Conventional Fertilization Research Articles

Nano-fertilizers: The future of nutrient approaches for cereals

Nanotechnology offers a promising solution to address the nutrient demands of cereals, which are nutrient-intensive crops typically reliant on large amounts of inorganic fertilizers. These large quantities of nutrients are supplied to the crop by applying a huge amount of inorganic fertilizer as a soil application led to a decline in environmental systems, particularly affecting the soil health, lesser use efficiency of fertilizers and water resources contamination. In this context, nanotechnology serves as a potential solution. The huge demand for nutrients in cereal crops is met by nano-fertilizers. The nano-fertilizers are now playing a promising role in fulfilling the nutrient requirement of the crops by replacing the normal conventional fertilizers not only for cereals but also for other agricultural crops. The mechanism of action of nano-fertilizers is that they are smaller than the pore size of plant cell walls, allowing them to easily enter and reach the plasma membrane. Nano-fertilizers have 100 times greater surface area than conventional fertilizers, allowing them to easily interact with plant surfaces and increase the absorption of nutrients. Therefore, the nutrient-use efficiency of the crop is increased and shown a positive effect on the physiological and growth parameters of cereal crops, resulting in enhanced yield and improved drought tolerance. This review discussed, the effects and efficiency of nano-fertilizers on cereal crop growth and the correlation between physiological, qualitative, quantitative traits with nano-form of application in detailed manner. This review concludes that nano-fertilizers are the potential nutrient source for cereal crops like rice (Oryza sativa L.), wheat (Triticum aestivum L.), maize (Zea mays) etc. and they are going to be a promising resource for nutrient management in agricultural crops.

Drought stress mitigation and improved yield in Glycine max through foliar application of zinc oxide nanoparticles.

The impact of climate change on agricultural production is apparent due to declining irrigation water availability vis-à-vis rising drought stress, particularly affecting summer crops. Growing evidence suggests that zinc (Zn) supplementation may serve as a potential drought stress management strategy in agriculture. Field studies were conducted using soybean (Glycine max var. Saba) as a model crop to test whether foliar application of zinc oxide nanoparticles (ZnO-NPs) or conventional Zn fertilizer (ZnSO4) would mitigate drought-related water stress and improve soybean yield. Each fertilizer was foliar applied twice at a two-week interval during the flowering stage. Experiments were concurrently conducted under non-drought conditions (70% field capacity) for comparison. Results showed drought significantly reduced relative water content, chlorophyll-a, and chlorophyll-b in untreated control plants by 35.7%, 47.7%, and 41.4%, respectively, compared to non-drought conditions (p < 0.05). Under drought conditions, ZnO-NPs (200mg Zn/L) led to 33.1% and 20.7% increase in chlorophyll-a and chlorophyll-b levels, respectively, compared to ZnSO4 at 400mg Zn/L. Likewise, catalase, peroxidase and superoxide dismutase activities increased by 62.6%, 39.5% and 28.5%, respectively, with ZnO-NPs (200mg Zn/L) under drought compared to non-drought conditions. Proline was significantly increased under drought but was remarkably suppressed (~ 54% lower) with ZnO-NPs (200mg Zn/L) treatment. More importantly, the highest seed yield was observed with ZnO-NPs (200mg Zn/L) treatment under drought (39% higher than untreated control) and non-drought (79.4% higher than control) conditions. Overall, the findings suggest that ZnO-NPs could promote seed yield in soybean under drought stress via increased antioxidant activities, increased relative water content, decreased stress-related proline content, and increased photosynthetic pigments. It is recommended that foliar application of 200mg Zn/L as ZnO-NPs could serve as an effective drought stress management strategy to improve soybean yield.

