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The state of Rio Grande do Sul (RS) is the third largest sunflower producer in Brazil. This study verified the existence of linear relationships between grain yield, oil content, and oil yield in sunflower (Helianthus annuus L.) genotypes evaluated in RS. The data on grain yield (GY), oil content (OC), and oil yield (OY) were obtained from 73 sunflower cultivar trials in 21 municipalities in RS from 1999 to 2018. Scatter diagrams were createdto investigate the relationships between the variables GY, OC, and OY. Then, Pearson's linear correlation coefficient (r) was calculated between the variables, and the Student's t-test was performed at a 5% significance level. There is a positive and significant linear relationship between PG and OY. However, no linear relationship was found between grain yield and oil content in sunflower genotypes. Additionally, a positive linear association of high magnitude (r = 0.9672) was observed between grain yield and oil yield, while a low magnitude (r = 0.2245) was found between oil content and oil yield. [ABSTRACT FROM AUTHOR]

Due to the economic importance of maize, it is essential to evaluate the performance of genotypes under environmental variations (years, locations, and seasons). Consequently, researchers have scrutinized genotype-environment (G×E) interactions to ensure reliability in genotype recommendations. Furthermore, when a G×E interaction exists, adaptability and stability analysis can be performed. This analysis enables one to identify genotypes with predictable responses and adaptability to environmental variability. Hence, this study sought to determine if there is a G×E interaction and evaluate the response of 16 maize genotypes across seven environments through adaptability and stability analyses. Seven experiments were conducted with 16 maize genotypes using a randomized complete block design with three replications. Tassel length (TL), tassel branch number (TBN), tassel dry matter (TDM), and grain yield (GY) were evaluated. Individual and joint variance analyses were performed, along with the F-test at a 5% significance level. The complex parts of the interaction between genotypes and pairs of environments were estimated, followed by adaptability and stability analyses using the Eberhart and Russell method. A genotype-environment interaction was found for TL, TBN, TDM, and GY, indicating that genotypes respond differently in various environments. However, considering all four traits, there is no indication of the ideal genotype. [ABSTRACT FROM AUTHOR]

It is important to determine the number of plants to be evaluated to allow accurate inferences about the traits under evaluation. Investigating the linear relations among traits is important for identifying traits for indirect selection. So, the objectives of this study were to determine the sample size (number of plants) necessary to estimate the means of forage pea traits and to investigate the relations among the traits. Experiments were carried out in 2021 with three sowing dates (May 3, May 26 and July 13). Five hundred plants were randomly sampled, 100 plants in each of the five evaluation dates (June 25, August 30, July 24, September 17, September 16). In these 500 plants, the traits plant height, number of branches, number of nodes, number of leaves, number of pods, fresh matter of leaves, fresh matter of stems, fresh matter of pods, fresh matter of shoots, dry matter of leaves, dry matter of stems, dry matter of pods, and dry matter of shoots, were evaluated. The sample size was calculated to estimate the means of these traits, based on Student's t-distribution, and the relations among traits were investigated through correlation and path analysis. In an experiment, to estimate the means of these 13 traits of forage pea, with an estimation error of approximately 10% of the mean, 99 plants per treatment should be sampled. The numbers of pods and leaves have a positive linear relations with fresh and dry matter of shoots. [ABSTRACT FROM AUTHOR]

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Copyright of Sigmae is the property of Universidade Federal de Alfenas (UNIFAL-MG) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Sigmae is the property of Universidade Federal de Alfenas (UNIFAL-MG) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Sigmae is the property of Universidade Federal de Alfenas (UNIFAL-MG) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Ciência Agronômica is the property of Revista Ciencia Agronomica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Multicollinearity must be diagnosed in multivariate analyses. Among the indicators, the condition number can be used to quantify the degree of multicollinearity. Hence, this study sought to determine the number of measurements (trials) necessary to estimate the number of condition in linear correlation matrices between rye traits. Five uniformity trials were carried out with 'BRS Progresso' rye, and eight morphological traits and eight productive traits were evaluated, forming two groups. In each group of traits, six cases (combinations of traits) were planned and the multicollinearity diagnosis was performed. Repeatability analyses were performed using the following methods: analysis of variance, principal component analysis, and structural analysis, and the number of measurements (trials) was determined for different levels of precision. A higher condition number of repeatability coefficients was obtained by the principal component methods (based on correlation and variance and covariance matrices) and structural analysis based on the variance and covariance matrix. A greater number of measurements (trials) is necessary to estimate the number of conditions in productive traits compared to morphological ones. One trial is enough to efficiently estimate the condition number with a minimum accuracy of 80% in morphological and productive traits of rye, whereas at least three trials are required for 95% accuracy. [ABSTRACT FROM AUTHOR]

