Basal Stem Diameter Research Articles

Natural growing site and cultivation of Pongamia (Pongamia Pinnata (L.) Pierre) as a source of biodiesel raw materials

Pongamia (Pongamia pinnata (L.) Pierre) is one of biodiesel source raw material plants. Natural site conditions and an appropriate planting technique of this species are necessary to be investigated. The purpose of this study was to assess the quality of natural growing site and the cultivation of pongamia through the plantation of seedlings based on provenances. The seedlings were originated from 5 different populations of Java Island. Soil was sampled at each location to determine the rate of soil fertility in natural habitat compared to soil sample at cultivation site. The plantation was carried out in Parungpanjang Research Forest with spacing of 3 m x 3 m. Characteristics of growth observed up to 6 months old were total height, stem base diameter, seedling survival percentage and leaf number. The results showed that pongamia in Java grows in less fertile natural habitats. The initial growth of pongamia provenance test in Parungpanjang showed that seedlings from Carita had the best growth of height (83.75 cm) and diameter (0.85 cm). Pongamia was able to adapt to the environmental conditions which are different from its natural conditions, indicated by the high percentage of survival i.e ranging from 88% (Kebumen) to 100% (Batukaras).

English

Black pod is an important fungal disease of Theobroma cacao L. which causes significant yield losses in the field and consequently, inhibits the growth and development of the plant. For this purpose, the objective of this work was to evaluate the impact of phosphates solubilizing bacteria on growth of cocoa-tree and the biocontrol of Phytophthora megakarya, which is the most aggressive agent of black pod disease. Five strains of phosphate solubilizing bacteria (PSB) were characterized on petri dishes and in liquid media in order to determine their aptitude to solubilize different types of rock phosphate. The aptitude of the strains to inhibit P. megakarya was been evaluated on discs of leaves under in vitro and in vivo culture. The results shown that, Pantoea sp. (63B) with index of solubilization (IS) =5.5 and Enterobacter sp. (196B) with IS = 434.364 are the strains able to solubilize the five different types of rock phosphates used. Moreover, the antagonism test shown that Pantoea sp. (111B) with 90.35%, presented the greatest percentage of inhibition on plate. Bacillus sp. (104B) with 0.5 for the tolerant hybrid genotype and 1.75 for the sensitive hybrid genotype and Pantoea sp. (111B) with 1 for the tolerant hybrid genotype and 1.75 for the sensitive hybrid genotype are the highest foliar sensitivity reduction. In addition, the growth of cocoa tree has been very improved by the strain Enterobacter sp. (196B) for the tolerant hybrid genotype which had increased the plant high up to 50%, 35% for the number of leaves, 38.88% for the stem base diameter and 67.37% for the total dry mass compared to the negative control which did not receive microorganisms. With regard to the hybrids of sensitive cocoa-tree, Pantoea sp. 63B involves an increase of 43.28% of plant high and of 61.11% of the total dry mass, Enterobacter sp. (196B) involves an increase of 22.05% of number of leaves and 31.76% for the stem base diameter compared to the negative control. These strains can therefore be recommended to farmers in order to improve cocoa cultivation in the field. Keys words: Rock phosphates, Phytophthora megakarya, biocontrol, black pod disease, Thebroma cacao.

Deepening Rooting Depths Improve Plant Water and Carbon Status of a Xeric Tree during Summer Drought

Exploring the effects of drought on trees of different sizes is an important research topic because the size-dependent mortality pattern of the major dominant species significantly affects the structure and function of plant communities. Here we studied the physiological performance and non-structural carbohydrates (NSCs) dynamics of a small xeric tree species, Haloxylon ammodendron (C.A.Mey.) of different tree size with varying rooting depth, during summer drought. We measured predawn (Ψpd) and midday (Ψm) leaf water potential, osmotic potential at saturated turgor (π100), and turgor lost point (Ψtlp), stomatal conductance (gs) at noon, maximum photochemical efficiency of photosystem II (Fv/Fm) in the morning, and NSCs concentration, from June–September. Our results demonstrated that the summer drought reduces the overall performance of physiological traits of the small young trees more than the larger adult trees. Ψpd, gs and Fv/Fm dropped larger in the small-diameter groups than the larger diameter groups. Substantial osmotic adjustments were observed in small size individuals (with lower π100 and Ψtlp) to cope with summer drought. Furthermore, mean concentration of NSCs for the leaf and shoot were higher in September than in July in every basal stem diameter classes suggested the leaf and shoot acted as reserve for NSC. However the root NSCs concentrations within each basal stem diameter class exhibited less increase in September than in the July. At the same time, the small young tress had lower root NSCs concentrations than the larger adult tree in both July and September. The contrasting root NSC concentrations across the basal stem diameter classes indicated that the roots of smaller trees may be more vulnerable to carbon starvation under non-lethal summer drought. The significant positive relationship between rooting depth and physiological traits & root NSCs concentration emphasize the importance of rooting depth in determining the seasonal variation of water status, gas exchange and NSCs.

