Biogels in Soils: Plant Mucilage as a Biofilm Matrix That Shapes the Rhizosphere Microbial Habitat

Mucilage is a gelatinous high-molecular-weight substance produced by almost all plants, serving numerous functions for plant and soil. To date, research has mainly focused on hydraulic and physical functions of mucilage in the rhizosphere. Studies on the relevance of mucilage as a microbial habitat are scarce. Extracellular polymeric substances (EPS) are similarly gelatinous high-molecular-weight substances produced by microorganisms. EPS support the establishment of microbial assemblages in soils, mainly through providing a moist environment, a protective barrier, and serving as carbon and nutrient sources. We propose that mucilage shares physical and chemical properties with EPS, functioning similarly as a biofilm matrix covering a large extent of the rhizosphere. Our analyses found no evidence of consistent differences in viscosity and surface tension between EPS and mucilage, these being important physical properties. With regard to chemical composition, polysaccharide, protein, neutral monosaccharide, and uronic acid composition also showed no consistent differences between these biogels. Our analyses and literature review suggest that all major functions known for EPS and required for biofilm formation are also provided by mucilage, offering a protected habitat optimized for nutrient mobilization. Mucilage enables high rhizo-microbial abundance and activity by functioning as carbon and nutrient source. We suggest that the role of mucilage as a biofilm matrix has been underestimated, and should be considered in conceptual models of the rhizosphere.

Estimation of Nutrient Loads With the Use of Mass-balance and Modelling Approaches on the Wełna River Catchment Example (Central Poland)

Nitrogen and phosphorus budgeting is considered to be a useful tool for policy makers and stakeholders when dealing with nutrient contamination issues. Although a variety of budgeting approaches have been employed in countries affected by this problem, the direct comparison of possible options for the same area is quite limited. The current study offers a detailed insight into the estimations of nutrient loads and their distribution between different sources for a middle-sized agricultural catchment, with the use of two approaches: mass balance method and SWAT modelling. As a result of their comparison, both methods revealed similar contributions of analysed nutrient sources, although the absolute loads were heterogeneous, which stems from drawbacks related to the quality of the monitoring data, the performance of the model and omission of some catchment processes. However, in light of the performed comparison, we suggest a hybrid solution, combining the best features of both approaches.

Frond Base Fracture and Dynamics of Palm Oil Inflorescence Applied With Different Nutrient Sources

Frond base fracture is an increasingly common phenomenon in oil palm plantations caused by various stress factors. This study aimed to determine the incidence of frond base fracture in the plantation where different nutrient sources were applied (palm oil mill effluent, oil palm EFB, and organic fertilizers) in relation to the dynamics of oil palm inflorescence. The incidence of frond base fracture and the production of male and female inflorescences were observed in 30 sample trees for each nutrient source. Observations were made three times with an interval monthly. To reveal the research objectives, it used descriptive analysis. The results showed that the routine application of POME increased the susceptibility of oil palms to fractured fronds and the sex ratio was higher other than that of EFB; the lowest incidence was found in the palm that was given inorganic fertilizers. frond base fracture trees produced fewer female inflorescence, although the number of male ones did not differ between frond base fracture palm and healthy ones.

Effect of different fertilizer doses on the production of Chaite-5 paddy variety in Dhanusha District, Nepal

The application of inorganic nutrient sources is necessary for proper agricultural growth that can ensure high quality food production. A field experiment was carried out in Hansapur, Dhanusha from March 2021 to July 2021 to study the effect of different fertilizer doses on the growth and yield of rice. The experiment was set up in a randomized complete block design (RCBD) with 7 different treatments following three replications. The treatments were named as T1: Control, T2: RDF (Recommended dose of fertilizers - 100:30:30 kg NPK/ha), T3: Double dose of RDF (200: 60: 60 kg NPK/ha), T4: A half dose of RDF (50: 15: 15 kg NPK/ha), T5: 125% dose of RDF (125: 37.5: 37.5 kg NPK/ha), T6: Locally available Azolla (300 kg/ha), and T7: FYM (6 ton/ha), respectively. Different doses of RDF showed a significant effect on growth, yield, and yield contributing characters of Chaite-5 variety. Results of the study showed that the application of a double dose of RDF (200: 60: 60 kg NPK/ha) gave the maximum yield (9.50 ton/ha). It was also recorded that 125% dose of RDF, recommended dose of fertilizers and FYM gave satisfactory results. Results revealed that the highest plant height, effective tillers/hill, panicle number, panicle length, total spikelet/hill, 1000-grain weight, grain yield, and straw yield were obtained from the use of a double dose of RDF (200: 60: 60 kg NPK/ha). It was observed that yield of rice can be increased substantially with the application of higher doses of nitrogenous fertilizers. Hence, a double dose of fertilizer can be the best supplement for improving growth and yield in rice.

Examining the Role of Marine Mammals and Seabirds in Southeast Alaska’s Marine Ecosystem Dynamics

Primary producers are the foundation of marine food webs and require reliable nutrient sources to maintain their important role with ecosystems. While marine mammals and seabirds can play critical roles in marine nutrient cycling, their contributions are often overlooked. Southeast Alaska’s marine environment supports abundant marine mammal and seabird populations in addition to valuable fisheries. Nonetheless, there is still relatively little known about nutrient sources and fluxes in this region which is a critical component of fisheries management. The goal of our study was to advance knowledge of the role of mammals and seabirds in marine nutrient cycling and to understand how changing marine mammal and seabird populations may alter ecosystem dynamics. We utilized qualitative network models (QNMs) to examine how a simulated Southeast Alaska ecosystem would respond to an increase in marine mammals, seabirds, and nutrients. Researchers are increasingly utilizing QNMs as a first step in the development of ecosystem-based fisheries management plans as their adaptable nature is well suited to address rapidly changing climatic conditions. Our results indicate that marine mammals and seabirds make important contributions to marine nutrient concentrations in the region and that these valuable ecosystem services should not be overlooked.

Phenotypic correlation and regression of hydroponics maize fodder as influenced by seed rate, nutrient sources and spray schedule

The experiments were carried out at AICRP on Dry Land Agriculture, University of Agricultural Science, GKVK, Bengaluru to study the “Phenotypic correlation and regression of hydroponics maize fodder as influenced by seed rate, nutrient sources and spray schedule” during 2017-2018. The results of revealed significantly positive correlation between fodder yield per kg seed and yield parameter like total fresh weight of fodder per kg seed (r=0.95**), total dry weight per kg of seed (r=0.86*), growth parameters like shoot length (r= 0.90**), root length (r=0.85*) and seedling vigour (r=0.84*), physiological parameters like water use efficiency (r=0.86*), relative water content (r=0.91*) and SPAD (r=0.92**). With respect to nutrition study correlation coefficients of traits with fodder yield revealed positive correlation growth components like shoot length (r=0.90**), root length (r=0.74**), seedling vigour (r=0.86**) and dry matter accumulation (0.97**), yield parameters like Total fresh weight of fodder (r=0.96**), individual fresh weight of plant (r=0.95**) and individual dry weight of plant (r=0.97**), physiological parameters like SPAD (r=0.78**) and WUE (r=1.00**), quality parameters like nitrogen content, crude protein, crude fibre and total carbohydrates (r=0.927**, 0.927**, 0.770* and 0.905**, respectively). The study revealed significantly higher fodder yield with two combined sprays of urea and MOP each @ 1 per cent at 3rd and 10th Days after sowing (DAS) with 2.5 kg m-2 under hydroponic conditions.