Si Fertilization Research Articles

Determination of Critical Soil Silicon Levels for Rice Production in Louisiana Using Different Extraction Procedures

ABSTRACTWhile silicon (Si) fertilization is widely practiced in rice production, establishing critical soil Si levels has remained understudied. Field trials were established at 12 sites across Louisiana from 2013 to 2015 to determine critical soil Si for rice cultivation. Five silica slag (14% Si) rates at 0, 1, 2, 4, 6, and 8 Mg ha−1 and two lime rates (2 and 4 Mg ha−1) were arranged in randomized complete block design with four replications. Post harvest soil samples were analyzed for Si using seven extraction procedures. The critical soil Si levels established by the linear plateau model using 0.5 M acetic acid-1 hr (OAc-1) extraction procedure were 36, 41 and 50 mg kg−1 for plant Si uptake, grain yield, and relative yield as response variables, respectively. Generally, soils having high initial Si and pH had minimal responses to Si fertilization, whereas Si content of soils with low initial Si was significantly increased.

Dynamic Modeling of Silicon Bioavailability, Uptake, Transport, and Accumulation: Applicability in Improving the Nutritional Quality of Tomato.

Silicon is an essential nutrient for humans, additionally is beneficial for terrestrial plants. In plants Si enhances tolerance to different types of stress; in humans, it improves the metabolism and increases the strength of skeletal and connective tissues as well as of the immune system. Most of the Si intake of humans come from edible plants creating a double benefit: first, because the absorption of Si increases the antioxidants and other phytochemicals in plants, thereby increasing its functional value, and second because the higher concentration of Si in plants increases intake in human consumers. Therefore, it is desirable to raise the availability of Si in the human diet through the agronomic management of Si accumulator species, such as corn, wheat, rice, soybeans, and beans. But also in such species as tomatoes, carrots, and other vegetables, whose per capita consumption has increased. However, there are few systematized recommendations for the application and management of Si fertilizers based on the physicochemical factors that determine their availability, absorption, transport, and deposition in cells and tissues. This study presents updated information about edaphic and plant factors, which determine the absorption, transport, and deposition rates in edible organs. The information was integrated into an estimated dynamic model that approximates the processes previously mentioned in a model that represents a tomato crop in soil and soilless conditions. In the model, on the other hand, was integrated the available information about key environmental factors related to Si absorption and mobilization, such as the temperature, pH, and soil organic matter. The output data of the model were compared against information collected in the literature, finding an adequate adjustment. The use of the model for educational or technical purposes, including the possibility of extending it to other horticultural crops, can increase the understanding of the agronomic management of Si in plants.

Phytolith‐rich biochar increases cotton biomass and silicon‐mineralomass in a highly weathered soil

AbstractNon‐essential silicon (Si) is beneficial to plants. It increases the biomass of Si‐accumulator plants by improving photosynthetic activity and alleviating stresses. Desilication, however, takes place because of natural soil weathering and removal of harvested biomass. Pyrolysis transforms Si‐rich biomass into biochar that can be used to supply bioavailable Si.Here, we applied two biochar materials differing in Si content on soils differing in weathering stage: a young Cambisol and a highly weathered Nitisol. We studied the impact of biochar supply on the bioavailability of Si, cotton biomass, and Si mineralomass. The biochar materials derived from, respectively: Miscanthus × giganteus (Mi; 34.6 g Si kg−1 in biochar) and soft woody material (SW; 0.9 g Si kg−1 in biochar). They were compared to conventional Si fertilizer wollastonite (Wo; CaSiO3). Amendments were incorporated in soils at the rate of 3% (w/w). The content of bioavailable Si in soil was determined through 0.01 M CaCl2 extraction.In the Cambisol, the proportion (CaCl2 extractable Si: total Si content) was significantly smaller for Mi (0.9%) than for Wo (5.2%). In the Nitisol, this proportion was much larger for Mi (1.4%) than for Wo (0.7%). Mi‐biochar significantly increased Si‐mineralomass relatively to SW‐biochar in both soils. This increase was, however, much larger in the Nitisol (5.9‐fold) than in the Cambisol (2.2‐fold).Mi biochar is thus an alternative Si fertilizer to Wo to supply bioavailable Si, increase plant biomass, and promote the biological cycle of Si in the soil‐plant system in the Nitisol. Besides, it increased soil fertility and soil organic carbon content.

