A salinidade e o déficit hídrico são os fatores abióticos que têm afetado acentuadamente a produção de espécies vegetais de importância socioeconômica nas regiões áridas e semi-áridas. Portanto, o objetivo do presente trabalho foi de avaliar os efeitos do cloreto de sódio (NaCl) e do polietilenoglicol (PEG 6000), agentes estressores comumente utilizados para simular os estresses salino e hídrico, respectivamente, na germinação de sementes de cártamo (Carthamus tinctorius L.), uma oleaginosa da família Asteraceae. A germinação foi conduzida em sistema de rolo, com delineamento experimental de sete tratamentos osmóticos (controle; "0,450; "0,852; "1,271 MPa), sendo três com concentrações isosmóticas de NaCl (100; 200 e 300mM) e PEG (188,35; 267,75 e 357,24 g/L), e cada tratamento com seis repetições. Durante a germinação, foram avaliados parâmetros como a porcentagem de germinação, o índice de velocidade de germinação (IVG), e três dias após o semeio, foram registrados o índice de crescimento relativo da radícula (ICRR) e a massa fresca dos eixos das plântulas. A porcentagem de germinação e o IVG não sofreram alterações significativas no tratamento osmótico de "0,450 MPa induzido por NaCl quando comparado com o controle, enquanto no mesmo tratamento, induzido pelo PEG, estes dois parâmetros apresentaram uma intensa diminuição e um leve aumento, respectivamente. O ICRR e a massa das plântulas apresentaram diminuições proporcionais à redução do potencial osmótico ao utilizar ambos os compostos. Com base nos resultados alcançados, pôde-se concluir que a germinação de sementes de cártamo é influenciada pelo tipo de estresse aplicado e sua respectiva dose. Adicionalmente, o estresse osmótico induzido por PEG 6000 é mais agressivo que o salino, e potenciais osmóticos mais baixos ("0,851 e "1,271 MPa) são limitantes para a germinação desta espécie.
The aim of this work was to evaluate physiological and biochemical responses of faveleira under salinity. Plants were grown in nutrient solution containing 0, 50, 100 or 150 mM NaCl. After 8 days of stress, plants were harvested and separated into roots, xylopodium, stem ? petiole (SP), and basal, median and apical leaves. Salinity reduced the dry weight of all plant parts, although the indicators of water status were not changed. Salt stress increased the content of Na ? in the different plant parts, especially in xylopodium, in which it increased approximately eightfold while the content of K ? decreased by approximately 40 % under 150 mM NaCl. As a consequence, the K ? /Na ? ratio decreased in all plant organs. In stressed plants, the content of soluble sugars was increased in the roots, SP and leaf strata and the content of soluble proteins increased in all organs. The content of total free amino acids increased in the roots, SP and apical leaves, while the proline content increased in all organs except in xylopodium. It is suggested that the xylopodium may be involved in a mechanism of exclusion and/or compartmentalization of Na ? in faveleira under salinity to avoid ionic toxicity in the leaves.
RESUMO -O objetivo do presente estudo foi avaliar o efeito de diferentes concentrações de NaCl nas fases de multiplicação e enraizamento in vitro do abacaxizeiro cultivar MD Gold. Brotos de abacaxizeiro foram inoculados em meio MS, na ausência e presença dos fitorreguladores ácido naftalenoacético (ANA) e 6-benzilaminopurina (BAP) e também de diferentes concentrações de NaCl (Controle -0; 50; 100 e 150 mM). Mensalmente, os brotos foram subcultivados e foram analisados altura média, número de folhas vivas e mortas, taxas de brotação e enraizamento. Durante a multiplicação e na ausência de ANA e BAP, o NaCl provocou significativa redução no crescimento e desenvolvimento de brotos de abacaxizeiro, expresso pela altura e pelo número de folhas, nas doses mais elevadas, contrariamente, na presença dos fitorreguladores. Durante os 60 dias iniciais, ocorreu aumento na produção de folhas. Contudo, aos 90 dias, observou-se decréscimo na média de folhas vivas nos brotos tratados com sal. O cultivo in vitro de abacaxizeiro em presença de sal é mais eficiente na presença de ANA e BAP, garantindo a manutenção do crescimento, aumentando o número de folhas, produzindo novas gemas e acelerando o processo de enraizamento. Termos para indexação: Ananas comosus, estresse salino, fitorreguladores, cultivo in vitro. SALINITY INDICATORS IN PINEAPPLE GROWN IN THE ABSENCE AND PRESENCE OF GROWTH REGULATORSABSTRACT -To assess the effects of salt on the pineapple MD Gold during the multiplication and rooting phases in vitro, this study evaluated its performance in different concentrations of NaCl in the absence or presence of growth regulators. Pineapple shoots were inoculated on MS solution in the absence and presence of the growth regulators naphthaleneacetic acid (NAA) and 6-benzlaminopurine (BAP) and different concentrations of NaCl (Control -0, 50, 100 and 150 mM). Monthly, shoots were subcultured and it was analyzed height, number of alive and dead leaves, and the rates of sprouting and rooting. During the multiplication in the absence of NAA and BAP, the NaCl treatments caused significant reduction in growth and development of pineapple shootings, expressed by the height and number of leaves, in the highest dose, which was not observed in the presence of growth regulators. During the first 60 days, an increase in leaf production occurred. However, after 90 days, there was a decrease in average living leaves in the shoots treated with salt. The in vitro cultivation of pineapple in the presence of salt is more efficient in the presence of NAA and BAP, ensuring continued growth, increasing the number of leaves, producing new buds and accelerating the process of rooting.
The aim of this study was to determine the concentration and exposure time to NaCl suitable for the micropropagation of banana, through the analysis of growth traits. Banana propagules were inoculated in MS medium with different concentrations of NaCl (0; 50; 75 and 100 mM) for 120 days (multiplication and rooting, 60 days each), with monthly subcultures. These propagules were measured for plant height, number of leaves, sprouting rate, average number of formed propagules, rooting rate, root length and survival rate. After 30 days, NaCl reduced sprouting rate at multiplication; the number of leaves, rooting rate and root length in rooting; and the height and propagules number in both phases. After 60 days, the NaCl affected the sprouting rate and propagules number in the multiplication; length of root in rooting; and the height and number of leaves in both phases. After 120 days, the reduction in the survival rate was proportional to the increase of NaCl in the medium. Thus, it is concluded that NaCl reduces most of the growth traits and the treatments with 75 and 100 mM NaCl affected multiplication and in vitro rooting more intensely.
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