Copyright of Revista Caatinga is the property of Revista Caatinga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Utilizando-se os dados de produtividade de grãos, se avaliou a adaptabilidade e estabilidade fenotipica de 12 genótipos de arroz sob condiçOes de solos com e sem inundação, visando a seleção de materiais com adaptação ampla ou especifica. 0ito experimentos foram conduzidos nos estados de Meta, Tolima e Huila, localizados na região leste da Colombia, durante os anos de 2005 e 2006. 0 delineamento experimental utilizado foi de blocos ao acaso com quatro repetiçOes. Para a avaliação da adaptabilidade e estabilidade, utilizaram-se os métodos propostos por Eberhart e Russell, e Annichiarico. A anãlise de variãncia revelou a existéncia da interação genótipo-ambiente. As duas metodologias revelaram resultados semelhantes. 0 genótipo 400094 foi considerado adaptãvel e estãvel segundo as metodologias empregadas, e deve ser recomendado para as duas condiçOes de cultivo avaliadas.

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Copyright of Revista Caatinga is the property of Revista Caatinga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Com o objetivo de verificar a existência de variabilidade temporal e espacial do tamanho de amostra da temperatura mínima do ar média mensal de trinta e sete municípios do Rio Grande do Sul, utilizaram-se os dados de temperatura mínima do ar do período de 1931 a 2000. Determinou-se o tamanho de amostra da temperatura mínima do ar média mensal em cada mês e município. Realizou-se análise de agrupamento dos meses e dos municípios pelo método hierárquico "vizinho mais distante". Há variabilidade do tamanho de amostra (número de anos) para a estimativa da temperatura mínima do ar média mensal no Estado do Rio Grande do Sul no tempo e no espaço. Maior tamanho de amostra, no Estado do Rio Grande do Sul, é necessário nos meses de maio, junho e julho, com diminuição gradativa em direção a janeiro e dezembro. Há variabilidade do tamanho de amostra entre os municípios do Estado do Rio Grande do Sul.

A falta da comparabilidade dos efeitos nos ensaios de competição de genótipos de milho (Zea mays) pode resultar em recomendações equivocadas. O objetivo deste trabalho foi verificar se o enquadramento dos genótipos de milho quanto ao ciclo é correto e se este altera a comparação das médias. Foram conduzidos seis experimentos de competição de genótipos de milho de ciclo superprecoce, precoce e normal, em dois níveis tecnológicos, na área experimental da UFSM, durante o ano agrícola de 2000/2001. O experimento bifatorial (genótipos nas parcelas principais e densidades nas subparcelas) foi conduzido no delineamento blocos ao acaso com três repetições. A proporção de experimentos de pressuposições adequadas foi alta, indicando análise de boa qualidade. Os genótipos de milho encontram-se mal agrupados quanto ao ciclo e, por conseqüência, quanto à estatura de plantas, aumentando a heterogeneidade nos experimentos e prejudicando a comparação das médias. Genótipos de milho com ciclo e/ou estatura de plantas diferentes não devem ser comparados na mesma densidade e experimento.

O objetivo deste trabalho foi verificar o ganho obtido na discriminação de cultivares de milho pelo ajuste da produtividade de grãos em experimentos inadequados quanto à população final de plantas. O ajuste, ou não, da produtividade de grãos, em função da população variável, nos 31 ensaios de competição de cultivares de milho utilizados, foi realizado com os métodos: sem correção, regra de três, método de Zuber, covariância da população média, covariância da população ideal, método de Cruz, método de Vencovsky & Cruz e método de correção estratificada. O índice de diferenciação de Fasoulas foi utilizado para verificar o ganho na discriminação das cultivares de cada método em relação aos dados sem correção da população. O ganho depende do método de ajuste empregado, obtendo-se, de maneira geral, ganhos mais elevados com o uso dos métodos de correção estratificada, covariância com a população ideal e covariância com a população média. Os ensaios com populações heterogêneas são mais proveitosos, embora a discriminação das cultivares seja menor que a obtida em ensaios com populações homogêneas. Ensaios com populações distanciadas do nível desejado permitem ganhos maiores, porém menor discriminação relativa a ensaios com populações adequadas.

