Respiratory activity in wheat seeds as related to physiological quality / Atividade respiratória em sementes de trigo correlacionada com a qualidade fisiológica

Seeds are a very important input for crops, and the use of low quality seeds and/or inadequate management affects the germination and hampers seedling emergence, which reduces the plant stand. There is a critical need for the development of rapid methods, which are both reliable and easy to perform, for evaluating the physiological potential of seeds. This would streamline the decision-making process regarding the management of lots and allow for the identification of seed lots of inadequate quality in the seed processing unit, which could then be discarded, and would consequently result in reduced costs associated with unnecessary processing. However, it is important that these methods are low cost and quick to perform. The aim of this study was to evaluate the correlation of respiratory activity of wheat seed, through Pettenkofer test, with tests that evaluate seeds physiological quality. We selected a seed lot of high physiological quality, then subjected the seeds to adverse temperature and relative humidity conditions to obtain different vigor levels. The adverse conditions used were 42ºC and 100% relative humidity, for periods of 6, 36, 66 and 96 hours. This process obtained seeds of five vigor levels which were subjected to the following tests: germination, field emergence, electrical conductivity, shoot and root length, total dry mass and respiratory activity. The results showed a negative correlation between respiratory activity and germination, emergence, shoot and root length and dry weight, whereas germination and emergence were strongly correlated with respiratory activity, r = -0.86 and r = -0.81, respectively. There was a significant positive correlation between conductivity and respiratory activity. Therefore, the respiratory activity test using the Pettenkofer method was correlated with other vigor tests, and allowed the classification of wheat seeds into lots of different levels of quality.

As sementes são um atributo muito importante para a cultura, sendo que o uso de sementes de baixa qualidade e/ou a gestão inadequada afeta a germinação e dificulta a emergência das plântulas, reduzindo o estande de plantas. A necessidade de métodos rápidos, confiáveis e de fácil execução é fundamental para a avaliação do potencial fisiológico das sementes. Eles poderiam agilizar as tomadas de decisões referentes ao manejo dos lotes e permitir o descarte de lotes de sementes com qualidade inadequada, na unidade de recepção e processamento de sementes, com a consequente redução de custos de um provável processamento desnecessário. Entretanto, é importante que os mesmos sejam de baixo custo e consideravelmente rápidos. O objetivo do presente trabalho foi correlacionar a atividade respiratória de sementes de trigo, através do teste de Pettenkofer, com testes que avaliam a qualidade fisiológica das sementes. Foi selecionado um lote de sementes com alta qualidade fisiológica e as mesmas foram submetidas a condições adversas de temperatura e umidade relativa do ar para obter diferentes níveis de vigor. As condições adversas foram de 42 ºC e 100% de umidade relativa, por períodos de seis, 36, 66 e 96 horas. Com o processo obteve-se cinco níveis de vigor e estas sementes foram submetidas aos seguintes testes: germinação, emergência a campo, condutividade elétrica, comprimento de parte aérea e raiz, massa seca total e atividade respiratória. Os resultados mostraram correlação negativa entre a atividade respiratória e os testes de germinação, emergência, comprimento da parte aérea e da raiz, e massa seca, sendo que o teste de germinação e a emergência apresentaram alta correlação com a atividade respiratória, r = -0,86 e r = - 0,81, respectivamente. Já a correlação da condutividade elétrica com a respiração foi significativa e positiva. Portanto, conclui-se que o teste da atividade respiratória pelo método de Pettenkofer se correlaciona com outros testes de vigor e permite a classificação dos lotes de sementes de trigo em diferentes níveis de qualidade.

