Stem Diameter Growth Research Articles

The Aboveground Biomass Allometry and Carbon Stocks of Serial Age Planted Rhizophora apiculata in Northern Sumatra, Indonesia

The biomass and carbon stocks of 2, 6 and 10 year planted mangroves were studied through destructive method of weighting each tree component. The objective was to establish new allometries and carbon production of R. apiculata. Two aboveground biomass allometries of R. apiculata have been developed based on D₃₀ (AGB_D = 0.1224 D₃₀^2.3380) and D₃₀²H (AGB_DH=0.1508 D₃₀²H^0.7793). Accuracy level of aboveground biomass estimation was 85.40% to the actual values of destructive calculation. Each biomass allometric equation can be applied accurately when the estimated mangrove ecosystem has similarity in species, age, tree-density, wood-density and growth factors of mangrove ecosystem where allometry is established. The allometric equation of above-ground carbon stock AGC_D=0.0368D₃₀^2.5996 (based on stem diamater) and AGC_DH=0.0422D₃₀²H^0.8730 (based on combined stem diameter and tree height) can be used to estimate the R. apiculata carbon stocks of non-destructive measurement. However, the accuracy level of AGC_D and AGC_DH allometries used to estimate non-destructive R. apiculata carbon stocks was 60.14% and 79.72% to the actual carbon value of destructive study. The average aboveground carbon stocks of 2 – 10 year R. apiculata were 37.2 MgC ha^-1 (destructive actual value), 30.2 MgC ha^-1 (D₃₀²H), and 29.9 MgC ha^-1 (D₃₀) respectively. It is concluded that the estimated allometric values of aboveground biomass and carbon productions of restored mangroves are closely related to the growth of stem diameter and tree height, but its values are lower than destructive actual value.

More timber from fewer trees – determining what tree density optimises silver beech merchantable yield based upon a long-term thinning trial

Background: The tree stem density which optimises merchantable timber yield (volume per unit area) is unknown for most of New Zealand’s indigenous tree species. While moderate thinning of even-aged stands can promote yield, intense thinning may decrease yield by creating space that cannot be filled by residual trees, increasing tree mortality or reducing tree height. We quantified the effects of density on silver beech (Lophozonia menziesii (Hook.f.) Heenan & Smissen) tree growth, height and mortality, identified the density leading to optimal merchantable yield and assessed if this density varied with stand age. Methods: Tree stem diameter growth, height, and mortality responses to density were determined using tagged individuals monitored over time on a long-term thinning trial combined with flexible, multilevel, non-linear models. Empirical stand yield responses to density were determined and compared to yield–density relationships in simulated stands. The stand simulations projected beyond the monitored stand ages using the tree-level responses fitted to empirical data. Results: Low densities (≤400 stems ha-1) sustained fast tree growth for longer than high densities (≥700 stems ha-1) after thinning, but density did not consistently affect merchantable tree heights. The probability of tree mortality increased after intense thinning, but only temporarily, and never exceeding c. 0.01 year−1. A regression of yield–density relationships identified an empirical optimum of c. 570 stems ha–1 for stand ages of 48 and 58 years. At this density, merchantable yield at 58 years was seven-fold greater than that in unthinned stands. The simulations suggested moderately higher densities for optimal yield than our empirical optimum, a moderate increase in optimal densities with stand age, and that c. 90 % of potential cumulative yield was attained at 80 years. Conclusions: Because thinning increased tree growth, but had minimal effect on tree mortality, our results alleviate concerns about the stability and productivity of thinned stands. Densities that optimise yield are about two-fold greater than those previously recommended for silver beech and they remain relatively stable as stands age. This suggests that a single density will be adequate for a range of harvest ages, although harvest should take place before a stand age of 80 years. Such conclusions are relevant to managing regeneration within coupes harvested under existing legislation and to areas planted with silver beech.

