Sazonalidade, luminosidade e déficit hídrico sobre aspectos ecofisiológicos em Erythroxylum pauferrense.

Seasonal variations of abiotic factors, such as irradiance and water availability, can influence the ecophysiology of understory species. In this context, this research was carried out with the objective of evaluating effects of the seasonal variation, luminosity and water availability on ecophysiological aspects in Erythroxylum pauferrense. In Article I, the objective was to evaluate the effects of seasonality on ecophysiological aspects of E. pauferrense in an open and closed canopy area. The research was carried out in the Mata do Pau-Ferro State Park, located in the municipality of Areia, Paraíba, Brazil. The readings were taken monthly in two periods of the year: dry (September 2017 to February 2018) and rainy (March to August 2018); and in two areas, A1 (open canopy) and A2 (closed canopy). The leaf area index, visible sky fraction and photosynthetically active radiation were measured in five individuals in the two areas. In each area, data of humidity and soil temperature, monthly precipitation and air temperature were also collected. Subsequently, the effects of these environmental variables on the variables of gas exchange, chlorophyll a fluorescence, leaf chlorophyll indices, morphofunctional attributes and water relations were analyzed. The data were submitted to multivariate analysis by means of canonical correlation analysis and principal component analysis to verify correlations between ecophysiological and environmental variables, subsequently to assess the differences between ecophysiological variables, the analysis of mixed effect variance with repeated measures over time, and then the means were grouped by the Scott-Knott test. E. pauferrense individuals respond to seasonal variations in A1 and A2, showing less ecophysiological development in the dry period. Seasonality influences the ecophysiological aspects of E. pauferrense in A1 and A2, with greater influence of soil moisture, precipitation and leaf area index in gas exchange, chlorophyll a fluorescence and chlorophyll indexes. In Article II, the objective was to evaluate morphophysiological aspects of E. pauferrense seedlings submitted to different levels of shading. The experiment was carried out at the Federal University of Paraíba, Campus II, Areia, Paraíba, Brazil, and conducted in a greenhouse in a completely randomized design, with five treatments: 0%, 30%, 50%, 70% and 90% shading, and eight repetitions. Growth characteristics, morphofunctional attributes, gas exchange, chlorophyll a fluorescence and chlorophyll indices were evaluated. The data were submitted to analysis of variance and polynomial regression. Plants submitted to shading of 30% have greater growth and physiological performance, which is the most recommended for the production of E. pauferrense seedlings. In Article III, the objective was to evaluate the morphophysiological characteristics of E. pauferrense plants submitted to water deficit. The research was carried out in a greenhouse, at the Federal University of Paraíba, Campus II, Areia, Paraíba, Brazil. The experimental design was in randomized blocks, with five water treatments [100%, 80%, 60%, 40% and 20% of the pot capacity (CP)], and four repetitions. The evaluated parameters were: growth, morphofunctional aspects, gas exchange, chlorophyll a fluorescence and leaf chlorophyll indices. The data were subjected to analysis of variance and in cases of significance, polynomial regression analyzes were performed. It was found that largest deficit (20% of CP) provided reductions in the parameters evaluated. The 80% CP regime is the most recommended for the production of E. pauferrense seedlings, promoting greater growth and significant changes in the morphofunctional aspects, gas exchange, chlorophyll a fluorescence and chlorophyll indexes.Variações sazonais de fatores abióticos, como a irradiância e disponibilidade hídrica, podem influenciar na ecofisiologia de espécies do sub-bosque. Nesse contexto, esta pesquisa foi realizada com o objetivo de avaliar efeitos da variação sazonal, luminosidade e disponibilidade hídrica sobre aspectos ecofisiológicos em Erythroxylum pauferrense. No Artigo I, objetivou-se avaliar os efeitos da sazonalidade sobre aspectos ecofisiológicos de E. pauferrense em área de dossel aberto e fechado. A pesquisa foi realizada no Parque Estadual Mata do Pau-Ferro, localizado no município de Areia, Paraíba, Brasil. As leituras foram realizadas mensalmente em dois períodos do ano: seco (setembro de 2017 a fevereiro de 2018) e chuvoso (março a agosto de 2018); e em duas áreas: A1 (dossel aberto) e A2 (dossel fechado). Foram mensurados o índice de área foliar, fração de céu visível e radiação fotossinteticamente ativa em cinco indivíduos nas duas áreas. Em cada área também foram coletados dados de umidade e temperatura do solo, precipitação mensal e temperatura do ar. Posteriormente analisaram-se os efeitos dessas variáveis ambientais sobre as variáveis de trocas gasosas, fluorescência da clorofila a, índices foliares de clorofila, atributos morfofuncionais e relações hídricas. Os dados foram submetidos a análise multivariada por meio da análise de correlação canônica e análise de componentes principais para verificar correlações entre as variáveis ecofisiológicas e ambientais, posteriormente para avaliar as diferenças entre as variáveis ecofisiológicas realizou-se a análise de variância de efeito misto com medidas repetidas no tempo, e em seguida as médias foram agrupadas pelo teste de Scott-Knott. Os indivíduos de E. pauferrense respondem às variações sazonais em A1 e A2, apresentando um menor desenvolvimento ecofisiológico no período seco. A sazonalidade influencia nos aspectos ecofisiológicos de E. pauferrense em A1 e A2, com maior influência da umidade do solo, precipitação e índice de área foliar nas trocas gasosas, fluorescência da clorofila a e índices de clorofila. No Artigo II, objetivou-se avaliar aspectos morfofisiológicos de mudas de E. pauferrense submetidas a diferentes níveis de sombreamento. O experimento foi realizado na Universidade Federal da Paraíba, Campus II, Areia, Paraíba, Brasil, e conduzido em casa de vegetação em delineamento inteiramente casualizado, com cinco tratamentos: 0%, 30%, 50%, 70% e 90% de sombreamento e oito repetições. Avaliaram-se características crescimento, atributos morfofuncionais, trocas gasosas, fluorescência da clorofila a e índices de clorofila. Os dados foram submetidos à análise de variância e de regressão polinomial. Plantas submetidas ao sombreamento de 30% possuem maior crescimento e desempenho fisiológico, sendo esse o mais recomendado para produção de mudas de E. pauferrense. No Artigo III, objetivou-se avaliar as características morfofisiológicas em plantas de E. pauferrense submetidas a déficit hídrico. A pesquisa foi desenvolvida em casa de vegetação, da Universidade Federal da Paraíba, Campus II, Areia, Paraíba, Brasil. O delineamento experimental foi em blocos casualizados, com cinco tratamentos hídricos [100%, 80%, 60%, 40% e 20% da capacidade de pote (CP)] e quatro repetições. Os parâmetros avaliados foram: crescimento, aspectos morfofuncionais, trocas gasosas, fluorescência da clorofila a e índices de clorofila. Os dados foram submetidos a análise de variância e nos casos de significância, realizaram-se análises de regressão polinomial. Constatou-se que o maior déficit (20% da CP) proporcionou reduções nos parâmetros avaliados. O regime de 80% da CP é o mais recomendado para produção de mudas de E. pauferrense promovendo maior crescimento e modificações significativas nos aspectos morfofuncionais, trocas gasosas, fluorescência da clorofila a e índices de clorofila

