 10 % filter it was 6.1 years, and for the 25 % filter, representing the most extensive fires, it was 6.4 years. Drought preconditions and dry conditions modulated by the PDO had significant influence on fire occurrence.

Conclusions

Historical reconstruction shows that the fire regime is frequent, of low intensity and with no change over the last four decades. To maintain these characteristics, monitoring and forest fuel management actions are important.

Introduction

The identification of Armillaria and Desarmillaria species associated with Armillaria root disease is important to determine management strategies, due to their variation in pathogenicity and virulence.

Objective

To identify Desarmillaria/Armillaria species associated with lychee (Litchi chinensis Sonn.), avocado (Persea americana Mill.), and pine (Pinus sp.) trees with symptoms and signs of Armillaria root disease.

Materials and methods

Root samples were collected from trees with signs and symptoms of Armillaria root disease from lychee trees in Veracruz, three avocado orchards in Michoacán, and a forest area in Michoacán. Eight fungal isolates were identified based on DNA sequences of the translation elongation factor 1-alpha (tef1) gene.

Results

Based on tef1 sequences, three isolates obtained from lychee trees in Veracruz were identified as Desarmillaria caespitosa; four isolates obtained from avocado trees and one from a pine tree in Michoacán were identified as Armillaria mexicana. Fungal isolates are deposited in the fungal culture collection of USDA Forest Service, RMRS, Moscow, Idaho, USA, and tef1 sequences are deposited in GenBank.

Conclusion

This study represents the first reports of D. caespitosa on lychee in Veracruz and A. mexicana on avocado and pine trees in Michoacán, Mexico.

Introduction

Plant communities dominated by pinyon pines host abundant species, as they often form ecotones between temperate forests and desert shrublands.

Objectives

To describe the floristic-structural attributes of pinyon pine forests in San Luis Potosí and to analyze the impact of some environmental factors on the characteristics of these associations.

Materials and methods

Arboreal plants and shrub flora of nine sites was recorded and analyzed quantitatively using the point-centred quarter method, and qualitatively, using physiognomic profiles and Dansereau diagrams. The groups defined with Jaccard\'s similarity index were ordered with the environmental factors using a canonical correspondence analysis.

Results and discussion

The floristic richness was 597 species including Pinus cembroides Zucc., Pinus pinceana Gordon. & Glend., Pinus nelsonii Shaw., Pinus discolor D. K. Bailey & Hawksw. and Pinus johannis Rob.-Pass., which form associations with Juniperus flaccida Schltdl., Yucca spp. and Quercus spp. The floristic similarity depends on several factors including altitude, slope, pH, organic matter and calcium in soil.

Conclusion

Pinyon pine forests in San Luis Potosí are dominated by five species of Pinus with heterogeneous floristic composition, so each community should be managed according to specific ecological characteristics.

Introduction

Pinus pseudostrobus, a species of ecological and economic importance in Mexico, has a wide distribution and intraspecific variation, which generates controversy regarding the identification of its operational taxonomic units (OTU).

Objectives

To evaluate morphological traits of cones and needles of P. pseudostrobus to distinguish varieties and identify traits with greater discriminatory capacity.

Materials and methods

Twelve traits in cones and 20 in needles were measured on samples from 153 trees identified in four putative OTU. Univariate and multivariate ANOVA, variance component estimation and canonical discrimination analysis (CDA) with cross-validation were carried out.

Results and discussion

Thirteen needle and 12 cone traits showed significant differences between OTU. The variance between OTU increased 6.8 %, on average, when considering the varieties oaxacana and apulcensis as distinct OTU. Multivariate analysis confirmed significant differences in foliage and cones between OTU. The variation explained by the CDA increased from 0.35 to 0.74 and 0.76 when using foliage, cones, and overall variables, respectively. Eight cone traits allowed discrimination among OTU with average error of 9.2 %.

Conclusions

Despite the wide intraspecific variation, it was possible to differentiate the main OTU of P. pseudostrobus with cone morphological markers, with important implications for a better management of genetic resources of this species. The present study shows evidence of morphoanatomical differences between oaxacana and apulcensis varieties.

Introduction

Particle board production is based on the use of sawmill and remanufacturing residues; however, the availability of this raw material has decreased significantly due to its use as biomass for firewood fuel.

Objective

To evaluate the effect of the replacement level of maize (Zea mays L.) and Pinus radiata D. Don residues on physical and mechanical board properties.

Materials and methods

Maize and P. radiata residue proportions between 0 % (control) and 30 % maize were evaluated. Urea-formaldehyde adhesive was used in proportions of 7.5 % and 9.5 % for fine and thick particles, respectively; pressing was based on industrial parameters with a thickness of 10 mm and 0.77 g∙cm^-3 density. Physical and mechanical properties were determined according to particle board standards.