Wind affects the growth, root anchorage and tensile strength of Australian pine (Casuarina equisetifolia) seedlings

ABSTRACTAustralian pine (Casuarina equisetifolia Forst.) is an important introduced reforestation species in windbreaks for agroforestry and ecological engineering. Nevertheless, the adaptive mechanism of its roots to withstand wind has not yet been fully investigated. In this study, a wind tunnel test was applied to investigate the effects of wind on growth, root architecture, root anchorage and tensile strength of Australian pine seedlings using root excavation method, pullout test and tensile test. After eight months of treatment with simulated wind load (8.2 m s−1) during the day, the non-wind-stressed control seedlings developed taller height (118%), larger stem base diameter (110%), root biomass (100%), shoot biomass (228%), and longer taproot length (56%) than those of wind-stressed seedlings. Furthermore, the wind-stressed seedlings distributed more roots at the windward side than at the leeward side, whereas the control seedlings distributed their root systems in all directions. The average maximum pullout resistance (0.25 ± 0.11 kN) of the control seedlings was significantly higher than that of the wind-stressed ones (0.08 ± 0.04 kN). Additionally, the control seedlings had significantly higher root tensile strength than the wind-stressed ones in 0–1, 1–2 and 2–5 mm root diameter classes, respectively. These results demonstrate that wind stress significantly decreases growth performance, root anchorage capability and tensile strength of Australian pine seedlings.

Maintenance of the Economic Performance of Eucalyptus in Competition With Weeds

The aim of this study was to evaluate the growth of the hybrid clone Eucalyptus grandis × Eucalyptus urophylla submitted to competition with weeds and determine the period prior to economic loss (PPEL). The experiment was carried out in Ulianópolis, Pará State, Brazil, and consisted of the treatments continuous control and no control of weeds. Weed management was carried out by integrating both mechanical and chemical control. Stem base diameter, height, canopy diameter of eucalyptus plants were measured on the 16th month after planting. Wood volume was estimated by means of a volumetric equation. The treatments continuous control and no control of weeds were compared using the Hotelling’s T2 test and the parameters for PPEL calculation were defined from volume estimation. The treatment continuous control promoted significant gains in eucalyptus growth. PPEL tended to be reduced by 3.8287 and 0.2393 units with the increase of a unit in the price of wood and the increase of planting yield, respectively. For different eucalyptus wood prices, the calculated PPEL ranged from 40 to 161 days of coexistence with weeds.

Magnesium Sources and Inoculation with Azospirillum brasilense in the Initial Development of Maize

The aim was to evaluate the initial development of maize plants when submitted to mineral fertilization with magnesium sources in the presence or absence of seed inoculation with Azospirillum brasilense. To do so, was conducted an experiment in greenhouse. In the essay was adopted a randomized blocks design, in a factorial scheme 3 × 2, represented by the magnesium sources: magnesium sulfate (MgSO4), magnesium oxide (MgO) and control without Mg fertilization, in the presence or absence of inoculation with A. brasilense. The Mg sources were supplied with a dose of 30 kg ha-1, being homogenized in the substrate before sowing the crop. The analysis were carried out in the V4 stage, evaluating: basal stem diameter (BSD); relative chlorophyll content (SPAD index), leaf dry mass (LDM), stem + sheath blade dry mass (SSDM) and root dry mass (RDM). No differences were observed for the factors interaction and for the Mg sources. When considered the seed inoculation there was increases of 7.1%; 6.61%; 19.23%; 28.32%; and 15.17 %, for basal stem diameter, SPAD index, leaf dry mass, stem + sheath blade dry mass and roots, respectively. The inoculation of maize seeds with A. brasilense increases the initial development of maize plants and the SPAD index in greenhouse conditions in the V4, while the fertilization with the magnesium sources do not interfere in the maize development.

