Desenvolvimento vegetativo e conteúdo de cálcio, potássio e sódio em melancieira sob estresse salino, em substratos orgânicos

The objective of this work was to evaluate the vegetative development and determine the concentration of sodium, potassium, and calcium in watermelon (Citrullus lanatus) grown on two organic substrates and under increasing saline concentrations. The substrates were soil + earthworm humus (S1) and soil + bovine manure (S2), and the saline treatments consisted of irrigation water with different electrical conductivities: 1.36 (control), 3.56, 5.76, and 7.96 dS m-1. The experimental design used was a randomized complete block in a 2×4 (substrate × conductivity) factorial arrangement with five replicates. Main branch length, root length, stem diameter, leaf number, leaf area, and fresh matter mass of shoots and roots, as well as the sodium, potassium, and calcium contents in the plants, were determined. All phenological parameters interacted with the substrates, and S1 improved plant performance. Substrates interacted significantly with: leaf area; leaf number; stem diameter; main branch length; root length; fresh matter mass of shoots and roots; and the contents of sodium, potassium, and calcium, in both shoots and roots of watermelon irrigated with saline water for up to 27 days after emergence. There are also interactions between substrates and salinity for stem diameter, main branch length, fresh matter mass of roots, and calcium contents in both shoots and roots, and potassium and sodium contents in the roots.O objetivo deste trabalho foi avaliar o desenvolvimento vegetativo e determinar a concentração de sódio, potássio e cálcio em melancieiras (Citrullus lanatus), cultivadas em dois substratos orgânicos e concentrações salinas crescentes. Os substratos foram solo + húmus de minhoca (S1) e solo + esterco bovino (S2), e os tratamentos salinos consistiram de irrigação com diferentes condutividades elétricas: 1,36 (controle), 3,56, 5,76 e 7,96 dS m-1. Utilizou-se o delineamento experimental de blocos ao acaso, em arranjo fatorial 2×4 (substratos × condutividade), com cinco repetições. Foram determinados comprimento do ramo principal e da raiz, diâmetro do caule, número de folhas, área foliar e massa fresca da parte aérea e da raiz, bem como o conteúdo de sódio, potássio e cálcio nas plantas. Todos os parâmetros fenológicos apresentaram interação com os substratos, e S1 promoveu melhor desempenho das plantas. Os substratos interagiram significativamente com: área foliar; número de folhas; diâmetro do caule; comprimento do ramo principal; comprimento de raiz; massa de matéria fresca da parte aérea e da raiz; e teores de sódio, potássio e cálcio na parte aérea e nas raízes de melancieiras irrigadas com água salina, até 27 dias após a emergência. Os substratos também interagiram com a salinidade para diâmetro do caule, comprimento do ramo principal, massa de matéria fresca de raiz, e teores de cálcio na parte aérea e raiz, e de potássio e sódio na raiz