Drought tolerance differs between urban tree species but is not affected by the intensity of traffic pollution

Key MessageIn an urban area, resistance and resilience of stem diameter growth differ substantially between tree species. Traffic emissions are reflected in wood nitrogen isotopes, but do not affect drought tolerance.With increasing drought and heat, the benefits of urban trees such as shading and cooling become more important. Yet, it is necessary to identify tree species able to withstand such extreme climatic conditions. We studied the resistance and resilience of stem diameter growth of five deciduous tree species in an urban area in Southwest Germany to three exceptional drought periods (2003, 2011 and 2015) for differences between and within species, especially considering the intensity of traffic emissions (NOx). Analyses of the stable isotopic composition of carbon (δ13C) and oxygen (δ18O) as well as the intrinsic water-use efficiency (WUEi) in the tree rings were carried out. Further, we investigated the stable isotopic composition of nitrogen in the wood (δ15N) to assess its potential as an indicator of NOx emissions from traffic. Stem diameter growth in all species was strongly limited by low water availability in spring, as was also reflected in elevated δ13C and δ18O values in Acer platanoides and Tilia cordata, which were particularly sensitive to drought. In contrast, growth of Platanus × hispanica and Quercus robur was less affected by drought, and resistance of Carpinus betulus ranged in between. Across species, δ15N was higher in trees located closer to roads and exposed to higher NOx traffic emissions. Unexpectedly, these conditions did not significantly affect drought resistance/resilience. Our study demonstrates the potential and interpretative challenges of coupled dendroecological and isotope analyses. It also indicates clear species-specific differences in drought tolerance and thus helps to identify suitable urban tree species.

Effects of Climate and Drought on Stem Diameter Growth of Urban Tree Species

Urbanization and climate change are two inevitable megatrends of this century. Knowledge about the growth responses of urban trees to climate is of utmost importance towards future management of green infrastructure with the aim of a sustainable provision of the environmental ecosystem services. Using tree-ring records, this study analyzed growth response to climate by stem diameter at breast height (DBH) of 1178 trees in seven large cities worldwide, including Aesculus hippocastanum L. in Munich; Platanus × hispanica Münchh. in Paris; Quercus nigra L. in Houston; Quercus robur L. in Cape Town; Robinia pseudoacacia L. in Santiago de Chile, Munich, and Würzburg; and Tilia cordata Mill. in Berlin, Munich, and Würzburg. Climate was characterized following the de Martonne aridity index (DMI). Overall, trees showed an 8.3% lower DBH under arid than humid climate at the age of 100. Drought-tolerant tree species were overall not affected by climate. However, R. pseudoacacia showed a lower diameter when growing in semi-dry than humid climate. In contrast, drought-sensitive tree species were negatively affected by arid climate. Moreover, the effect of drought years on annual diameter increment was assessed. P. × hispanica and R. pseudoacacia appeared as the most drought-resistant species. The highest sensitivity to drought was detected in T. cordata and Q. robur. A. hippocastanum and Q. nigra showed a lower diameter growth during drought events, followed by a fast recovery. This study’s findings may contribute to a better understanding of urban tree growth reactions to climate, aiming for sustainable planning and management of urban trees.

Linking crown structure with tree ring pattern: methodological considerations and proof of concept

Key messageStructural characteristics of tree crowns obtained by TLidar scanning can be used for estimating the course of the stem diameter growth in the past.To improve human well-being through sustainable management of ecosystems, particular attention is given to the structures, functions, and services of forest trees and stands. The classical timber provision has become only one of many other forest ecosystem services. At the same time, the methods of ecosystem observation, analysis, and modelling have enormously improved. Here, we fathomed the information potential of the tree crown structure. Our overarching hypothesis was that the crown structure reflects essential characteristics of the tree ring pattern. The empirical part of this study was based on sample trees from the combined spacing-thinning trial in Norway spruce (Picea abies [L.] Karst.) Fürstenfeldbruck 612 in Southern Germany. First, we showed that the external characteristics of tree crowns and the internal stem structure are functionally linked. Second, we derived metrics for the tree ring pattern and crown shape, and found especially close relationships between the level and bending of the growth curve and the size and stereometric shape of the crown. Third, we investigated how the derived statistical relationships between tree ring pattern and crown structure can be applied to derive the course of tree growth from the crown structure. We showed how measures such as size and variability of the crown could be used to estimate the course of diameter growth. Finally, we showed that the revealed link could be used to assess past and future growth and life expectancy of trees. These findings can be used to monitor the stress defence potential, resistance, and resilience of trees.

