Germinação de Jatropha curcas L. sob envelhecimento / salinidade e desenvolvimento do pacote para análise de dados de germinação - GerminaR

Abstract

Jatropha curcas L. is a crop with good qualities for biofuel production. It is widely known for its drought resistance characteristics and ability to grow in degraded soils and with low fertility. However, there are few works, studding the conservation of the species to the seed storage conditions and germination under saline conditions. In addition, there is a great difficulty in processing the germination variables, which are highly complex. For this reason, this work had three objectives: (i) generation of a package in the statistical software R for data analysis and graphical presentation of the main variables of seed germination; (ii) evaluate if it is possible to stabilize the loss of seed germinability through the storage reducing the water in the atmosphere; (iii) to evaluate the germinative responses and the initial development of five genotypes of J. curcas from different geographic regions of Brazil in the presence of different concentrations of NaCl. In Chapter 1, a R package was developed and called "GerminaR", which has four main functions, (a) calculation of eleven germination variables;(b) temporal evaluation of germination; (c) graphic expression of results and (d) interactive application "GerminaQuant for R". The software is available both in the installable version for PC, through the R and in the online version for use in any mobile device, without the need of installing the software, and prior knowledge of programming by the user. In Chapter 2, two experiments were carried out, the first one being the study of the maintenance of the viability and biochemical properties caused by the natural aging during the storage of the seeds of Jatropha curcas L. for a period of up to 12 months. The results show that the reduction of moisture in the interstice of the seeds allowed to stabilize the germinability and maintain it viable, besides conserving the oil content until the sixth month, in a similar way were registered with other biochemical characteristics of the seeds, a fact corroborated by the drastic reduction in the respiratory rate and the osmotic potential of the seeds. In the second experiment, five different genotypes of J. curcas and five concentrations of NaCl (0, 50, 75, 100 and 150 mM L-1) were tested in the irrigation water. The data showed that the addition of NaCl had negative effects on most parameters of germination and initial development of seedlings. At the concentration of 150 mM there was only 4% of germination; and the plants had difficult to develop. The mean germination time increased linearly with increasing salt concentrations. In the control treatment, the germination started on the third day, delayed effect in four days on average in the treatment of 150 mM. Although the germination was evaluated up to 150 mM, the biometric and biomass parameters were computed only up to 100 mM. Among these parameters, leaf dry weight, leaf area per plant and total leaf area as well plant height were the main characteristics negatively influenced by salinity. According to the multivariate analyzes, genotypes 114, 171 and 183 were shown to be potentially tolerant while the 218 and 133 sensitive genotypes, result that can be corroborated by the different studied parameters.