Ecophysiological response of Lippia gracilis (Verbanaceae) to duration of salt stress

The objective of this work was to investigate the effects of salinized water on Lippia gracilis by determining the ion accumulation capacity and morphophysiological changes as a function of salinity and time of exposure to stress. L. gracilis was irrigated with water containing different concentrations of salts and electrical conductivities. The analyses were conducted 25 and 50 days after stress (DAS), in leaf, stem/branches, and roots. Plant height (Hplants), basal stem diameter (Φstem), and mean unitary leaf area (ULA) were determined. After that, the plant material was dried, and the total dry biomass (TDB) (in g plant−1), leaf dry biomass (LDB), stem dry biomass (SDB), and the roots dry biomass (RDB) were determined. Based on these data, the following variables were calculated: total leaf area (TLA) in cm2 plant−1; biomass allocation fraction (BAF) obtained by dividing the biomass of the stem, leaves, and roots, separately, with the total plant biomass; relative growth rate (RGR); net assimilation rate (NAR); leaf area ratio (LAR); specific leaf area (SLA); and sclerophylly index (SI). The concentrations of potassium and sodium ions were quantified by atomic absorption spectrophotometry and the chloride ion concentration was determined by argentometric titration. L. gracilis showed a variable response to salt stress as a function of time, having a considerable capacity to withstand an increasing load of toxic ions, while maintaining a positive growth rate, highlighting the potential use of the species in moderately saline environments.

Developing allometric models to predict the individual aboveground biomass of shrubs worldwide

AbstractAimExisting global models to predict standing biomass are based on trees characterized by a single principal stem, well developed in height. However, their use in open woodlands and shrublands, characterized by multistemmed species with substantial crown development, generates a high level of uncertainty in biomass estimates. This limitation led us to (a) develop global models of shrub individual aboveground biomass based on simple allometric variables, (b) to compare the fit of these models with existing global biomass models, and (c) to assess whether models fit change when bioclimatic variables are considered.LocationGlobal.Time periodPresent.Major taxa studied118 species of shrubs.MethodsWe compile a database of 3,243 individuals across 49 sites distributed worldwide. Including stem basal diameter, height and crown diameter as predictor variables, we built potential models and compared their fit using generalized least squares. We used mixed effects models to determine if bioclimatic variables improved the accuracy of biomass models.ResultsAlthough the most important variable in terms of predictive capacity was stem basal diameter, crown diameter significantly improved the models’ fit, followed by height. Four models were finally chosen, with the best model combining all these variables in the same equation [R2 = 0.930, root mean square error (RMSE) = 0.476]. Selected models performed as well as established global biomass models. Including the individual bioform significantly improved the models’ fit.Main conclusionsStem basal diameter, crown diameter and height measures could be combined to provide robust aboveground biomass (AGB) estimates of individual shrub species. Our study supplements well‐established models developed for trees, allowing more accurate biomass estimation of multistemmed woody individuals. We further provide tools for a methodological standardization of individual biomass quantification in these species. We expect these results contribute to improve the quality of biomass estimates across ecosystems, but also to generate methodological consensus on field biomass assessments in shrubs.

Substrates Formulated with Biochar for Seedling Production of Moringa oleifera Lam.

Moringa oleifera is an allogamous plant that is propagated by seeds and cuttings, rich in vitamin A and C, phosphorus, calcium and proteins. However, its best propagation form for the large-scale production is still unknown, as well the most suitable substrate for seedling production. Production of forest species seedlings with a high quality is directly related to physical and chemical substrates properties. Using biochar as substrate for seedlings production is an economical and sustainable solution for this proposal. The aim of this study was to evaluate the influence of three biochar types, in two concentrations, for production of Moringa oleifera seedlings. Three types of substrates were formulated using residues of dry coconut shells, sewage sludge and orange bagasse. The experiment was carried out in a greenhouse, installed in a completely randomized design, consisting of seven treatments (substrates formulated with biochar in two doses, 1 and 2%) and the control, with four replicates, totalizing 28 seedlings. One month after sowing, the seedlings were evaluated biweekly for 60 days in relation to stem base diameter, shoot heigh, leaves number, shoot dry matter, root dry matter, total seedling dry matter and Dickson Quality Index. The substrate formulated using sewage sludge biochar at 2% provided a greater increasing in shoot dry matter. This concentration improved seedling height and stem base diameter in 10.5 and 0.83 mm, respectively, compared to the control. In general, biochar improved physical and chemical soil quality, promoting a better M. oleifera seedlings development.