Utilization of Bokasi Solid Organic Fertilizer on Corn Plants (Zea mays, L) in Matang Seping Village, Aceh Tamiang

This study aims to determine the effect of the dose of solid bokashi fertilizer and determine the best dose on the growth of maize (Zea mays L.). The research was carried out in Matang Seping Village, Kec. Banda Mulia, Kab. Aceh Tamiang. The time of the study was carried out from October to December 2019. This study used a Randomized Block Design (RAK), which was given treatment and was non-factorial. The dose factor of bokashi fertilizer with notation (P), which consists of levels, namely: P0 = Without Bokashi, P1 = 200 grams, P2 = 300 grams, P3 = 400 grams. , 4th week and 6th week gave a significant effect on P3 treatment, namely at a dose of 400 grams/plant on the growth of plant height, stem diameter and number of leaves on corn (Zea mays L.).2.Use of solid bokashi fertilizer in the 2nd week, 4th week to 6th week can spur the growth of corn plants so that it has a significant effect on plant height, stem diameter and number of leaves on corn plants (Zea mays L.) in P3 treatment with a dose of 400 grams / plant.

Diameters of phloem sieve elements can predict stem growth rates of woody plants.

Understanding forest dynamics is crucial to addressing climate change and reforestation challenges. Plant anatomy can help predict growth rates of woody plants, contributing key information on forest dynamics. Although features of the water-transport system (xylem) have long been used to predict plant growth, the potential contribution of carbon-transporting tissue (phloem) remains virtually unexplored. Here, we use data from 347 woody plant species to investigate whether species-specific stem diameter growth rates can be predicted by the diameter of both the xylem and phloem conducting cells when corrected for phylogenetic relatedness. We found positive correlations between growth rate, phloem sieve element diameter and xylem vessel diameter in liana species sampled in the field. Moreover, we obtained similar results for data extracted from the Xylem Database, an online repository of functional, anatomical and image data for woody plant species. Information from this database confirmed the correlation of sieve element diameter and growth rate across woody plants of various growth forms. Furthermore, we used data subsets to explore potential influences of biomes, growth forms and botanical family association. Subsequently, we combined anatomical and geoclimatic data to train an artificial neural network to predict growth rates. Our results demonstrate that sugar transport architecture is associated with growth rate to a similar degree as water-transport architecture. Furthermore, our results illustrate the potential value of artificial neural networks for modeling plant growth under future climatic scenarios.

Short-term suboptimal low temperature has short- and long-term effects on melon seedlings

Crop adaptation to environmental changes showed a short-term effect characterized by physiological and biochemical changes, and a long-term effect characterized by changes in dry matter accumulation. The effects of suboptimal low temperature (15 °C/10 °C, day/night, 5 days) on physiological characters, growth and development were investigated in 16 genotypes of melon seedlings. For short-term effect, suboptimal low temperature mainly induced free proline (up to 179.5%) and soluble sugar accumulated (up to 181.4%), impaired plasma membrane, and inhibited chlorophyll biosynthesis and PSII activity. For long-term effect, it mainly inhibited plant height and the first female flower opening (FFFO), but promoted stem diameter growth. Comprehensive analysis showed that nine indicators were suitable for assessing suboptimal low temperature effect on melon seedlings, including chlorophyll content (total, chl.a and chl.b), plant height, internode length, stem diameter, free proline, soluble sugar, and FFFO. Furthermore, sixteen genotypes were divided into four groups based on the nine parameters. Cluster I was characterized by high chlorophyll content and plant height (two genotypes); Cluster II was mainly characterized by intermediate value in 7 - 8 indexes (five genotypes); Cluster III was characterized by most indexes were about one third of the maximum value (seven genotypes); Cluster IV was characterized by lower value in all indexes (two genotypes). Our research can provide detailed data to clarify the response characteristics of different melon populations to suboptimal low temperature, and provide reference for cold acclimation of melon and other cucurbits in practice.