Potential of Silicon Amendment for Improved Wheat Production.

Many studies throughout the world have shown positive responses of various crops to silicon (Si) application in terms of plant health, nutrient uptake, yield, and quality. Although not considered an essential element for plant growth, Si has been recently recognized as a “beneficial substance” or “quasi-essential” due to its important role in plant nutrition, especially notable under stressed conditions. The goal of this study was to evaluate the effect of Si on wheat plant height, grain yield (GY), and grain protein content (GP). The experiment was conducted during two consecutive growing seasons in Idaho. A split-plot experimental design was used with three Si fertilization rates (140, 280, and 560 kg Si ha−1) corresponding to 100, 50, and 25% of manufacturer-recommended rates and two application times—at planting and tillering (Feekes 5). MontanaGrowTM (0-0-5) by MontanaGrow Inc. (Bonner, MT, USA) used in this study is a Si product sourced from a high-energy amorphous (non-crystalized) volcanic tuff. There was no significant effect of Si rate and application time on plant height, nutrient uptake, GY, or GP of irrigated winter wheat grown in non-stressed conditions. These results could be directly related to the Si fertilizer source used in the study. We are planning to further evaluate Si’s effect on growth and grain production of wheat grown in non-stressed vs. stressed conditions utilizing several different Si sources and application methods.

TIME AND DIRECTION EFFECT OF BORON (B) AND SILICON (Si) APPLICATION ON OIL PALM (Elaeis guineensis) THROUGH LEAVES

This study was aimed to obtain the time and the effective way of giving B and Si for reducing the effects of drought. It had been implemented in Bendosari village, Madurejo village, Prambanan sub-district, Sleman regency. The study used 3x3 +1 factorial complete randomized block design (RAKL) with with 3 blocks as replicates. The first factor was the time of fertilization, the second factor was way of fertilization and added one control (control) without fertilization treatment. The data obtained were analyzed using the Varian Analysis (ANOVA) at the 5% level and continued by the smallest real difference test (LSD) and orthogonal contrast if the variance analysis showed a significant difference between treatments. The results showed that there was no interaction effect between time and direction of B and Si fertilization through leaves on all observed variables of oil palm seedlings exposed to drought stress.

Effect of KOH-enhanced biochar on increasing soil plant-available silicon

Bio-based alternative Si fertilizers were developed by pyrolyzing Si-rich agricultural crop residue biomass of rice straw, sugarcane harvest residue, miscanthus, and switchgrass with KOH pretreatment at 0:100, 1:100, 5:100, 10:100, 25:100 and 50:100 KOH:Feedstock biomass ratios (termed 0 KB, 1 KB, 5 KB, 10 KB, 25 KB and 50 KB) and were evaluated for enhancing bioavailable Si in soils. KOH pretreatment enhanced plant-available Si in all feedstocks-derived biochars with rice straw-derived 10 KB biochar exhibiting the highest Si release. SEM-EDX mapping images showed morphological and structural changes of phytoliths in KOH-enhanced biochars which contributed to the increased bioavailable Si. Application of 1% KOH-enhanced biochars to soils significantly increased plant-available Si in soils with minimum effect on soil pH. Perennial ryegrass grown in 10 KB rice straw biochar treated soil increased Si uptake by 31% over 0 KB treated soil and was comparable with mineral Si treatment. Overall, KOH-enhanced biochar as alternative Si source could provide multiple functions in disease control, K nutrition, and C sequestration.