Método no destructivo para estimar el área foliar de Erythroxylum pauferrense (Erythroxylaceae) a partir de las dimensiones lineales de las láminas foliares

Background and Aims: Determining the leaf area is essential for studies on growth, propagation, and ecophysiology of forest species. Developing quick, practical, and accurate methods is needed to estimate leaf area without destroying leaves. Therefore, this research aimed to obtain an equation from regression models that meaningfully estimate the leaf area of Erythroxylum pauferrense using linear dimensions of its leaf blades. Methods: For this purpose, 1200 leaves were randomly collected from different plants in the Mata do Pau-Ferro, a state park located in Areia city, Paraíba state, Brazil. Equations were fitted from simple linear, linear without intercept, quadratic, cubic, power, and exponential regression models. Next, the best equation was selected by checking the following assumptions: higher determination coefficient (R²) and Willmott's index (d), lower Akaike information criterion (AIC) and root mean square error (RMSE), as well as the BIAS index closest to zero. Key results: Based on the criteria used, all equations fitted using the product of length by width (L.W) can estimate the leaf area of E. pauferrense. Conclusions: The equation ŷ=0.6740*LW from the linear model without intercept significantly estimates the leaf area of E. pauferrense in a quick and practical way (R²=0.9960; d=0.9953; AIC=1231.61; RMSE=0.4255; BIAS=-0.0130).Antecedentes y Objetivos: La determinación del área foliar es esencial para los estudios sobre crecimiento, propagación y ecofisiología de especies forestales. Es necesario desarrollar métodos rápidos, prácticos y precisos para estimar el área de la hoja sin destruir las hojas. Por lo tanto, esta investigación tuvo como objetivo obtener una ecuación a partir de modelos de regresión que estimen significativamente el área foliar de Erythroxylum pauferrense, utilizando dimensiones lineales de sus láminas foliares. Métodos: Para este propósito, se recolectaron al azar 1200 hojas de diferentes plantas en Mata do Pau-Ferro, un parque estatal ubicado en la ciudad de Areia, estado de Paraíba, Brasil. Las ecuaciones se ajustaron a partir de modelos de regresión lineal simple, lineal sin intercepción, cuadrática, cúbica, de potencia y exponencial. Luego, se seleccionó la mejor ecuación verificando los siguientes supuestos: coeficiente de determinación más alto (R²) e índice de Willmott (d), criterio de información de Akaike más bajo (AIC) y error cuadrático medio (RMSE), así como el índice BIAS más cercano a cero. Resultados clave: Basado en los criterios utilizados, todas las ecuaciones ajustadas usando el producto de largo por ancho (L.W) pueden estimar el área foliar de E. pauferrense. Conclusiones: La ecuación ŷ=0.6740*LW del modelo lineal sin intercepción estima significativamente el área foliar de E. pauferrense de una manera rápida y práctica (R²=0.9960; d=0.9953; AIC=1231.61; RMSE=0.4255; BIAS=-0.0130)

