RESUMEN
Objective: To investigate the effects of exogenous nitric oxide (NO) on the physiology of the seed germination and seedling growth of Silybum marianum under NaCl stress. Methods: The seeds of S. marianum were treated by sodium nitro prusside (SNP) at the concentration of 0.05-0.60 mmol/L under 0.7% NaCl stress. Some physiological indexes were measured, such as germination energy, germination rate, germination index, and vigor index of the seeds, and contents of malondialdehyde (MDA), photosynthetic pigment, osmosis substances, and the activities of the protective enzymes in leaves. Results: The seed germination and seedling growth of S. marianum were obviously inhibited under NaCl stress. Soaking seeds with 0.05-0.60 mmol/L SNP could alleviate the damage of NaCl stress. Under this treatment, the contents of photosynthetic pigment (including chlorophyll a, chlorophyll b, total chlorophyll, and carotinoid) and osmosis substances (including soluble sugar, soluble protein, and proline), and the activities of protective enzymes (including SOD, POD, and CAT) in the leaves were significantly increased, while the MDA content in the leaves was decreased. Conclusion: Soaking seeds with 0.05-0.60 mmol/L SNP could promote the salt resistance of the seeds and seedlings of S. marianum. The different cultivars of S. marianum differ in the sensitivity to SNP. The optimal concentration of SNP for the seed soaking of S. marianum with white and black skins is 0.10 and 0.40 mmol/L, respectively.
RESUMEN
Resumo Objetivo: avaliar a evolução do crescimento de crianças alimentadas exclusivamente com leite materno durante os primeiros 6 meses de vida. Métodos: estudo longitudinal de 184 crianças que receberam atenção primária em instituição pública (Programa de Incentivo ao Aleitamento Materno Exclusivo) de Belém (PA), entre fevereiro de 2000 e janeiro de 2001. Finalizaram o estudo 102 lactentes nascidos a termo, com peso igual ou superior a 2.500 g, sem intercorrências no período neonatal e alimentados exclusivamente com leite materno sob livre demanda desde o nascimento. Acompanhados mensalmente, foram avaliados os registros de peso e comprimento ao nascer, no primeiro, quarto e sexto meses de vida. Avaliou-se o crescimento através das médias de peso e estatura para cada idade, comparando-se os resultados com o percentil 50° dos gráficos de crescimento do National Center for Health Statistics (NCHS) e com outros estudos anteriores com crianças brasileiras em aleitamento materno exclusivo. Resultados: as crianças tiveram crescimento adequado, dobrando de peso antes do quarto mês de vida, com desaceleração do ganho pôndero-estatural após o quarto mês, porém chegando aos 6 meses com médias de peso superiores aos padrões utilizados para comparação. Conclusões: os resultados mostraram que crianças em aleitamento materno exclusivo chegaram aos 6 meses com peso médio superior ao percentil 50° do NCHS, confirmando as vantagens nutricionais do leite materno, principalmente quando as mães recebem orientação sobre a técnica adequada para amamentar.
Summary Objective: to evaluate the growth of exclusively breastfed infants from birth to 6 months of life. Methods: this was a longitudinal study of 184 children who received primary care at a public institution (Exclusive Breastfeeding Stimulation Program, PROAME) in Belém, state of Pará, Brazil, between February 2000 and January 2001. A total of 102 children completed the study. All were born at full term with a birth weight greater than or equal to 2,500 g. No events were recorded during the neonatal period and the infants were exclusively breastfed, on demand, since their birth. The infants were followed up monthly, and the weight and length measured at birth and at the end of the first, fourth and sixth months of life were compared to the 50th percentile line of the NCHS growth charts and to other previous studies of Brazilian children who were exclusively breastfed. Results: growth was adequate for all the children, who doubled their weight before the fourth month of life. Despite a slow-down in weight and height gain after the fourth month, the weight averages at 6 months were greater than the standards used for comparison. Conclusions: the average weight of these exclusively breastfed children was above the 50th percentile of the NCHS curve at 6 months, thus confirming the nutritional advantages of breast milk, especially when the mothers receive guidance regarding the appropriate techniques for breastfeeding.