RESUMO
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.
RESUMO
This study aimed to investigate the role of Se supply in improving osmotic stress tolerance in coffee seedlings while also evaluating the best timing for Se application. Five times of Se foliar application were assessed during induced osmotic stress with PEG-6000 using the day of imposing stress as a default, plus two control treatments: with osmotic stress and without Se, and without osmotic stress and Se. Results demonstrated that osmotic stress (OS) promoted mild stress in the coffee plants (ψw from -1.5MPa to -2.5 MPa). Control plants under stress showed seven and five times lower activity of the enzymes GR and SOD compared with the non-stressed ones, and OS was found to further induce starch degradation, which was potentialized by the Se foliar supply. The seedlings that received foliar Se application 8 days before the stress exhibited higher CAT, APX, and SOD than the absolute control (-OS-Se)-771.1%, 356.3%, and 266.5% higher, respectively. In conclusion, previous Se foliar spray is more effective than the Se supply after OS to overcome the adverse condition. On the other hand, the post-stress application seems to impose extra stress on the plants, leading them to reduce their water potential.
RESUMO
Water deficit inhibits plant growth by affecting several physiological processes, which leads to the overproduction of reactive oxygen species (ROS) that may cause oxidative stress. In this regard, iodine (I) is already known to possibly enhance the antioxidant defense system of plants and promote photosynthetic improvements under adverse conditions. However, its direct effect on water deficit responses has not yet been demonstrated. To verify the efficiency of I concerning plant tolerance to water deficit, we exposed soybean plants to different concentrations of potassium iodide (KI) fed to pots with a nutrient solution and subsequently submitted them to water deficit. A decline in biomass accumulation was observed in plants under water deficit, while exposure to KI (10 and 20 µmol L-1) increased plant biomass by an average of 40%. Furthermore, exposure to KI concentrations of up to 20 µM improved gas exchange (~71%) and reduced lipid peroxidation. This is related to the higher enzymatic antioxidant activities found at 10 and 20 µM KI concentrations. However, when soybean plants were properly irrigated, KI concentrations greater than 10 µM promoted negative changes in photosynthetic efficiency, as well as in biomass accumulation and partition. In sum, exposure of soybean plants to 10 µM KI improved tolerance to water deficit, and up to this concentration, there is no evidence of phytotoxicity in plants grown under adequate irrigation.
RESUMO
Zinc (Zn) is an essential micronutrient for plant growth, and Zn deficiency is a global issue, especially in tropical soils. This study aimed to investigate the effects of humic acid (HA) and the Zn addition (Zn sulfate + HA) on the growth of maize and brachiaria in two contrasting Oxisols. The potential complexation of Zn sulfate by HA was evaluated by Fourier-transform infrared (FTIR) spectroscopy analysis. Zinc content and its availability in solution and the shoot and root biomass of maize and brachiaria were determined. FTIR spectroscopy revealed the complexation of Zn sulfate by HA through its S and C functional groups. In both Oxisols, solution Zn increased due to the combined use of Zn and HA. In a soil type-dependent manner, maize biomass and Zn in its shoots were affected only by the exclusive use of Zn fertilization. In the Yellow Oxisol, brachiaria growth and Zn accumulated in its shoot were positively affected by the combined use of Zn fertilization with HA. In the Oxisol with lower organic matter content, HA can assure adequate supplying of residual Zn, while increasing growth of brachiaria cultivated in sequence to maize.