A NON-DESTRUCTIVE METHOD FOR ESTIMATING LEAF AREA OF Ceiba glaziovii (Kuntze) K. Schum.

The determination of leaf area is of fundamental importance in studies involving ecological and ecophysiological aspects of forest species. The objective of this research was to adjust an equation to determine the leaf area of Ceiba glaziovii as a function of linear measurements of leaves. Six hundred healthy leaf limbs were collected in different matrices, with different shapes and sizes, in the Mata do Pau-Ferro State Park, Areia, Paraíba state, Northeast Brazil. The maximum length (L), maximum width (W), product between length and width (L.W), and leaf area of the leaf limbs were calculated. The regression models used to construct equations were: linear, linear without intercept, quadratic, cubic, power and exponential. The criteria for choosing the best equation were based on the coefficient of determination (R²), Akaike information criterion (AIC), root mean square error (RMSE), Willmott concordance index (d) and BIAS index. All the proposed equations satisfactorily estimate the leaf area of C. glaziovii, due to their high determination coefficients (R² ≥ 0.851). The linear model without intercept, using the product between length and width (L.W), presented the best criteria to estimate the leaf area of the species, using the equation 0.4549*LW

Gas exchanges and water-use efficiency of Nopalea cochenillifera intercropped under edaphic practices

The Nopalea forage cactus (Nopalea cochenillifera) is the main xerophilic species cultivated in Brazil, highlighted as a compatible biological element with the semiarid environment. However, studies on its physiological aspects are still scarce. In this context, an experiment was performed in the Pendência Experimental Station, belonging to the State Company of Agricultural Research of Paraíba (EMEPA-PB), municipality of Soledade, state of Paraíba, Brazil, aiming to evaluate the gas exchanges and the water-use efficiency of intercropped Nopalea Cochenillifera plants in the soil under different edaphic managements. The treatments were distributed in randomized blocks, with three replications in a 2 × 5 factorial scheme, corresponding to the soil without and with mulch and five types of cultivation of Nopalea forage cactus, in monoculture and intercropped with forage watermelon, millet, sorghum, and buffelgrass. The analyzed variables were: stomatal conductance, transpiration rate, net photosynthesis rate, and internal CO2 concentration, besides the instantaneous water-use efficiency, intrinsic water-use efficiency, and instantaneous carboxylation efficiency. The use of soil mulch satisfactorily increased the photosynthetic rate of the forage cactus; this type of practice can aid in the productive development of the crop in semiarid zones, whereas the intercropping with buffelgrass and forage watermelon stimulated photosynthesis and the water-use efficiency.The Nopalea forage cactus (Nopalea cochenillifera) is the main xerophilic species cultivated in Brazil, highlighted as a compatible biological element with the semiarid environment. However, studies on its physiological aspects are still scarce. In this context, an experiment was performed in the Pendência Experimental Station, belonging to the State Company of Agricultural Research of Paraíba (EMEPA-PB), municipality of Soledade, state of Paraíba, Brazil, aiming to evaluate the gas exchanges and the water-use efficiency of intercropped Nopalea Cochenillifera plants in the soil under different edaphic managements. The treatments were distributed in randomized blocks, with three replications in a 2 × 5 factorial scheme, corresponding to the soil without and with mulch and five types of cultivation of Nopalea forage cactus, in monoculture and intercropped with forage watermelon, millet, sorghum, and buffelgrass. The analyzed variables were: stomatal conductance, transpiration rate, net photosynthesis rate, and internal CO2 concentration, besides the instantaneous water-use efficiency, intrinsic water-use efficiency, and instantaneous carboxylation efficiency. The use of soil mulch satisfactorily increased the photosynthetic rate of the forage cactus; this type of practice can aid in the productive development of the crop in semiarid zones, whereas the intercropping with buffelgrass and forage watermelon stimulated photosynthesis and the water-use efficiency

