X-Ray analysis to assess mechanical damage in sweet corn seeds

The X-ray test is a precise, fast and non-destructive method to detect mechanical damage in seeds. In the present study, the efficiency of X-ray analysis in identifying the extent of mechanical damage in sweet corn seeds and its relationship with germination and vigor was evaluated. Hybrid 'SWB 551' (sh2) seeds with round (R) and flat (F) shapes were classified as large (L), medium (M1, M2 and M3) and small (S), using sieves with round and oblong screens. After artificial exposure to different levels of damage (0, 1, 3, 5 and 7 impacts), seeds were X-rayed (15 kV, 5 min) and submitted to germination (25 °C/5 days) and cold (10 °C/7 days) tests. Digital images of normal and abnormal seedlings and ungerminated seeds from germination and cold tests were jointly analyzed with the seed X-ray images. Results showed that damage affecting the embryonic axis resulted in abnormal seedlings or dead seeds in the germination and cold tests. The X-ray analysis is efficient for identifying mechanical damage in sweet corn seeds, allowing damage severity to be associated with losses in germination and vigor.

The geographic dynamics of industry employment in Brazilian metropolitan areas: lessons for São Paulo

ABSTRACTWe discuss historic trends in large metropolitan areas in Brazil showing that manufacturing has decreased its share in the country but the movement was, in general, more intense in large metropolitan areas and particularly in the São Paulo Metropolitan Area (SPMA). This movement was more intense in the 1980s and in the first half of the 1990s. From mid 1990s up to the end of the 2000s, the manufacturing share trend became flat. We speculate that the first period reflects the exhaustion of the process of import substitution that took place in the previous three decades (1950 to 1980). The second period, from 1993 to 2009, is representative of a new model of growth and the evidence that manufacturing share became flat is reinforcing the idea of a new period in terms of manufacturing employment. While concentration has risen from 1996 to 2005, it decreased again in the second half of the first decade of the 2000s. The SPMA reinvented itself very quickly from late 1970s to mid-2000s.