Assuntos
Brachiaria/efeitos dos fármacos , Substâncias Húmicas/análise , Solo/química , Zea mays/efeitos dos fármacos , Sulfato de Zinco/farmacologia , Brachiaria/crescimento & desenvolvimento , Brasil , Fertilizantes/análise , Concentração de Íons de Hidrogênio , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/crescimento & desenvolvimento , Análise de Componente Principal , Espectroscopia de Infravermelho com Transformada de Fourier , Zea mays/crescimento & desenvolvimento , Sulfato de Zinco/análise , Sulfato de Zinco/químicaRESUMO
Humic acid (HA) can increase eucalyptus growth due to its biostimulant effect and improvement in plant nutrient uptake. Magnitude of these stimuli varies according to the source, chemical composition, presence of bioactive fragments, and concentration of HA. The aim of this study was to evaluate the effect of HA sources and concentrations on dry matter, accumulation and uptake efficiency (UpE) of nutrients for eucalyptus seedlings cultivated in nutrient solution. A randomized block experimental design was adopted, with four replications, in a 3x4+1 factorial scheme, in which three sources of HA (HA-L1 and HA-L2, derived from different commercial HA extracted from leonardite with 0.5 mol L-1 NaOH and 0.5 mol L-1 KOH, respectively, and HA-Com, which was extracted from compost with 0.5 mol L-1 KOH) were combined with four concentrations of C-HA (5, 10, 25, and 100 mg L-1) as well as a control treatment in which eucalyptus was cultivated without HA. Eucalyptus seedlings were grown for 20 days, maintaining three plants per pot. At the end of the experiment, production of shoot dry matter (SDM), root dry matter (RDM), and total dry matter (TDM); the Root: Shoot dry matter ratio; and the accumulations of N, P, K, Ca, B, Cu, Fe, and Zn in the shoot and root were evaluated as well as the UpE of these nutrients by the seedlings. Maximum production of SDM was reached at the concentrations of 14 and 13.5 mg L-1 of C-HA, for HA-L1 and HA-Com, respectively. The RDM increased with the use of HA-Com, with optimal concentration of 55 mg L-1 of C-HA. Accumulation of Fe in the eucalyptus shoot decreased in HA-treated pots, compromising Fe translocation from the root to the shoot. Regardless of HA source used, Cu accumulation by plants diminishes as C-HA concentration increases. A greater growth of eucalyptus at concentrations lower than 15 mg L-1 of C-HA occurs more through the stimulus to shoot and root growth than due to greater acquisition and UpE of nutrients by plants...(AU)
O ácido húmico (AH) pode aumentar o crescimento do eucalipto devido a seu efeito bioestimulante e aumento da absorção de nutrientes pelas plantas. A magnitude desses estímulos varia conforme a fonte, composição química, presença de fragmentos bioativos e concentração de AH. Objetivou-se, assim, avaliar o efeito de fontes e concentrações de AH na massa seca, aquisição e eficiência de absorção (EAbs) de nutrientes por mudas de eucalipto cultivadas em solução nutritiva. O experimento foi realizado em delineamento de blocos casualizados, com quatro repetições, em esquema fatorial 3x4+1, sendo testadas três fontes de AH (AH-L1 e AH-L2, derivados de diferentes produtos comerciais de AH, tendo como material de extração leonardita, sendo extraídos com NaOH 0,5 mol L-1 e KOH 0,5 mol L-1, respectivamente e o AH-Com, que foi extraído de composto, com KOH 0,5 mol L-1), que foram combinadas com quatro concentrações de C-AH (5, 10, 25 e 100 mg L-1), além de um tratamento controle onde o cultivo do eucalipto foi feito sem aplicação de AH. Mudas de eucalipto foram cultivadas durante 20 dias, mantendo-se três plantas por vaso. Ao final do experimento, foram avaliados a produção de massa seca da parte aérea (MSPA), raiz (MSR) e total (MST), relação de massa seca raiz/parte aérea e os acúmulos de N, P, K, Ca, B, Cu, Fe e Zn na parte aérea e raiz, além da EAbs desses nutrientes pelas mudas de eucalipto. Há máxima produção de MSPA para concentrações de 14 e 13,5 mg L-1 de C-AH, respectivamente, para AH-L1 e AH-Com. A MSR aumentou com o uso de AH de composto, sendo máximo o crescimento de raiz para a concentração de 55 mg L-1 de C-AH. O acúmulo de Fe na parte aérea do eucalipto diminuiu com a aplicação de AH, comprometendo a translocação do nutriente da raiz para a parte aérea. Há restrição severa no acúmulo de Cu pelas plantas à medida que se aumenta a concentração de C-AH, independentemente da fonte de AH utilizada...(AU)