Estimation of Thunbergia grandiflora leaf area from allometric models

Sky vine (Thunbergia grandiflora Roxb) is a vine with important structural components for forest environments. Studies on growth and development are necessary, because of the environmental and economic importance. The leaf area determination is essential for ecophysiological studies to understand the relationship of the plant with the environment. The objective of this work was to estimate an allometric equation to estimate the leaf area of T. grandiflora from linear dimensions. 200 leaves of different shapes and sizes were collected from adult plants and the length (L), width (W), the product between length and width (LW), and real leaf area (LA) were measured. The linear regression, linear without intercept, quadratic, cubic, power, and exponential models were used to estimate the equations. The criteria for determining the best model were higher determination coefficient (R2), Willmott's agreement index (d), lower Akaike information criterion (AIC), the root of the mean error square (RMSE), and BIAS index closer to zero. The leaf area of T. grandiflora can be estimated satisfactorily by the equation ŷ = 0.58*LW.Sky vine (Thunbergia grandiflora Roxb) é uma planta trepadeira com importantes componentes estruturais para ambientes florestais. Estudos sobre crescimento e desenvolvimento são necessários, devido à importância ambiental e econômica. A determinação da área foliar é essencial para estudos ecofisiológicos para entender a relação da planta com o meio ambiente. O objetivo deste trabalho foi estimar uma equação alométrica para estimar a área foliar de T. grandiflora a partir de dimensões lineares. 200 folhas de diferentes formas e tamanhos foram coletadas de plantas adultas e o comprimento (L), largura (W), o produto entre comprimento e largura (LW) e área foliar real (LA) foram medidos. Os modelos de regressão linear, linear sem intercepto, quadrático, cúbico, potência e exponencial foram usados ​​para estimar as equações. Os critérios para determinar o melhor modelo foram maior coeficiente de determinação (R2), índice de concordância de Willmott (d), menor critério de informação de Akaike (AIC), raiz do quadrado do erro médio (RMSE) e índice BIAS mais próximo de zero. A área foliar de T. grandiflora pode ser estimada de forma satisfatória pela equação ŷ = 0,58*LW

Aspectos morfofisiológicos de mudas de Erythroxylum pauferrense Plowman submetidas ao sombreamento

Sunlight directly influences on the development of forest species by affecting the attributes of plant growth and physiology. Among these species, Erythroxylum pauferrense Plowman is considered a rare species, as its distribution is restricted only to the state of Paraíba. Therefore, studies are needed that seek to evaluate the adaptation, development and propagation of the species under different environmental conditions. This study aimed to evaluate morphophysiological aspects of Erythroxylum pauferrense seedlings submitted to different levels of shading. The experiment was carried out under greenhouse condition in a completely randomized design with five treatments (0, 30, 50, 70, and 90% shading) and eight replicates. Growth characteristics, morphofunctional attributes, gas exchange, chlorophyll (Chl) a fluorescence, and Chl content were evaluated. Data were submitted to analysis of variance followed by polynomial regression analysis. Results showed that plants grown under 30 to 50% shading showed higher plant height, stem diameter, absolute growth rate for plant height, leaf dry mass, stem dry mass, total dry mass, Dickson’s quality index, leaf area, and leaf area index, as well as net assimilation rate of CO2, stomatal conductance, transpiration, instantaneous water use efficiency, and Chl a, b, and a+b contents. Therefore, levels from 30 to 50% shading are the most recommended for the production of Erythroxylum pauferrense seedlings. We recommend using Erythroxylum pauferrense to reforest the understory in disturbed areas in Brejos de Altitude and large-scale production of seedlings under intermediate levels of shading.A luz solar influencia diretamente no desenvolvimento das espécies florestais, afetando os atributos de crescimento e fisiologia das plantas. Dentre essas espécies, Erythroxylum pauferrense Plowman é considerada uma espécie rara, pois sua distribuição é restrita apenas ao estado da Paraíba. Diante disso, são necessários estudos que busquem avaliar a adaptação, desenvolvimento e propagação da espécie em diferentes condições ambientais. Este trabalho teve como objetivo avaliar os aspectos morfofisiológicos de mudas de Erythroxylum pauferrense submetidas a diferentes níveis de sombreamento. O experimento foi conduzido em casa de vegetação, em delineamento inteiramente casualizado, com cinco tratamentos (0, 30, 50, 70 e 90% de sombreamento) e oito repetições. Foram avaliadas as características de crescimento, atributos morfofuncionais, trocas gasosas, fluorescência da clorofila (Chl) a e teor de Chl. Os dados foram submetidos à análise de variância seguida de análise de regressão polinomial. Os resultados mostraram que as plantas cultivadas sob 30 a 50% de sombreamento apresentaram maior altura da planta, diâmetro do caule, taxa de crescimento absoluto para altura da planta, massa seca da folha, massa seca do caule, massa seca total, índice de qualidade de Dickson, área foliar e índice de área foliar, bem como a taxa de assimilação líquida de CO2, condutância estomática, transpiração, eficiência instantânea do uso da água e conteúdo de Chl a, b e a+b. Portanto, níveis de 30 a 50% de sombreamento são os mais recomendados para a produção de mudas de Erythroxylum pauferrense. Recomenda-se o uso de Erythroxylum pauferrense para reflorestar o sub-bosque em áreas perturbadas nos Brejos de Altitude e a produção em larga escala de mudas em níveis de 30 a 50% de sombreamento

