Si Fertilization Research Articles

Optimizing Wheat Growth and Yield: The Synergistic Effects of Nitrogen and Silicon Levels

Enhancing wheat production is essential to meet global food security needs, especially in sustainable agriculture. Among nutrient management practices, Nitrogen (N) and Silicon (Si) are known to improve growth and stress resilience in crops. However, while the individual effects of N and Si on crop performance are well-documented, limited research has explored their combined influence on wheat growth and yield. This study aimed to address this gap by evaluating the synergistic effects of N and Si fertilizer levels on wheat agronomic performance. A field experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, from November 2022 to March 2023. The experiment utilized wheat variety BWMRI 3 in a two-factor Randomized Complete Block Design (RCBD) with three replications. Treatments consisted of four N levels (0, 80, 120, and 160 kg N ha-1) and four Si levels (0, 100, 150, and 200 kg Si ha-1). Statistical analyses using R programming revealed that the combination of 120 kg N ha-1 and 150 kg Si ha-1 (N2:S2) resulted in the highest growth and yield performance, including a 48.32% increase in tiller number, 33.63% improvement in effective spikelets, 12.97% increase in 1000-grain weight, 34.54% rise in grain yield, and a 15.88% increase in biological yield compared to the control (without N and Si). The findings indicate that the combined application of 120 kg N ha-1 and 150 kg Si ha-1 significantly enhanced wheat growth and yield, suggesting that integrating these nutrient management practices is an effective strategy for optimizing wheat production, ultimately contributing to both higher yields and sustainable agriculture.

Determine the Balance of Nitrogen, Potassium, and Silicon Fertilization for the Control of Rice Tungro Disease Using Response Surface Methodology

This study evaluates the efficacy of combined N, K, and Si treatments to find the balance of these three elements for tungro disease control and rice grain production. The study was conducted in a pot under a glasshouse. These elements were chosen as several findings have indicated the positive benefits of nitrogen (N), potassium (K), and silicon (Si) fertilization on plant development, yield, and biotic stress relief. The methods used were central composite design and response surface methodology. Complete and balanced nutrition has always been the first line of defense for plants due to the direct involvement of mineral elements in plant protection. The results showed that rice tungro disease could be controlled with 138:42:62:200 (N:P2O5:K2O:Si). A high rate of nitrogen is needed to reduce disease development. The results on N may explain that not all conditions of rice plants are at risk with high N rates. Adding Si fertilizer contributes to plant defense mechanisms and plays a role in yield formation. In contrast, the balance of fertilizer for maximizing grain yield per plant was found to be not dependent on nitrogen but needed either low K (62 kg K2O/ha) or high K (80 kg K2O/ha) but with moderate Si (150 kg Si/ha). Prioritizing tungro disease control and adopting the rate of N:K2O:Si (138:62:200), it was found that there was a yield reduction of an average of 7.7%.

Cover crops and P‐fertilizer management affect microbial activity in a US Midwest corn and soybean rotation

AbstractMicroorganisms can have a substantial effect on labile phosphorus (P), which may be lost from the soil surface and impact water quality. Changes in nutrient availability and soil health from agricultural management can affect microbial biomass carbon (MB‐C), microbial biomass phosphorus (MB‐P), and the expression of P cycling enzymes. The objective of this research was to investigate biological mechanisms affecting P availability and potential loss to runoff in a no‐till, corn (Zea mays)–soybean (Glycine max) cropping system with two cover crops (cover crop [CC] and no cover crop [NC]) and three P management treatments (fall broadcast [FB], spring injected ammonium polyphosphate [SI], and no phosphorus application [NP]). Treatments were applied to a randomized block design with three replicates. Soil samples were analyzed for MB‐P, MB‐C, phosphatase activity, and Mehlich‐III P (PM). The P supply to the soil solution was measured using diffusive gradient thin film P (PDGT). In Spring 2018, Fall 2018, and Spring 2019, all phosphatase activity was greater in CC versus NC (p < 0.01). Microbial biomass C was greater in CC compared with NC in spring but not fall samplings. On average, MB‐P was fivefold greater in the P fertilized than unfertilized treatments (p < 0.001). CCs did not change MB‐P, PM, or PDGT within FB or NP, but did affect SI fertilizer treatments. Our results suggest CC can increase potential for organic P mineralization, application of P fertilizer increases MB‐P, and an interaction between SI P fertilizer management and CC may increase P supply to the soil solution.