The objective of this study was to determine the optimal plot size to evaluate fresh matter productivity of sorghum (Sorghum bicolor (L.) Moench) and showy rattlebox (Crotalaria spectabilis Roth.). Fifteen uniformity trials (blank experiments) with sorghum and showy rattlebox, in single or intercropping, were carried out. The fresh matter productivity was evaluated in 540 basic experimental units (BEU) of 1 x 1 m (15 trials x 36 BEU per trial). The plot size was determined by the method of Hatheway (1961), in scenarios formed by combinations of treatment numbers, repetitions numbers, and levels of experimental precision. To evaluate the fresh matter productivity of sorghum and showy rattlebox, in single or intercropping, with 5 to 30 treatments and with five repetitions, plots of 10 m² of useful area are sufficient for differences between treatments of 24% of the overall average of the experiment to be considered significant at 0.05 probability. [ABSTRACT FROM AUTHOR]

Hectolitre weight (HW) is the principal quantitative parameter used by receiving units as an indicator of the quality of wheat grain (Triticum aestivum L.). The moisture content and the equipment used can be considered important sources of variation to assess a batch, requiring correct sizing of the sample used to measure the HW. This research identified the variability between the equipment used to evaluate HW with or without correcting the grain moisture content, and to estimate the ideal number of samples for the commercial classification of wheat batches. The experiment was carried out in a randomised block design with four replications. Seven batches of wheat grain from different cultivars and/or production sites were used to measure the HW using three types of equipment (Equipment ‘A’, Equipment ‘B’ and Equipment ‘C’), with and without correcting the grain moisture content to 13%. Higher values for HW were determined with Equipment ‘A’ (77.15) compared to Equipment ‘B’ (75.08) and Equipment ‘C’ (74.69), classifying the wheat according to type. The moisture content affected the HW, but did not change the final classification of the wheat in terms of type. The ideal number of samples for HW ranged from 1 to 18 at the lowest level of precision (HW=mean±1 kg hl-1) and from 67 to 1820 samples for the highest precision (HW=mean±0.1 kg hl-1). Equipment ‘B’ requires a smaller number of samples (possibly as few as one) for the same level of precision (HW=mean±1 kg hl-1), whereas Equipment ‘A’ requires a greater number of samples for the majority of batches. Correctly classifying wheat by HW therefore depends on a larger number of samples. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the appropriate harvest interval for the phytomass production of peppermint (Mentha x piperita L.) transplanted in summer and winter. Two experiments were carried out in soilless cultivation, one with transplantation in summer and the other with transplantation in winter, in a completely randomized design, with five harvest intervals (30, 45, 60, 72, and 90 days) and four replicates. Fresh and dry matter weights of leaves, branches and shoots were determined. The fresh matter weight of peppermint leaves and the daily growth rate of this trait were similar between the harvest intervals for the transplantation performed in the summer. The dry matter weight of leaves was higher for the intervals of 72 days (90.80 g plant-1) and 90 days (90.24 g plant-1). For the transplantation performed in winter, the fresh matter and dry matter weights of leaves were higher for the intervals of 60 days (660.54 g plant-1, 107.14 g plant-1) and 90 days (630.40 g plant-1, 105.95 g plant-1). The same was observed for the daily growth rates of these traits. Peppermint harvests at 60-day intervals in winter transplantation are more appropriate for phytomass production. In summer transplantation, one can opt for the 45-day interval. [ABSTRACT FROM AUTHOR]

The objectives of this work were to verify the adjustment of time series of monthly minimum (Tmín) and monthly maximum (Tmáx) air temperatures, in the State of Rio Grande do Sul, to the normal, log-normal, gamma and weibull probability distributions, to determine probabilities of occurrence and prepare maps with the interpolation of isolines. The Kolmogorov-Smirnov test was applied to 216 time series of Tmín and 216 time series of Tmáx (18 cities × 12 months). Based on the normal distribution, values of Tmín were determined, whose probability of occurrence of Tmín less than or equal to this value is 90%, and values of Tmáx, whose probability of occurrence of Tmáx greater or equal to this value is 90%. From these values, maps were prepared with interpolation of isolines with a difference of 0.5°C. The Tmín and Tmáx data adjust the normal, log-normal, gamma and weibull distributions, showing better adherence to the normal distribution. The maps with the isolines are useful to verify the probability of occurrence of harmful or favorable Tmín and Tmáx for agricultural crops in the State of Rio Grande do Sul, during the months of the year. [ABSTRACT FROM AUTHOR]