Balanced Fertilization Enhances the Nutritional Value and Flavor Profile of Tomato Fruits

The tomato is a key fruit in China. However, the drive to produce higher-quality tomatoes has resulted in fertilizer overuse, soil degradation, and environmental pollution in recent years. Therefore, investigating the effects of balanced fertilization on the nutritional and flavor qualities of tomato plants is crucial. This study applied four fertilizer treatments to assess their effects on sugar and acid contents, sugar-metabolism-related enzyme activity, nitrate levels, ascorbic acid, pigments, polyphenols, and volatiles, and we performed a correlation analysis. The results showed that balanced fertilization increased glucose and fructose contents by 45% and 31% compared to CK (conventional fertilizer), while tartaric, citric, acetic, malic, and shikimic acid contents were reduced by 59%, 27%, 22%, 26%, and 4%, respectively. Additionally, balanced fertilization increased the activities of sucrose synthase (SS), sucrose phosphate synthase (SPS), acid invertase (AI), and neutral invertase (NI) by 58%, 26%, 19%, and 35%, respectively, compared to CK (conventional fertilizer) and upregulated the expression of phosphoenolpyruvate carboxykinase (PEPCK), neutral invertase (NI), sucrose-phosphate synthase (SPS), and fructose-1,6-bisphosphatase (FBP) genes. Moreover, balanced fertilization significantly enhanced the polyphenol content, as well as the diversity and concentration of volatiles. Correlation analysis confirmed that sugar-metabolism-related enzymes and genes were positively correlated with sugar fractions and negatively correlated with the organic acid content. Principal components analysis demonstrated that the balanced fertilization treatment was distinct from the other treatments, and all polyphenols, except for caffeic acid, were positively associated with balanced fertilization.

Modeling the Effect of Milk Vetch–Rice Rotation on N Runoff Loss in the Middle and Lower Reaches of the Yangtze River

The winter planting of green manure (GM) is widely used in South China to reduce chemical nitrogen (N) fertilizer use, improve soil fertility, and maintain rice yields, but its effect on N runoff loss in paddy fields remains unclear. This study combines multi-site field experiments with a process model (WHCNS-Rice) to assess how GM with reduced N fertilizer impacts N runoff loss and its forms in the Yangtze River’s middle and lower reaches, considering different rainfall years. The network field experiments included four treatments: conventional fertilization (FR), conventional fertilization plus straw return (FRS), GM with a 40% N reduction (MR), and GM-straw combined return with a 40% N reduction (MRS). Monitoring the results showed that compared to the winter fallow treatment, the GM treatments reduced the peak and average total N (TN) concentrations by 11.1–57.9% (average 26.9%) and 17.1–27.3% (average 22.3%), respectively. The TN runoff loss under the GM treatment decreased by 3.50–10.61 kg N ha−1 (22.5–42.1%). GM primarily reduced the runoff loss of dissolved inorganic N (DIN), with reductions at different sites ranging from 0.22 to 9.66 kg N ha−1 (8.4–43.4%), indicating GM effectively decreases N runoff by reducing DIN. Model simulations of ponding water depth, runoff, TN concentration in surface water, and TN loss in paddy fields produced the consistency indices and simulation efficiencies of 0.738–0.985, 0.737–0.986, 0.912–0.986, and 0.674–0.972, respectively, indicating that the model can be used to evaluate water consumption and N runoff loss in the GM-paddy system. The simulations showed that GM with a 40% N fertilizer significantly reduced N runoff loss under all rainfall conditions, with the greatest reductions in wet years. Under wet, normal, and dry conditions, the GM treatments significantly reduced average TN loss by 0.37–5.53 kg N ha−1 (12.77–29.17%), 0.21–5.32 kg N ha−1 (9.95–24.51%), and 0.02–3.2 kg N ha−1 (1.78–23.19%), respectively, compared to the winter fallow treatment. These results indicate that the combination of GM and a 40% reduction in N fertilizer can significantly reduce N runoff loss from paddy fields, demonstrating good effectiveness under various rainfall conditions, making it a green production model worth promoting.