Assuntos
Eucalyptus/efeitos dos fármacos , Eucalyptus/crescimento & desenvolvimento , Substâncias Húmicas/análise , Nutrientes/biossínteseRESUMO
Humic acid (HA) can increase eucalyptus growth due to its biostimulant effect and improvement in plant nutrient uptake. Magnitude of these stimuli varies according to the source, chemical composition, presence of bioactive fragments, and concentration of HA. The aim of this study was to evaluate the effect of HA sources and concentrations on dry matter, accumulation and uptake efficiency (UpE) of nutrients for eucalyptus seedlings cultivated in nutrient solution. A randomized block experimental design was adopted, with four replications, in a 3x4+1 factorial scheme, in which three sources of HA (HA-L1 and HA-L2, derived from different commercial HA extracted from leonardite with 0.5 mol L-1 NaOH and 0.5 mol L-1 KOH, respectively, and HA-Com, which was extracted from compost with 0.5 mol L-1 KOH) were combined with four concentrations of C-HA (5, 10, 25, and 100 mg L-1) as well as a control treatment in which eucalyptus was cultivated without HA. Eucalyptus seedlings were grown for 20 days, maintaining three plants per pot. At the end of the experiment, production of shoot dry matter (SDM), root dry matter (RDM), and total dry matter (TDM); the Root: Shoot dry matter ratio; and the accumulations of N, P, K, Ca, B, Cu, Fe, and Zn in the shoot and root were evaluated as well as the UpE of these nutrients by the seedlings. Maximum production of SDM was reached at the concentrations of 14 and 13.5 mg L-1 of C-HA, for HA-L1 and HA-Com, respectively. The RDM increased with the use of HA-Com, with optimal concentration of 55 mg L-1 of C-HA. Accumulation of Fe in the eucalyptus shoot decreased in HA-treated pots, compromising Fe translocation from the root to the shoot. Regardless of HA source used, Cu accumulation by plants diminishes as C-HA concentration increases. A greater growth of eucalyptus at concentrations lower than 15 mg L-1 of C-HA occurs more through the stimulus to shoot and root growth than due to greater acquisition and UpE of nutrients by plants...
O ácido húmico (AH) pode aumentar o crescimento do eucalipto devido a seu efeito bioestimulante e aumento da absorção de nutrientes pelas plantas. A magnitude desses estímulos varia conforme a fonte, composição química, presença de fragmentos bioativos e concentração de AH. Objetivou-se, assim, avaliar o efeito de fontes e concentrações de AH na massa seca, aquisição e eficiência de absorção (EAbs) de nutrientes por mudas de eucalipto cultivadas em solução nutritiva. O experimento foi realizado em delineamento de blocos casualizados, com quatro repetições, em esquema fatorial 3x4+1, sendo testadas três fontes de AH (AH-L1 e AH-L2, derivados de diferentes produtos comerciais de AH, tendo como material de extração leonardita, sendo extraídos com NaOH 0,5 mol L-1 e KOH 0,5 mol L-1, respectivamente e o AH-Com, que foi extraído de composto, com KOH 0,5 mol L-1), que foram combinadas com quatro concentrações de C-AH (5, 10, 25 e 100 mg L-1), além de um tratamento controle onde o cultivo do eucalipto foi feito sem aplicação de AH. Mudas de eucalipto foram cultivadas durante 20 dias, mantendo-se três plantas por vaso. Ao final do experimento, foram avaliados a produção de massa seca da parte aérea (MSPA), raiz (MSR) e total (MST), relação de massa seca raiz/parte aérea e os acúmulos de N, P, K, Ca, B, Cu, Fe e Zn na parte aérea e raiz, além da EAbs desses nutrientes pelas mudas de eucalipto. Há máxima produção de MSPA para concentrações de 14 e 13,5 mg L-1 de C-AH, respectivamente, para AH-L1 e AH-Com. A MSR aumentou com o uso de AH de composto, sendo máximo o crescimento de raiz para a concentração de 55 mg L-1 de C-AH. O acúmulo de Fe na parte aérea do eucalipto diminuiu com a aplicação de AH, comprometendo a translocação do nutriente da raiz para a parte aérea. Há restrição severa no acúmulo de Cu pelas plantas à medida que se aumenta a concentração de C-AH, independentemente da fonte de AH utilizada...