Growth and gas exchanges of arugula plants under silicon fertilization and water restriction

ABSTRACT The objective of this article was to study the growth and gas exchange of arugula plants under silicon (Si) fertilization and water stress. The experiment was installed in a greenhouse, located in the municipality of Pombal, PB, Brazil, whose geographic coordinates are 6º 46 ‘S latitude and 37º 49’ W longitude and 178 m of altitude, situated in the 'Sertão Paraibano' micro-region. The experimental design was in randomized blocks, in 5 x 2 factorial scheme, corresponding to five Si doses (0, 50, 100, 150 and 200 mg L-1) and two irrigation depths [50 and 100% of real evapotranspiration (ETr) based on weighing lysimeter], with four replicates. Silicon application was performed as foliar spray, using a commercial product composed of 0.75% Si and 0.15% Mo. Arugula growth and gas exchange was evaluated. Higher values for number of leaves and plant height were obtained in plants cultivated under 100% ETr. Silicon application between 100 and 120 mg L-1 led to better results in the physiological variables of arugula plants under water stress. Silicon application between 30 and 60 mg L-1 in arugula plants under 100% ETr irrigation allowed greater phytomass accumulation.

Effect of Nitrogen and Silicon on Rice Submerged at Tillering Stage

Core Ideas Basal silicon promotes rice growth and development at the tillering stage.After flooding, foliar spraying N or silicon timely had a better effect.Foliar spraying N had more advantages than silicon. Flooding is a major threat to rice (Oryza sativa L.) yields. We wondered if basal Si and foliar spraying fertilizer had an influence on rice submerged at tillering stage. The results showed that basal Si application promoted rice growth and development at the tillering stage, improving rice seedling tolerance to submergence stress. After the occurrence of flooding, timely foliar spraying of N or Si had significant remedial effects, and spraying N along with Si had a better effect. The combination of basal Si and post‐flooding N and Si spraying was the most promising method of nutrient application and as resistance to damage during submergence was enhanced, plants rapidly resumed growth and development. By maintaining a great number of green leaves and tillers as well as higher aboveground and belowground dry mass, sugar contents and antioxidant enzyme activities, these plants yielded significantly more grain. We conclude that reasonable use of Si leads to resistance and alleviation of the damaging effects of submergence and contributes to reducing yield losses in rice.

Soil Application of Silicon: Effects on Economic Yield and Nutrition of Phosphorus, Zinc and Iron in Rice (Oryza sativa L.)

A field experiment was conducted for the two consecutive seasons to evaluate the effect of diatomaceous earth as a silicon (Si) source along with recommended doses of fertilizer nitrogen (N), phosphorus (P), potassium (K) and zinc (Zn) as well as farmyard manure (FYM) in nine different treatment combinations on the yield and P, Zn and iron (Fe) nutrition of rice. The results showed a significant increase in grain yield of rice upon Si application with a concomitant improvement of P metabolism. Increased phosphatase activities in soil by the application of Si showed synergism between Si and P in grain (r = 0.91**) and straw (r = 0.90**). Zinc and Fe nutrition was affected by Si application through 600 kg diatomaceous earth ha−1 with a decline in their concentrations in the grains by 39.6 and 25.7 per cent and in straw by 21.1 and 27.1 per cent, respectively over standard fertilizer practice. Better P metabolism as a results of Si fertilization may increase the production of phytic acid in rice which may retard translocation of micronutrients.

Diatomaceous earth as source of silicon on the growth and yield of rice in contrasted soils of Southern India

Application of diatomaceous earth (DE) could improve the quality of soil, but its application in agriculture as a Si fertilizer requires additional research. Pot experiments were conducted with graded levels (0, 150, 300, 600 kg ha-1) of DE with recommended dose of N, P, K, in three types of soil (acidic, neutral and alkaline) from Southern India under two moisture conditions (field capacity and submergence) using rice as a test crop. The chosen DE consisted of biogenic silica, smectite, kaolinite and quartz. The grain yield was lower in plants grown in FC than in SUB moisture conditions regardless of the soil type and the DE added. Higher grain yield was observed with different DE applications under the SUB moisture condition in the three soils. The Si uptake increased for acidic and alkaline soils but not for neutral soil under the SUB moisture condition, whereas under the FC condition, the Si uptake was increased over the control only in alkaline soil. Increased nutrient and Si uptake was explained by the combination of physical and chemical properties of DE and was not only due to the contribution of amorphous silica. DE might be useful for improving the crop yield, but the soil composition and water regimes play a key role that influences the availability of nutrients in soils.