Silica Accumulation in Potato (Solanum tuberosum L.) Plants and Implications for Potato Yield Performance-Results from Field Experiments in Northeast Germany.

The potato is the most important non-cereal food crop, and thus improving potato growth and yield is the focus of agricultural researchers and practitioners worldwide. Several studies reported beneficial effects of silicon (Si) fertilization on potato performance, although plant species from the family Solanaceae are generally considered to be non-Si-accumulating. We used results from two field experiments in the temperate zone to gain insight into silica accumulation in potato plants, as well as corresponding long-term potato yield performance. We found relatively low Si contents in potato leaves and roots (up to 0.08% and 0.3% in the dry mass, respectively) and negligible Si contents in potato tuber skin and tuber flesh for plants grown in soils with different concentrations of plant-available Si (field experiment 1). Moreover, potato yield was not correlated to plant-available Si concentrations in soils in the long term (1965-2015, field experiment 2). Based on our results, we ascribe the beneficial effects of Si fertilization on potato growth and yield performance reported in previous studies mainly to antifungal/osmotic effects of foliar-applied Si fertilizers and to changes in physicochemical soil properties (e.g., enhanced phosphorus availability and water-holding capacity) caused by soil-applied Si fertilizers.

The Effects of Water Management, Foliar Fertilizers, and Lime Application on the Accumulation of Cd and As in Rice Grains Based on a Field Trial

The aim of this study was to explore the feasible measurement of the control of cadmium (Cd) and arsenic (As) accumulation in rice grains. A field experiment was carried out to research the effect of different treatments, including spraying silicon (Si)/selenium (Se) foliar fertilizers, the application of lime (CaO), water management (continuous flooding), and the co-application of foliar fertilizers and flooding, on Cd and As accumulation in rice grains in Guangxi Province. The results indicate that Cd accumulation in rice grains decreased under different treatments and Cd content in rice grains reached the threshold of 0.2 mg kg−1. In the single technical treatments, CaO application, flooding, spraying foliar Se fertilizer, and spraying foliar Si fertilizer decreased Cd content by 73.15%, 60.44%, 45.76%, and 36.07%, respectively. However, flooding and CaO amendment enhanced As accumulation in rice grains. The co-application of flooding and spraying foliar fertilizer can simultaneously reduce Cd and As in rice grains. In addition, they resulted in lower Cd content than the single technical treatments. Among the treatments, the lowest bioaccumulation factors of Cd and As were found after the co-application of flooding and Si foliar fertilizer, which decreased these factors by 74.02% and 22.72%, respectively. These results suggest that spraying foliar Si fertilizer combined with flooding may be a promising method to synchronously inhibit the accumulation of Cd and As in rice.

Application of Diverse Silicon Sources to Soil for Reducing Wheat Blast Disease

Despite the economic potential of wheat for food security, blast disease is one of the major constraints to wheat production in warm and humid areas. Silicon (Si) increases crop yields and resistance to both biotic and abiotic stresses. The effect of various Si sources, including Na2SiO3, MgSiO3, CaSiO3, and rice hull ash (RHA), on suppressing wheat blast (WB) incidence was studied at Bangladesh Institute of Nuclear Agriculture field from November 2019 to March 2020 using a complete randomized design (CRD) with three replications. Total 42 plastic pots were filled with the recommended doses of fertilizers and Si. On 17 days after inoculation (DAI), the lowest WB incidence (83.16%) and severity matrix (80.20%) were found with the treatment of CaSiO3 @ 100 kg ha-1. At 15 DAI, the same treatment reduced the WB incidence and severity matrix by 21.10% and 41.73%, respectively. Most yield indicators were significantly improved by the Si fertilizers, except for grain spike-1 quantity, weight, and thousand grain weight (g). However, pots that were fertilized with Si distinguished out from both the control and absolute control groups. While CaSiO3 at 75 kg ha-1, RHA at 6.0 t ha-1, and MgSiO3 at 100 kg ha-1 produced respectable yields, the maximum was achieved by CaSiO3 at 100 kg ha-1. There was a significant positive relationship between the leaf concentrations of K and Si, with the highest concentration found in plants treated with CaSiO3. A large number of yield metrics showed moderate to strong positive associations with leaf K and Si concentrations, whereas the disease severity matrix revealed the maximum significant negative correlation with these elements. The best outcomes were obtained by applying Si as CaSiO3 @100 kg ha-1, which has potential as an environmentally acceptable source for controlling WB disease and increasing wheat yields. J Bangladesh Agril Univ 22(3): 295–309, 2024