A Review on Nano Enabled Controlled Release Fertilizers and their Nutrient Release Mechanisms

The imbalance in nutrient release from conventional fertilizers and plant nutrient uptake leads to a surplus accumulation of nutrients in the soil. A key approach to tackle this issue involves the engineering of nano-enabled fertilizers for the controlled release of nutrients to crops. In this context, it is important to understand the strategies for designing and utilizing nano-enabled fertilizers that can effectively regulate nutrient release and enhance nutrient use efficiency (NUE). This review focuses on nano-structured materials that serve as nutrient carriers: nano-clays, hydroxyapatite (HA) nanoparticles, mesoporous silica, carbon-based nanomaterials, polymeric nanoparticles, and other nanomaterials. In addition, the nutrient release mechanisms in controlled release fertilizers (CRFs)/slow-release fertilizers (SRFs) are discussed. The discussion and perspectives presented emphasizes the need for standardized and comprehensive fertilizer evaluation systems, design of multifunctional nanomaterials, and the creation of stimuli-responsive nanocarriers to improve NUE.

Greener Production and Application of Slow-Release Nitrogen Fertilizer Using Plasma and Nanotechnology: A Review

The potential of both plasma and nanotechnology in producing slow-release fertilizer is immense. These technologies, when combined, may offer green and inexpensive nitrogen fertilizers, from rich renewable resources available in local areas. Together, these technologies may overcome some limitations of conventional synthetic fertilizers, which are currently expensive and associated with low nitrogen use efficiency and significant environmental concerns. This review explores the utilization of recent advances in plasma and nanotechnology, which can be leveraged to create new slow-release nitrogen fertilizers. It emphasizes their crucial role in addressing nitrogen depletion and improving crop production. Despite the lack of attempts to develop slow-release nanofertilizers from low-cost liquid nitrate generated by emission-free nonthermal plasma, the effectiveness of plasma nitrate matches that of conventional fertilizer for crop production. We propose a more efficient electrocatalytic conversion of plasma nitrate to ammonium salt, then coating it with plant-based cellulose nanoparticles to create a slow-release form. This set of processes would synchronize nutrient release with the dynamic N requirements of plants. Formulations using agro-based, low-cost cellulose nanomaterials could replace high-cost carrier hydrogels associated with low mechanical strength. This review also highlights the isolation of nanocellulose from various plant materials and its characterization in different formulations of slow-release nanoplasma N fertilizer. Additionally, we discuss mechanisms of N loss, slow-release, and retention in the soil that can contribute to the production and use of efficient, sustainable fertilizers to improve food security and, consequently, the health of our planet.

Foliar Fertilization Improves the Nitrogen Nutrition of Sugarcane

Increasing the recovery of N fertilizer (RNf) is the main challenge in managing nitrogen fertilization in sugarcane. This study aimed to evaluate the efficiency of complementary foliar fertilization in managing nitrogen nutrition in sugarcane. Four fertilization managements, combining soil (5.0 and 4.5 g plot−1 of N) and foliar (1.0 and 1.5 g plot−1 of N) fertilization in up to two application events (0.5 + 0.5 and 0.75 + 0.75 g plot−1 of N), were compared with conventional fertilization (6.0 g plot−1 of N in soil). The change from 6.0 g plot−1 to 4.5 g plot−1 of N reduced the RNf by 46% before the first foliar fertilization. The RNf (26%) was similar between managements after the first foliar fertilization. After the second foliar fertilization, the RNf was 38% higher than that for conventional management. The accumulation of N in the aerial part of sugarcane was similar between managements until the first foliar fertilization. After the second foliar fertilization, the accumulation of N increased by 3.5% with foliar fertilization. The biomass accumulated by the managements was similar before and after the first and second foliar fertilization. The splitting of foliar fertilization increased the accumulation of N and RNf by 22% and 24%, respectively. The fertilization management with 4.5 g plot−1 of N applied to the soil, with two applications of 0.75 g plot−1 of N on the leaf, obtained greater accumulations of N and RNf. Foliar fertilization increases the efficiency of fertilization and improves the N nutrition of sugarcane.

