Rajesh Kumar

Rhizoctonia solani is a major soil-borne pathogen that causes severe agricultural damage to maize, rice, soybean, and potato. The increasing resistance of pathogens to conventional fungicides and environmental concerns necessitate the development of new, effective, and eco-friendly antifungal compounds. Guided by a comparative docking study, 5-substituted-1,3,4-thiadiazole-2-thiol derivatives were synthesized, characterized, and evaluated for their antifungal efficacy against R. solani. Several derivatives exhibited strong antifungal activity (EC₅₀: 3.6 to 196.56 μg/mL), particularly those with halogen-substituted phenyl rings. The compound, 5-((2,4-dichlorophenoxy)methyl)-1,3,4-thiadiazole-2-thiol (A-3), showed the highest activity comparable to the reference fungicide hexaconazole (EC₅₀ = 2.33 μg/mL). Structure-activity relationship analysis and ergosterol inhibition activity affirmed their potential as effective agricultural fungicides, while ECOSAR model predictions indicated their promise as environmentally safe bioactive compounds for plant disease management.

Nitrogen (N) losses from conventional N fertilizers contribute to environmental degradation and low N use efficiency. Highlighting the need for slow-release fertilizers (SRFs) to mitigate these problems, this study aims to develop slow-release N fertilizers using starch-grafted-poly[(acrylic acid)-co-acrylamide] based nanoclay polymer composites (NCPCs) and investigate their efficacy for slow N delivery in soil. Three types of NCPCs, NCPC(A) (poly [(acrylic acid)-co-acrylamide]), NCPC(W) (wheat starch-grafted-poly[(acrylic acid)-co-acrylamide), and NCPC(M) (maize starch-grafted-poly[(acrylic acid)-co-acrylamide) were prepared and characterized using FTIR spectroscopy and X-ray diffraction techniques. N-release behaviour of the products was assessed under two distinct soils, i.e., Assam (Typic Hapludults, pH 4.2) and Delhi (Typic Haplustepts, pH 7.9) soils. Additionally, the effects of varying soil moisture and temperature levels on N release were studied in the Assam soil. The N-release kinetics of the synthesized fertilizers were assessed using zero-order, first-order, Higuchi, and Korsmeyer−Peppas models. Degradability of the NCPCs was evaluated by measuring evolved CO₂–C under various soil conditions as an indicator of microbial degradation. The results indicated that NCPC fertilizers significantly slowed down the release of N compared to urea. According to the R² values obtained, it was evident that the first-order kinetic model most accurately describes the N release from both urea and NCPC-based N fertilizers in the studied soils. Among the formulations, NCPC(A) exhibited the lowest N release (42.94–53.76%), followed by NCPC(M) (51.05–61.70%), NCPC(W) (54.86–67.75%), and urea (74.33–84.27%) after 21 days of incubation. The rate of N release was lower in the Assam soil compared to the Delhi soil, with higher soil moisture and temperature levels accelerating the release. Starch addition improved the biodegradability of the NCPCs, with NCPC(W) showing the highest cumulative CO₂-C evolution (18.18–22.62 mg g⁻¹), followed by NCPC(M) (15.54–20.97 mg g⁻¹) and NCPC(A) (10.89–19.53 mg g⁻¹). In conclusion, NCPC-based slow-release fertilizers demonstrated a more gradual N release compared to conventional urea and the inclusion of starch enhanced their degradability in the soil, which confirms their potential for sustainable agricultural applications. However, soil properties and environmental factors influenced the N release and degradation rates of NCPCs.

