ABSTRACT The objective of this study was to fit the Logistic growth model for plant height and number of nodes of two buckwheat cultivars at sowing times, as well as comparing the cultivars and sowing times. Twenty uniformity trials were carried out, formed by the combination of two buckwheat cultivars (IPR91-Baili and IPR92-Altar), sown at five times, for two consecutive years. Evaluations were carried out twice a week throughout the vegetative stage until the end of flowering. In each evaluation, five plants were randomly collected from each trial to measure plant height and count the number of nodes on the main stem. The logistic model was fitted with the values of the five plants of each evaluation. Model parameters were estimated, as well as their respective confidence intervals. The goodness of fit of the model was assessed through the coefficient of determination, Akaike information criterion, and residual standard deviation. The plant height and number of nodes of buckwheat, cultivars IPR91-Baili and IPR92-Altar, were described by the Logistic model. The Logistic model satisfactorily describes the growth of buckwheat plants, and a specific fit considering each cultivar and sowing time is needed.

RESUMO O objetivo deste trabalho foi comparar três métodos de estimação do tamanho ótimo de parcela para avaliar a produtividade de matéria fresca de milheto (Pennisetum glaucum L.), crotalária ochroleuca (Crotalaria ochroleuca) e crotalária spectabilis (Crotalaria spectabilis). Foram conduzidos 27 ensaios de uniformidade com milheto, crotalária ochroleuca e crotalária spectabilis, em cultivo solteiro e em consórcio. Foi avaliada a produtividade de matéria fresca em 972 unidades experimentais básicas (UEB) de 1 m × 1 m (36 UEB por ensaio). Foi determinado o tamanho ótimo de parcela por meio dos métodos da curvatura máxima modificado, do modelo linear de resposta com platô e do modelo quadrático de resposta com platô. O tamanho ótimo de parcela difere entre os métodos e decresce na seguinte ordem: modelo quadrático de resposta com platô (9,94 m2), modelo linear de resposta com platô (7,41 m2) e curvatura máxima modificado (3,49 m2). O tamanho ótimo de parcela para avaliar a produtividade de matéria fresca de milheto, crotalária ochroleuca e crotalária spectabilis, em cultivo solteiro ou em consórcio é de 7,41 m2. Esse tamanho pode ser utilizado como referência para futuros experimentos.

ABSTRACT This study aimed to compare three methods of estimating the optimum plot size to evaluate the fresh matter productivity of pearl millet (Pennisetum glaucum L.), slender leaf rattlebox (Crotalaria ochroleuca), and showy rattlebox (Crotalaria spectabilis). Twenty-seven uniformity trials were carried out with pearl millet, slender leaf rattlebox, and showy rattlebox cultivated alone and intercropped. Fresh matter productivity was evaluated in 972 basic experimental units (BEU) of 1 m × 1 m (36 BEU per trial). The optimum plot size was determined using the methods modified maximum curvature, linear response with plateau model, and quadratic response with plateau model. The optimum plot size differs between methods and decreases in the following order: quadratic response with plateau model (9.94 m2), linear response with plateau model (7.41 m2), and modified maximum curvature (3.49 m2). The optimum plot size to evaluate the fresh matter productivity of pearl millet, slender leaf rattlebox, and showy rattlebox cultivated alone or intercropped is 7.41 m2. This size could be used as a reference for future experiments.

RESUMO - O objetivo deste trabalho foi determinar o tamanho ótimo de parcela para avaliar a massa de matéria fresca de milheto (Pennisetum glaucum L.) e de crotalária ochroleuca (Crotalaria ochroleuca) em cenários formados por combinações de números de tratamentos, números de repetições e níveis de precisão experimental. Foram conduzidos 15 ensaios de uniformidade com milheto e crotalária ochroleuca, em cultivo solteiro e em consórcio. Foi avaliada a massa de matéria fresca em 540 unidades experimentais básicas (UEB) de 1 m × 1 m (15 ensaios × 36 UEB por ensaio). Foi estimado o índice de heterogeneidade do solo de Smith (1938). Foi determinado o tamanho de parcela por meio do método de Hatheway (1961) em cenários formados pelas combinações de i tratamentos (i = 5, 10, 15 e 20), r repetições (r = 3, 4, 5, 6, 7 e 8) e d níveis de precisão (d = 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18% e 20%). Para avaliar a massa de matéria fresca de milheto e de crotalária ochroleuca, em cultivo solteiro ou em consórcio, nos delineamentos inteiramente casualizado ou de blocos completos ao acaso, com 5 a 20 tratamentos e com cinco repetições, parcelas de 10 m² de área útil são suficientes para que diferenças entre tratamentos de 10% da média geral do experimento sejam consideradas significativas a 0.05 de probabilidade.

ABSTRACT - The objective of this study was to determine the optimal plot size to evaluate fresh matter in millet (Pennisetum glaucum L.) and slender leaf rattlebox (Crotalaria ochroleuca), in scenarios formed by combinations of numbers of treatments, numbers of replicates, and levels of precision. Fifteen uniformity trials with millet and slender leaf rattlebox, in single cropping or intercropping, were carried out. Fresh matter was evaluated in 540 basic experimental units (BEU) of 1 m × 1 m (15 trials × 36 BEU per trial). The soil heterogeneity index of Smith (1938) was estimated. Plot size was determined by the method of Hatheway (1961) in scenarios formed by combinations of i treatments (i = 5, 10, 15 and 20), r replicates (r = 3, 4, 5, 6, 7 and 8), and d precision levels (d = 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18% and 20%). To evaluate the fresh matter of millet and slender leaf rattlebox, in single or intercropping, in experiments in completely randomized or randomized block designs, with 5 to 20 treatments and with five replicates, plots with 10 m² of usable area are sufficient for differences between treatments of 10% of the overall mean of the experiment to be considered significant at 0.05 probability level.

Resumo: O objetivo deste trabalho foi determinar o intervalo de colheita para produção de fitomassa de manjerona (Origanum majorana), em transplantes no verão e no inverno. Foram realizados dois experimentos independentes em cultivo fora do solo: um com transplante no verão e outro no inverno, em delineamento inteiramente casualizado, com cinco intervalos de colheita (30, 45, 60, 72 e 90 dias) e quatro repetições. Foram determinadas as massas de matéria fresca e seca de folhas, ramos e parte aérea. Para cada planta, foi calculada a produção acumulada nas colheitas em função dos dias após o transplante. A massa de matéria fresca de folhas foi superior nos intervalos de 60 e 90 dias, no transplante de verão, e de 72 e 90 dias, no transplante de inverno. Colheitas em intervalos de 60 dias, no transplante de verão, e de 72 dias, no transplante de inverno, são apropriadas para produção de fitomassa de manjerona.

Abstract: The objective of this work was to determine the harvest interval for phytomass production of marjoram (Origanum majorana) in summer and winter transplants. Two independent experiments were performed in off-ground cultivation: one with a summer and another with a winter transplant, in a completely randomized design with five harvest intervals (30, 45, 60, 72, and 90 days) and four replicates. The fresh and dry masses of leaves, branches, and aerial part were determined. For each plant, the production accumulated in the harvests was calculated as affected by days after the transplant. The fresh matter mass of the leaves was higher at the intervals of 60 and 90 days, in the summer transplant, and of 72 and 90 days, in the winter transplant. Harvesting at intervals of 60 days in the summer transplant and of 72 days in the winter transplant are appropriate for marjoram phytomass production.