Diagnostic leaf to evaluate the nutritional status of Jatropha

Abstract

RESUMOSubmitted on 07/07/2014 and aproved on 07/14/2015. 1 Embrapa Agropecuária Oeste, Dourados, Mato Grosso do Sul, Brazil. carlos.kurihara@embrapa.br; cesar.silva@embrapa.br *Corresponding author: carlos.kurihara@embrapa.br Diagnostic leaf to evaluate the nutritional status of JatrophaThe analytical determination of nutrient levels in recently mature leaves in order to diagnose nutritional status is based on the fact that leaves are metabolically active and more sensitive to variation in nutrients of the soil. In most of cases, there is a well known relation between foliar content and the development and yield of the plant. However, for a more accurate interpretation, it is essential to establish the index leaf. There are few published studies about Jatropha with contrasting results. In order to establish the index leaf, in adult plants, the macronutrient levels were evaluated in samples collected in experimental plots, in which doses of nitrogen and phosphorus were applied, in two parts of the floral branches (in the top and in the middle thirds); and in three positions of leaves of the floral branch (between the 1 st and 3 rd , 6 th and 8 th , and 13 th and 15 th leaves below the inflorescence). The location of the leaf on the plant significantly affects nutrient contents. Nitrogen, phosphorus, potassium and sulfur tend to have higher concentration in young tissues. Calcium and magnesium showed higher levels in the basal leaves of floral branches. Samples collected in the top third of plants (between the 6 th and 15 th leaves of the floral branch) are more sensitive to variations of nitrogen and phosphorus fertilization. Therefore, we inchcate the 6 th to 15 th leaves of the top third of plants as index leaves to estimate nutritional status of Jatropha. Folha diagnóstica para a avaliação do estado nutricional do pinhão-mansoA determinação analítica dos teores de nutrientes em amostras de folhas recém-maduras, visando à diagnose do estado nutricional, é embasada no fato de este órgão ser metabolicamente ativo e mais sensível a variações na disponibilidade de nutrientes no solo, havendo, até certo ponto, relação direta com o desenvolvimento e a produção da planta. Contudo, para que a sua interpretação seja adequada, é preciso estabelecer a folha diagnóstica. Para o pinhão-manso, trabalhos publicados sobre este assunto têm mostrado resultados conflitantes. Assim, com o objetivo de se definir a folha diagnóstica em plantas adultas, avaliaram-se teores de macronutrientes em amostras coletadas em parcelas experimentais, nas quais se aplicaram doses de nitrogênio e de fósforo, em duas posições dos ramos florais (terço superior e terço médio da planta) e em três posições das folhas no ramo floral (entre a 1ª e a 3ª, entre a 6ª e a 8ª e entre a 13ª e a 15ª folhas abaixo da inflorescência). A localização da folha na planta influencia significativamente os teores de nutrientes, sendo que N, P, K e S tendem a apresentar maior concentração nos tecidos mais novos e, Ca e Mg, nas folhas basais do ramo floral, pri...

Selection of index leaf for foliar diagnosis of critical nutrient levels in physic nut (Jatropha curcas)

“…The critical levels of nutrients in the physic nut leaves were compared with those proposed by Raviv and Lieth (2008) in plant tissues and medium concentrations found by Laviola and Dias (2008), Lima et al (2011b) and Kurihara and Silva (2015) on physic nut leaves.…”

“…In medium nutrient concentrations, Lima et al (2011b) reported that in physic nut plants the critical levels were low for the macronutrients and high for the micronutrients except to Zn, with low concentrations, when sampled leaves from the basal section of floral branches from fifth to tenth position from the apex without mentioning the position. For the average macronutrient concentrations in leaf samples located from the sixth to fifteenth position from the apex of floral branches in the middle third of physic nut, Kurihara and Silva (2015) found that, the critical levels were high for Ca, adequate for N and S and low for P, K and Mg. In this study, changes in the classification of critical levels of nutrients can be observed compared with other reports (Raviv and Lieth, 2008, Laviola and Dias, 2008, Lima et al, 2011band Kurihara and Silva, 2015.…”

“…For the average macronutrient concentrations in leaf samples located from the sixth to fifteenth position from the apex of floral branches in the middle third of physic nut, Kurihara and Silva (2015) found that, the critical levels were high for Ca, adequate for N and S and low for P, K and Mg. In this study, changes in the classification of critical levels of nutrients can be observed compared with other reports (Raviv and Lieth, 2008, Laviola and Dias, 2008, Lima et al, 2011band Kurihara and Silva, 2015. The differences in recommendation of plant parts to be sampled caused misunderstandings in the diagnosis of the nutritional state of physic nut.…”

“…For the Ca and Mg, sampling from the basal leaves is more appropriate and phenological stage of the vegetative or floriferous branch does not influence the nutrient concentrations, except Cu and Fe (Lima et al, 2011b). Similarly, Kurihara and Silva (2015) recommended sampling of leaves from those located between the sixth and fifteenth of the floral branches for nutritional diagnosis of physic nut, because they are more sensitive and reflective to variations in nutrient availability in the soil. Foliar diagnosis is recommended to collect physiologically mature leaves, i.e.…”

“…It has also been recommended that samples from the basal leaves, those located in the fifth or tenth position are more appropriate for detection of Ca and Mg, because in this phenological stage, the vegetative or floriferous branch does not influence the nutrient concentrations, except Cu and Fe. Also without correlation, Kurihara and Silva (2015) indicated the collection of sixth and tenth position leaves in floral branches of the upper third of the plant because they were more sensitive to variations in availability of macronutrients in the soil for nutritional diagnosis of physic nut. Without the objective of obtaining the index leaf for physic nut, Laviola and Dias (2008) obtained nutrient concentrations of crops by sampling leaves with expanded limbs, located between the sixth and eighth leaves from the apex of the branch below the inflorescence, without specifying type of main or lateral branch.…”