Ammonium nutrition enhances rhizosphere mobilization and uptake of silicon in white lupin grown in low phosphorus soil

Abstract Background and Aims While nitrogen (N) supply can enhance plant silicon (Si) accumulation, the mechanisms by which different forms of N affect Si mobilization in the rhizosphere are not well understood. This study aims to elucidate how pH changes induced by ammonium (NH4+) and nitrate (NO3−) affect Si availability in the rhizosphere, especially under low phosphorus (P) conditions. Methods White lupin (Lupinus albus) plants were grown in non-fertilized low-P soil, supplied with a low dose of N, either as NH4+ or NO3−, with or without supply of monosilicic acid. We measured Si levels in various rhizosphere soil pools, along with different plant and rhizosphere soil parameters. Results The addition of NH4+ significantly lowered rhizosphere pH and decreased both Si adsorbed to pedogenic Fe/Mn oxides and amorphous phytogenic Si, resulting in higher concentrations of plant available Si in the white lupin rhizosphere. This led to greater Si uptake and improved plant growth compared to both the –N and + NO3− treatments. The supply of Si further enhanced these effects, with NH4+ showing a consistently different pattern of influence compared to NO3−. Additionally, –N white lupin plants accumulated more P than those treated with N, while Si supply significantly improved P acquisition across all treatments. Conclusions Our study demonstrates that rhizosphere acidification induced by NH4+ nutrition can significantly enhance Si mobilization from the rhizosphere soil in the absence of Si supply and reduce Si adsorption when Si is applied. These findings may have practical implications for improving both Si mobilization in the rhizosphere and the effectiveness of Si fertilizers.

Mitigating citrus fruit cracking: the efficacy of chelated calcium or silicon foliar fertilizers in 'Okitsu no. 58' citrus fruit.

The 'Okitsu No. 58' citrus variety is highly prone to fruit cracking, which jeopardizes yield and results in economic losses. In this study, we investigated the impacts of spraying 5 distinct concentrations (0.1, 0.2, 0.3, 0.4, and 0.5 g/L) of chelated calcium (Ca) or silicon (Si) fertilizers at the young fruit stage (60-90 days after flowering, DAF) on fruit cracking and quality in the citrus variety 'Okitsu No. 58'. The results showed either Ca or Si fertilizer treatments reduced fruit cracking. We found that all Ca and partial Si treatments (0.4 and 0.5 g/L) significantly promoted the accumulation of Ca content in the peel. Notably, Ca or Si treatments significantly reduced polygalacturonase (PG) activity and inhibited the production of water-soluble pectin (WSP) in the peel. Additionally, Ca or Si treatments elevated the superoxide dismutase (SOD) activity and decreased the malondialdehyde (MDA) content of the peels. Changes in these parameters likely contributed to strengthening the durability of peel cell wall constituents, thus enhancing the fruit's resistance to fruit cracking. Overall, except for the C3 (0.3 g/L of Ca), Ca or Si fertilizers contributed to fruit conventional quality, mainly in terms of higher soluble sugars (SS) and SS/TA (titratable acid). Therefore, our findings will provide a reference for the prevention and control of citrus fruit cracking and the development of new fertilizers.

Foliar Application of Silicon Influences Crop Productivity, Dry Matter Accumulation, Water Use Efficiency, Lodging Score, and Aphid Density in Wheat (Triticum aestivum L.)