Origin of silica in rice plants and contribution of diatom Earth fertilization: insights from isotopic Si mass balance in a paddy field

Background and aims: The benefits of Si for crops is well evidenced but the biogeochemical cycle of Si in agriculture remains poorly documented. This study aims at identifying and quantifying the Si sources (primary and secondary soil minerals, amorphous silica, irrigation, Si-fertilizer) to rice plants. Method: Field experiments were carried out with and without application of diatomaceous earth (DE) under rice and bare conditions to determine the water and dissolved mass balance in paddy fields (Karnataka, Southern India). The fate of the Si brought by irrigation (DSi) (uptake by rice, uptake by diatoms, adsorption) was assessed through a solute mass balance combined with silicon isotopic signatures. Results: Above the ground-surface, about one third of the DSi flux brought by borewell irrigation (545 mmol Si.m−2) to bare plots and half of DSi in rice plots were removed from solution within minutes or hours following irrigation. Such rate is consistent with the rate of DSi adsorption onto Fe-oxyhydroxides but not with diatom blooms. In rice and rice + DE experiments, the isotopic fractionation factor (30e) between bore well and stagnant water compositions is close to −1 ‰, i.e. the isotopic fractionation factor known for rice, indicating that above-ground DSi removal would be dominated by plant uptake upon adsorption. Within the soil layer, pore water DSi decreases much faster in rice experiments than in bare ones, demonstrating the efficiency of DSi rice uptake upon adsorption. Total irrigation-DSi to plant-Si would then represent 24 to 36% in rice experiments (over 1460 ± 270 mmol Si m−2 in biomass) and 15 to 23% in rice + DE ones (over 2250 ± 180 mmol Si m−2). The δ30Si signature of whole plants was significantly different in the rice + DE plot analyzed, 0.99 ± 0.07 ‰, than in the rice one, 1.29 ± 0.07 ‰. According to these δ30Si signatures, the main Si source from the soil would be the amorphous silica pool (ASi). A slight contribution of DE to the rice plant could be detected from the Si isotopic signature of rice. Conclusions: The δ30Si signatures of the various soil-plant compartments, when associated to Si mass balance at soil-plant scale, constitute a reliable proxy of the Si sources in paddy fields. The solute Si balance is controlled by rice uptake in rice plots and by adsorption in bare ones. The main Si sources for the rice plants were soil ASi, irrigation Si and to a lesser extent Si fertilizer when it was applied.

Silicon‐mediated resistance against specialist insects in sap‐sucking and leaf‐chewing guilds in the Si non‐accumulator collard

AbstractSoil amendment with Silicon (Si) can increase plant resistance against insect herbivores, but the underlying mechanisms remain unclear. The mechanical resistance hypothesis (MRH) states that Si accumulated in epidermal cells directly and passively protects against herbivores by creating a mechanical barrier. The physiological resistance hypothesis (PRH) states that Si enhances resistance by activating plant biochemical and physiological processes. We tested both hypotheses by manipulating Si fertilization of the Si non‐accumulator collard, Brassica oleracea L. cv. acephala (Brassicaceae). Then, we assessed functional and ultrastructural plant responses and the developmental and reproductive performance of the leaf‐chewing larvae of the diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), and the sap‐sucking cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae). There was a 20% increase in leaf Si content. Silicon deposition in epidermal cells was identified by confocal microscopy and directly coincided with lower performance of P. xylostella, but did not affect B. brassicae. On the other hand, we found no unequivocal evidence that Si‐mediated changes in primary and secondary metabolism improved plant resistance against the insects. Negative mechanical effects of Si on the insects may have masked beneficial effects of increased water, nitrogen, and mineral contents in Si‐treated collards. Silicon did not change leaf contents of hemicellulose, cellulose, and lignin. Although Si‐mediated increases in leaf glucosinolates (GLS) correlated with lower larval performance and higher oviposition preference of P. xylostella, both P. xylostella and B. brassicae are highly specialized in overcoming such secondary metabolites. Thus, mechanical resistance may have impaired P. xylostella, rather than the Si‐mediated increase in GLS. We suggest that the PRH may depend on the degree of insect feeding specialization, so that toxic Si‐mediated defenses may be more efficient against unadapted polyphagous herbivores. For them, a toxic barrier may be added to the mechanical resistance.

