Marcos Toebe

Estimação da área foliar de canola por dimensões foliares

The objective of this work was to model and identify the best models to estimate the leaf area determined by digital photos, of three canola hybrid, with the length or width and / or the product length width of the leaf. Three uniformity trials were carried with the culture of canola (Brassica napus L.). In each trial was valued one of the following hybrids: Hyola 61, Hyola 76, Hyola 433. In each hybrid were collected 125 leaves at 77, 84, 91, 97 days after sowing, totaling 1,500 leaves. In these 1,500 leaves were measured length (C) and width (L) and calculated the length width (C×L) of the leaf. Was determined the leaf area of each leaf, by the method of digital photos (Y). After, for each hybrid were separated, randomly, 80% of the leaves (100 leaves by collects × 4 collects by hybrid = 400 leaves per hybrid) to build models of quadratic, potency and linear type for Y function of the C, L and/or C×L. The remaining 20% of the leaves (100 leaves by hybrid), separately, were used to validate the models. In canola, the potency model for hybrid Hyola 61 (Ŷ = 1.3000x1.9336, R2 = 0.9531), Hyola 76 (Ŷ = 1.0579x2.0383, R2 = 0.9733) and Hyola 433 (Ŷ = 1.4154x1.9096, R2 = 0.9613), are adequate for estimation of leaf area determined by digital photos (Y) as function of the width of the leaf (x).

Tamanho de unidades experimentais básicas e tamanho ótimo de parcelas para nabo‑forrageiro

The objective of this work was to determine the effect of the basic experimental unit size (BEU) on the optimum plot size estimation for the evaluation of forage turnip ( Raphanus sativus ) fresh matter weight. Data from fresh matter weight of 3,456xa0BEUs of 0.5×0.5xa0m (0.25xa0m 2 ) were used, and 36xa0BEU plans, with sizes from 0.25 to 16xa0m 2 , were formed. For each BEU plan, the optimum plot size was determined by the method of maximum curvature of the coefficient of variation model. The least significant difference was calculated by Tukey’s test in 2,016 scenarios formed by the combinations of 36xa0optimum plot sizes (one for each BEU plan), i treatments (i = 5, 10, 15, and 20), and r replicates (r = 3, 4, 5, 6, 10, 15, and 20), considering both the completely randomized designs and the complete block ones. Optimum plot size depends on the size of the basic experimental unit. In uniformity trials with forage turnip, the evaluation of fresh matter weight should be done in basic experimental units with the smallest possible size.

Tamanho de parcela e número de repetições na cultura do milheto em épocas de avaliação

The objectives of this work were to determine the optimum plot size (Xo) and number of repetitions, to evaluate the fresh weight of aerial part of millet, in evaluation times. Forty-two uniformity trials with 6 m×4 m (24 m2) were conducted. Each trial was divided in 24 experimental units basic (UEB) with 1 m×1 m (1 m2). At 52, 69 and 82 days after sowing were evaluated, respectively, 18, 6 and 18 trials, where the fresh weight of plants was weighed in each UEB. The Xo was determined by the method of maximum curvature of the model coefficient of variation and the means compared, among evaluation times, by Student’s t test. The number of repetitions for experiments on completely randomized and randomized block designs, in scenarios of combinations of i treatments (i=3, 4, ..., 50) and d minimal differences between treatments means, to be detected as significant, 5% probability by Tukey test, expressed in percentage of the average of the experiment (d=10%, 12%, ..., 30%), was determined by iterative process until convergence. The optimum plot size to evaluate the fresh weight of aerial part of millet is 4.46 m2, to the three evaluation times. To evaluate up to 50 treatments, in completely randomized and randomized block designs, four replications are sufficient for differences between treatment means of 28.75% of the average experiment are significant at 5% probability, by Tukey’s test.

Dimensionamento amostral e associação linear entre caracteres de Crotalaria spectabilis

Os objetivos deste trabalho foram determinar o tamanho de amostra necessario para a estimacao da media de caracteres e avaliar as relacoes lineares existentes entre caracteres de plantas de Crotalaria spectabilis. Foi conduzido um experimento com C. spectabilis na safra 2014/2015, sendo os seguintes caracteres avaliados em 100 plantas: altura da planta (AP), numero de ramos produtivos (NRP), massa seca da parte aerea (MSPA), massa seca de vagens (MSVG), numero de vagens (NVG), peso medio de cada vagem (PMVG), numero de sementes (NS), numero medio de sementes por vagem (NSVG), massa de cem graos (MCG) e peso total de sementes (PTS). Foram calculadas medidas de tendencia central, de dispersao e de distribuicao, foi verificada a normalidade dos dados e determinado o tamanho de amostra necessario para a estimacao da media de cada caractere, assumindo-se erros de estimacao iguais a 1, 2, …, 20% da media. Depois, foram calculados os coeficientes de correlacao linear de Pearson e estimados os efeitos diretos e indiretos das variaveis explicativas sobre PTS por meio de analise de trilha. Em C. spectabilis, sao necessarias 121 plantas para estimacao da media dos caracteres NRP, MSPA, MSVG, NVG, NS e PTS com erro maximo de 10% da media. Ja para a estimacao da media de AP, PMVG, NSVG e MCG nesse mesmo nivel de precisao, sao necessarias 6 plantas. A variavel NS apresentou elevada correlacao e efeito direto sobre PTS, indicando relacao de causa e efeito e possibilidade de selecao indireta. As demais variaveis explicativas apresentaram efeitos indiretos sobre PTS via NS.