The present investigation aims to study adsorption-desorption behavior of glyphosate and tricyclazole in rice straw-compost biomixtures. To enhance pesticide adsorption and performance of the bio-purification system, rice straw-compost (BM) biomixture was mixed with wheat straw biochar (WBC, 1% and 5%), and adsorption of both pesticides in control (BM) and WBCBM(1%) and WBCBM(5%) biomixtures was compared. The kinetics study suggested that the pseudo-second-order model best explained the time-dependent adsorption of both pesticides and intraparticle adsorption was not the rate-determining step. Tricyclazole was more sorbed than glyphosate in all biomixtures which can be attributed to its lower water solubility. The WBC increased the sorption of both pesticides, but the effect varied with the nature of pesticides and biochar content. The adsorption coefficient values in BM, WBCBM(1%), and WBCBM(5%) biomixtures were 26.74, 38.16, and 51.97 (glyphosate) and 38.07, 59.94, and 84.54 (tricyclazole), respectively. The adsorption data was subjected to the Freundlich, the Langmuir, and the Temkin isotherms, and among them, the Freundlich isotherm best explained pesticide adsorption behavior. Desorption results suggested that the adsorption of glyphosate was more irreversible than tricyclazole and depended upon initial pesticide concentration. This study suggested that biochar mixed rice straw-compost biomixtures can be exploited in bio-purification systems for glyphosate and tricyclazole.

Meeting the escalating demand for food presents a challenge, necessitating the inevitable use of chemical pesticides to ensure a sufficient level of food production. However, these pesticides, have drawbacks and can adversely affect non-target organisms and the environment. Nanoparticles for disease management offer a powerful solution, bringing numerous benefits such as enhanced efficacy, minimized pesticide use, reduced impact on the environment, etc. In the present study, the supernatant of two fungi, Fusarium verticillioides and Bipolaris maydis were used for copper nanoparticles (CuNPs) synthesis. A 5 mM CuSO4 solution was used as a precursor and the reaction was carried out at an optimized pH of 8.5 in dark conditions.The shift in the reaction mixture's colour from light blue to yellowish-green and reddish-brown with F. verticillioides and B. maydis supernatant, respectively, preliminarily confirmed particle size reduction. Characterization of fungal-mediated synthesized CuNPs (FM-CuNPs) using transmission electron microscope measured the size of 8.62-52 nm and 27.96 to 65 nm by employing F. verticillioides and B.maydis, respectively, with a spherical shape. Dynamic light scattering measured the hydrodynamic size of FM-CuNPs 141.8 nm and 170.2 nm with zeta potential of -19.5 mV and -22.5 mV, respectively. Fourier transform infrared spectroscopy revealed the presence of functional groups such as amines, amides, and OH groups speculated to have a pivotal role in the reduction and stabilization of particle. Additionally, the in vitro evaluation efficacy of FM-CuNPs against Xanthomonas oryzae pv. oryzae exhibited a significant inhibition zone starting from 100 microgram ml (1.70 cm) as compared to control. The study demonstrates the -1 remarkable efficacy of FM-CuNPs synthesized for the first time using two aforesaid fungal species. . KEYWORDS :Bipolaris maydis, CuNPs, Fusarium verticillioides, Management, Xanthomonas oryzae pv. Oryzae

Twenty-two eco-friendly, novel Schiff bases were synthesized from 2,4,5-trichloro aniline and characterized by using FT-IR, ¹H NMR, and ¹³C NMR techniques. Fungicidal activity against pathogenic fungi Sclerotium rolfsii and Rhizoctonia bataticola and insecticidal activity against the stored grain insect pest Callosobruchus maculatus of the test compounds were evaluated under control condition. All of the investigated compounds, according to the study, exhibited moderate to good antifungal and insecticidal activities. The best antifungal activity against both pathogenic fungi was demonstrated by C15 and C16 whose ED₅₀ values were recorded 11.4 and 10.4 μg/mL against R. bataticola and 10.6 and 11.9 μg/mL against S. rolfsii, respectively. They were further screened in for disease suppression against both pathogenic fungi under pot condition through different methods of applications in green gram (Vigna radiata L.) crop. The compounds C10 and C18 had the highest insecticidal activity, with LD₅₀ values of 0.024 and 0.042 percentages, respectively. Stepwise regression analysis using root mean square error (RMSE) and correlation coefficient (R) method used to validate the quantitative structure activity relationship (QSAR) of synthesized compounds in addition to their fungicidal and insecticidal actions. To the best of our knowledge, this investigation on the 22 new Schiff bases as possible agrochemicals is the first one that has been fully reported.