Effects of Silicon-Based Fertilizer on Growth, Yield and Nutrient Uptake of Rice in Tropical Zone of Vietnam

Application of silicon (Si) could greatly boost rice yield and mitigate abiotic stress, especially drought. A field experiment was conducted during 2015 at the research farm of Hong Duc University, Thanh Hoa City, Vietnam, to evaluate the effects of five different combined doses of standard fertilizer practice and Si fertilizer on growth, yield and yield components, as well as nutrient uptake of rice. The treatments consisted of the recommended dose of fertilizer (RDF, 110kg/hm2 N + 90kg/hm2 P2O5 + 80kg/hm2 K2O) as the control, RDF + 100kg/hm2 SiO2, RDF + 200kg/hm2 SiO2, RDF + 300kg/hm2 SiO2 and RDF + 400kg/hm2 SiO2. The results showed that the growth, grain and straw yields as well as yield components (number of grains per panicle, seed-setting rate and 1000-grain weight) were significantly affected by Si application. The highest grain yield of 3 705kg/hm2 was obtained with the highest level of Si fertilizer in combination with RDF (RDF + 400kg/hm2 SiO2), however, it was statistically at par with the yields obtained with RDF + 300kg/hm2 SiO2 (3 664kg/hm2) and RDF + 200kg/hm2 SiO2 (3 621kg/hm2). The optimum dose of Si fertilizer with maximized grain yield (3 716kg/hm2) was 329kg/hm2 SiO2. The nutrient (Si, N, P and K) uptakes of rice were also significantly enhanced by Si application. Si application at the level of 329kg/hm2 along with RDF would help in the sustainable production of rice in the tropical zone of Vietnam.

Effect of Different Silicon Sources on Yield and Silicon Uptake of Rice Grown under Varying Phosphorus Rates.

A series of pot experiments were conducted to: (1) evaluate the effects of different Si sources (soil- and foliar-applied) on grain yield and Si accumulation of rice supplied with varying P rates, and (2) evaluate Si absorption of rice using foliar- and soil-applied Si fertilizers. Three P rates, (0, 112, and 224 kg ha−1) combined with five Si treatments (wollastonite and slag applied at 4.5 ton ha−1 and one foliar Si solution applied at 20, 40 and 80 mg Si L−1) and a check were arranged in a randomized complete block design with four replications. The presence of P and Si in the soil created a synergistic effect on soil Al, Mn, and As (P < 0.01), but not on rice growth and P uptake. Wollastonite and slag application were most effective in raising rice Si content than foliar applied Si (P < 0.001). While there was an improvement in biomass (42%) and tiller production (25%) for rice receiving foliar Si, no supporting evidence was obtained in these experiments to verify leaf surface Si absorption. The application of Si-rich materials to soil still remains the most effective method for enhancing Si uptake by plants.

Effects of Si fertilization on Si in soil solution, Si uptake by rice, and resistance of rice to biotic stresses in Southern Vietnam

Silicon (Si) mitigates abiotic and biotic stresses for rice plants (Oryza sativa L.). Here, we test relationships between Si cycling, plant growth, and pest and fungal attacks in rice agroecosystems. We conducted a plot experiment on Si fertilization in a Southern Vietnamese paddy, where plant-available Si was inherently low. For two cropping seasons, we investigated the temporal dynamics of Si in soil solution, plant Si uptake, and the occurrence of leaf folders (Cnaphalocrocis medinalis) and rice blast caused by the fungus Magnaporthe oryzae. Silicon application increased Si concentrations in soil solutions collected in the field as expected from previous laboratory experiments. Soil solution Si concentrations were furthermore affected by Si uptake by plants and by recycling Si with rice straw ash. Silicon concentrations in rice leaves at tillering stage increased with increasing Si application. However, surprisingly, no relationship between Si in soil solution and Si concentration in straw at maturity stage was found. The occurrences of leaf folders and rice blast disease were mitigated by increased Si uptake. However, rice biomass production was not affected, probably because the biotic stress level was generally low. Our field data emphasize the importance of recycling crop residues in rice fields for the Si supply to plants, especially in regions with low Si availability. They furthermore show that under field conditions, the relationship between dissolved Si in soil solution and Si uptake by rice plants is not as straightforward as expected and thus needs to be further investigated.