Water potential in peach branches as a function of soil water storage and evaporative demand of the atmosphere

1Part of Master’s Dissertation of the first author. 2PhD student, no PPG-Management and Conservation of Soil and Water (MACSA), Universidade Federal de Pelotas, Pelotas RS, FAPEG Scholar. Email: alexbeckermonteiro@gmail.com 3Researcher at EMBRAPA Clima Temperado, Pelotas RS. Email: carlos.reisser@embrapa.br 4PhD student at PPG-Management and Conservation of Soil and Water (MACSA), Universidade Federal de Pelotas, Pelotas RS. Email: luciano.romano@cas. ifmt.edu.br 5Associate Professor III, Departamento de Engenharia Rural, Universidade Federal de Pelotas, Pelotas RS. Email: lctimm@ufpel.edu.br 6Professor, Universidade Federal do Pampa, Campus Itaqui RS. Email: m.toebe@gmail.com Abstract-The use of water potential indicators in the plant has been adopted in irrigation management, in recent years, since it is accepted that the plant is the best indicator of its own water status. The objective of this study was to verify the relationship between water potential in peach tree branches and the evaporative demand of the atmosphere and the water availability in two textural classes of an Aquertic Hapludalf soil, aiming to adopt irrigation management strategies based on the water potential in the plant. Research was carried out in a commercial peach orchard, cv. Esmeralda, in the municipality of Morro Redondo-Rio Grande do Sul state, Brazil. Four peach tree rows were evaluated, being two irrigated and two non irrigated. The irrigation management was based on the replacement of the potential crop evapotranspiration. It was concluded that the water potential in the peach tree branch is positively related with the evaporative demand of the atmosphere and negatively related with soil water storage. Future studies should adopt irrigation management strategies for peach trees based on the water potential mainly for the irrigation management of post-harvest peach trees.

Associações lineares entre caracteres fenológicos, morfológicos, produtivos e nutricionais energéticos em milho

The objective of this work was to verify if there is linear dependence between the phenological, morphological, and productive traits and the energetic-nutritional ones in early maturing and super-early maturing corn genotypes. A total of 36 early maturing and 22 super-early maturing corn genotypes were evaluated in a randomized complete block design with three replicates, and the phenological, morphological, productive, and energetic-nutritional traits were measured. The matrix of phenotypic correlation coefficients among traits was determined; the multicollinearity diagnosis was carried out within each group of traits; and the canonical correlation analysis was performed. Linear dependence was observed between the groups of phenological, morphological, and productive traits and of the energetic-nutritional ones. In early maturing genotypes, significant canonical correlation shows the existence of linear dependence between the morphological and energetic-nutritional traits. The significant canonical pair shows that taller plants have lower amylose contents in the grains and reduced nitrogen-corrected apparent metabolizable energy. In super-early maturing genotypes, significant canonical correlations of the phenological, morphological, and productive traits with the energetic-nutritional ones indicate that a greater number of days from sowing to female flowering and ear insertion height, as well as a lower number of ears, increase ether extract contents in the grains.

Direct effects on scenarios and types of path analyses in corn hybrids

The objective of this study was to estimate the direct effects of explanatory variables on the grain yield of corn in the combinations formed by three types of hybrids x two harvests x nine scenarios of explanatory variables x two types of path analyses. Eleven explanatory variables were measured in 361, 373, and 416 single-, triple-, and double-cross hybrid plants from the 2008/2009 harvest, respectively, and in 1777, 1693, and 1720 single-, triple-, and double-cross hybrid plants from the 2009/2010 harvest, respectively: plant height at harvest (PH), ear insertion height (EIH), ear weight (EW), number of grain rows per ear (NR), ear length (EL), ear diameter (ED), cob weight (CW), cob diameter (CD), 100-grain mass (HGM), number of grains per ear (NGE), grain length (GL) and, the main variable, grain yield (YIELD). Before conducting the traditional and ridge path analyses, 0, 1, 2, 3, 4, 5, 6, 7, and 8 explanatory variables were excluded from scenarios 1, 2, 3, 4, 5, 6, 7, 8, and 9, respectively. Next, the direct effects of explanatory variables on YIELD were estimated for each hybrid, harvest, scenario, and type of path analysis. The variables EW, NGE, and HGM had stronger direct effects on YIELD in the first three scenarios and the variables EL and ED had stronger direct effects on YIELD in the other scenarios regardless of hybrid or harvest. The use of the ninth scenario of path analysis is recommended regardless of hybrid and harvest given the ease of explanatory variable measurement (EIH, EL, and ED), the low degree of multicollinearity and the good prediction of the path analysis (R2 ≥ 0.78).