Growth and gas exchange of soursop under salt stress and hydrogen peroxide application

ABSTRACT The cultivation of irrigated soursop in semiarid Northeastern Brazil highlights the need for information regarding its responses to the salinity of irrigation water and the use of techniques that allow its exploration, such as the use of hydrogen peroxide. Thus, the study aimed to evaluate the effect of soaking of seeds and foliar application of hydrogen peroxide on soursop plant growth and physiology under conditions of salt stress. The study was conducted in lysimeters in a greenhouse, and the treatments were distributed in a randomized block design and 4 × 4 factorial scheme, with four values of electrical conductivity of the irrigation water - ECw (0.7, 1.7, 2.7, and 3.7 dS m-1) and four concentrations of H2O2 (0, 25, 50, and 75 μM), with three replicates and one plant per plot. H2O2 concentrations were applied via seed imbibition and foliar spray. Irrigation with water from 0.7 dS m-1 impairs gas exchange and absolute growth rates of plant height and stem diameter and relative growth rate in height of soursop plants. Concentrations of 35, 33 and 23 µM of hydrogen peroxide favored the relative and absolute growth rates of plant height and transpiration, respectively. Compared to the aerial part, the root of soursop plants is more affected when irrigated with water from 1.6 dS m-1.

Dynamics of nonstructural carbohydrates in a deciduous woody species from tropical dry forests under recurrent water deficit.

In tropical dry forests, both the dry and the short rainy seasons have become increasingly irregular. This study replicated these conditions to investigate the effects of two water deficit cycles on Cenostigma microphyllum seedlings. Impacts were assessed by measuring growth traits, water relations, gas exchange, and dynamics of nonstructural carbohydrate (NSC) content in the whole plant under greenhouse conditions in potted plants. In the first water deficit cycle, the leaf relative water content (RWC) was maintained at the expense of a rapid drop in gas exchange. Furthermore, there was a slight accumulation of NSC, mainly soluble sugars (SS) in the stem wood and roots, to the detriment of height and stem diameter growth. In the second cycle, the leaf RWC remained 40% higher than the lowest level measured in the first water deficit, and CO2 assimilation remained twice as long in previously stressed plants. The SS content of the stems and roots was strongly correlated with the predawn leaf RWC. No strong reduction was observed in the bark stock even with the gradual increase of SS in the wood. Our data suggest that under recurrent water deficit prior to leaf drop, CO2 assimilation is maintained, with the highest possible leaf RWC, under reduced stomatal conductance. This assists in SS transport to wood and root, which is no longer used to support the growth of the aboveground parts.

Growth and Quality of Yerba Mate Seedlings Affected by Fertilizer Doses in South Brazil

Given the lack of information on the use of controlled-release fertilizers in yerba mate seedlings production, this study aimed to evaluate growth and morphological characteristics of seedlings produced with two controlled-release fertilizers applied at different doses. We used seeds from a clonal seed orchard, which were sown in a commercial substrate based on peat and vermiculite, with Osmocote® MiniPrill 3M (CRF 3M) and Basacote® Plus 9M (CRF 9M) fertilizers, both in doses of 0, 2, 4, 6, 8, 10, and 12 kg m-3. Seedling height and stem diameter were measured at 60, 90, 120, and 180 days after sowing and, at 180 days, shoot, root, and total biomass, tube withdrawal ease, and root aggregation. From these data, we calculated Dickson's quality index, technical efficiency, Height/Stem diameter ratio, and maximum technical efficiency dose. We verified values statistically superior to control treatment (0 kg m-3) in all variables in response to controlled-release fertilizer 3M and 9M, demonstrating the viability of yerba mate seedling production using controlled-release fertilizers. This is also evidenced through results obtained for growth in height and stem diameter. Although CRF 3M favored seedling growth, CRF 9M showed similar efficiency. The Osmocote® MiniPrill 3M is more efficient than Basacote® Plus 9M in most of the variables analyzed and has a lower input required to obtain quality seedlings. For these reasons, Osmocote® MiniPrill 3M is indicated to produce yerba mate seedlings in the dose 8.50 kg m-3.