Silicon Transporters and Effects of Silicon Amendments in Strawberry under High Tunnel and Field Conditions.

Together with longer production periods, the commercial transition to day-neutral strawberry (Fragaria × ananassa) varieties has favored the development of diseases such as powdery mildew (Podosphaera aphanis) that thrives in late summer-early fall. In an attempt to find alternative solutions to fungicides currently employed to curb the disease, we wanted to investigate the potential of silicon (Si) amendments that have been associated with prophylactic properties against powdery mildews. To this end, our first objective was to determine if strawberry was a Si-competent species following the recent characterization of the properties of Si transporters that plants must carry to uptake silicic acid. Based on genomic data, we were able to conclude that strawberry contained both functional influx (Lsi1) and efflux (Lsi2) transporters for Si uptake. Subsequently commercial experiments under high tunnel and field conditions were conducted with different Si fertilization regimes: constant soluble Si feeding in high tunnel, and bi-weekly soluble Si feeding or three concentrations of calcium silicate fertilization in the field. Results from high tunnel experiments showed that strawberry could accumulate as much as 3% Si on a dry-weight basis, the highest concentration ever reported for this species. All six tested cultivars contained roughly the same concentration, thereby confirming the limited genetic variability, also observed in other species, associated with the trait. Silicon fertilization under high tunnel led to a significant reduction of powdery mildew severity in both years and on all cultivars, and a significant increase in yield of marketable fruits reaching as much as 300% with cv. Monterey. By contrast, Si fertilization under field conditions in soils deficient in plant available Si, either in soluble or solid form, did not result in significant accumulation of Si in plants, regardless of the cultivars, year or concentrations. Our results have thus provided both genotypic and phenotypic proof that strawberry can greatly benefit from Si fertilization, but have also highlighted the importance of validating the fertilization regime to ensure that Si is properly absorbed and/or available to the plant.

Effects of Silicon Application on Wheat Growth and Some Physiological Characteristics under Different Levels and Sources of Salinity

ABSTRACTWe investigated the effects of silicon (Si) and the levels and sources of salinity on the growth and some physiological properties of wheat (Triticum aestivum cv. Chamran) in a sandy loam soil under greenhouse conditions. Treatments comprised four Si levels (8, 50, 100 and 150 mg kg−1 soil), four salinity levels (0.46, 4, 8 and 12 dS m−1) and two salinity sources (sodium chloride (NaCl) and four-salt combination). Salts combination included NaCl, sodium sulfate (Na2SO4), calcium chloride (CaCl2) and magnesium sulfate (MgSO4) at a molar ratio of 4:2:2:1. The experiment was arranged as a completely randomized design in a factorial manner, with three replications. Increasing salinity level resulted in a significant decrease in shoot dry weight, chlorophyll content and catalase (CAT) activity, and it caused a marked increase in proline and glycine betaine (GB) concentrations and superoxide dismutase (SOD) enzyme activity. The stimulating effect on GB accumulation and SOD activity was more intense in NaCl-treated plants. However, the source of salinity had no significant effect on shoot dry weight, chlorophyll and proline concentrations, and CAT activity. Si application enhanced all the above-mentioned parameters, except for proline. The suppressing effect of salinity on shoot dry weight, chlorophyll concentration and CAT activity was alleviated by Si supplementation. The stimulating effects of Si fertilization on shoot dry weight and chlorophyll concentration became more pronounced at higher salinity levels. It could be concluded that a decrease in soil osmotic potential, nutrient imbalance and increasing reactive oxygen species (ROS) in salt-treated plants caused growth suppression, while Si supply decreased the deleterious effects of excess salt on wheat growth. Consequently, it appears that when wheat plants are to be grown in salt-affected soils, it is highly recommended to supply them with adequate available silicon (Si).

