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The seed treatment with Mo associated with other elements, such as Ni and Co, and with micronutrients, such as Cu, Mn, and Zn, has been highlighted. The use of these associations can affect the adequate dose of Mo and the risk of toxicity. This study aimed to determine whether the optimal and the toxic dose of Mo can be affected by the accompanying elements of the group Co and Ni in relation to Cu, Mn, and Zn for the treatment of soybean seeds. Two experiments were carried out. The treatments in experiment I consisted of five doses of a product containing Mo, Co, and Ni at the concentrations of 0, 30-, 60-, 90-, and 120-mL ha−1. In experiment II, the treatments consisted of five doses of a product containing Mo, Cu, Mn, and Zn at the concentrations of 0, 50-, 100-, 200-, and 400-mL ha−1. The optimal dose of Mo was low (6.7 g ha−1) when applied along with Cu, Mn, and Zn as accompanying elements in relation to Co and Ni (17.5 g ha−1 of Mo). Application of the optimal dose provided an increase in N accumulation and in the chlorophylls, carotenoids, and phenolic compounds, decreasing the extravasation of electrolytes and increasing photosynthetic efficiency, dry matter, and yield. Mo toxicity was more severe with Cu, Mn, and Zn as accompanying elements, already occurring at the low dose of 18.9 g ha−1 Mo, which is much lower when Mo is associated with Co and Ni (32 g ha−1 Mo). [ABSTRACT FROM AUTHOR]

High root absorption of silicon (Si) in sugarcane plants that accumulate the element attenuates water deficit‐induced damage. However, there is a lack of research to identify whether the low relative absorption of Si via leaf spraying compared to root application has an immediate antioxidant effect on plants under water restriction. For this purpose, the objective of this research was to evaluate the effect of Si applied via leaf spraying and via nutritive solution (root) in mitigating the damage caused by short‐term water deficit induced by PEG‐6000 in pre‐sprouted sugarcane seedlings. The treatments were arranged in a 3 × 2 factorial scheme, consisting of the forms of Si supply: via nutrient solution (SiR) (2.0 mmol/L), via foliar spraying (SiL) (3.4 mmol/L) plus the absence of Si (−Si), combined with the presence (−0.6 MPa) and absence of water deficit, arranged in randomized blocks with 6 repetitions. The experiment was developed in a hydroponic system, in which Si was initially supplied during the seedling production phase; subsequently, water deficit was induced with PEG‐6000 for a period of 72 hr. Plants under water deficit increased the accumulation of Si with the supply of the element via root application and via foliar spraying by 2118% and 98%, respectively, in comparison to the absence of Si. However, although Si foliar absorption was relatively low in comparison to the root, the physiological effects in relieving water deficit‐induced stress were equal to or even higher than those of root application. In conclusion, the amount of Si absorbed by the plant is not a major factor to induce an antioxidant defence response to mitigate the immediate effects of water deficit, since the two forms of application of Si were similar. Si foliar spraying promotes physiological and biochemical effects that alleviate damage done water deficit short term, even on plants with an active absorption mechanism such as sugarcane. [ABSTRACT FROM AUTHOR]

Production of sugarcane and more recently of energy cane strengthen renewable bioenergy production capacity. However, droughts resulting from climate change have limited the production of these crops. One of the strategies to attenuate water deficit damage in these crops is the use of silicate, which contributes to plant physiology. This strategy is likely to increase water use efficiency, thus promoting crop sustainability. Notwithstanding, studies on this issue are still incipient. This study assesses whether Si applied via fertigation and foliar spraying in the seedling production phase and as a complement after seedling transplanting to the soil is efficient in attenuating water deficit in sugarcane and energy cane. The study further elucidates physiological and biochemical mechanisms involved in this process. For this, the authors conducted two experiments: one with sugarcane and the other with energy cane. Treatments were arranged in randomized blocks with 5 replications, in a 2 × 2 factorial scheme. Factors consisted of the absence (-Si) and presence of Si (+ Si) applied via fertigation and foliar spraying; and two water regimes: 70% (without water deficit) and 30% (severe water deficit) of the soil water retention capacity. Silicon was supplied during the formation phase of presprouted seedlings and during the transplanting of seedlings to pots filled with samples of Entisol (Quartzipsamment). In these pots, water regimes were induced from 7 to 160 days after transplanting. Severe water deficit reduced the water content and water potential of plants. This situation induced oxidative stress and impaired gas exchange and photosynthetic water use efficiency, reducing plant growth. Silicon supply via fertigation in association with foliar spraying in the seedling formation phase with complementation after transplanting was efficient in increasing Si accumulation in the plants. Silicon was effective in attenuating severe water deficit damage up to initial culm formation through mechanisms that maintain water and physiological balance by favoring the antioxidant defense system in sugarcane and energy cane plants. [ABSTRACT FROM AUTHOR]