Comparison of STCR and Conventional Fertilizer Approaches for Improved Yield, Uptake and Nutrient Use Efficiency in Greengram

The present study investigates the effects of various fertilizer recommendation approaches on yield, nutrient uptake and nutrient use efficiency in greengram (BGS-9), conducted at ZARS, GKVK, Bengaluru during summer-2024. Soil test crop response (STCR) based fertilizer prescription equations were developed during kharif-2022 by following the methodology of Ramamoorthy et al., (1967) and were validated alongside post-harvest soil test value prediction equations. Results indicated that significantly higher seed yield (17.99 q ha⁻¹) was recorded in the STCR approach for the target yield of 15 q ha-1, where nutrients were applied through integrated approach based on actual soil test values (T3). The highest haulm yield (30.25 q ha⁻¹) was recorded in T2, which followed the STCR inorganic approach targeting 15 q ha⁻¹, based on predicted soil test values. Nutrient uptake results indicated that significantly higher nitrogen (110.73 kg ha⁻¹), phosphorus (11.39 kg ha⁻¹) and potassium (140.06 kg ha⁻¹) uptake were recorded in STCR treatments, particularly in those with an integrated approach. These treatments also validated better nutrient recovery and agronomic use efficiency compared to low, medium and high (LMH) and package of practice (POP) approaches. The findings confirm the accuracy of predicted soil test values in fertilizer prescription, indicating that repeated soil testing between crops may be unnecessary. The STCR based integrated approach provided balanced nutrient application, leading to optimal yield and nutrient uptake. This study highlights the effectiveness of STCR methodologies for efficient nutrient management and improved productivity in greengram.

Effect of Nano-fertilizers in Wheat Crop Nutrition: A Review

The use of nano - fertilizers in wheat cultivation represents a promising approach to overcoming some of the inefficiencies and environmental challenges associated with conventional fertilizer practices. Traditional fertilizers often suffer from low nutrient use efficiency, leading to excessive application, nutrient runoff, and environmental harm. Nano fertilizers, due to their nano-scale size and enhanced reactivity, improve nutrient uptake by plants, leading to better growth, higher yields, and reduced nutrient wastage. Studies show that Nano formulations of both macronutrients (such as nitrogen, phosphorus, and potassium) and micronutrients (like zinc and iron) can significantly enhance wheat productivity. Nano fertilizers not only increase crop yield but also reduce the overall cost of fertilizer application by minimizing nutrient loss and improving absorption by the plants.

Treating Tropical Soils with Composted Sewage Sludge Reduces the Mineral Fertilizer Requirements in Sugarcane Production

Conventional mineral fertilization (CMF) is a common practice in infertile sugarcane-cultivated tropical soils, increasing production costs and environmental concerns. Combining CMF with composted sewage sludge (CSS) could be a sustainable strategy. We aim to evaluate changes in soil chemical properties, macro- and micronutrient concentrations in the soil surface (Ap1; 0–25 cm) and subsurface (Ap2; 25–50 cm) horizons, after CSS application with or without CMF in sugarcane cultivation (first and second ratoon cane). Eleven treatments, featured by CSS increase rates and mixed with CMF at different concentrations, were tested in the first ratoon; during the second, the CSS residual effect was evaluated. Applying CSS in sugarcane-cultivated soils, improved the following: (i) soil organic matter, pH, the sum of bases, cation-exchange capacity, and base saturation; (ii) overall nutrient concentrations (P, K, Ca, Mg, B, Cu, and Zn). The treatments showing the best performances were those with 5.0 Mg ha−1 of CSS. Composted sewage sludge has the potential for use as an organic natural fertilizer reducing the need for CMF. When applied in infertile tropical soils, additional positive effects can be achieved, such as decreasing production costs and providing socio-economic benefits.

Eco-toxicological impact of biologically synthesized FeONPs on rice plants and PGP bacteria