Sample size for estimation of direct effects in path analysis of corn

The objective of this study was to assess the sample size required for estimating the direct effects of explanatory variables on the grain yield of corn in the combinations formed by three types of hybrids x two harvests x nine scenarios of explanatory variables x two types of path analyses x four levels of accuracy. A total of 6340 plants were evaluated (361, 373, and 416 plants from single-, triple-, and double-cross hybrids in the 2008/2009 harvest, respectively, and 1777, 1693, and 1720 plants from single-, triple-, and double-cross hybrids in the 2009/2010 harvest, respectively). Eleven explanatory variables were measured in each plant: plant height, ear insertion height, ear weight, number of grain rows per ear, ear length and diameter, cob weight and diameter, 100-grain mass, number of grains per ear, grain length and, the main variable, grain yield. Thus, nine scenarios were planned (scenarios 1, 2, 3, 4, 5, 6, 7, 8, and 9 with 0, 1, 2, 3, 4, 5, 6, 7, and 8 explanatory variables excluded, respectively) and two types of path analyses conducted (traditional and ridge path analyses). The sample size required for estimating the direct effect of each explanatory variable on grain yield was assessed using resampling with replacement at four accuracy levels [95% confidence interval ranges (95%CI) of 0.15, 0.25, 0.35, and 0.45]. The use of the ninth scenario of path analysis is recommended regardless of hybrid and harvest given the smaller sample size required compared to the previous scenarios. To estimate direct effects with the maximum 95%CI of 0.25, 10 to 530 plants are required depending on the type of hybrid, harvest, scenario, type of path analyses, and explanatory variables. To estimate the direct effects in the ninth scenario with a maximum 95%CI of 0.25, 120 plants suffice regardless of the type of hybrid, harvest, or type of path analyses.

Relações lineares entre caracteres de frutos de maçã

The study of linear associations between traits is critical for the selection or the indirect quantification of the interest traits. Thus, the objective of this research was to evaluate the linear relationships among traits of apple fruits, in ‘Royal Gala’ and ‘Fuji’ cultivars, at harvest and after cold storage. In this investigation, 120 fruits of ‘Royal Gala’ and 120 fruits of ‘Fuji’ at harvest and 120 fruits of ‘Royal Gala’ and 111 fruits of ‘Fuji’ after cold storage were evaluated. Morphological/productive (mass, longitudinal diameter, major and minor transverse diameters) and quality traits (firmness, total soluble solids, titratable acidity, juice content, ethylene production and respiration) were measured. In each cultivar (‘Royal bAsic AreA Note Linear relations between apple traits Marcos Toebe1*, Vanderlei Both2, Fabio Rodrigo Thewes2, Alberto Cargnelutti Filho2, Auri Brackmann2 1. Universidade Federal do Pampa Itaqui (RS), Brazil. 2. Universidade Federal de Santa Maria Departamento de Fitotecnia Santa Maria (RS), Brazil. *Corresponding author: m.toebe@gmail.com Received: Dec. 19, 2015 – Accepted: Feb. 17, 2016 Gala’ and ‘Fuji’) and time of evaluation (at harvest or after cold storage), the Pearson’s linear correlation coefficients among the pairs of traits and the canonical correlation among the groups of morphological/productive and of quality traits were calculated. At harvest, the apple fruits with higher mass had lower firmness and higher total soluble solids, regardless of the cultivar. After cold storage, the apple fruits with higher mass had higher total soluble solids and lower respiration, regardless of the cultivar, and higher juice content in the ‘Fuji’ cultivar.O estudo das associacoes lineares existentes entre caracteres e fundamental para a selecao ou quantificacao indireta de caracteres de interesse. Assim, o objetivo deste trabalho foi avaliar as relacoes lineares entre caracteres de frutos de maca das cultivares ‘Royal Gala’ e ‘Fuji’, na colheita e apos armazenamento refrigerado. Foram avaliados 120 frutos de ‘Royal Gala’ e 120 frutos de ‘Fuji’ na colheita e 120 frutos de ‘Royal Gala’ e 111 frutos de ‘Fuji’ apos armazenamento refrigerado. Foram mensurados os caracteres morfologicos/produtivos (massa, diâmetro longitudinal e diâmetros transversais maior e menor) e os caracteres de qualidade (firmeza de polpa, solidos soluveis totais, acidez titulavel, teor de suco, producao de etileno e respiracao). Em cada cultivar (‘Royal Gala’ e ‘Fuji’) e momento de avaliacao (na colheita ou apos armazenamento refrigerado), foram calculados os coeficientes de correlacao linear de Pearson entre os pares de caracteres e a correlacao canonica entre os grupos de caracteres morfologicos/produtivos e de qualidade. Na colheita, os frutos com maior massa apresentaram menor firmeza de polpa e maior teor de solidos soluveis totais, independentemente da cultivar. Apos o armazenamento refrigerado, os frutos com maior massa apresentaram maior teor de solidos soluveis totais e menor respiracao, independentemente da cultivar, e maior teor de suco na cultivar ‘Fuji’.