ABSTRACT Silicon (Si) is a versatile nutrient that plays an instrumental role in mitigating biotic and abiotic stresses besides improving growth and yield of graminaceous crops. We hypothesized that application Si would significantly improve productivity and resilience of wheat. Hence, the objectives were a) to assess the impact of Si application on wheat growth, productivity, nutrient uptake, water use efficiency, and b) to determine the potentiality of Si in mitigating lodging and aphid density. Therefore, we conducted a field experiment with five levels of Si (0, 2, 4, 6, and 8 g Si liter−1) at three growth stages (crown root initiation, tillering, and jointing stage) using a factorial randomized block design replicated three times. The results showed that increasing Si doses positively influenced plant height, dry matter accumulation (DMA), leaf area index (LAI), yield, and nutrient uptake. The highest grain and straw yield were observed with 8 g Si liter−1, followed by 6 g Si liter−1, while the control had the lowest yields. With 8 g Si liter−1, grain yield, straw yield, and Si uptake increased by 10.5%, 13.5%, and 26.3%, respectively, compared to the control. Additionally, Si application at 8 g Si liter−1 significantly reduced the density of S. avenae (aphids) by 81.4% and lodging by 75.1% compared to the control. Overall, the study demonstrated that increasing Si doses enhanced various growth and yield parameters, with 8 g Si liter−1 and 6 g Si liter−1 showing superior results. Among the growth stages, foliar application of Si during the tillering stage exhibited better performance in terms of growth, yield, and nutrient uptake in wheat. Therefore, the study concludes that Si fertilization at a rate of 8 g Si liter−1 during the tillering stage can effectively improve growth, productivity, and nutrient uptake in wheat in the southern region of Rajasthan.

Optimized silicon fertilization regime weakens cadmium translocation and increases its biotransformation in rice tissues

In acidic paddy fields of South China, rice (Oryza sativa L.) faces the dual challenges of cadmium (Cd) toxicity and silicon (Si) deficiency. Although previous studies have highlighted the functions of Si application timing and strategies in mitigating Cd-stressed rice, the precise mechanisms underlying the health restoration of Cd-toxic rice and the assurance of grain safety remain elusive. This study explored Cd translocation and detoxification in the shoots of rice regulated by various Si fertilization regimes: Si(T) (all Si added before transplanting), Si(J) (all Si added at jointing), and Si(TJ) (half Si added both before transplanting and at jointing). The findings revealed that the regime of Si(TJ) was more beneficial to rice health and grain safety than Si(T) and Si(J). The osmotic regulators such as proline, soluble sugars, and soluble proteins were significantly boosted by Si(TJ) compared to other Si treatments, and which enhanced membrane integrity, balanced intracellular pH, and increased Cd tolerance of rice. Furthermore, Si(TJ) was more effective than Si(T) and Si(J) on the Cd sequestration in the cell wall, Cd bio-passivation, and the down-regulated expression of the Cd transport genes. The concentrations of Cd in the xylem and phloem treated with Si(TJ) were reduced significantly. Additionally, Si(TJ) facilitated much more Cd bound with the outer layer proteins of grains, and promoted Cd chelation and complexation by phytic acid, phenolics, and flavonoids. Overall, Si (TJ) outperformed Si(T) and Si(J) in harmonizing the phycological processes, inhibiting Cd translocation, and enhancing Cd detoxification in rice plant. Thereby the split Si application strategy offers potential for reducing Cd toxicity in rice grain.

Silicon drip fertigation improved sugar beet root and canopy growth and alleviated water deficit stress in arid areas

