2 research outputs found

    InfluĂȘncia do cultivar, do tipo de folha e do tempo de cultivo na medida indireta da clorofila (spad) em mudas de goiabeira Influence of cultivars, type of leaf, and cultivation time in the indirect measurement of chlorophyll (SPAD) in guava (psidium guajava l.) seedlings

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    A anĂĄlise foliar de nitrogĂȘnio, comumente empregada em laboratĂłrios de rotina, Ă© destrutiva e nem sempre rĂĄpida, obstante para a tomada de decisĂŁo. Objetivou-se com a pesquisa estudar as medidas SPAD, em mudas de goiabeira (Psidium guajava L.) cultivada em solução nutritiva completa, observando-se as diferenças entre cultivares, Ă©pocas de amostragem e tipos de folhas avaliadas. O delineamento foi inteiramente casualizado, com quatro repetiçÔes, em parcelas sub-subdivididas. Assim, foi utilizada como parcela as duas cultivares de goiabeira (Paluma e SĂ©culo XXI), como subparcelas os tipos de folhas (+1, +2 e +3) e, cinco Ă©pocas de amostragem ao longo do perĂ­odo experimental (60, 75, 90, 105 e 120 dias, apĂłs o transplantio de mudas) Concluiu-se que a leitura SPAD em mudas de goiabeira Ă© influenciada pela cultivar, tipo de folha e Ă©poca de amostragem. O terceiro par de folhas mostrou-se mais adequado para avaliar o estado nutricional do nitrogĂȘnio nas mudas de goiabeira a partir da leitura SPAD. As cultivares de goiabeira apresentaram diferença na leitura SPAD apenas aos 60 e 90 dias apĂłs o transplantio, independentemente do tipo de folha.<br>Foliar nitrogen analysis, also used in routine laboratories, is destructive and not always fast enough for decision making. The objective of this research was to study SPAD measurements, in guava seedlings (Psidium guajava L.) cultivated in a complete nutritive solution, observing the differences between cultivation, times of sampling, and types of evaluated leaves. The experimental design was a completely randomized scheme, with four repetitions, in split lots. The lots consisted of two guava cultivars (Paluma and SĂ©culo XXI), as sub-lots, the types of leaves (+1, +2 ,and +3), and five sampling times throughout the experimental period (60, 75, 90, 105, and 120 days). It was concluded that the SPAD measurements in guava seedlings are influenced by cultivation, type of leaf, and time of sampling. The third pair of leaves was shown to be more adequate for evaluating the nutritional status of nitrogen in the guava seedlings from the SPAD reading. The guava cultivars presented differences in SPAD readings only at 60 and 90 days, regardless of the type of leaf
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