Agricultural Practices for Growing Kenaf in Iowa: I. Morphology, Stem, and Fiber Yield

Core Ideas Two kenaf cultivars were compared for stem fiber yield under combinations of planting rate, row spacing, and N fertilization rate. Tainung 2 produced greater stem fiber yield than Whitten. Nitrogen fertilization rate did not influence stem fiber yield. Stand density, core/bast fiber ratio, and basal stem diameter were influenced by three‐way interactions. ABSTRACTKenaf (Hibiscus cannabinus L.) is a promising biorenewable resource for producing natural fibers but few studies have investigated the crop when grown in cooler climates, such as the American Midwest. The objectives of this study were to: (i) determine the agricultural practices (row spacing, seed, and N rates) leading to optimal kenaf dry matter (DM) stem and fiber yield in cultivars Tainung 2 and Whitten; (ii) evaluate stem height, basal diameter, and leaf area index (LAI) over the growing season; and (iii) assess the influence of management practices on fiber (bast and core lignocellulose) composition, and–2C, N, and total ash concentration. Kenaf cultivars Tainung 2 and Whitten were planted in Boone County, Iowa,–2in 2014 and 2015 at 247,000 or 371,000 seed ha−1, in 38‐cm or 76‐cm rows that received 0, 56, 112, 168, or 224 kg N ha−1. Stand density, core:bast fiber ratio, and basal stem diameter were influenced by three‐way interactions. Stem height at harvest was influenced by the main effects of row spacing, seeding rate, and N fertilization rate. Nitrogen fertilization did not influence stem DM yield, regardless of application rate. Kenaf is a promising multi‐purpose crop that could contribute to the natural fiber marker, as well as diversifying the landscape. Kenaf is well adapted to Iowa and can be produced with a range of management practices.

BIOLOGICAL MANAGEMENT OF Pratylenchus brachyurus IN SOYBEAN CROPS

ABSTRACT The efficiency of biological products combined with biological fertilization for controlling Pratylenchus brachyurus in soybean crops, and effects of these treatments on soybean crops were evaluate. A greenhouse experiment was conducted at the Mato Grosso State University, in Brazil, using a randomized block design with a 10×2 factorial arrangement, and four replications. The treatments consisted of Trichoderma asperellum, B. subtilis, Purpureocillium lilacinum, B. subtilis + T. asperellum, B. subtilis + P. lilacinum, T. asperellum + P. lilacinum, B. subtilis + T. asperellum + P. lilacinum and abamectin, and Controls with, and without nematodes. Nematode population, plant height, stem base diameter, and soil microbiological characteristics (at 60 and 120 days after sowing - DAS), shoot dry weight (60 DAS), and number of pods per plant, and grain yield (120 DAS) were evaluated. The treatments were efficient for the control of phytonematodes at 60 DAS; the efficiency of treatments with biological products increased when combined with biological fertilization. The biological products were more efficient for controlling the nematodes than abamectin at 120 DAS; and the percentage of control were higher when they were combined with biological fertilization, in both growing periods. The biological treatments resulted in better agronomic characteristics, and higher number of pods per plant, and grain yield, affecting the plants in the first growing period, and significant interaction with the biological fertilizer for these variables in the second growing period. The interaction between treatments and biological fertilization was significant for soil microbiological characteristics in the second growing period.

Early seedling establishment of endangered and valuable tree species in cloud forest restoration plantings

Tropical montane cloud forests (TMCF) host high biodiversity and endemicity and are severely threatened by illegal selective logging, deforestation, fragmentation and climate change. The fragments of TMCF present high heterogeneity over short spatial intervals and a regional forest restoration approach must therefore incorporate seedling performance throughout the TMCF elevation range. We examined early seedling establishment in 12 endangered and valuable TMCF species in the understory of unplanned selectively logged TMCF and assessed the influence of elevation and canopy cover on seedling performance. Tree seedlings (10-18 mo-old) were transplanted into restoration plantings in 6 forest sites along an elevation range (1,250 to 1,995 m) in Veracruz, Mexico. In each forest, 30 seedlings per species were planted and their survival and relative growth rates in height (RGRh) and basal stem diameter (RGRd) recorded, along with canopy cover. Survival was high for all species after one year (81.1 to 99.4%) and was unaffected by elevation. Canopy cover positively affected the survival probability of 3 species. Both RGRh and RGRd decreased at lower elevations in 4 species; however, overall growth rates were positive. Our results indicate a positive early seedling establishment response in the evaluated tree species under the TMCF canopy (66-97% of canopy cover).