Crop growth is highly susceptible to drought stress due to water scarcity in arid areas. Silicon (Si) fertilizer could improve the tolerance of crops to drought stress, but the effect of drip fertigation of Si fertilizer on the growth and yield of sugar beets under drought stress is still unclear. In this field experiment conducted in 2022 and 2023 in the arid northwest China, the effects of different Si fertilizer application rates (0 kg ha−1 (Si0), 15 kg ha−1 (Si1), 38 kg ha−1 (Si2), 75 kg ha−1 (Si3)) on the growth, yield, and resource use efficiency of sugar beets (cultivars Beta356 (BT) and Strube13092 (ST)) under deficit irrigation (60 % of crop evapotranspiration (ETc), W2) were explored. The results showed that deficit irrigation (W2Si0) reduced the taproot and fibrous root growth, leaf net photosynthetic rate (Pn), leaf relative water content (LRWC), and leaf area index (LAI) of cultivar BT compared with full irrigation (100 % of ETc, W1). Under deficit irrigation, Si application (W2Si1, W2Si2, and W2Si3) alleviated the drought stress by increasing the number of fibrous roots in 17.5–70.0 cm soil layer and promoted the growth of taproots. Besides, it also increased the leaf moisture and photoassimilate production by increasing plant Si uptake, LRWC, LAI, and Pn. This finally increased the taproot yield (TY), irrigation water use efficiency (IWUE), and partial factor productivity of nitrogen (PFPN) by 11.2 % - 22.9 %, 6.5 % - 19.3 %, and 6.3 % - 19.3 %, respectively in cultivar BT and by 8.8 % - 27.1 %, 13.4 % - 30.8 %, and 13.4 % - 30.8 %, respectively in cultivar ST, compared with W2Si0. Regression analysis showed that the Si fertilizer application rate 64 kg ha−1 could maximize the TY of cultivar BT, but the net revenue (NR) was significantly lower than that of the W1 treatment. The Si fertilizer application rate 71 kg ha−1 could increase the TY of cultivar ST and achieve a NR similar to that of the W1 treatment. Therefore, in arid regions, Si application could alleviate the adverse effects of drought stress on drip-irrigated sugar beet root and shoot growth and improve yield, but the Si application rate varied with sugar beet cultivars.

Physiology and transcriptomic analysis revealed the mechanism of silicon promoting cadmium accumulation in Sedum alfredii Hance

Silicon (Si) effectively promote the yield of many crops, mainly due to its ability to enhance plants resistance to stress. However, how Si helps hyperaccumulators to extract Cadmium (Cd) from soil has remained unclear. In this study, Sedum alfredii Hance (S. alfredii) was used as material to study how exogenous Si affected biomass, Cd accumulation, antioxidation, cell ultrastructure, subcellular distribution and changes in gene expression after Cd exposure. The study has shown that as Si concentration increases (1, 2 mM), the shoot biomass of plants increased by 33.1%–63.6%, the Cd accumulation increased by 31.9%–96.6%, and the chlorophyll, carotenoid content, photosynthetic gas exchange parameters significantly increased. Si reduced Pro and MDA, promoted the concentrations of SOD, CAT and POD to reduce antioxidant stress damage. In addition, Si promoted GSH and PC to chelate Cd in vacuoles, repaired damaged cell ultrastructure, improved the fixation of Cd and cell wall (especially in pectin), and reduced the toxic effects of Cd. Transcriptome analysis found that genes encoding Cd detoxification, Cd absorption and transport were up-regulated by Si supplying, including photosynthetic pathways (PSB, LHCB, PSA), antioxidant defense systems (CAT, APX, CSD, RBOH), cell wall biosynthesis such as pectinesterase (PME), chelation (GST, MT, NAS, GR), Cd absorption (Nramp3, Nramp5, ZNT) and Cd transport (HMA, PCR). Our result revealed the tentative mechanism of Si promotes Cd accumulation and enhances Cd tolerance in S. alfredii, and thereby provides a solid theoretical support for the practical use of Si fertilizer in phytoextraction.

Silicon in paddy fields: Benefits for rice production and the potential of rice phytoliths for biogeochemical carbon sequestration