Water deficit limits the establishment of sugarcane plants from pre-sprouted seedlings (PSS). Silicon (Si) can mitigate such stress, and your supply in plants with the active absorption mechanism is carried out through roots. However, foliar spraying has been practiced to supply Si in PSS production nurseries. Althought it is known that Si via roots can alter C: N: P ratios, nothing has been reported about its supply via foliar spraying, nor whether such changes interfere with structural nutrient use efficiency and with plant physiological responses. Thus, this study aimes to asses whether Si foliar spraying changes C: N: P ratios and increases the nutritional efficiency of PSS, as well as whether water deficiency interferes with such a relationships. For these purposes, three experiments were carried out. In experiment I, treatments consisted of two sugarcane cultivars (CTC 4 and RB 966928) and three Si supply forms (in nutrient solution via roots [SiR], via foliar spraying [SiL], and one control with the absence of Si [-Si]). The same Si supply forms were used in the other two experiments. In experiment II, a short-term water deficit was induced by polyethylene glycol addition to nutrient solution (-0.6 MPa) for three days. In experiment III, a long-term water deficit was imposed using levels of soil water retention capacity (70% [no water deficit], 50% [moderate water deficit], and 30% [severe water deficit] for 30 days. Our findings revealed that Si supply decreased C concentrations regardless of water conditions and that N and P concentrations varied with Si supply form and water deficit level. Moreover, root- and foliar-applied Si modified the C: N: P stoichiometry and increased C use efficiency in PSS, which thus increased N and P use efficiencies. Such an increased nutritional performance helped adjust physiological parameters and increase dry matter yield in PSS, both under water stress and non-stress conditions. Further, Si foliar spraying promoted structural effects on PSS regardless of water conditions, even if sugarcane has an active absorption via roots. In conclusion, foliar spraying can be used to supply Si in PSS production nurseries. [ABSTRACT FROM AUTHOR]

• Calcium carbonate nanoparticles have remediating effects of sunburn in pineapple. • Calcium carbonate nanoparticles enhanced firmness and ascorbic acid in pulp. • Calcium carbonate nanoparticles maintain the quality and color characteristics on the fruit. • Two spraying of calcium carbonate nanoparticles during pineapple cultivation is efficient against sunburn. This study aimed to evaluate the effect of different concentrations of calcium carbonate nanoparticles preharvest sprayed on pineapple fruit. The treatments consisted of five concentrations of calcium carbonate nanoparticles: 0, 12.5, 25, 50, 100, and 200 g ha−1. The quality parameters were analyzed: soluble solids content (SSC), titratable acidity (TA), ratio (SSC/TA), ascorbic acid content, and firmness; also, colorimetric parameters on fruit pulp and peel: lightness (L*), coordinates a* and b * , chroma, hue angle, and yellowing index. The spraying of calcium carbonate nanoparticles reduced the damage caused by sunburn, increasing fruit quality. This effect was evidenced in fruit color by the increased L * , higher Hue angles, and lower yellowing index in the peel and pulp. In addition, we observed increased firmness, SSC/TA, and ascorbic acid in the pulp. Thus, it maintained quality characteristics and fruit color. This study proposes two calcium carbonate nanoparticles spraying during pineapple cultivation to control fruit sunburn, especially in tropical regions, guaranteeing high-quality fruit production and extending its postharvest commercialization. [ABSTRACT FROM AUTHOR]