PENGARUH PEMUPUKAN Si C AIR TERHADAP PR ODUKSI DAN RENDEMEN TEBU / Effect of Liquid Si Fertilizer on Yield and Commercial Can e Content of Sugarcane

&lt;p&gt;Sugarcane is proved to absorb more Si than any other nutrient from soil; therefore continuous cropping of the plant at the same soil would bring consequences of more Si and organic matter depletion. Silicon (Si) is considered a beneficial nutrient for sugarcane production. Field study was carried out in 2013-2014 at Kempleng village; Purwoasri sub district; Kediri district; East Java. The objective was to find out the effect of frequency and concentration of Si liquid fertilizer on Si and N absorptions, stem diameter and length, yield and commercial cane sugar (CCS) of sugarcane var PSBM 901. Split plot design with three replicates was employed to arrange the treatments. As main plots were frequency of spraying (one time, two times, three times, and four times with interval of 20 days started at 30 days after planting), while as sub plots were concentration of Si fertilizer (0, 15% Si, 30% Si). Results showed that interaction between frequency and concentration of Si affected on all parameters observed. Spraying of sugarcane four times with 30% Si gave highest value of cane yield, rendement, and sugar yield, i.e. 184.16 tons/ha and 8.36%, 15.37 ton/ha respectively.&lt;/p&gt;

The effects of silicon fertilizer on denitrification potential and associated genes abundance in paddy soil

This study evaluated the effect of silicate fertilizer on denitrification and associated gene abundance in a paddy soil. A consecutive trial from 2013 to 2015 was conducted including the following treatments: control (CK), mineral fertilizer (NPK), NPK plus sodium metasilicate (NPK + MSF), and NPK plus slag-based silicate fertilizer (NPK + SSF). Real-time quantitative PCR (qPCR) was used to analyze the abundances of nirS, nirK, and nosZ genes. Potential N2O emissions and ammonium and nitrate concentrations were related to the nirS and nirK gene abundance. Compared with the NPK treatments, the addition of a Si fertilizer decreased N2O emission rates and denitrification potential by 32.4–66.6 and 22.0–59.2%, respectively, which were probably related to increased rice productivity, soil Fe availability, and soil N depletion. The abundances of nirS and nirK genes were decreased by 17.7–35.8% and 21.1–43.5% with addition of silicate fertilizers, respectively. Rates of total N2O and N2O from denitrification (DeN2O) emission were positively correlated with the nirS and nirK gene abundance. Nitrate, exchangeable NH4+, and Fe concentrations were the main factors regulating the nirS and nirK gene abundance. Silicate fertilization during rice growth may serve as an effective approach to decreasing N2O emissions.

Role of Silicon on Plant-Pathogen Interactions.

Although silicon (Si) is not recognized as an essential element for general higher plants, it has beneficial effects on the growth and production of a wide range of plant species. Si is known to effectively mitigate various environmental stresses and enhance plant resistance against both fungal and bacterial pathogens. In this review, the effects of Si on plant–pathogen interactions are analyzed, mainly on physical, biochemical, and molecular aspects. In most cases, the Si-induced biochemical/molecular resistance during plant–pathogen interactions were dominated as joint resistance, involving activating defense-related enzymes activates, stimulating antimicrobial compound production, regulating the complex network of signal pathways, and activating of the expression of defense-related genes. The most previous studies described an independent process, however, the whole plant resistances were rarely considered, especially the interaction of different process in higher plants. Si can act as a modulator influencing plant defense responses and interacting with key components of plant stress signaling systems leading to induced resistance. Priming of plant defense responses, alterations in phytohormone homeostasis, and networking by defense signaling components are all potential mechanisms involved in Si-triggered resistance responses. This review summarizes the roles of Si in plant–microbe interactions, evaluates the potential for improving plant resistance by modifying Si fertilizer inputs, and highlights future research concerning the role of Si in agriculture.