Genotype x environment interaction (GEI) causes constant interference in soybean [Glycine max (L.) Merr.] grain yield. This complexity tends to increase when comparing highland and lowland cultivation systems, and there has been little referenced work for these in the situation of subtropical conditions. Hence, the aims of this study were to verify the effects of genotypes, environments and GEI for soybean grain yield in highland and lowland areas with subtropical climate and to compare the adaptability and stability methodologies. The trials were carried out in two locations of the state of Rio Grande do Sul, Brazil, with 20 soybean cultivars on three sowing dates for each location. The experiments were conducted in a randomised block design with three replications. Given the observed magnitude of the GEI, its simple and complex parts were quantified for further analysis of adaptability and stability, using the Additive Main Effect and Multiplicative Interaction (AMMI), Genotype plus Genotype–Environment interaction (GGE) and Best Linear Unbiased Prediction (BLUP) modelling approaches, followed by the verification of similarity between the methodologies via Spearman's correlation coefficient. The complex part of the GEI represented 82.11% of the total variation associated with the GEI, whereas the simple part accounted for 17.89% of that variation. The second sowing date, in both locations, was the one that presented the best rankings according to the models used, and also, cases of specific genotype adaptability were identified in each environment. The highest yield averages were obtained in the highlands. The GGE and BLUP techniques presented genotypic ranking concordance. [ABSTRACT FROM AUTHOR]

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The objective of this study was to determine the optimal plot size to evaluate the mass of fresh matter in millet (Pennisetum glaucum L.) and showy rattlebox (Crotalaria spectabilis Roth.), in scenarios formed by combinations of treatment numbers, repetitions numbers, and levels of experimental precision. Fifteen uniformity trials with millet and showy rattlebox, in single or intercropping, were carried out. The mass of fresh matter was evaluated in 540 basic experimental units (BEU) of 1 × 1 m (15 trials × 36 BEU per trial). The heterogeneity index of Smith (1938) was estimated. The plot size was determined by the method of Hatheway (1961) in scenarios formed by combinations of i treatments (i = 5, 10, 15, 20, and 25), r repetitions (r = 3, 4, 5, 6, 7, 8, 9, and 10), and d precision levels (d = 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20%). To evaluate the mass of fresh matter of millet and showy rattlebox, in single or intercropping, with 5 to 25 treatments and with five repetitions, plots of 10 m² of useful area are sufficient for differences between treatments of 9% of the overall average of the experiment to be considered significant at 0.05 probability. [ABSTRACT FROM AUTHOR]

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Fungal diseases in Brazilian regions with tropical and subtropical climates reduce the production potential of corn crops. The use of fungicides is one of the strategies to maintain productivity. This study evaluated the agronomic performance and grain quality of corn hybrids associated with the preventive use of fungicides in subtropical environments. Six experiments were conducted in Santa Maria-RS, São Vicente do Sul-RS, and Frederico Westphalen-RS during two sowing seasons. The experiment was conducted in a randomized complete block design with a split-plot arrangement, in which the main plot consisted of two levels of the fungicide factor (with and without) and the sub-plot consisted of six levels of corn hybrids (AG9025, AS1730, P3016, MG300, DKB230, and FEROZ). A total of 216 experimental plots were evaluated for grain productivity, and eight plants per plot were evaluated for other traits, totaling 1,728 evaluated plants. Therefore, environmental conditions influence the interaction between the factors of fungicide use and hybrid cultivar positioning, with no significant interaction in years with a water deficit. Early sowings in subtropical environments indicate better agronomic performance and a lower percentage of moldy grains regardless of the cultivation location, contributing to grain quality. [ABSTRACT FROM AUTHOR]

Copyright of Revista Caatinga is the property of Revista Caatinga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was to determine the season that promotes the highest production and best quality of marjoram (Origanum majorana L.) essential oil in summer and winter transplantations. Two experiments were performed in a protected cultivation, the first with transplanting in summer and the second with transplanting in winter, with a completely randomized design with four treatments, corresponding to the seasons of the year. Content, yield, and chemical composition of the essential oil were determined. The essential oil was extracted by hydrodistillation and analyzed by gas chromatography. In the summer transplanting, the essential oil content and yield were higher in the summer and spring seasons. In the winter transplanting, the essential oil content was higher in the summer season and the yield in summer and spring. Carvacrol was the major component of marjoram essential oil regardless of harvest and transplanting season. Of the other main compounds, only terpinolene was detected in all samples analyzed, with the other essential oil components varying between transplanting and harvest seasons. The highest production of marjoram essential oil is obtained in summer and spring harvests from plants transplanted in summer and winter. Carvacrol was the major component of marjoram essential oil and the other main components vary among seasons. [ABSTRACT FROM AUTHOR]