Purpose: The objective was to evaluate soluble sources of silicon (Si) applied through fertigation in mitigating water deficit in maize plants. Another objective was to determine the physiological and nutritional effects involved. Methods: The study was carried out in a greenhouse in pots filled with Oxisol. The treatments were arranged in a 3 x 2 factorial scheme, consisting of Si supply from soluble sources: sodium and potassium silicate stabilized with sorbitol (Si-alkali), potassium silicate (Si-K), plus the control (absence of Si); and two soil water regimes: 70% (without deficit) and 30% (severe water deficit) of soil water retention capacity. The experiment used a randomized block design, with six replications. Si was supplied at a concentration of 2 mmol L-1, applied through fertigation. Four applications were performed, starting at 12 days after seedling emergence. Results: The soluble sources of Si applied through fertigation promoted the uptake of this element by maize plants even under water restriction. Si mitigated the damage caused by severe water deficit in maize plants because it kept the relative leaf water content, decreased the cell leakage index, and preserved the content of photosynthetic pigments, which increased quantum efficiency of photosystem II, content and use efficiency of macronutrients, thus leading to greater growth and biomass. Conclusion: The damage caused by severe water deficit in plants can be mitigated by using a relatively low supply of Si through fertigation. Si addition in irrigated crops improves the use of water resources, proving to be a strategy for sustainable agricultural production. [ABSTRACT FROM AUTHOR]

Forages are one of the most cultivated crops in the world. However, nutritional deficiency is common, specifically in N, P, and Ca in many forage-growing regions. Silicon (Si) can attenuate the stress caused by nutritional deficiency, but studies on Si supply's effects on forage plants are still scarce. This research was carried out to evaluate whether the Si supply can mitigate the effects of N, P, and Ca deficiencies of two forages and the physiological and nutritional mechanisms involved. Two experiments were carried out with two forage species (Urochloa brizantha cv. Marandu and Megathyrsus maximum cv. Massai). We used nutrient solution under balanced nutrition conditions and nutritional stress due to the lack of N, P, and Ca combined with the −Si and +Si. The deficiencies of N, P, and Ca in both forages' cultivation caused damage to physiological and nutritional variables, decreasing the plant dry matter. However, in both forage species, the Si addition to the nutrient solution decreased the extravasation of cellular electrolytes and increased the content of phenolic compounds, the green colour index, the quantum efficiency of photosystem II, the efficiencies of use of N, P and Ca and the production of shoot dry matter. The beneficial effects of Si were evidenced in stressed and non-stressed plants. The research emphasised the advantage of using Si to grow U. brizantha and M. maximum under N, P, and Ca deficiency, contributing to their sustainable cultivation. [ABSTRACT FROM AUTHOR]

Climate change has increased the occurrence of water deficit in regions where sugarcane and energy cane are cultivated, jeopardizing dry matter production of stems. It was hypothesized that the reasons behind this fact relate to C:N:P stoichiometric modifications in these species that impair the conversion rates of accumulated nutrients in the stems, which could be attenuated by supplying silicon (Si) to the crops. Thus, the aims of this study were to evaluate the effects of water deficit in sugarcane and energy cane ratoons in the presence and absence of Si, in the C:N:P stoichiometry of stems, in the use efficiency of these nutrients and in the accumulation of dry matter in stems. Two experiments were carried out, using sugarcane (Saccharum officinarum) and energy cane (S. spontaneum), cultivated in pots filled with a Typic Quartzipisamment. The treatments for both experiments were arranged in a factorial scheme 2 × 2, without (70% of the soil's water retention capacity) and with (30% of the capacity) water deficit, without and with the application of Si via fertirrigation, associated with foliar pulverization, both at a concentration of 2.5 mmol L−1, arranged in randomized blocks. The reduction in dry matter production of stems in both species caused by water deficit was due to modifications of the C, N and P stoichiometric homeostasis, but the benefit of Si in these plants when increasing dry matter production was not a reflection of the change in homeostasis, thus it may be involved in other mechanisms that remain unknown and should be further studied. [ABSTRACT FROM AUTHOR]

