SINTOMAS DE DESORDENS NUTRICIONAIS EM ESTÉVIA Stevia rebaudiana (Bert.) Bertoni

Abstract

São descritos e discutidos os sintomas de deficiência de N, P, K, Ca, Mg e B, e de toxicidade de B e Zn, em estévia cultivada em solução nutritiva. -N: desenvolvimento reduzido, folhas pequenas, pouca ramificação, e amarelecimento generalizado. -P: crescimento reduzido. -K: folhas encurvadas, precocemente, para baixo, aparentando menor teor de água; amarelecimento e necrose das folhas mais velhas e menor proporção de ramos. -Ca: pontuações escuras, clorose e necrose nas folhas, além de murchamento e colapso da porção superior do caule. -Mg: clorose internerval em algumas folhas mais velhas, em forma de "V" invertido. -B: raízes com diminuição do crescimento, engrossamento, ramificação curta e escurecimento geral; clorose, necrose e deformação das folhas; em folhas jovens, com sintomas, houve menor teor de clorofila; caule com rachaduras de coloração avermelhada, semelhante às nervuras salientes das folhas; menor proporção de ramos. Plantas com toxicidade de B exibiram manchas pardas nas bordas e ápices das folhas mais velhas, seguido de necrose. Plantas com excesso de Zn exibiram manchas necróticas, inicialmente nas folhas mais velhas, de tamanho e forma irregulares, levando ao murchamento e morte da planta.<br>Symptoms of the deficiencies of N, P, K, Ca, Mg and B, as well as the toxicity symptoms of B and Zn in stevia plants, growing in nutrient solution, are described. -N: reduced development, small leaves, few branches and generalized yellowing. -P: reduced growth. -K: leaves curving downward, seeming to have lower water content, yellowing and necrosis of older leaves and smaller stem plus branches proportion. -Ca: dark spots, chlorosis and necrosis in leaves as well as wilting and collapse at the upper portion of stem. -Mg: interveinal paling in some older leaves, with an inverted V appearance. -B: roots with growth reduced, thickening, short ramification and general darkening; chlorosis followed by necrosis and deformation of leaves; young leaves with symptoms had smaller chlorophyll content; stem and branches showed crackings with reddish coloration, like salient veins of the leaves; plants had fewer branches. Plants with B toxicity showed brown spots at margins and tips of older leaves, followed by necrosis. Plants with Zn toxicity had necrotic spots, first in older leaves, with irregular size and shape, followed by wilting and death of the plant

Steviol Glycosides: Chemical Diversity, Metabolism, and Function

“…Similarly, application of N-, P-, or K-based fertilizers did not change steviol glycoside levels, but did cause precocious flower budding. ,− Visual symptoms of nutrient deficiency in S. rebaudiana include changes in leaf color to dark green (P, B), yellow (N, K), or pale green (chlorosis; S, Mg), sometimes mottled (K) or with dark necrotic spots (Ca, K, S), and an impairment of overall growth (N, P). These deficiencies reduced steviol glycoside levels within the leaves, with the most severe decreases generally observed in Ca, K, and S deficiencies. ,− On the other hand, addition of 5 ppm B to hydroponically grown plants resulted in 50% higher yields of stevioside ( 37 ) and rebaudioside A ( 38 ). , Addition of Zn may also increase steviol glycoside levels significantly . Studies with in vitro cultures further showed that the addition of 3–5% sucrose could effectively increase steviol glycoside production. , …”

Applying boron to coconut palm plants: effects on the soil, on the plant nutritional status and on productivity boron to coconut palm trees

“…Boron deficiency, in general, reduces root growth (Lima Filho and Malavolta, 1997;Viegas et al, 2004) and in the coconut palm tree, production of total roots is reduced by 30% and of thin roots by 48% ( Pinho et al 2008a), Sobral (1998), Broschat (2005, and Santos et al (2003) observed that boron deficiency also damages the plant aerial part ,which produces less expanded young leaves with signs of blighted, necrotic, and corky areas. The primary symptoms of B deficiency in coconut trees are leaflet tip truncation, leaf crumpling or distortion, and failure of the spear leaf to open normally.…”

MORPHOLOGICAL ANALYSIS AND ACCUMULATION OF NUTRIENTS IN Peltophorum dubium (Spreng.) Taub. SEEDLINGS PRODUCED IN ORGANIC SUBSTRATES WITH DIFFERENT PROPORTIONS

“…Fernandes et al (2013), studying nutritional deficiencies of macronutrients and sodium in peach palm seedlings, observed that seedlings deficient in P showed an increase in the length of the primary roots and a smaller amount of root hairs. B deficiency, in turn, can reduce the production of total and thin roots, cause thickening of the roots and short branches (Lima Filho and Malavolta, 1997;Salvador et al, 1999;Pinho et al, 2008). Well-developed roots represent an increase in the dry matter production capacity of plants, as they are responsible for the water and nutrients uptake, besides the storage of carbohydrates and proteins responsible for the production and continuity of the plant.…”