Results

Thickness, density, moisture, modulus of elasticity and modulus of rupture were similar among maize residue proportions and met the industrial requirement. At 2 and 24 h, absorption and swelling met the industrial and regulatory requirement, except for swelling at 2 h when 30 % maize residues was used. The internal bond (IB) met the industrial requirement with all proportions, but from 20 % onwards there was a significant decrease (P < 0.05).

Conclusions

Maize residue proportions between 0 and 10 % had similar performance. A proportion of up to 20 % maize provided regulatory and industrial compliance, so it has potential for the particle board industry.

Introduction

Gene expression studies require extraction protocols that allow obtaining high quality RNA, especially when working with tissues rich in polysaccharides, lipids and polyphenols such as pecan nut (Carya illinoinensis [Wangenh.] K. Koch) embryo tissue.

Objective

To evaluate the efficiency of eight methods of total RNA extraction from pecan nut embryo tissue.

Materials and methods

Eight total RNA extraction protocols based on TRI Reagent®, CTAB (hexadecyltrimethylammonium bromide) buffer and a commercial kit were evaluated. Total RNA yield and quality were determined by spectrophotometry (UV/visible). RNA viability and integrity were analyzed by RT-PCR using actin as a reference gene.

Results and discussion

Extraction protocols based on TRI Reagent® provided high concentrations of total RNA, but with a high degree of contamination. The commercial kit was used to extract total RNA, but without the expected optimal purity. Finally, protocols based on CTAB buffer achieved total RNA yields of optimal quality.

Conclusions

The quality of total RNA varies according to the efficiency of the method used. The CTAB 4 protocol represents an efficient alternative for the isolation of RNA from embryonic tissues of C. illinoinensis.

Introduction

Clonal orchards increase genetic gain, usually established by grafting. In pines, scion-rootstock genetic compatibility could improve grafted plant production.

Objectives

To evaluate scion-rootstock compatibility of Pinus patula Schiede ex Schltdl. & Cham. in response to genotypic variation.

Materials and methods

Scions of four outstanding genotypes (G105, G106, G114 and G115) were grafted onto rootstocks of the same half-sib families (F105, F106, F114 and F115) in all combinations in a randomized complete block design. The following were evaluated: grafting, survival, needle development and growth in length and diameter of the graft.

Results and discussion

The analysis of variance indicated that grafting ranged from 70 to 82.5 %; the effect was significant only for the scion genotype factor (P < 0.0001), being higher with G115. The genotype*family interaction had significant effect (P < 0.0001) on graft survival; the best combinations were G115 + F114 (85 %), G114 + F105 (80 %), G115 + F105 (75 %) and G115 + F106 (75 %). G105 (26 cm) and G115 (2 mm) had the highest values (P < 0.05) for growth in length and diameter, respectively. All the grafts developed needles after five months.

Conclusions

Grafting with genotype G115 and family F105, in combination with any family or genotype, were the most successful. Scions and rootstocks of the same genotype or family were not favorable for graft compatibility in P. patula.

Introduction

Sawflies (Hymenoptera: Diprionidae) affect conifers and other forest species in the northern hemisphere, reducing forest productivity and causing stand death, thereby justifying control actions.

Objective

The aim was to collect baculoviral strains from Mexican sawfly populations and explore their potential for developing biopesticides.

Materials and methods

A search for baculovirus-infected field populations was carried out. Twenty-three samples of live or dead larvae were collected from 12 localities. Microscopic diagnosis at 400X or 1000X under phase contrast, a DNA hybridization test, and a pathogenicity test were performed.

Results and discussion

Samples from eleven localities showed baculoviral polyhedra. Three subsamples of Zadiprion ojedae DNA from Guachochi, Chihuahua, hybridized with a synthetic probe of the Neodiprion sertifer Polh gene sequence, confirming they harbored baculovirus infection.

Five tested inocula produced disease and mortality in all treated larvae; two of them induced baculoviral polyhedra proliferation in ≥89 % of the resulting cadavers. The rictus mortem of sawfly larvae killed by baculovirus differs from that observed in Lepidoptera: most baculovirus-bearing cadavers remain firm or hard, flattened or not, obscured or not, and do not hang from the hind legs. For most of the cadavers found with liquefied tissues, the agent that most probably caused death was not the baculovirus but the accompanying microbiota (bacilli, cocci, or fungi).

Conclusions

Baculovirus strains are widely present in Mexican sawfly populations and several of them were pathogenic and promising for developing bioinsecticides.