Medição do CO2 como método alternativo para a diferenciação do vigor de lotes de sementes de melancia / Measurement of CO2 an alternative method to differentiate vigor seed lots of watermelon

A melancia, uma hortaliça nativa da África, é considerada uma das mais importantes produzidas e comercializadas no Brasil, cujo cultivo é realizado de maneira intensiva e deve ser estabelecido com o uso de sementes de alta qualidade, que germinem rápido e uniformemente. Portanto, o objetivo nesta pesquisa foi avaliar a atividade respiratória e correlacioná-la com outros testes tradicionais de vigor, com a finalidade de verificar se a medição do CO2 é um método eficiente na diferenciação do vigor de lotes de sementes de melancia. A pesquisa foi desenvolvida na Universidade Federal de Pelotas, utilizando sementes da cultivar 'Crimson sweet', representada por cinco lotes. As variáveis avaliadas foram o grau de umidade, germinação, primeira contagem de germinação, comprimento de parte aérea e raízes de plântulas, condutividade elétrica, emergência de plântulas e atividade respiratória. Os lotes de sementes foram classificados em diferentes níveis de qualidade fisiológica, conforme o grau de precisão de cada teste, sendo o lote 3 de qualidade inferior aos demais. A atividade respiratória permite a separação dos lotes de sementes de melancia, no entanto, não há correlação positiva e significativa com os demais testes de vigor.

Watermelon is a vegetable crop native of Africa, regarded as one of the most important produced and marketed in Brazil. The cultivation of most vegetables is usually performed intensively and should be established with the use of high quality seeds that germinate quickly and uniformly. Therefore, the aim of this research was to evaluate the respiratory activity and correlate it with other traditional tests of strength, in order to verify if the measurement of CO2 is an efficient method to differentiate vigor seed lots of watermelon. The research was developed at the Universidad Federal of Pelotas, using seeds of the cultivar Crimson sweet represented by five lots. The variables evaluated were moisture content, germination, first germination count, length of shoot and root of seedling, electrical conductivity, seedling emergence and respiration. The results allowed us to classify the lots in different vigor levels, as the accuracy of each test emphasizing lot 3 for being inferior to the others. The respiratory allows separation of seed lots of watermelon, however no significant positive correlation with other vigor tests.

Max von Pettenkofer (1818-1901) as a pioneer of modern hygiene and preventive medicine

Max von Pettenkofer (1818-1901) belonged to the scientific elite of the 19th century. With his stringent search for the laws of nature and his fight for scientific truth, Pettenkofer was the prototype of a modern researcher. In the field of hygiene, he sought ways and means of preserving health and preventing sickness. With his consistent application of the experimental method to the field of public health, Pettenkofer helped the discipline of hygiene to provide precise and reliable answers to sanitary questions. In his experimental work on hygiene, Pettenkofer sought an answer to every imaginable question concerning the connection between the human organism and its environment.To proceed in this direction, Pettenkofer combined medical expertise with physics, chemistry, technique and statistics. This even today modern "crossover-thinking" made hygiene to the first interdisciplinary medical field. With his Institute of Hygiene, Pettenkofer established 1879 the first centre of competence for hygiene and environment in the world, opening a new era of environmental observation.In the framework of hygiene, Pettenkofer turned also to questions of nutrition and the quality of foodstuff. The science of hygiene owes to Max von Pettenkofer not only its development and cartography, but also its introduction as an academic discipline. Finally he regarded hygiene also as an economic and cultural feature. His idea about a clean soil in the cities and his promotion of adequate water supply and sufficient sewage networks are linked to his theory of the cholera. Pettenkofer believed that a battle against this epidemic could be won.

Academic Influence on Japan of Edmund Alexander Parkes, Pioneer of Modern Hygiene

In Japan, Max von Pettenkofer is highly regarded as a pioneer of modern hygiene. The contribution of Edmund Alexander Parkes, however, is not yet sufficiently appreciated. This paper outlines the life and achievements of E.A. Parkes and discusses his influence in Japan.

Academic influence on Japan of Edmund Alexander Parkes, pioneer of modern hygiene

In Japan, Max von Pettenkofer is highly regarded as a pioneer of modern hygiene. The contribution of Edmund Alexander Parkes, however, is not yet sufficiently appreciated. This paper outlines the life and achievements of E.A. Parkes and discusses his influence in Japan.