Identifying traits at crop maturity and models for estimation of lodging susceptibility in bread wheat

Lodging is the permanent displacement of plant shoots from an upright position and represents a major obstacle to reaching yield potential in bread wheat (Triticum aestivum L.). Breeding programs would benefit from the identification of lodging-related traits amenable to easy and rapid screening, even in the absence of lodging. However, no locally tested lodging model is available for the Pampas region of Argentina, and most lodging models are based on measurements before crop maturity. We adapted two existing models and generated a new one, using easily measurable traits at crop maturity in 24 cultivars (14 for model fit and 10 for model validation) grown in plot trials with no nutritional, water or disease restrictions in three crop seasons at Balcarce, Argentina. Of 17 traits evaluated, 16 showed differences between cultivars (P<0.05), and in 11 of these traits, no genotype×environment interaction was detected (P>0.05). Estimations of the safety factor against stem lodging, proposed by Crook et al., and the wind velocity that produces lodging, proposed by Berry et al., showed a high correlation with lodging score (R2=0.60 and 0.72, respectively), but when the estimators were tested with another set of cultivars there was no association. A new empirical regression model was based on three traits measured at maturity: plant height, spike dry weight, and the inertia moment of the stem base (stem resistance to bending estimated from stem diameter and wall thickness). The model was then simplified by replacing the third trait with basal stem diameter, and it showed an even better fit (R2=0.90). These models were satisfactorily validated by rank correlations with a different cultivar set. The regression model proposed in this study can easily be applied to the evaluation of commercial cultivars and may be used to screen breeding materials. Measurements at maturity are convenient and easy to combine with other traits of possible selective advantage.

Morphology of yellow passion fruit seedlings submitted to triazole induced growth inhibition

ABSTRACT Inhibiting seedling vegetative growth may be a strategy for improving modulation against biotic and abiotic stresses after transplanting. The objective of this study was to evaluate morphological responses of yellow passion fruit (Passiflora edulis) seedlings to growth inhibition resulted from the application of an inhibitor of gibberellin biosynthesis. The experiment was carried out in a greenhouse using seedlings grown in 290 cm3 polyethylene tubes. At 40 days after emergence, trays containing the seedlings were immersed in solutions at concentrations of 0, 40, 80, 120 and 160 mg (Paclobutrazol) PBZ L-1 up to substrate saturation. These five treatments were laid out in a randomized block design with four replicates. At 15, 30 and 45 days after PBZ application (DAA), basal stem diameter was measured; at 45 DAA, stem diameter, individual leaf area, specific leaf area, root diameter and root volume were measured, lignin content and the anatomy of leaves, stems, and roots were analyzed. Triazole-induced anatomical alterations in stems, leaves and roots cause morphological traits and intensify the specific reagent staining of phenolic compounds and lignin in yellow passion fruit (Passiflora edulis) seedlings.