Nanoformulations of plant micronutrients can improve nutrient use efficiency and availability in plants compared to conventional fertilizers and, therefore, may prove helpful in addressing the widespread challenge of nutrient deficiency in agricultural soils. In this study, iron-oxide nanoparticles (FeONPs) were bio-synthesized using Aspergillus terreus cell-free extract and tested for bio-efficacy in rice (Oryza sativa L., ssp. japonica, T309) in situ. Physicochemical characteristics of biosynthesized FeONPs (B-FeONPs) were analyzed through UV-visible spectroscopy (UV-Vis), dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray (EDX). Bio-efficacy was tested at both environmentally relevant concentrations (0-50 mg.kg−1) as well as supra-environmental concentrations (100 mg.kg−1). Germination, wet and dry biomass, root length, shoot length, chlorophyll and carotenoid content, and iron fortification in rice plants were evaluated under greenhouse conditions. Potential eco-toxic effects of B-FeONPs were investigated in multiple strains of plant growth-promoting (PGP) bacteria. A significant increment in plant growth parameters (p < 0.05), including wet biomass, dry biomass, root length, and chlorophyll and carotenoid content was observed in B-FeONPs treated rice plants as compared to those treated with bulk Fe-fertilizer FeSO4. B-FeONPs caused no oxidative stress and increased the % Fe content in the plants. Uptake and accumulation of the B-FeONPs were also confirmed in the roots and leaves of plants using TEM. The B-FeONPs did not demonstrate bactericidal activity against any of the tested strains of PGP bacteria at both environmentally relevant and supra-environmental concentrations. In conclusion, the data demonstrate that B-FeONPs exhibit significant potential in enhancing nutrient use efficiency and promoting growth in rice plants. These findings underscore the potential of B-FeONPs as sustainable alternatives to conventional Fe fertilizers, offering sustainable solutions for addressing nutrient deficiencies in agricultural soils.

Preparation of nutrient hydrogels with core-shell structure for seed germination and seedling growth in high temperature saline environment.

Drought and soil degradation are the key factors in desertification control. How to improve the utilization efficiency of water and fertilizer has always been the focus of research in desert areas. The conventional hydrogel-loaded fertilizer is not suitable because of the high salinity and large temperature difference in sandy land. Therefore we prepared a novel temperature/pH-responsive core-shell structured hydrogel and loaded urea in three ways: in situ polymerization, encapsulation, and immersion, and germination and seedling growth experiments on Artemisia absinthium and Cabbage (Brassica campestris L. ssp. chinensis Makino) seeds. The results showed that the immersion hydrogel SAP4 (PCP-g-PAA/P(DMAEMA-co-AMPS))/urea had the best repetitive swelling performance, achieving 163.89 % of the original water absorption performance after 16 repetitions and the highest nitrogen release of 151.37 mg at 40 days. For A. desertorum, the treatment group applying the in situ composite hydrogel SAP2 (PCP-g-PAA/P(DMAEMA-co-AMPS)/urea) had the highest germination rate of 70 %; for B. campestris, the treatment groups applying SAP2, the encapsulated hydrogel SAP3 (PCP-g-PAA/urea/P(DMAEMA-co-AMPS)) and SAP4 hydrogels had higher germination rates, with SAP3 having a 100 % germination rate. This phenomenon suggests that the three urea-loaded temperature/pH-responsive core-shell structured hydrogels we have prepared are very promising as an aid to seed germination and seedling growth.

Optimizing Nitrate Fertilizer Production Using Plasma-Activated Water (PAW) Technology: An Analysis of Dielectric Properties

This study investigates the potential of Plasma-Activated Water (PAW) technology for the production of nitrate fertilizer, focusing on the dielectric properties of plasma-treated water, such as the dielectric constant and dielectric loss factor. The research aims to elucidate the impact of plasma treatment and varying water flow rates on these properties. An experimental approach was employed wherein ion-free water was subjected to plasma treatment at different flow rates (0.5, 1.0, and 2.0 L/min) and durations (1, 2, and 3 h). The results reveal a marked enhancement in the dielectric properties of the water following plasma treatment, with the most significant improvements observed at a flow rate of 0.5 L per minute and a treatment duration of 3 h, and dielectric efficiencies of 97.82%, 97.21%, and 96.61% achieved at flow rates of 0.5, 1.0, and 2.0 L/min, respectively. These findings demonstrate that PAW technology enhances the efficiency of nitrate fertilizer production by optimizing energy storage and reducing energy losses. The study underscores the potential of PAW as a sustainable, environmentally benign alternative to conventional chemical fertilizers, contributing to more efficient and sustainable agricultural practices.

