RESUMOA salinização dos solos reduz a capacidade das plantas de absorver água o que, em geral, provoca diminuição na sua taxa de crescimento. As respostas das plantas ao estresse salino são melhor correlacionadas com o potencial osmótico do que com a condutividade elétrica do extrato de saturação do solo. Com o objetivo de avaliar os efeitos do estresse salino no crescimento, evapotranspiração e potencial osmótico foliar do feijoeiro vigna [Vigna unguiculata L. (Walp.)] conduziu-se um experimento em casa de vegetação da Universidade Federal Rural de Pernambuco (Recife, PE, Brasil). Os tratamentos constaram de um arranjo fatorial 2 x 4 composto de duas texturas de solo e quatro níveis de salinidade do solo (4, 8 e 12 dS m -1 a 25 ºC além da testemunha sem a adição de sais) com cinco repetições. Concluiu-se que a salinidade do solo causa redução no consumo de água, no potencial osmótico foliar, na altura das plantas, no número de folhas e na biomassa seca da parte aérea do feijoeiro vigna. Palavras-chave: potencial osmótico, salinidade, feijão caupiHydric behaviour and growth of cowpea cultivated in salinized soils ABSTRACT Soil salinization reduces the capacity of plants to absorb water, and in general causes decrease in plant growth. Plant responses to salt stress are better correlated with osmotic potential compared to electrical conductivity of soil saturation extract. In order to evaluate the effect of salt stress on growth, water use and leaf osmotic potential of cowpea [Vigna unguiculata L. (Walp.)], an experiment was carried out in a greenhouse of the Federal Rural University of Pernambuco (Recife-PE, Brazil). The treatments were in a factorial arrangement of 2 x 4, comprising of two soil textures and four levels of soil salinity (4, 8 and 12 dS m -1 at 25 °C, and the control without salt addition) with five replications. It was concluded that soil salinity causes reduction in water consumption, leaf osmotic potential, plant height, number of leaves and dry biomass of shoot of cowpea.
Com o objetivo de avaliar o ponto de murcha permanente fisiológico, a umidade foliar e o potencial osmótico no feijoeiro caupi, sob duas condições de estresses (salino e salino + hídrico), foram conduzidos dois experimentos em casa de vegetação na Universidade Federal Rural de Pernambuco (Recife, PE, Brasil). O delineamento experimental adotado foi o inteiramente casualizado, em arranjo fatorial 2 x 4, sendo duas classes texturais de solos (franco-arenoso e franco-argiloso) e quatro níveis de salinidade do solo, equivalentes às condutividades elétricas do extrato de saturação do solo 4, 8 e 12 dS m-1, mais testemunha, com cinco repetições. A cultura teste utilizada foi o feijoeiro caupi [Vigna unguiculata L. (Walp.)], cultivar Pele de Moça. O ponto de murcha permanente do feijoeiro caupi é menor quando determinado pelo método fisiológico do que o determinado na câmara de pressão de Richards; o incremento da salinidade do solo (CEes) até 12 dS m-1 não influencia a umidade foliar, independente da textura do solo; e o potencial osmótico foliar do feijoeiro caupi diminui com o aumento da salinidade do solo e pode ser usado como variável importante em ambientes salinizados.
Jatropha curcas is a common species in Brazil, potentially being an option to produce oil for bioenergetic purposes. Around the world, J. curcas has been cultivated in areas of low fertility, in the presence of salts, and with the use of brackish groundwater.Salt stress can hinder the absorption of nutrients and allow entry of ions in toxic concentrations, affecting the development and productivity of plants. This study aimed to evaluate the effect of salinity on the gaseous exchange and the dynamics of some mineral nutrients in the leaves, stems and roots of J. curcas, subjected to two levels of NaCl (0 and 150 mM) in four genotypes: CNPAE183 (tolerant-like), JCAL171 (sensitivelike) and CNPAE133 and CNPAE266 (confused responses to tolerance). Salt treatment promotes a strong reduction in photosynthesis and plant height in all genotypes, although more drastic in CNPAE266 (77.5% and 70% respectively). Additionally, NaCl reduced the content of manganese, calcium, potassium and phosphorus in the leaves, elements linked to gas exchange. The salt-tolerant-like (CNPAE183) and salt-sensitivelike (JCAL171) transcriptome matched the applied sequences, with few chimeric sequences and novel transcripts with no similarities.
Efeito do polímero hidratassolo sobre propriedades físico-hídricas de três solos RES UMOTêm-se testado diversos produtos, no intuito de aumentar a armazenagem d'água nos solos. Estudo de laboratório foi realizado com o objetivo de caracterizar o polímero hidratassolo, no que se refere à sua capacidade de absorção hídrica, e avaliar o efeito de doses desse polímero sobre as propriedades físico-hídricas dos solos: Neossolo Quartzarênico, Latossolo Amarelo e Neossolo Flúvico. Os tratamentos com solos constaram de: testemunha (sem polímero); 0,05; 0,10 e 0,20 dag kg -1 de hidratassolo, referindo-se ao peso seco do polímero e do solo. Os resultados mostram que o polímero possui elevada capacidade de absorção em água deionizada mas, quando submetido a soluções salinas de sódio, potássio e cálcio, com condutividade elétrica de 8 dS m -1 , suas hidratações foram reduzidas, respectivamente, a 82,8, 80,7 e 94,7%. Ao se comparar os valores de água disponível dos 3 solos estudados referentes à maior dosagem do polímero com a testemunha, observaram-se acrés-cimos da ordem de 1,81, 2,02 e 1,10 vezes, para Neossolo Quartzarênico, Latossolo Amarelo e Neossolo Flúvico, respectivamente.Palavras-chave: condicionador de solo, retenção hídrica, manejo do solo Effect of 'hidratossolo' polymer on the hydrophysical proprieties of three soils AB S TR ACTSeveral products have been tested in order to increase the water-holding capacity of soils. A laboratory study was carried out with the objective to characterize the 'hidratassolo' in respect to its water absorbing capacity and evaluate the effect of dose of this polymer upon physical and hydraulic properties of the following soils: Quartzarenic Neosol, Yellow Latosol and Fluvisol. The treatments consisted of control (no polymer); 0.05; 0.10 and 0.20 dag kg -1 of 'hidratassolo', referring to the dry weight of the polymer and of the soil. The results showed that the polymer has a high absorption capacity in deionized water, but when submitted to salty solutions of sodium, potassium and calcium, having electrical conductivity of 8 dS m -1 its hidratations were reduced, respectively to 82.8; 80.7 and 94.7%. When compared the available water values of the 3 studied soils, referring to the higher dose of the polymer and the control, gains were observed varying of 1.81; 2.02 and 1.10 times, for Quartzarenic Neosol, Yellow Latosol and Fluvisol, respectively.
New procedures seek to subsidize studies on biomass and carbon in forests and wood, mainly of tropical species. Thus, the work aimed to compare four methods of carbon determination in wood. A pre-dried sample of tropical wood was prepared and previously ground. In this sample, the carbon content was determined, applying four different methodologies, namely: conversion of organic matter, volumetric method, colorimetric method and dry combustion (LECO). The Tukey test was performed to determine the difference between the carbon levels obtained by each method. As a result, all methods differed statistically from each other: the colorimetric method underestimated the levels of organic carbon in a tropical wood; although widely used, the volumetric method has become obsolete; and the organic matter conversion method requires specific conversion factors for each material. So, from the environmental point of view and accuracy in obtaining data, the dry combustion method, in addition to being the closest to the standard, is also the one that generates less waste, being the most suitable to determinate carbon in wood.
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