Silicon (Si) biogeochemical cycling is beneficial for crop productivity and carbon (C) sequestration in agricultural ecosystem, thus offering a nonnegligible role in alleviating global warming and food crisis. Compared with other crops, rice plants have a greater quantity of phytolith production, because they are able to take up a lot of Si. However, it remains unclear on Si supply capacity of paddy soils across the world, general rice yield-increasing effect after Si fertilizer addition, and factors affecting phytolith production and potential of phytolith C sequestration in paddy fields. This study used a meta-analysis of >3500 data from 87 studies to investigate Si supply capacity of global paddy soils and elaborate the benefits of Si regarding rice productivity and phytolith C sequestration in paddy fields. Analytical results showed that the Si supply capacity of paddy soils was insufficient in the major rice producing countries/regions. Dealing with this predicament, Si fertilization was an effective strategy to supply plant-available Si to improve rice productivity. Our meta-analysis results further revealed that Si fertilization led to the average increasing rate of 36 % and 39 % in rice yield and biomass, which could reach up to 52 % and 46 % with the increasing doses of Si fertilizer, respectively. Especially, this strategy also improved the potential of phytolith C sequestration through the increased phytolith content and rice biomass, despite that this potential might have a decline in old paddy soils (≥ 7000 year) compared to in young paddy soils (≤ 1000 year) due to the slow migration and dissolution of phytoliths at millennial scale. Our findings thus indicate that a deep investigation on the benefits of Si in agroecosystem will further improve our understanding on regulating crop production and the potential of biogeochemical C sequestration within phytoliths in global cropland.

Equisetum arvense as a silica fertilizer

The aim was to use the agricultural weed and silica (Si) hyperaccumulator Equisetum arvense as Si fertilizer in plant cultivation. We investigated (1) the Si uptake in various Equisetum species, (2) where Si accumulates in the Equisetum plant, (3) processing methods to release as much Si as possible from dried, ground E. arvense plants and (4) which treatment yields gives the highest uptake of Si in young wheat plants cultivated in soil containing ground E. arvense. The results showed that E. arvense containes 22% Si and was among the best Si accumulators. Equisetum arvense accumulates Si as both soluble and firmly bound fractions. Amorphous silica (SiO2) accumulates in the outer cell walls of epidermis of the entire plant. Regarding the processing method, a longer treatment time, greater concentration of Equisetum, boiling, and the addition of sodium bicarbonate increased the Si availability in ground, dried E. arvense. The addition of untreated, ground, dried E. arvense to the soil, corresponding to 160 kg Si ha−1, increased the available Si in the soil and the Si uptake in wheat plants by five-fold, compared with the control. Boiling the ground E. arvense increased the Si uptake by 10 times, and the of sodium bicarbonate increased the availability and uptake by 40 times, compared with the control. In conclusion, dried, ground E. arvense can be used as a Si fertilizer as is, after boiling for a slightly better effect, or with sodium bicarbonate (up to a similar amount as the ground material) for best effect.

Effect of Silicon based Fertilizer and Biochar from Crop Residues on Dry Matter Accumulation and Si Uptake by Rice Crop in Central Vietnam

Background: Silicon (Si) has been considered a beneficial element for many plants. Si-rich biochar (Sichars) from rice husk or peanut shell have been suggested to be a potential source of bioavailable Si for Si-accumulator plants. Our study aimed to assess the Si-fertilization efficiency from chemical fertilizer and rice husk and peanut shell biochars on rice dry matter and shoot Si uptake. Methods: Pot trials were conducted in two crop seasons in 2023 (from February to April - spring season and from May to July- summer season) in the close net house. Treatments included 1 treatment with pure soil (control), 4 treatments with Si and N–P–K fertilizers and 6 treatments with biochar amendments and N-P–K fertilizers. These pot experiments were designed in the randomized complete block (RCBD) with 4 replications. Result: Shoot dry matter increased from 35.6 to 66.7% compared with control in different rates of Si fertilizer application and was also found the highest values in RHB and PSB at 15 g/kg soil application. Different Si and biochar application rates had a significant effect (P less than 0.05) on Si uptake by rice shoot. Therefore, Si-rich biochar considers as potential material for providing available Si to maintain the required level of available Si in soil and plant for healthy and high crop production.