Controlled-Release Iodine Fertilizer Improved Iodine Accumulation, Antioxidant Capacity, and Quality of Lettuce

To clarify the effects of newly developed controlled-release iodine fertilizer (CRIF) on enhancing lettuce (Lactuca sativa L.) iodine accumulation, improving the physiological traits, and reducing iodine leaching from soil, a greenhouse pot experiment was conducted. Polymer-coated iodate (PCIO), polymer-coated iodide (PCI), and two conventional iodine fertilizers—iodate (CIO) and iodide (CI)—were applied at a rate of 15 mg iodine per kg soil. The study found that the coating of iodine fertilizers had no significant effects on the biomass of lettuce. The iodine concentration in lettuce leaves subjected to PCIO treatment was elevated by 50.1% and 45.5%, respectively, in comparison to leaves treated with CIO and PCI. The soil-to-leaf transfer factor (TFleaf, dry weight basis) for plants treated with PCIO was significantly higher than that of PCI-treated plants. PCIO also significantly reduced iodine leaching by 46.3% compared to CIO. In lettuce leaves with PCIO treatment, the enzymatic activities of superoxide dismutase (SOD) and catalase (CAT) significantly increased by 50.8% and 27.6%, respectively. Likewise, malo-naldehyde (MDA) levels decreased by 23.2% compared to the control samples. PCIO also demonstrated advantages in enhancing the quality of the lettuce. In conclusion, the application of controlled-release iodine fertilizer could be a highly effective and eco-friendly approach to cultivating iodine-rich vegetables.

IVF with frozen-thawed sperm after prolonged capacitation yields comparable results to ICSI in horses: A morphokinetics study

Intracytoplasmic sperm injection (ICSI) is the current clinical practice for the in vitro production of equine embryos. The use of conventional fertilization methods such as in vitro fertilization (IVF), has historically been associated with poor success in horses. However, recent improvements have led to better outcomes with IVF, though only when using fresh semen, which limits its use in clinical practice. IVF remains in its infancy in equine reproduction, and several unknowns remain about the technique. One significant gap in knowledge concerns the morphokinetics of IVF embryos and how they differ from their ICSI counterparts. To address this, we performed IVF using frozen-thawed sperm from five different stallions following sperm selection and a prolonged capacitation period of 10 h, on a total of 109 oocytes. We then analyzed the cleavage rate (cleaved/initial oocytes), blastocyst rate (blastocyst/initial zygotes), and blastocyst development (blastocyst/cleaved zygotes) of the IVF cycles, and compared them with those of the clinical ICSI cycles during the same period. We also evaluated time-lapse images of the developed embryos to assess developmental time points such as time to morula compaction and blastocyst expansion, as well as morula and blastocyst sizes. Overall, developmental rates were not different between IVF and ICSI cycles (blastocyst rate 41.1 % IVF and 41.8 % ICSI, p > 0.05). However, development proceeded faster in IVF cycles (blastocyst expansion IVF 155.5 ± 18.5 h; ICSI 167.2 ± 19.6 h; p < 0.05) and IVF embryos were also larger (blastocyst area IVF 22608 ± 2857 μm2; ICSI 20806 ± 1505 μm2; p < 0.05). The faster development and larger size might suggest a more advanced developmental stage. The implications of these findings need to be further evaluated to assess their association with pregnancy potential. The successful developmental rates achieved in IVF cycles demonstrate the potential of this technique for clinical application, although the amount of frozen-thawed semen required is significantly higher in IVF than in ICSI, which is an important consideration for mare and stallion owners. Nonetheless, the use of frozen-thawed semen in equine IVF, coupled with comparable blastocyst rate, presents promising potential for broader clinical adoption of the IVF technique.

