Sample size and water dynamics on germinating diaspores: the first step for physiological and molecular studies on the germination process

Abstract

Water dynamics on germinating diaspores is normally used as a chronological marker in molecular biology and physiological studies focusing on germination. However, there is no protocol to analyze this process, which may undermine all results generated. In this context, we determined the sufficient sample size to study water dynamics on germinating diaspores by means of a modified maximum curvature method (MMCM). As a biological model, we used diaspores from agricultural species with different physiological qualities. These diaspores were put in contact with distilled water and were analyzed regarding mass, every hour, until embryo protrusion. Data collected in the last observation were used to measure the sufficient sample size. Here, we show that (i) MMCM is an adequate method to measure the variability of water dynamics on germinating diaspores; (ii) the b coefficient can be used to infer the homogeneity of water dynamics on diaspores of different species as a function of the increase in sample size; (iii) in general, to study this process in an easier, safer and standardized way, seven diaspores are needed and (iv) water dynamics on germinating diaspores estimated by weighted mass demonstrated to be a very stable process which depends more on the species than on the physiological quality. We also discussed why the sample size and water dynamics on germinating diaspores should be the first step for protocols on physiological and molecular aspects of the germination process.

Keywords:

• Germination sensu stricto
• imbibition
• MMCM
• seed
• water relations

Acknowledgments

We are grateful to the Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) and to the Coordenacão de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for financial support and the scholarship of the first author; to the Programa de Pós-Graduacão em Agronomia (UFU) for the support currently given to the first author as a postdoctoral (PNPD); to Dr. Denise Garcia de Santana for the elucidative dialogs, making the understanding of the model easier; to the Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA), DuPont Pioneer® and Qualiteste Análises Agronômicas for providing the diaspore samples and to Mr. Roger Hutchings for the English review of the manuscript.