Calcium and Magnesium Ratio in Alfalfa Cultivation

The Alfalfa is an important forage for animal feeding, used in breeding of specialized herds due to its high protein content, besides having high palatability and energy value. In this context, the objective of this study was to evaluate the effect of calcium and magnesium ratio in the correction of Oxisol for the cultivation of alfalfa (Medicago sativa L.) cv. Creole. The experiment was conducted in the greenhouse at Federal University of Mato Grosso, Campus Rondonopolis-MT. The experimental design was completely randomized with nine treatments relating about calcium/magnesium nutrients: 0/0; 1/0; 0/1; 3/1; 6/1; 9/1; 12/1; 15/1 and 18/1, with 5 repetitions. The evaluated variables were plant height, number of leaves, number of basal shoots, SPAD index, stem diameter, fresh and shoot dry mass, root dry mass and root volume, soil pHCaCl2 and water use efficiency. The results were submitted to analysis of variance and Scott-knott test (p ? 0.05). Both the first and second cut, plant height was lower (24.76 ± 2.57 and 32.82 ± 13.01 cm, respectively) in absence of fertilizers (0/0) in relation to the other ratios. However, the treatments with Ca and/or Mg did not vary significantly, with a mean of 38.07 ± 2.94 and 51.73 ± 7.43 cm, in the first and second cut, respectively. The shoot dry mass showed similar behavior. Lower mass was observed in absence of Ca/Mg in the first cut (1.12 g DM pot-1) and second cut (1.84 g DM pot-1). In the other relations, it was observed a mean of 2.90 and 4.79 g DM pot-1 between the cuts. Likewise, the production of root was lower in absence of fertilizers (1.66 ± 1.05 g DM pot-1) and the others Ca/Mg ratios did not differ from each other (6.14 ± 1.98 g DM pot-1). The SPAD index there was significant effect only in the first cut between the ratio 0/0 and the others, with a mean of 43.48 ± 2.83 and 48.85 ± 2.19, respectively. In the second cut, SPAD index was 38.47 ± 5.82. Soil pH ranged from 5.87 to 5.31 between the cuts. Alfalfa was low sensitive to calcium and magnesium ratios in soil correction, but responded positively to the plant development with increased base saturation.

Potential use of biochar in raising machine-transplanted rice seedlings

Improving seedling quality is important for obtaining high yield in machinetransplanted rice production. In recent years, it has been of interest to use biochar in growing media. However, limited information is available on the potential use of biochar in raising machine-transplanted rice seedlings. This study was conducted to provide such information through determining the effects of biochar addition on machine-transplanted rice seedling traits in a tray experiment. Root length, surface area, volume, and biomass of machine-transplanted rice seedlings grown in nursery soil amended with biochar at a volume-by-volume ratio of 3: 1 (NMSC) were 21–53% greater than those in soil only (NMS). Leaf area, height, basal stem diameter and shoot biomass were 6–21% greater in machinetransplanted rice seedlings grown in NMSC than in NMS. Water culture test showed that number of newly formed roots was 42% more in machine-transplanted rice seedlings grown in NMSC than in NMS. Length of the longest new root was 13% longer in machinetransplanted rice seedlings grown in NMSC than in NMS. These results suggest that biochar presents a potential use in raising machine-transplanted rice seedlings.

Pine recolonization dynamics in Mediterranean human-disturbed treeline ecotones

Worldwide treelines seem to share a twofold condition: over 50% of them are advancing and 50% appear to be static. In this study we compared the encroachment patterns of four pine species across anthropogenic treelines in Southern Europe. Using a synchronic approach, we studied structure and recent spatio-temporal patterns of pine recruitment at upper treeline ecotones in Albania, Italy, Montenegro and Spain. Within altitudinal transects we mapped and sampled 964 living individuals of Pinus heldreichii, Pinus peuce, Pinus sylvestris and Pinus uncinata growing above the current forest line. We measured their basal diameter, total height, and counted the number of seed cones. We differentiated seedlings (height < 0.5 m) from saplings (0.5 m ≤ height < 2 m) and trees (height ≥ 2 m). From individuals with basal stem diameter >4 cm we extracted one increment core for cambial age determination and tree-ring width measurements. On smaller specimens, we estimated the age by counting annual internodes (terminal bud scars) along the whole stem. We compared the ground cover around each pine, applied point pattern analyses, modelled the probability of seed cone production and estimated the average distance of seed dispersal. The four pine species exhibited heterogeneous density values (87-1552 N° ha−1). The overall averaged means ranged 2–7 cm for basal diameter, 54–106 cm for total height and 9–20 years for cambial age, suggesting a recent encroachment process. None of these structural variables decreased with increasing relative altitude and distribution patterns exhibited a few higher density spots but not cohort spatial structure. Ground cover differed between species and more significantly between size classes. Grass was the most frequent type at all sites except for P. sylvestris where shrubs prevailed (>50%). Further differences appeared when discriminated by height thresholds, with larger share of saplings and trees neighboring shrubs and rocks. Basal area increments increased from 1990 and stabilized in recent years at all species except for P. peuce. Height and basal diameter predicted cones production better than cambial age. P. heldreichii and P. peuce dispersed seeds at longer distances than P. uncinata and P. sylvestris, suggesting different potential for further encroaching. Pine recruitment above the forest lines is quite synchronic at all sites (last 30 years), but in some cases it appeared as a high altitude tree densification process, whereas in others as a starting treeline advance. The use of permanent transects provides a detailed monitoring of tree survival and a more precise prediction of future treeline expansion.