The intensity damages caused by nutritional deficiency in growing plants can vary with nutrients. The effects caused by nutrient omission in the plant nutritional efficiency in relation to the absorption and use of the missing nutrient, and the reasons why these damages reflect in other nutrients have not yet been reported in the culture of scarlet eggplant. A better understanding of the nutritional mechanisms involved may clarify why certain nutrients cause greater limitations than other during plants growth. Thus, this study was designed with the aim of evaluating the damages caused by macronutrients deficiency in the culture of scarlet eggplant in the accumulation of these nutrients, nutritional deficiency, plants growth and in visual symptoms. The experiment was carried out in a controlled environment where plants were cultivated in a hydroponic system. Treatments consisted of supplying a complete Hoagland and Arnon solution (CS), and other nutrient solutions with individual omissions of nitrogen (-N), phosphorus (-P), potassium (-K), calcium (-Ca), magnesium (-Mg) and sulphur (-S). When a nutrient deficiency arose, nutritional analyses, growth and visual symptoms were analyzed. The omissions of N, S and K in the nutrient solution resulted in lower accumulation of all macronutrients in both the above and below ground biomass. Individual omissions resulted in nutritional imbalances with reflexes in the absorption efficiencies and use of the missing nutrient, as well as of other nutrients, revealing that the metabolism involves multiple nutritional interactions. Losses of nutritional efficiencies of macronutrients caused detrimental effects on plants growth, with reduced height, stem diameter, number of leaves, leaf area, and biomass production in above ground and below ground. From the losses in production in above ground biomass, the order of macronutrients limitation was N, S, K, Ca, Mg, and P, with reductions of 99, 96, 94, 76, 51 and 46%, respectively, in comparison to plants cultivated in CS. The most limiting nutrients were N, S, and K, seen that its deficiencies affected the metabolism of all other nutrients. This study demonstrates the importance of an adequate nutritional management of N, S, and K in the cultivation of scarlet eggplant. [ABSTRACT FROM AUTHOR]

Climate change has increased the occurrence of droughts and the use of deficient irrigation associated with silicon (Si) can be a strategy to mitigate water deficit in crops; however, the mechanisms involved have to be understood. The objective of this study was to evaluate whether the application of Si via fertigation associated with leaf spray mitigates the effects of water deficit by improving the physiological aspects and modifying C: N: P stoichiometry, inducing an increase in nutrient use efficiency in the ratoon of two sugarcane species (Saccharum officinarum - conventional sugarcane and S. spontaneum - energy cane). Two experiments were carried out in a greenhouse, using conventional sugar cane (variety-RB 966928) and energy cane (variety-VX2). In both experiments, the treatments were arranged in a 2 × 2 factorial scheme, without water deficit and with severe water deficit (30% of soil water retention capacity) without and with application of Si via fertigation associated with leaf spray, both in a concentration 2.5 mmol L−1, arranged in randomized blocks. At 80 days after ratoon regrowth, the following parameters were evaluated: Si content and accumulation, efficiency of using C, N and P, C: Si, C: N and C: P ratios, quantum efficiency of PS II, relative content of water, leaf water potential, leaf area, number of leaves and tillers and dry matter production. In the absence of Si, water deficit affected the physiological variables and the growth of the two sugarcane species. The supply of Si via fertigation associated with foliar spraying of soluble Si increased the absorption of this element in the ratoon of conventional sugarcane and energy cane, regardless of water condition. Si attenuated the effects caused by severe water deficit because of the increase in the relative water content and water potential, thus decreasing oxidative stress, impacting photosynthesis efficiency and also modifying the C: N: P stoichiometry, increasing use efficiency for these nutrients and the growth of the two study species. • The application of Si to mitigate the effects of water deficit was examined. • Silicon attenuates the effects of water deficit, modifying stoichiometry C: N: P. • The application of Si increases the dry matter of the plant. • The beneficial effect of Si in attenuating water deficit is evidenced. [ABSTRACT FROM AUTHOR]