Effect of Artificial Humic Acids Derived from Municipal Sludge on Plant Growth, Soil Fertility, and Dissolved Organic Matter

Due to its high nutrient utilization efficiency, liquid organic fertilizer has become a research hotspot in the field of agricultural planting. Artificial humic acids, which are near-nature products, can be deemed as a green liquid organic fertilizer, but few studies have been reported, which has limited their further application. In this study, artificial humic acids were derived from municipal sludge, and their effect on rice growth, soil fertility, and dissolved organic matter was investigated using multi-chamber root box experiments. The shoot and root biomass of rice can be significantly enhanced by artificial humic acids, and the heavy metal concentration in rice was within safe limits. Artificial humic acids can limit the decrease in soil pH, especially in the far-rhizosphere zone, and improve the distribution of nutrients in the rhizosphere, near-rhizosphere, and far-rhizosphere zones. The use of artificial humic acids led to a significant decrease in soil electrical conductivity. The dissolved organic carbon content in the root zone was significantly increased, and the fluorescence intensity of dissolved organic matter in the rhizosphere was significantly increased. The proportion of specific components of dissolved organic matter was just slightly changed in the rhizosphere and near-rhizosphere zones. Artificial humic acids promoted the humification of dissolved organic matter in the near-rhizosphere and far-rhizosphere zones. The findings indicate that the environmental impact of artificial humic acids is significantly different from conventional chemical fertilizers, and they show huge potential in the agriculture field.

Microbe-Friendly Plants Enable Beneficial Interactions with Soil Rhizosphere Bacteria by Lowering Their Defense Responses.

The use of plant growth-promoting rhizobacteria presents a promising addition to conventional mineral fertilizer use and an alternative strategy for sustainable agricultural crop production. However, genotypic variations in the plant host may result in variability of the beneficial effects from these plant-microbe interactions. This study examined growth promotion effects of commercial vegetable crop cultivars of tomato, cucumber and broccoli following application with five rhizosphere bacteria. Biochemical assays revealed that the bacterial strains used possess several nutrient acquisition traits that benefit plants, including nitrogen fixation, phosphate solubilization, biofilm formation, and indole-3-acetic acid (IAA) production. However, different host cultivars displayed genotype-specific responses from the inoculations, resulting in significant (p < 0.05) plant growth promotion in some cultivars but insignificant (p > 0.05) or no growth promotion in others. Gene expression profiling in tomato cultivars revealed that these cultivar-specific phenotypes are reflected in differential expressions of defense and nutrient acquisition genes, suggesting that plants can be categorized into "microbe-friendly" cultivars (with little or no defense responses against beneficial microbes) and "microbe-hostile" cultivars (with strong defense responses). These results validate the notion that "microbe-friendly" (positive interaction with rhizosphere microbes) should be considered an important trait in breeding programs when developing new cultivars which could result in improved crop yields.

Analysis of Physicochemical Properties, Enzyme Activity, Microbial Diversity in Rhizosphere Soil of Coconut (Cocos nucifera L.) Under Organic and Chemical Fertilizers, Irrigation Conditions

The application of chemical fertilizers and organic fertilizers, as well as irrigation, is an important agricultural practice that can increase crop yields and affect soil biogeochemical cycles. This study conducted coconut field experiments to investigate the effects of conventional fertilization (NCF), optimized fertilization (MCF), conventional fertilization + organic fertilizer (NOF), optimized fertilization + organic fertilizer (MOF), conventional fertilization + organic fertilizer + irrigation (NOFW), and optimized fertilization + organic fertilizer + irrigation (MOFW) treatments on soil physicochemical properties, soil enzyme activity, bacterial and fungal community structure and diversity, and compared the controls (CK, non-fertilizer and non-irrigation). The results showed that MOFW significantly increased soil electrical conductivity (EC), organic matter (OM), alkaline nitrogen (AN), available phosphorus (AP), available potassium (AK), available calcium (ACa), and available magnesium (AMg) levels. At the same time, it also significantly enhanced the activities of soil catalase (CE), polyphenol oxidase (POE), sucrase (SE), urease (UE), acid protease (APE), and acid phosphatase (APPE) (p &lt; 0.05). The PCA analysis of soil microorganisms in the coconut rhizosphere soil showed indicated significant changes in bacteria and fungi community structure under fertilization treatments. The fertilization application leaded to an increase in the relative abundance and diversity of bacteria, but a decrease in fungi. Acidobacteriota, Proteobacteria, and Actinobacterota were the dominant bacterial phyla, and Ascomycota, Basidiomycota, Rozellomycota, and Mortierellomycota were the significant fungal phyla. Compared with CK, MOFW significantly increased the abundance of Acidobacteriota, Proteobacteria, Basidiomycota, and Mortierellomycota. Redundancy analysis (CCA) and Mantel test further revealed that pH, EC, OM, and AP were the main soil fertility factors driving changes in microbial communities. CE, SE, UE, APE, APPE were significantly correlated with microbial communities. Compared with NOFW, MOFW has a lower proportion of N, P, and K fertilizers in its fertilizer composition. The results indicated that MOFW can better improve the nutrient and enzyme status of the soil, which is a promising method for maintaining the balance of soil microorganisms in coconut orchards, and accordingly, reducing chemical fertilizers within a certain range can not only ensure consistency with conventional fertilizers, but also effectively improve soil conditions.

