Tamanho de amostra para teste de germinação de Mimosa caesalpiniifolia Benth, espécie nativa da Caatinga

Abstract

Resumo -O objetivo desse trabalho é definir o tamanho da amostra para teste de germinação de Mimosa caesalpiniifolia Benth. O experimento foi realizado em delineamento experimental inteiramente casualizado em esquema fatorial 6 x 8, seis números de sementes (20; 25; 30; 50; 70 e 100) e oito números de repetições (3; 4; 5; 6; 7; 8; 9 e 10), com cinco repetições. Foram utilizados 20 repetições para cada número de sementes, das quais se realizaram sorteios para obtenção das repetições de cada tratamento. O teste de germinação foi realizado em germinador, tipo BOD, a 30 °C com fotoperíodo 12 h, em papel germitest. As características avaliadas foram: índice de variação para percentagem de germinação e para velocidade de germinação. O número de sementes que resultou em menor índice de variação, para os números de repetições seis, sete, oito e dez, variou de 65 a 79 sementes por repetição. Para três e cinco repetições constatou-se tendência de redução do índice de variação para percentagem de germinação com o aumento do número de sementes por repetição, justificando utilizar para testes de germinação no mínimo seis repetições. Para o índice de velocidade de germinação não se constatou efeito do número de repetição sobre o índice de variação, enquanto que o número de sementes que resultou em menor índice de variação, independente do número de repetições, foi 75 sementes. Para o lote de sementes avaliado, recomendam-se utilização de seis repetições com número de sementes por repetição variando de 65 a 79 sementes. Palavras-chave -Sementes florestais. Repetição. Número de sementes.Abstract -The objective of this work was to define the sample size to germination test of Mimosa caesalpiniifolia Benth. The experiment was arranged in a completely randomized design, in 6 x 8 factorial, six different seed quantities (20; 25; 30; 50; 70 and 100) and eight numbers of repetitions (3; 4; 5; 6; 7; 8 ; 9 and 10), with five repetitions. Were used 20 repetitions for each number of seeds, with drawings to obtain repetitions of each treatment. The germination test was conducted in BOD germination, at 30 °C with 12 hours photoperiod, on germitest paper. The characteristics evaluated were: variation index for germination percentage and for germination velocity. The seed number that resulted in a lower variation index for the number six, seven, eight and ten repetitions, ranged from 65 to 79 seeds per repetition. For three and five repetitions was found a tendency of reduction of the variation index for germination percentage with increasing on the number of seeds per repetition, justifying the use for germination test of, at least, six repetitions. For the germination velocity index, the effect was not observed on the number of repetition, on the variation index, while the seed number that resulted in lower variation index, regardless of the number of repetitions was 75 seeds. For the batch of seeds evaluated was recommended the use of six repetitions with the number of seeds per repetition ranging from 65 to 79.

Sample size for determination of the physiological potential of coriander (Coriandrum sativum L.) seeds

“…In this study, less than four replications of 50 seeds reduced the accuracy of estimates of germination of both coriander seed lots. Similar results were obtained by Freitas et al (2011) who investigated number of replications ranging from three to ten for estimating germination of Mimosa caesalpiniifolia seeds. The authors concluded that with three replications it was not possible to define the ideal number of seeds.…”

“…As the number of seeds per replication increased, the index of variation was appreciably low (Figure 2), for both seed lots. Freitas et al (2011) also observed a reduction in the IV (%) with increasing number of seeds per replication in a study of germination of Mimosa caesalpiniifolia seeds. The effect of the number of seeds on the germination of each sample of Bowdichia virgilioides Kunth was studied using samples comprising 100, 200 or 400 seeds arranged in four replications.…”

“…Concerning the germinability of coriander seeds, that is, the ability to form normal seedlings at 21 days after sowing, it was observed that four replications of 30 seeds were sufficient to estimate this parameter in lots with high or low physiological potential ( Figure 2). Freitas et al (2011) investigated the effect the number of seeds (20, 25, 30, 50, 70 and 100) of Mimosa caesalpiniifolia per replication and reported that when four replications were used, variations in the number of seeds had no effect on the germination tests. Contrasting data were obtained for Brachiaria brizantha Stapf cultivar Marandú in an investigation of the influence of the number of seeds (50, 100, 150 and 200) per replication (four) on germinative performance (Carneiro, 1994).…”

“…And the subsample is expected to have the sample accuracy. Contrasting data were obtained by Freitas et al (2011) in an investigation with Mimosa caesalpiniifolia seeds: three replications with 75 seeds each were considered sufficient for the estimation of seed vigor through GSI. The evaluation of seed vigor by the GSI should be used with caution, since the number of seeds per replication interferes directly with the result once it is used in the calculation.…”