Metabolismo bioquímico de plântulas de mamoeiros sob estresse salino

The objective of this work was to evaluate the biochemical metabolism of papaya seedlings submitted to different levels of salinity and cultivated in three types of substrates in order to determine which substrate promoted a better osmotic adjustment to saline stress. For the production of the seedlings of the cultivar Hawaii were used tubes with capacity 300 cm3. The completely randomized design was used in the 3x4 factorial scheme. The treatments were composed of three types of substrates: S1 = vermiculite+earthworm humus (1/1); S2 = vermiculite+humus+goat manure (1/1/1); S3 = vermiculite+manure (1/1) and four levels of electrical conductivity in irrigation water: C1 = C1= 0.0; C2= 2.5; C3= 5.0 e C4= 7.5 dS m-1 with five replicates. The saline solution for irrigation was obtained with NaCl addition and monitored with the aid of a conductivity meter. After the emergence of the seedlings the saline treatments were started until the 15th day after the emergency. The content of total soluble sugars, total free amino acids and proline content in shoot and root were analyzed. Based on the data analysis, it was observed that papaya seedlings grown on S1 substrate increased total soluble sugars and total soluble amino acids in root and shoot, proportional to the increase in salinity levels. In conclusion, the substrate vermiculite+earthworm humus (1/1) promoted a possible osmotic adjustment to the seedlings under conditions of salt stress, through the increase of nitrogen compounds.Objetivou-se com presente trabalho, avaliar o metabolismo bioquímico de plântulas de mamoeiro submetidas a diferentes níveis de salinidade, e cultivados e três tipos de substratos, a fim de determinar qual substrato promoveu um melhor ajustamento osmótico ao estres salino. Para produção das mudas da cultivar Havaí foram utilizados tubetes com capacidade 300 cm3. Empregou-se o delineamento inteiramente casualizado, no esquema fatorial 3x4. Os tratamentos foram compostos por três tipos de substratos: S1= vermiculita+húmus de minhoca (1/1); S2= vermiculita+húmus+esterco caprino (1/1/1); S3= vermiculita+esterco (1/1) e quatro níveis de condutividade elétrica na água de irrigação: C1= 0,0; C2= 2,5; C3= 5,0 e C4= 7,5 dS m-1 com cinco repetições. A solução salina para a irrigação foi obtida com a adição NaCl e monitorada com auxílio de um condutivimetro. Após a emergência das plântulas iniciou-se os tratamentos salinos até o 15º dia após a emergência. Analisou-se o conteúdo de açúcares solúveis totais, aminoácidos livres totais e teor de prolina em parte aérea e raiz. Com base na análise dos dados, observou-se que plântulas de mamoeiro cultivadas em substrato S1 incrementaram os teores de açúcares solúveis totais e aminoácidos solúveis totais em raiz e parte aérea, proporcional ao aumento dos níveis de salinidade. Concluindo, portanto, que o substrato vermiculita+húmus de minhoca (1/1) promoveu um possível ajustamento osmótico às plântulas em condições de estresse salino, através do aumento de compostos nitrogenados

Vegetative development and content of calcium, potassium, and sodium in watermelon under salinity stress on organic substrates

<div><p>Abstract: The objective of this work was to evaluate the vegetative development and determine the concentration of sodium, potassium, and calcium in watermelon (Citrullus lanatus) grown on two organic substrates and under increasing saline concentrations. The substrates were soil + earthworm humus (S1) and soil + bovine manure (S2), and the saline treatments consisted of irrigation water with different electrical conductivities: 1.36 (control), 3.56, 5.76, and 7.96 dS m-1. The experimental design used was a randomized complete block in a 2×4 (substrate × conductivity) factorial arrangement with five replicates. Main branch length, root length, stem diameter, leaf number, leaf area, and fresh matter mass of shoots and roots, as well as the sodium, potassium, and calcium contents in the plants, were determined. All phenological parameters showed interaction with the substrates, and S1 improved plant performance. Substrates interacted significantly with: leaf area; leaf number; stem diameter; main branch length; root length; fresh matter mass of shoots and roots; and the contents of sodium, potassium, and calcium, in both shoots and roots of watermelon irrigated with saline water for up to 27 days after emergence. There are also interactions between substrates and salinity for stem diameter, main branch length, fresh matter mass of roots, and calcium contents in both shoots and roots, and potassium and sodium contents in the roots.</p></div

KI Increases Tomato Fruit Quality and Water Deficit Tolerance by Improving Antioxidant Enzyme Activity and Amino Acid Accumulation: A Priming Effect or Relief during Stress?

A water deficit can negatively impact fruit yield and quality, affecting critical physiological processes. Strategies to mitigate water deficits are crucial to global food security. Iodine (I) may increase the efficiency of the antioxidant system of plants, but its role against water deficits is poorly understood. This study aimed to evaluate the effectiveness of I in attenuating water deficits and improving fruit quality, investigating whether metabolic responses are derived from a “priming effect” or stress relief during water deficits. Tomato plants were exposed to different concentrations of potassium iodide (KI) via a nutrient solution and subjected to a water deficit. A water deficit in tomatoes without KI reduced their yield by 98%. However, a concentration of 100 μM of KI increased the yield under a water deficit by 28%. This condition is correlated with increased antioxidant activity, photosynthetic efficiency improvement, and malondialdehyde reduction. In addition, the concentration of 100 μM of KI promoted better fruit quality through antioxidant capacity and a decline in the maturation index. Therefore, KI can be an alternative for attenuating water deficits in tomatoes, inducing positive responses during the water deficit period while at the same time improving fruit quality