James D. Maguire

Bio: James D. Maguire is an academic researcher. The author has contributed to research in topics: Germination & Seedling. The author has an hindex of 1, co-authored 1 publications receiving 4436 citations.

How and why to measure the germination process

Abstract: In the last two centuries, papers have been published including measurements of the germination process. High diversity of mathematical expressions has made comparisons between papers and some times the interpretation of results difficult. Thus, in this paper is included a review about measurements of the germination process, with an analysis of the several mathematical expressions included in the specific literature, recovering the history, sense, and limitations of some germination measurements. Among the measurements included in this paper are the germinability, germination time, coefficient of uniformity of germination (CUG), coefficient of variation of the germination time (CVt), germination rate (mean rate, weighted mean rate, coefficient of velocity, germination rate of George, Timson’s index, GV or Czabator’s index; Throneberry and Smith’s method and its adaptations, including Maguire’s rate; ERI or emergence rate index, germination index, and its modifications), uncertainty associated to the distribution of the relative frequency of germination (U), and synchronization index (Z). The limits of the germination measurements were included to make the interpretation and decisions during comparisons easier. Time, rate, homogeneity, and synchrony are aspects that can be measured, informing the dynamics of the germination process. These characteristics are important not only for physiologists and seed technologists, but also for ecologists because it is possible to predict the degree of successful of a species based on the capacity of their harvest seed to spread the germination through time, permitting the recruitment in the environment of some part of the seedlings formed.

Seed vigor testing: an overview of the past, present and future perspective

Abstract: The assessment of seed vigor has many important implications to the seed industry as a basic monitoring of seed physiological potential during different phases of seed production and a support for strategic decisions regarding the selection of high quality seedlots to meet the consumer demand. The potential attributes of seed vigor as a fundamental physiological seed characteristic and its association with field stand establishment and crop productivity has been worldwide recognized from the 1960s onward. This led to the diversification of research approaches involving the synchronization of different physiological characteristics and events that determine the potential for high performance during seed storage and after sowing. The basic objective of vigor testing is to provide a consistent identification of differences in physiological potential among seedlots of commercial value and this represents a more sensitive parameter than the germination test. There are various procedures to assess seed vigor including those that directly or indirectly evaluate seed metabolic state or identify seed tolerance to specific stress(es). At the same time, in more recent years, new knowledge has come from molecular biology, biotechnology, biophysics and seed and seedling imaging analyses; these approaches has been important complements to traditional seed research.. This text has the purpose to emphasize the role of Brazilian research in seed vigor, whose competence is internationally recognized, and to provide an overview of the evolution of knowledge also attempting to highlight events that contributed to the advancement of research on the subject.

Comparative Effects of NaCl and Polyethylene Glycol on Germination, Emergence and Seedling Growth of Cowpea

Abstract: Seeds of Paceno and Cuarenteno cultivars of cowpea (Vigna unguiculata L. Walp.) were tested for salt and drought tolerance at germination, seedling emergence and early seedling growth in NaCl and PEG-8000 solutions of different osmotic potentials (0, −0.2, −0.4, −0.6, and −0.8 MPa). Daily and final germination and emergence percentage, as well as germination and seedling emergence rate, and seedling growth were recorded under controlled conditions. Results showed that germination and emergence rate were delayed by both solutions in both cultivars, with differences between cultivars among growth stages, given that cultivar Cuarenteno, showed a higher germination rate than Paceno in NaCl, but Paceno was less affected by NaCl and PEG solutions at the emergence stage. Sodium chloride had a lesser effect on both cultivars in terms of germination rate, emergence rate and the final germination and emergence percentage than did PEG-8000. This conclusively proves that the adverse effect of PEG-8000 on germination, emergence and early seedling growth was due to the osmotic effect rather than the specific ion. Seedling growth was reduced by both stresses, but NaCl usually caused less damage than PEG to cowpea seedlings, suggesting that NaCl and PEG acted through different mechanisms.

Impact of bulk and nanosized titanium dioxide (tio2) on wheat seed germination and seedling growth

Abstract: The impacts of different concentrations of bulk and nanosized TiO2 on seed germination and seedling growth of wheat were studied in a randomized completely design with four replications in the College of Agriculture, Ferdowsi University of Mashhad, Iran, in 2011. The experimental treatments included five concentrations of bulk (1, 2, 10, 100, and 500 ppm), five concentrations of nanosized TiO2 (1, 2, 10, 100, and 500 ppm), and control (without any TiO2). Results indicated that among the wheat germination indices, only mean germination time was affected by treatments. The lowest and the highest mean germination time (0.89 vs. 1.35 days) were obtained in 10 ppm concentration of nanosized TiO2 and control treatments, respectively. In addition, shoot length, seedling length, and root dry matters were affected by bulk and nanosized TiO2 concentrations, significantly. Shoot and seedling lengths at 2 and 10 ppm concentrations of nanosized TiO2 were higher than those of the untreated control and bulk TiO2 at 2 and 10 ppm concentrations. Employing nanosized TiO2 in suitable concentration could promote the seed germination of wheat in comparison to bulk TiO2 but in high concentrations had inhibitory or any effect on wheat.