Long-term effects of compound passivator coupled with silicon fertilizer on the reduction of cadmium and arsenic accumulation in rice and health risk evaluation

Cadmium (Cd) and arsenic (As) are precedence-controlled contaminants in paddy soils, that can easily accumulate in rice grains. Limestone and sepiolite (LS) compound passivator can obviously reduce Cd uptake in rice, whereas Si fertilizer can effectively decrease rice As uptake. Here, the synergistic effects of the LS compound passivator coupled with Si fertilizer (LSCS) on the soil pH and availability of Si, Cd, and As, as well as rice grain Cd and As accumulation and its health risk were studied based on a 3-year consecutive field experiment. The results showed that the LSCS performed the best in terms of synchronously decreasing soil Cd and As availability and rice Cd and As uptake. In the LSCS treatments, soil pH gradually decreased with the rice-planting season, while soil available Cd and As contents gradually increased, suggesting that the influence of LSCS on Cd and As availability gradually weakened with rice cultivation. Nonetheless, the contents of Cd and inorganic As (i-As) in rice grains treated with LSCS were slightly affected by cultivation but were significantly lower than the single treatments of LS compound passivator or Si fertilizer. According to the Cd and As limit standards in food (GB2762-2022), the Cd and i-As content in rice grains can be lowered below the standard by using the 4500 kg/hm2 LS compound passivator coupled with 90 kg/hm2 Si fertilizer in soil and spraying 0.4 g/L Si fertilizer on rice leaves for at least three years. Furthermore, health risk evaluation revealed that LSCS treatments significantly reduced the estimated daily intake, annual excess lifetime cancer risk, and hazard quotient of Cd and i-As in rice grains. These findings suggest that LSCS could be a viable approach for reducing Cd and As accumulation in rice grains and lowering the potential health risks associated with rice.

The Effect of N, P, K and Si Fertilizers on Some Soil Chemical Properties, N, P uptake and Growth of Black Rice (Oryza sativa L. indica) in Ultisols

This study aims to determine the effect of the combination of fertilizers N, P, K, and Si on the pH, N-total, Al-dd, N, P- uptake, and grown of black rice (Oryza sativa L. indica) in Ultisols from Jasinga. This research was conducted from October 2021 to January 2022 at the Experimental Land for Soil Chemistry and Plant Nutrition in Jatinangor, Faculty of Agriculture, Universitas Padjadjaran, Jatinangor, Sumedang, West Java with an altitude of 752 meters above sea level. The experimental design was carried out using a Randomized Block Design (RAK) consisting of eight treatments and three replications, consisting of: control; 1 N, P, K without Silica; 1 N, P, K + ½ Silica; 1 N, P, K + 1 Silica; 1 N, P, K + 2 Silica; ¾ N, P, K + 1 Silica; ¾ N, P, K + 1½ Silica; ¾ N, P, K + 2 Silica; and without N, P, K + 2 Silica. The results showed that the combination of fertilizer doses of 1 N, P, K (Urea 300 kg/ha, SP-36 100 kg/ha, and KCl 100 kg/ha) with 1 Silica (2 mL/L) gave the best black rice yields in increasing plant height by 60.34 cm and number of tillers 34, plus those dose is the best dose in increasing soil pH by 5.63, but the fertilizer dose was not able to increase soil P-Availability and N-Total.

The effect of nitrogen, sulfur and silicate fertilizer application on growth, yield, and biochemical content of vegetable soybean pod (Glycine max L. Merr.)

Optimized fertilizer management, focusing on nitrogen, sulfur, and silica, plays a crucial role in agriculture production. This study aimed to investigate the effects of administering sulfur and silica on the growth, production yield, and biochemical contents of vegetable soybean. The investigation was conducted in factorial randomized block design with two factors and three replications. The first factor was the nitrogen (46% N) fertilizer dosage (N1 = 50 kg/ha and N2 = 100 kg/ha), while the second variable was the dosage with the following sulfur-silica soluble compound (2.3% S – 10% Si) fertilizer ratios (P0 = 0 ml/L (control), P1 = 1 ml/L (23 mg/L S and 100 mg/L Si), P2 = 1.33 ml/L (30,7 mg/L S and 133 mg/L Si), and P3 = 2 ml/L (46 mg/L S and 200 mg/L Si). The results indicated that applying 2 ml/L S-Si fertilizer along with 100 kg/ha of nitrogen can lead to the most favorable results in number of branches, number of leaves, number of pods, pod weight per plant, weight of 100 seeds and plant biomass weight. The fertilizer dose comprising of 50 kg/ha of N and 9.2-40 mg/plant of S-Si clearly demonstrated the highest protein content, measuring 110.6 mg/g. S-Si fertilizer dosages, exhibiting a linear escalation in the 11S/7S globulin ratio within vegetable soybean seeds. The peak 11S/7S ratio was observed in the treatment of 100 kg/ha of N - 2 ml/L of S-Si. The study results indicate that a combination of nitrogen fertilizer and sulfur-silicon yields the best vegetable soybean pod yield, improving soybean protein nutritional quality. Therefore, sulfur and silica treatments should be standardized in vegetable soybean management