Sources and splitting of special fertilizers application in coffee crop

This study assesses special and mineral fertilizers and the splitting of fertilizer application in coffee - a crop with high nutritional requirements for full yield potential. A 4 × 3 factorial scheme was implemented with four fertilizers [mineral, mineral with polymer, organomineral with cellulosic residue (OM-CR), or sugarcane filter cake (OM-FC)] and three application times, or splits (100% at once, 50%+50%, 33.3%+33.3%+33.3%). Coffee plant height, canopy diameter, plagiotropic branch growth, leaf chlorophyll, nutrient contents in the soil and leaves, and harvest yield after fruit maturation were evaluated in two consecutive crop cycles. The results indicated that organomineral fertilizers performed similarly to other fertilizers regarding coffee leaf chlorophyll and plant height. Only one fertilizer application effectively increased canopy diameter in both crop cycles. In the first crop cycle, OM-FC and conventional mineral fertilizers were significantly better for coffee foliar N content. In contrast, in the second crop cycle, mineral-P, OM-CR, and OM-FC achieved satisfactory results with one fertilizer application, whereas conventional mineral fertilizer required three applications for superior results. There are no differences in leaf P content among different sources and frequencies of application. Still, mineral-P and OM-CR had better soil P content than the conventional mineral fertilizer. OM-CR required two applications to reach high levels of leaf K content, while other fertilizers achieved it with one application. Organomineral and protected mineral fertilizers performed similarly in both crop cycles, with two applications resulting in greater coffee yield in the second cycle, regardless of the fertilizer used.

Low Nitrogen Availability in Organic Fertilizers Limited Organic Watermelon Transplant Growth

Fertilization guidelines for organic watermelon transplant production are rare. We investigated the effect of four commercial organic fertilizers and seven organic fertilizer blends, along with one conventional fertilizer (Peter’s Professional 20-20-20) on watermelon transplants. The four organic fertilizers were Nature Safe (fertilizer label: 7-7-7), Miracle-Gro (8-8-8), Dr. Earth fertilizer tea (4-4-4), and Drammatic (2-4-1). The seven blended organic fertilizers were created by supplementing Drammatic with nitrogen (N)-rich and/or potassium (K)-rich fertilizers to balance its N:phosphorus (P):K ratios. Watermelon ‘Jubilee’ was sown in organic substrate, and fertilizer treatments were applied weekly with a total of 0.4 g nitrogen/L substrate. Miracle-Gro and Drammatic had the highest N mineralization rate after 21 days and the highest inorganic N concentration, respectively, and resulted in the highest shoot dry weight among organic fertilizers. Miracle-Gro also resulted in the highest root dry weight. Dr. Earth fertilizer tea supplied the lowest N and P, and resulted in stunted transplants. Our results indicated that nitrate concentration was the most important factor influencing both shoot and root growth. Supplementing Drammatic with N-rich and/or K-rich fertilizers to balance its N:P:K ratio did not affect shoot and root dry weight. Combined, we concluded that nitrogen availability rather than nutrient balance is the key factor influencing watermelon transplant growth.