Impact of the shoot-boring moth Dichrorampha odorata (Lepidoptera: Tortricidae) on growth and reproductive potential of Chromolaena odorata (Asteraceae) in the laboratory

ABSTRACTA 9-month laboratory study was carried out to determine the impact of herbivory by a moth with shoot-boring larvae, Dichrorampha odorata Brown and Zachariades (Lepidoptera: Tortricidae) on growth and reproductive ability of its host plant, Chromolaena odorata (L.) King and Robinson (Asteraceae), a major invasive alien plant species in southern Africa. Newly hatched D. odorata larvae were inoculated onto 0 (control), 50 and 100% of the shoot tips of C. odorata in the laboratory. At all treatment levels, the basal stem diameter of C. odorata was not affected by D. odorata larval feeding. Larval feeding by D. odorata significantly reduced the height of the main shoot and flower production in C. odorata relative to the control treatment but promoted branching by increasing the number of shoot tips. However, the differences in plant height and number of flowers between the 50 and 100% inoculation levels were not statistically significant. Dichrorampha odorata is the first shoot-tip attacking agent that is being released as a biological control agent against C. odorata in South Africa. In general, the impacts of D. odorata on the weed were relatively small even though statistically significant. The findings of this study suggest that high levels of damage by the moth will modestly reduce the height, flower production, and the competitiveness of C. odorata, thereby contributing to the biological control of the weed in South Africa.

Substrates to produce Jambolan (Syzygium cumini) seedlings

Jambolan ('Syzygium cumini' L., also known as jambul, java plum, Portuguese plum, among others) is used as an ornamental, medicinal and edible plant and, given its large and diverse uses, high-quality seedlings are desired for fruit farming. This study sought to evaluate the growth and formation of 'Syzygium cumini' seedlings in several substrates. The experiment was conducted in a completely randomized design, with 13 treatments comparing different substrates (S) made with different proportions of bovine manure, subsurface soil, Bioplant, superfine vermiculite and fine sand. Growth variables of the seedlings, such as height, stem base diameter, mass and biometric ratios were evaluated. Substrates containing 10 to 30% bovine manure and 20 to 40% vermiculite, as in S7 (30%BM+30%SS+10%BP+20%FV+10%FS) and S9 (S9=10%BM+30%SS+10%BP+40%FV+10%FS), yielded the best seedlings with adequate values for diameter, mass and Dickson quality index. Substrates with the largest amounts of bovine manure (50%) showed the worst mass distributions. Substrates with high amounts of Bioplant or fine sand are not recommended for jambolan seedling formation.

Nitrogen supplementation improves the high-light acclimation of Guazuma ulmifolia Lam. seedlings

High nitrogen supply prevents dynamic photoinhibition in Guazuma ulmifolia seedlings and improves their morphophysiological quality during the high-light acclimation in the nursery. Acclimation under full sun is an important step in the production of tree seedlings in nurseries because it increases plant resistance to stressful conditions. Thus, the development of management techniques that improve high-light acclimation could facilitate the production of higher-quality seedlings. Given the importance of nitrogen (N) for plant growth and photosynthetic metabolism, here we evaluated whether supplementation with high N levels (HN) could positively affect the high-light acclimation of seedlings of Guazuma ulmifolia Lam., a tree species widely used in reforestation programs in the neotropics. We compared the morphophysiological parameters of seedlings transferred from the shaded sector of the nursery to full sun that were supplemented with or without HN. HN supply prevented the midday depression of both photosystem II (PSII) activity and the CO2 assimilation rate, suggesting the avoidance of dynamic photoinhibition by HN. This effect was related to HN-induced increases in the electron transport rate of PSII, carboxylation efficiency and mesophyll conductance to CO2 and not to reduced stomatal limitation. A decrease in excess excitation energy in PSII resulting from energy-demanding N assimilation, as suggested by increases in the light saturation points of the CO2 assimilation and PSII electron transport rates, might also contribute to the protective effect of N. In addition, HN treatment increased seedling biomass accumulation and stem base diameter, enhancing the Dickson quality index of the acclimated seedlings. Overall, these results indicate that HN supply during high-light acclimation in the nursery improves the morphophysiological quality of G. ulmifolia seedlings.