Exogenous Silicon Application Improves Chilling Injury Tolerance and Photosynthetic Performance of Citrus

Low-temperature stress is an important limiting factor affecting citrus growth and fruit yields. Therefore, increasing citrus cold stress tolerance may enhance the growth, yield, and quality of citrus production in marginal areas. The objective of this study was to determine the efficacy of silicon (Si) fertilizer application on cold-tolerance enhancement in citrus. Two citrus cultivars (Delta and Nules) were subjected to Si fertilization (control, 1000 mg L−1) and cold-stress temperature treatments (control and 0 °C for 72 h) using a 2 × 2 × 2 factorial treatment structure with six replications. Leaf gas exchange and chlorophyll fluorescence parameters, such as net photosynthetic rate (A), stomatal conductance (gs), transpiration rate (Tr), internal CO2 concentration (Ci), intrinsic water-use efficiency (iWUE), minimal fluorescence (Fo), maximum fluorescence (Fm), maximum quantum efficiency of PSII primary photochemistry of dark-adapted leaves (Fv/Fm), maximum quantum efficiency of PSII primary photochemistry of dark-/light-adapted leaves (F’v/F’m), electron transport rate (ETR), non-photochemical quenching (NPQ), and the relative measure of electron transport to oxygen molecules (ETR/A), were measured. The application of Si drenching to trees that were subsequently exposed to cold stress reduced gs, Tr, and Ci but improved iWUE and Fo in both cultivars compared to the Si-untreated trees. In addition, specific adaptation mechanisms were found in the two citrus species; NPQ and ETR were improved in Si-treated Valencia trees, while A, Fm, and ETR/A were improved in Clementine trees under chilling stress conditions. The current research findings indicate the potential of Si application to enhance cold stress tolerance in citrus, which can provide a strategy for growing citrus in arid and semi-arid regions that may experience cold stress. Overall, after the application of silicon drenching, the cold-sensitive citrus Valencia cultivar became as cold-tolerant as the cold-tolerant Clementine cultivar.

Variations of yield, biochemical and antioxidative responses in sesame with silicon and cytokinin treatments under drought stress

Drought is one of the major limiting factors for crops that severely reduce plant growth and productivity. The appli­cation of cytokinin (Ck) and silicon (Si) fertilizers can help increase tolerance to drought stress in sesame plants. The present study aimed to evaluate the effects of Ck and Si fertilizers on seed yield, malondialdehyde (MDA) content, proline content, and antioxidant enzyme activities in sesame plants under drought-stress conditions. The experiment was conducted as a split plot-factorial in a randomized complete block design with three replications at Firuzkandeh Agricultural Research Station during two crop years of 2020 and 2021. The main plot was three drought stress levels: control, moderate drought stress (MDS), and severe drought stress (SDS), whereas the subplots were three Si appli­cation levels: control or non-use of Si, calcium silicate and nano-Si, and two Ck application levels: control or non-use of Ck, Ck application. The results indicated that the sesame seed yield was reduced by 9.3% under MDS and by 32.7% under SDS when compared with control conditions. The highest MDA content and proline accumulation were observed when the plants were subjected to SDS, whereas the higher activity of antioxidant enzymes occurred under MDS. Higher activity of antioxidant enzymes and reduction of MDA content was observed in the plants treated by combined application of Si and Ck under MDS. However, the higher seed yield, greater proline content, and higher antioxidant enzyme activities were obtained from plants treated by nano-Si than calcium silicate. Overall, the results of the present study revealed that the foliar application of nano-Si + Ck can be a promising option for mitigating the negative impacts of drought stress and improving sesame seed yield.