The objectives of this work were to determine the sample size (number of plants) necessary to estimate the indicators of the of multicollinearity degree - condition number (CN), determinant of the correlation matrix (DET), and variance inflation factor (VIF) - in productive traits of rye and to verify the variability of the sample size between the indicators. Five and three uniformity trials were conducted with the cultivars BRS Progresso and Temprano, respectively, and seven productive traits were evaluated in 780 plants. Twentyone cases were obtained from seven traits, combined five to five. In each case, 197 sample sizes were planned (20, 25, 30, …, 1,000 plants) and in each size 2,000 resampling were performed, with replacement. For each resample the CN, DET and FIV were determined and the average among 2,000 estimates of each indicator of the multicollinearity degree was calculated. Then, for each case and indicator, the sample size was determined through three models: models of maximum modified curvature, segmented linear with plateau response, and segmented quadratic with plateau response. There was superiority the quadratic model segmented with plateau in adjusting the degree of multicollinearity according to the sample size for all indicators. There is a need greater sample size to detect multicollinearity when diagnosed by DET and for sizes larger than 101, 258 and 102 plants when diagnosing for the number of conditions, determinant and inflation factor performed, respectively. [ABSTRACT FROM AUTHOR]

The number of replications is assumed to interfere in the estimates of the path analysis coefficients. Thus, the objective of this work was to determine the sufficient number of replications for the path analysis of traits in maize cultivars. An experiment was conducted with 15 maize cultivars in a complete randomized block design with nine replications, and seven variables were measured. Then, 511 data files (matrices) formed by all combinations of the nine replications were organized, in groups of 1, 2, 3, 4, 5, 6, 7, 8 and 9 replications. In each matrix, containing the averages of 15 cultivars for the seven variables, Pearson's linear correlation coefficients were estimated, the multicollinearity diagnostics and path analysis were performed and dispersion diagrams were constructed. The sufficient number of replications for the path analysis was determined from the parameter estimates of the quadratic response plateau model. With the replications number increases, the accuracy of the path analysis coefficient estimates improves, but the gains in accuracy gradually decrease. Six replications are sufficient to perform the path analysis of agronomic traits of maize cultivars and can be used as a reference for designing future experiments. [ABSTRACT FROM AUTHOR]

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The objectives of this study were to fit the Gompertz and Logistic models for the fresh and dry matter of leaves and the fresh and dry matter of shoots of three lettuce cidtivars and indicate the best model to describe their growth in autumn-winter. The lettuce cultivars Gloriosa, Pira Verde, and Stella were evaluated in the autumn-winter of 2016 and 2017, in soilless in a protected environment. After transplantation, the fresh and dry matter of leaves and shoots were weighed every seven days. These dependent variables were fit using the accumulated thermal sum. The parameters of the Gompertz and Logistic models were estimated, the assumptions of the models were verified, the indicators of fit quality and critical points were calculated and the parametric and intrinsic curvature measures quantified. The Logistic and Gompertz models presented a satisfactory adjustment for the fresh and dry matter of leaves and the fresh and dry matter of shoots, for the lettuce cultivars Gloriosa, Pira Verde and Stella, in autumn-winter. The Logistic model best describes the growth of the lettuce cultivars. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Agricultural Sciences / Revista Brasileira de Ciências Agrárias is the property of Universidade Federal Rural de Pernambuco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was to determine the optimal plot size for evaluating the fresh weight of black oats (Avena strigosa Schreb) and the common vetch (Vicia sativa L.) in scenarios comprising combinations of the number of treatments, number of replications and levels of precision. Fifteen uniformity trials were conducted with single-crop and intercropped black oats and vetch. Fresh weight was evaluated in 540 basic experimental units (BEU), each of 1 m x 1 m (36 BEU per trial). The Smith index of soil heterogeneity (1938) was estimated. Plot size was determined using the HATHEWAY method (1961), in scenarios comprising combinations of i treatments (i = 5, 10, 15 and 20), r replications (r = 3, 4, 5, 6, 7 and 8) and d levels of precision (d = 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18% and 20%). To evaluate the fresh weight of monocropped or intercropped black oats and vetch in a completely randomized or randomized complete block design, with from 5 to 20 treatments and five replications, plots of 10 m2 are sufficient to identify, at a probability of 0.05, significant differences between treatments of 10% of the overall mean value of the experiment. [ABSTRACT FROM AUTHOR]

