Synthesis of silver nanoparticles by cell-free extract (CFE) of Pseudomonas aeruginosa M6 isolated from a mangrove ecosystem was demonstrated using two physical methods, namely, boiling (conventional thermal treatment (CTT)) and microwave treatment (MWT) at pH 9. X-ray diffraction (XRD) analysis revealed the presence of smaller (10.4 nm), pure silver nanoparticles synthesized via CTT (C-NPs) and larger silver oxide nanoparticles in majority with negligible concentration of pure silver particles by MWT. Transmission electron microscopy (TEM) analysis showed that C-NPs are spherical in shape. Atomic force microscopy (AFM) analysis also confirmed the presence of large-sized, aggregated nanoparticles synthesized via MWT (M-NPs). Electrophoresis indicated the size and charge-based mobility in agarose gel (0.4%), wherein the C-NPs moved faster than M-NPs, because of their relatively smaller size. The zeta potential value of C-NPs and M-NPs was found to be −30.1 mV and −23.1 mV, respectively. Fourier transform infrared (FT-IR) results revealed that both C-NPs and M-NPs were capped with proteins, but with different conformations. Furthermore, TEM analysis of bacterial cells exposed to aqueous silver nitrate showed the presence of spherical silver nanoparticles accumulated in periplasmic space, indicating the possible involvement of periplasmic nitrate reductase in this process. In addition, both C-NPs and M-NPs have also shown good antibacterial and anticandidal activities. Thus, marine Pseudomonas aeruginosa M6 can be a potential source for the synthesis of silver nanoparticles.

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Vermicompost and NPK Fertilizer Effects on Morpho-Physiological Traits of Plants, Yield and Quality of Tomato Fruits: (Solanum lycopersicum L.) A field experiment was conducted with an objective to investigate the effects of vermicompost and NPK fertilizer application on morpho-physiological traits, yield and quality attributes of tomato (Solanum lycopersicum L.) with an ultimate aim of optimizing nutrient requirements of tomato in mild-tropical agro-climate. The application of vermicompost together with NPK fertilizer increased plant height, leaf area, leaf weight, fruit weight, fruit yield, fruit density, post-harvest life and TSS of tomato. Application of vermicompost alone too increased the shelf-life by 250% and TSS beyond 4.5%, both of which are traits highly desirable for summer production of tomato and the related processing industry. Present study reveals that application of vermicompost in the amount of 7.5 t·ha-1 in combination with 50% dose of NPK fertilizer (60:30:30 kg·ha-1) was optimum for obtaining better quality and productivity of field grown tomatoes in mild-tropical agro-climate, eventually integrated nutrient supply will sustain the soil fertility and plant productivity eco-friendly.

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Land-use change, particularly soil organic carbon (SOC) loss induced by shifting cultivation (jhum) is a common land degradation issue in the hilly tracts of the humid tropics. The SOC concentration comprises different pools (labile and recalcitrant fractions), and each fraction responds to temporal dynamics of adopted management practices at varying magnitudes, such as deforestation followed by cultivation. However, information on the variation of different SOC pools due to cultural practices of vegetation burning and postburn agricultural practices (crop production) associated with shifting cultivation remains inadequate. In the present investigation, we examined the effect of burning and postburning cultivation on SOC pools across different forest fallow periods at Kolasib district, Mizoram state of the north-eastern Himalayan Region of India. Results revealed increase in the soil C stocks and total organic carbon (TOC) due to the increase in the length of fallow periods ranging from 3 to 23 years. The TOC decreased significantly compared with antecedent concentrations before vegetation burning. This was mostly attributed to the reduction in contribution of active pools (very labile and labile) to TOC from 69% to 60%. However, contribution of passive pools (less labile and nonlabile) to TOC concentration increased from 31% to 40%. Postburn cultivation also resulted in reduction of TOC as well as considerable variation in the proportion of different SOC pools to TOC concentration. Among the different pools of SOC, the very labile C pool was most sensitive to land-use change induced by shifting cultivation (phytomass burning and postburn cultivation). The labile SOC pools can act as a sensitive indicator for devising suitable location specific management practices for restoration of soil health through SOC dynamics in degraded jhum lands in hilly ecosystems.

Climate change is shifting agricultural production, which could impact the economic and cultural contexts of the oilseed industry, including sesame. Environmental threats (biotic and abiotic stresses) affect sesame production and thus yield (especially oil content). However, few studies have investigated the genetic enhancement, quality improvement, or the underlying mechanisms of stress tolerance in sesame. This study reveals the challenges faced by farmers/researchers growing sesame crops and the potential genetic and genomic resources for addressing the threats, including: (1) developing sesame varieties that tolerate phyllody, root rot disease, and waterlogging; (2) investigating beneficial agro-morphological traits, such as determinate growth, prostrate habit, and delayed response to seed shattering; (3) using wild relatives of sesame for wide hybridization; and (4) advancing existing strategies to maintain sesame production under changing climatic conditions. Future research programs need to add technologies and develop the best research strategies for economic and sustainable development.

Biological control using entomopathogenic fungi could be a promising alternative to chemical control. Entomopathogenic fungi, Beauveria bassiana (Balsamo) Vuillemin, Metarhizium anisopliae (Metschnikoff) Sorokin, Lecanicillium lecanii (Zimmerm.) Zare and Gams, and Paecilomyces fumosoroseus (Wize) Brown and Smith, were tested for their pathogenicity, ovicidal effect, and median lethal concentrations (LC50) against exotic spiralling whitefly, Aleurodicus dispersus Russell. The applications were made at the rate of 2 × 109 conidia mL−1 for evaluating the pathogenicity and ovicidal effect of entomopathogenic fungi against A. dispersus. The results of pathogenicity test showed that P. fumosoroseus (P1 strain) was highly pathogenic to A. dispersus recording 100% mortality at 15 days after treatment (DAT). M. anisopliae (M2 strain) had more ovicidal effect causing 37.3% egg mortality at 8 DAT. However, L. lecanii (L1 strain) caused minimum egg hatchability (23.2%) at 10 DAT as compared to control (92.6%). The lowest LC50 produced by P. fumosoroseus (P1 strain) as 8.189 × 107 conidia mL−1 indicated higher virulence against A. dispersus. Hence, there is potential for use of entomopathogenic fungi in the field conditions as an alternate control method in combating the insect pests and other arthropod pests since they are considered natural mortality agents and are environmentally safe.