FITOMASSA E CRESCIMENTO DE MANJERICÃO ROXO IRRIGADO COM ÁGUA SALINA SOB ADUBAÇÃO FOLIAR NITROGENADA

Basil is a species with high exploitation potential. However, its production in semiarid regions is compromised due to the salts contained in the soil and in the water used in irrigation, requiring the adoption of techniques that increase the tolerance of plants to salinity, such as nitrogen fertilization. Thus, this study aimed to evaluate the effect of leaf nitrogen fertilization on growth and phytomass allocation in purple basil plants under irrigation with saline water. The experiment was carried out in a randomized block design in an incomplete factorial scheme, with five levels of salinity (0.0; 0.81; 2.75; 4.69 and 5.50 dS m-1) and five levels of nitrogen (0.00; 58.58; 200.00; 341.42 and 400.00 mg L-1). Leaf succulence, sclerophilia index and shoot dry mass production, stem, leaf and root dry mass allocation, specific leaf area and leaf area ratio were evaluated. Foliar application of N attenuated the effects of salt stress on phytomass allocation, leaf succulence and shoot phytomass production index. N and salinity increased the specific leaf area and leaf area ratio in basil plants.O manjericão é uma espécie de elevado potencial de exploração. No entanto, sua produção em regiões semiáridas é comprometida decorrentes dos sais contidos no solo e na água utilizada na irrigação, sendo necessário a adoção de técnicas que aumente a tolerância das plantas a salinidade, como a fertilização com nitrogênio. Assim, objetivou-se avaliar o efeito da adubação nitrogenada foliar no crescimento e na alocação de fitomassa em plantas de manjericão roxo sob irrigação com águas salinas. O experimento foi realizado em delineamento de blocos casualizados em esquema fatorial incompleto, constando com cinco níveis de salinidade (0,0; 0,81; 2,75; 4,69 e 5,50 dS m-1) e cinco doses de nitrogênio (0,00; 58,58; 200,00; 341,42 e 400,00 mg L-1). Avaliou-se a suculência foliar, os índices de esclerofilia e de produção de fitomassa seca da parte aérea, alocação de fitomassa seca do caule, das folhas e da raiz, área foliar específica e razão de área foliar. A aplicação foliar de N atenuou os efeitos do estresse salino sobre a alocação de fitomassa, suculência foliar e no índice de produção de fitomassa da parte aérea. O N e a salinidade aumentou a área foliar específica e a razão de área foliar nas plantas de manjericão. Palavras-chave: estresse salino; Ocimum basilicum L.; nitrogênio.   Phytomass  and growth of purple basil irrigated with saline water under nitrogen foliar fertilization   ABSTRACT: Basil is a species with high exploitation potential. However, its production in semiarid regions is compromised due to the salts contained in the soil and in the water used in irrigation, requiring the adoption of techniques that increase the tolerance of plants to salinity, such as nitrogen fertilization. Thus, this study aimed to evaluate the effect of leaf nitrogen fertilization on growth and phytomass allocation in purple basil plants under irrigation with saline water. The experiment was carried out in a randomized block design in an incomplete factorial scheme, with five levels of salinity (0.0; 0.81; 2.75; 4.69 and 5.50 dS m-1) and five levels of nitrogen (0.00; 58.58; 200.00; 341.42 and 400.00 mg L-1). Leaf succulence, sclerophilia index and shoot dry mass production, stem, leaf and root dry mass allocation, specific leaf area and leaf area ratio were evaluated. Foliar application of N attenuated the effects of salt stress on phytomass allocation, leaf succulence and shoot phytomass production index. N and salinity increased the specific leaf area and leaf area ratio in basil plants. Keywords: salt stress, Ocimum basilicum L.; nitrogen