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To control whiteflies on soybean crops in an effective and economically viable way, it is necessary to quantify the occurrence and density of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) on the leaflets. Estimating the number of B. tabaci cm‐2 on leaflets is difficult, because its distribution pattern on the various parts of the plant canopy and on the leaflet surface is unknown. The aim of this study was to evaluate the distribution of B. tabaci nymphs on soybean plants and leaflets, under greenhouse and field conditions. One hundred soybean plants infested with all nymph stages were randomly selected in a greenhouse, and 25 in a field. Of each plant, a trifoliate leaf of the middle third of the plant's height was selected and its central leaflet was collected (greenhouse experiment), or a trifoliate leaf of each third layer (upper, middle, and lower), of which the left, central, and right leaflets were collected (field experiment). The collected leaflets were divided into 32 sections (1 cm2 per section), arranged in an array of eight rows and four columns to count whitefly nymphs. The Morisita index (Iδ), the negative binomial parameter k, and the dispersion index (I) were calculated for each leaflet, using the number of nymphs as variable. The highest population densities of whitefly nymphs were found in the middle third of the soybean plants. In leaflets from the middle third, the nymphs concentrated in the middle and bottom parts of the leaflets, whereas in the upper and lower thirds of the plant, they were randomly distributed on the leaflets. [ABSTRACT FROM AUTHOR]

In order to obtain reliable models for estimating the leaf area, it is important that parameter estimates be accurate and, for that, they must be generated based on an appropriate number of leaves. The objective of this research was to determine the number of leaves required to model the leaf area of velvet beans (Stizolobium cinereum) as determined by digital photos (Y) with regard to the width of the central leaflet limb of the leaf (x), using a potency model (Y=axb), generated through iterative process. In six periods of culture development (29, 43, 57, 73, 87 and 101 days after emergence) were collected, randomly, 790 leaves. Each leaf is composed of left, center and right leaflets. The width of the central leaflet (x) was measured and leaf area (the leaf area sum of the left, center and right leaflets) was determined through the method of digital photos (Y). The number of leaves, necessary for estimating parameters a and b of the potency model and the coefficient of determination (R2), was determined by resampling, with replacement. In the case of the velvet bean, the potency model (Ŷ=4.4019x1.8697, R2=0.9821) based on the width of the central leaflet (x) is adequate to estimate the leaf area obtained through digital photos (Y). Measuring 240 leaves is sufficient to build accurate potency models of the velvet bean leaf area determined by digital photos (Y) with regard to the width of the central leaflet limb of the leaf (x). [ABSTRACT FROM AUTHOR]

The objectives of this work were to determine the optimum plot size (Xo) and number of repetitions to evaluate the fresh and dry matter of rye (Secale cereale L.), and to investigate the variation of Xo between two cultivars and five sowing times. Thirty uniformity trials were conducted. Each trial with dimensions of 6 x 4 m was divided into 24 basic experimental units (BEU) of 1 x 1 m. Fresh and dry matter of rye were evaluated in the 720 BEU. The Xo was determined by the method of maximum curvature of the coefficient of variation model. The number of repetitions was determined in scenarios formed by combinations of treatments, experimental designs, and levels of precision. The optimal plot sizes to evaluate fresh and dry matter of rye are, respectively, 3.43 and 3.82 m². Six repetitions are sufficient to evaluate fresh and dry matter in completely randomized and randomized block design with up to 50 treatments and make it possible to obtain a least significant difference less than or equal to 20% of the experiment mean. [ABSTRACT FROM AUTHOR]

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The objective of this study was to determine the necessary number of experiments to analyze the adaptability and stability of maize cultivars (Zea mays L.) using the Lin and Binns method. Grain yield data extracted from 63 maize cultivar trials were used. Trials were divided in six groups of experiments, according to the cycle (early and super early) and the agricultural year (2002/2003, 2003/2004, and 2004/2005). In each group, from the set of all experiments (reference file) new data files were formed by combinations in groups of 2, 3, 4, ..., n-1 experiments, with a total of 10,683 files. For each file, the estimation of the adaptability and stability parameter (Pi) of the Lin and Binns method was calculated. To verify the degree of association of the estimates of Pi obtained with the combinations of experiments and with all the experiments (reference), Spearman correlation coefficient (r) was used. Number of experiments giving values of r≥0.80 in 100% of the combinations was considered sufficient. Seven experiments sufficed for the analysis of adaptability and stability of maize cultivars by the method of Lin and Binns. [ABSTRACT FROM AUTHOR]