Remineralizer and controlled-release fertilizer increase Mimosa scabrella Benth. seedlings growth

Contextualization: M. scabrella is a native tree species of the Brazilian Mixed Ombrophilous Forest, with a high ecological importance and economic potential. Knowledge gap: There is a lack of information about the use of resources that favour the seedlings production of this species. Purpose: This study aimed to determine the most appropriate doses of controlled-release fertilizer (CRF) combined with the addition of remineralizer for production of M. scabrella seedlings. Methodology: Seedlings were produced using four doses of CRF (0, 4, 8, and 12 kg m-3) and four doses of remineralizer (0 %, 10 %, 20 %, and 30 %), in a 4 x 4 factorial scheme. At 180 days of seedling production, growth in height and stem diameter, shoot (SDB), root (RDB) and total biomass (TDB), and Dickson quality index (DQI) were evaluated. Results and conclusions: The use of remineralizer provided an increase in density and water retention capacity of substrates, as well as a reduction of macroporosity and total porosity. Combined with doses of 4 and 8 kg m-3, CRF contributed to the increase of biomass and DQI. The addition of 10 % remineralizer, associated with 4.0 kg m-3 CRF, provides adequate growth to produce M. scabrella seedlings. Above this percentage of remineralizer and CRF dose, species growth rate is reduced.

Is Cork Growth a Reliable Proxy for Stem Diameter Growth in Cork Oak (Quercus suber L.)? Implications for Forest Management under Climate Change in Mediterranean Regions

Cork-ring widths have been extensively used in dendroecological studies assessing the relationship between cork growth patterns and climate (precipitation and temperature). Generally, cork growth is assumed as a proxy for stem diameter growth to address cork oak (Quercus suber L.) growth sensitivity to climate and cork yield modeling. Cork growth represents a large part of stem radial increment in this species due to the enhanced activity of phellogen when compared to the cambium activity; thus, similar inter-annual variations of cork-ring widths and tree diameter growth might be expected. However, so far, the influence of rainfall and temperature on stem diameter growth has scarcely been addressed; moreover, it is still not clear whether tree size relates, and in what way, to the variations in radial growth of cork and stem diameter and whether these reflect (proportional) quantitative variations in stem basal area growth. In this study, we computed the annual growth of cork and of stem diameter at breast-height in data series of 47 trees, from 2000 to 2012, corresponding to a full cork production cycle. Results showed a tight link between cork-ring width and stem diameter growth indices. However, while cork growth strongly correlated with climate conditions in autumn–winter prior to the growing season, stem diameter growth correlated with climate conditions of the current growing season, and, more importantly, it was tree size-related. The extrapolation from cork-ring increments to stem basal area growth is likely to progressively underestimate tree growth and biomass increment in larger cork oaks and to further bias it due to climate change effects in the Mediterranean region.

Phytotoxicity in Seedlings of Rhizophora mangle (L.) Exposed to 2,4-Dichlorophenoxyacetic Acid under Experimental Conditions

Mangroves are considered one of the most productive ecosystems worldwide, providing multiple environmental goods and services; however, in recent years, there have been modifications and deterioration in the structure and function of these ecosystems, caused by various natural events and anthropic activities, such as the construction of roads, wastewater discharge, unsustainable livestock, and agricultural practices, as well as the impact of chemicals, such as heavy metals, oil spills, and the use of herbicides. In this research, phytotoxic effects on seedlings of Rhizophora mangle were evaluated at an exposure of five dilutions w/v (5%, 10%, 25%, 50%, and 100%) of the commercial presentation of 2,4-dichlorophenoxyacetic acid (2,4-D). Propagules grown in a greenhouse under local tidal regimes were used, so the growth of stem diameter, height, biomass production in root, leaves, and stems, as well as the concentration of chlorophyll a of the exposed seedlings were measured. The comparison of these parameters in seedlings with only seawater presented significant differences (p ≤ 0.05) and inhibitory effects on growth (diameter), the stem concentration of chlorophyll a, and the production of biomass of leaves, stems, and roots. The inhibitory effect of exposure to 2,4-D on chlorophyll production and root biomass is highlighted, with an average decrease of 45% relative to the control. The sensitivity of the Rhizophora mangle seedlings to the applied concentrations of herbicide evidence the inhibitory effects on the morphological variables of biomass production and chlorophyll a production in mangrove leaves.