Photochemical efficiency and growth of sugar apple under irrigation with saline water and foliar nitrogen

Salt stress has compromised the worldwide expansion of fruit farming by causing damage to light energy regulation and crop growth, which can be mitigated by applying foliar nitrogen (N). From this perspective, this study aimed to evaluate the chlorophyll contents, fluorescence, and the growth of sugar apple seedlings under irrigation with saline water and foliar N fertilisation. The experiment was conducted in a plant nursery and following a randomized block design referring to five electrical conductivity levels of irrigation water (0.5, 1.15, 2.75, 4.35, and 5.0 dS m-1) and five foliar N levels (0.0, 0.33, 1.15, 1.97, and 2.3 g L-1), with four replications and two plants per plot, totaling nine combinations generated by the Box central composite design. Irrigation water salinity reduces the growth of sugar apple seedlings irrigated with conductivity levels over 1.7 dS m-1 at 90 days after emergence. Foliar N fertilisation increased the photochemical efficiency and growth of sugar apple seedlings. The foliar application of 1.93 g L-1 mitigate the deleterious effects of water salinity on the photochemical efficiency and growth of sugar apple seedlings

CONHECIMENTO LOCAL E USO DE ESPÉCIES VEGETAIS NATIVAS DA REGIÃO DA SERRA DE SANTA CATARINA, PARAÍBA, NORDESTE DO BRASIL

A etnobotânica busca compreender a interação do homem com as populações de plantas do seu convívio. O presente estudo objetivou registrar o conhecimento e uso das espécies vegetais na comunidade Caatinga, município de São José de Lagoa Tapada no sertão paraibano. Utilizou-se de formulário semiestruturado para a coleta de informações sendo aplicado aos chefes domiciliares totalizando 98 informantes (41 homens e 57 mulheres). Foi registrado 70 plantas identificadas em 44 espécies pertencentes a 38 gêneros e 20 famílias. As citações de usos foram classificadas em 10 categorias, obtendo maior destaque para tecnologia (34,75%, 42 espécies), seguido de construções (35,38%, 39 espécies) e combustível (9,71%, 33 espécies), as categorias com caráter madeireiro apresentaram maior destaque devido sua disponibilidade durante todo o ano, entretanto, preocupa, pois acarreta a retirada parcial ou total da planta. A espécie que obteve maior destaque quanto ao valor de uso foi Myracrodruon urundeuva Allemão (6,44), seguido de Croton blanchetianus Baill. (6,38) e Tabebuia sp. (3,74), a pressão exercida nas plantas mais uteis, afim de satisfazer as necessidades tem contribuído para sua extinção local

Estimation of leaf area of Erythroxylum citrifolium from linear leaf dimensions

Erythroxylum citrifolium is a neotropical plant species recorded in all regions of Brazil. Determining leaf area is of fundamental importance to studies related to plant propagation and growth. The objective was to obtain an equation to estimate the leaf area of E. citrifolium from linear dimensions of the leaf blade (length and width). A total of 200 leaf blades were collected in Parque Estadual Mata do Pau-Ferro in the municipality of Areia, state of Paraíba, Northeast Brazil. The models evaluated were: linear, linear without intercept, quadratic, cubic, power and exponential. The best model was determined by the criteria of: high coefficient of determination (R²), low root mean square error (RMSE), low Akaike information criterion (AIC), high Willmott concordance index (d) and a BIAS index close to zero. All of the models constructed satisfactorily estimated the leaf area of E. citrifolium, with coefficients of determination above 0.9050, but the power model using the product between length and width (L*W) ŷ = 0.5966 * LW1.0181 was the best, with the highest values of R² and d, low values of RMSE and AIC, and a BIAS index closest to zero