Stem Radial Growth Is Negatively Related to Tree Defoliation and Damage in Conifers, Northern Italy

Although several manipulative experiments provided evidence for a negative effect of defoliation on tree growth, results from observational studies were less univocal. This may be due to the ability of observed defoliation to reflect the health status of individual trees, to the influence of site condition and to the amplitude of time window used for growth assessment. Here, we investigated the relationship between two tree health indicators (crown defoliation, damage symptoms) and annual (measured by tree-ring width on 69 Norway spruce trees) and periodical (5-year and 10-year diameter increments, 346 trees from five coniferous species) tree growth. Data originated from 14 (seven for tree rings) ICP Forests Level I plots in Trentino, northern Italy. Diameter, defoliation and damage were measured between 1997 and 2011 as part of the annual crown condition survey, while cores for tree-rings were collected on a sub-sample of trees in 2012. We carried out regression modeling combined with model selection in one-step (periodical data) and two-step (annual data) approaches, using moving averages for the annual data with varying time window widths. Our results indicated an overall negative correlation between defoliation and annual or periodical stem diameter growth. The relationship between defoliation and growth changes in relation to the time window considered, and becomes stronger when data are aggregated over longer time windows (>3 years), when also the occurrence of damage symptoms plays a significant role. The effect of the amplitude of the time windows for data aggregation is probably due to the mechanisms behind the defoliation-growth relationship, which may change according to the causal factors involved. In particular, when larger time windows are considered, short-term fluctuations are likely to be smoothed out, and more general patterns may emerge. We concluded that radial growth is significantly negatively related to defoliation, and this supports the use of defoliation as a rapid indicator for forest health and vitality.

Daily variations in tomato stem diameter as a criterion for irrigation management

The process of daily variation in tomato stem diameter is examined in order to justify the use of this parameter to control drip irrigation. Changes in the size of individual plant parts depend on the provision of water, light, heat and nutrients to the production process. Therefore, such plant parameters as leaf temperature, xylem flow rate, fruit and stem diameter can be indicators of availability of necessary resources. The research was carried out in Novosibirsk region in June - September 2020. The value of the range of daily variations in stem diameter, which has a close relationship to relative soil moisture, was used as an indicator of plant water stress. The source of the information is the results of measurements of soil moisture and stem diameter growth of tomato. Experiments to assess the effect of water deficit on stem parameters were carried out on a plant set out in the open ground separately from the rest. Artificial water stress conditions were created by watering once a week. Data were collected using a PM-11z phytomonitor, soil moisture and stem diameter growth sensors. The results of measurements were processed in Microsoft Office Excel program. It was found that the range of daily fluctuations of stem diameter growth depends on moisture availability. When soil moisture is below 30%, the plant experiences water stress and the range of stem diameter fluctuations increases. The maximum growth in stem diameter was observed at 7-10 a.m. and the minimum at 13-15 p.m. local time. The difference between the maximum and minimum of the daily stem diameter increase characterizes the range of the daily stem diameter difference, which correlates closely with soil moisture. The correlation coefficient between them is 0.72. The limit for the daily stem diameter difference is 0.025 mm at 30% soil moisture. If the actual value of this parameter exceeds the limit value, the irrigation system can be activated. The implementation of this approach makes it possible to automate the irrigation process and to take into account the indicator that signals water stress of the plant.

Short-term stem diameter variations in irrigated and non-irrigated stone pine (Pinus pinea L.) trees in a xeric non-native environment

Irrigation of adult stone pine trees growing in a xeric non-native habitat had positive effects not only in stem diameter growth but also in tree response to climatic variability. Stone pine is a key species from Mediterranean Europe increasingly planted in South America. The knowledge about irrigation impact on short-term stem diameter dynamics is still limited in non-native arid areas. To improve our understanding of the effect of irrigation on (1) stem diameter changes of stone pine trees in a drought-prone environment in Chile and (2) the sensitivity of the species to weather conditions. We studied daily stem diameter changes in irrigated and non-irrigated 31-year-old stone pine trees during a growing season with below average precipitation in Chile. Short-term diameter changes were recorded using high-resolution dendrometers. The detrended daily stem diameter changes, expressing tree water status, were correlated with weather variability in both irrigated and non-irrigated trees. The growth period lasted longer and the cumulative sum of daily changes increased by 130% in irrigated trees. Moreover, a similar correlation of tree water status with climatic variables was found in non-irrigated, with the exception of precipitation. Irrigation increased stone pine productivity in this xeric environment and reduced the correlations between daily stem diameter variations and local climatic variability.

CRECIMIENTO DE PLÁNTULAS DE CAOBA (Swietenia macrophylla King) EN RESPUESTA A EXTRACTOS VEGETALES

La caoba (Swietenia macrophylla King) requiere nutrientes para que las plantas muestren buena calidad durante su crecimiento en vivero. El objetivo de este estudio fue evaluar la respuesta a extractos foliares de Ricinus communis L., Solanum torvum Sw. y frutos de Solanum mammosum L. en plántulas de caoba. La hipótesis fue que estos extractos mejoran la calidad de las plántulas. El diseño experimental fue completamente al azar, con cuatro tratamientos: T1) R. communis L., T2) S. torvum Sw., T3) S. mammosum L., y T4) testigo sin extracto vegetal, y con cuatro repeticiones de 45 unidades experimentales. Las variables evaluadas fueron morfológicas (tasas de crecimiento de altura y diámetro de tallo, y longitud y número de raíces) y de calidad (peso seco, índice de robustez e índice de calidad de Dickson). Los datos se analizaron mediante ANDEVA de una vía y las medias se compararon con la prueba de Tukey (p≤0.05). Los tratamientos se aplicaron a las plántulas a los 15 d de emergencia y los extractos se aplicaron vía foliar cada 15 d, con dosis de 60 mL 20 L-1 de cada extracto. Las unidades se midieron cada 15 d, durante 60 d. La aplicación de los extractos produjo tasas de crecimiento y pesos secos 38% superiores respecto a los testigos. El extracto de R. communis obtuvo las tasas más altas y el mejor índice de calidad de Dickson (0.28). Por lo tanto, el extracto de esta especie fue la mejor alternativa orgánica para mejorar el crecimiento y la calidad de las plántulas de caoba en vivero.

Growth diversity, heritability, and genetic correlation of 4-years-old of Alstonia angustiloba progeny test in Wonogiri, Central Java

Alstonia angustiloba is a local tree species that have potential for community forest plantation; therefore, it is important to provide improved seeds. This study aimed to determine the diversity of growth, estimate the value of heritability, and the genetic correlation of the 4-years-old A. angustiloba progeny test. Randomized Completely Block Design with two factors (population and family) were used in this study. In this study, families are nested in the population. The population factors consisted of 4 levels, and family factors consisted of 43 families. The analysis of variance showed that height and stem diameter growth were significantly different between populations and families at four years old. The best height and stem diameter growth at the population level was obtained from the Pendopo population, 4.45 m and 7.71 cm, respectively. At the family level, the best height growth was obtained from 9 families (4.46-5.06 m), and the best stem diameter growth was obtained from 11 families (7.48-8.72 cm). The estimated individual heritability value for height was 0.41, and stem diameter was 0.23. Estimated family heritability values were 0.66 for height and 0.50 for stem diameter. The genetic correlation between height and stem diameter was 0.97.

Domestication reduces phenotypic plasticity in chaya (<em>Cnidoscolus aconitifolius</em> (Mill.) I.M. Johnst)

Background: Natural selection optimizes phenotypic plasticity in plants found in environmentally variable habitats. However, it is unclear how artificial selection has affected the phenotypic plasticity of crops. Reduced plasticity in crop yield is often considered a desirable feature in cultivated plants; however, limited phenotypic plasticity in this and other traits may also affect the ability of crops to cope with environmental variation. Study species: Wild and domesticated chaya (Cnidoscolus aconitifolius (Mill.) I.M. Johnst). Question: How domestication has affected the phenotypic plasticity of vegetative traits in response to the light environment? Methods: Leaf area, leaf perimeter, leaf specific area, leaf production, trichome density, stem elongation, growth in stem diameter and slenderness were measured in clones of wild and domesticated plants. These clones were allocated to two contrasting light treatments: fully exposed to sun vs. placement beneath a shade cloth. The phenotypic traits and reaction norms were compared between the genotypes of wild and domesticated plants. Results: Lower plasticity in leaf production and slenderness was observed in the domesticated compared to the wild plants. Leaf production and slenderness are associated with the shade avoidance syndrome, which was evident in wild plants but not manifested in domesticated plants. Reduced plasticity in leaf production also suggests yield stability. Conclusion: Artificial selection reduces phenotypic plasticity in the yield of chaya and in its response to variation in light availability.