Nitrogen management can boost rice (Oryza sativa L.) production near aluminium smelter: A field study

Nitrogen (N) management is a key to sustain rice yield under submerged condition. Time and amount of N application boost rice production under adverse environmental situation. To test this hypothesis a field experiment was conducted at different villages in and around Hindustan Aluminium Company Ltd. (HINDALCO), Hirakud, Sambalpur, Odisha in the year 2015 and 2016. The rice ecosystems were selected on the basis of distance from the smelter plant. Different treatments were framed to test the hypothesis as T1-Farmers practice (60:30:30 kg N: P2 O5:K2O ha-1); T2- 75% recommended dose of fertilizer (RDF) of nitrogen(N) ; T3 -100% RDF of N; T4 -125% RDF of N; T5 -150% RDF of N. It was conducted in a randomized block design with four replications in the farmer's field. The test crop was rice cv.Tejaswinee. Growth parameters like plant height (cm), panicle length (cm) and number of effective tillers per hill were found to be highest in the plots where 125% RDF of N was applied. However the chlorophyll content(mg g-1 fresh)was estimated highest with 150 % RDF of N applied plots. The grain and straw yield (q ha-1) of rice were also observed highest with treatments receiving125% RDF of N.The rice ecosystems which are nearer to aluminium smelter plant were supposed to be affected with less yield as compared to far distance rice ecosystems. The grain quality parameterof rice like protein content (%) was also affected at smelter sites as compared to far distances. However with increasing the N level to 125 % RDF protein content was increased.

THE CONTROLLING FACTORS OF SILICON SOLUBILITY IN SOIL SOLUTION

Silica is a beneficial element for rice plants which can protect from blast disease, increase stem strength, and alleviate abiotic stress. Silicon in soil solution is affected by several factors such as pH, temperature, organic matter, and redox potential (Eh). This study aims to investigate the controlling factor of Si solubility in soil solution. In the present study, Japanese silica gel (JSG) and Ultisols were collected from Japan. In laboratory experiment, the effects of Ca (calcium), Mg (magnesium) and others on solubility of Si (silica) were investigated. Under submerged condition, ten gram of soil with silica gel, Ca and Mg in plastic tube were incubated at 300C for 29 days. Calcium and Mg were applied into soil, at the concentration of 5, 10, 15 mg Ca L-1(T2, T3, T4 respectively) and 5, 10, 15 mg Mg L-1(T5, T6, T7 respectively). There was two controls as a follow T0 (soil) and T1 (soil + silica gel). During incubation, Si, Ca, Mg, Fe, and Mn concentrations in surface water were measured using ICP spectroscopy at day 8, 15, and 29. The results show the soil before treatment was slightly acidic (pH 5.7) and extractable Si concentration was 267.1 mg SiO2 kg-1. It was classified to be below critical level of available Si for rice (300 mg SiO2 kg-1). Total concentration of Ca and Mg in soil solution were highest for treatment T4 and T7, respectively compared with other treatments. On the first 8 days of incubation, Si released into soil solution was higher in T1 and T2 compared to other treatments. The solubility of Si was significantly positive correlated with Mn, Eh, and negatively correlated with pH, that indicated these were the controlling factors of the Si release in soil solution. There was no correlation between Si and Ca or Mg concentration in soil solution.

Co-culture of human alveolar epithelial (A549) and macrophage (THP-1) cells to study the potential toxicity of ambient PM2.5: a comparison of growth under ALI and submerged conditions

Fine particulate matter (PM2.5) in the ambient atmosphere is strongly associated with detrimental health effects. However, these particles from various sources and regions are unlikely equally toxic. While animal studies are impractical for high-throughput toxicity testing, appropriate in vitro models are urgently needed. Co-culture of A549 and THP-1 macrophages grown at air–liquid interface (ALI) or under submerged conditions was exposed to same concentrations of ambient PM2.5 to provide accurate comparisons between culture methods. Following 24-h incubation with PM2.5 collected in Harbin in China, biological endpoints being investigated include cytotoxicity, reactive oxygen species (ROS) levels and pro-inflammatory mediators. The co-culture grown under submerged condition demonstrated a significant increase in ROS levels and all tested pro-inflammatory indicators [interleukin (IL)-1β, IL-6, IL-8 and tumor necrosis factor-α] in mRNA expression and released protein levels. Similar but a declining response trend was observed using the same PM2.5 incubation after grown at ALI. We further observed a significant increase of PM2.5-induced phosphorylation of p38 MAPK and activation of NF-κB p65 in a dose-dependent trend for co-cultures grown under submerged condition. These results provide important implications that culture conditions (ALI versus submerged) can induce different extents of biological responses to ambient PM2.5; the co-culture grown at ALI is less likely to produce false-positive results than submerged culture. Hence, culture conditions should be discussed when comparing in vitro methods used for high-throughput PM2.5 toxicity assessment in future.

An Extension of Taylor’s φ-Circle Method and Some Stability Charts for Submerged Slopes

Taylor’s φ-circle method is a classical method for slope stability calculation, which has analytical solutions. Taylor derived equations in two cases separately, namely, (i) the outlet of the critical failure surface is at the slope toe and (ii) the outlet of the failure surfaces is not at the slope toe. The method is only appropriate for two conditions (without underground water table in slopes or totally submerged slopes). In this study, a general equation that unifies the equations of the two cases is proposed and partially submerged condition is introduced. The critical failure surfaces corresponding to the minimum factor of safety are determined using the computer program proposed by the authors. The general expression of the safety factor of slopes under the following four conditions is derived, namely, (i) partly submerged, (ii) completely submerged, (iii) water sudden drawdown, and (iv) water slow drawdown. The corresponding charts for practical use are available.

Molecular characterization of submergence tolerance genes and locus in the deep-water rice cultivars

Most of the rice cultivars exhibit suspension of growth when submerged to overcome the reduced availability of oxygen. When the situation continues, majority of the cultivars unable to recover after the flood recedes. However, there are fortunately some rice genotypes that can withstand such submerged condition for up to two weeks by adapting two totally opposite mechanisms. One type of cultivars elongates enormously at a very short span of time and the leaves come above the water level. In the second type, they remain under water without any growth. Cultivars of both types tolerate the submergence but the first category easily lodges when flood water recede. In those lines, yields are reduced drastically. In this study, we focus on characterize the genetic variation at the Sub1 locus and to associate its relevance, if any, to submergence tolerance among the deep water landraces. As a first step, seeds of some rice cultivars collected from North-east Indian regions were initially selected for the characterization of genetic variation. The PCR based analysis involving several genes known to be associated with submergence tolerance did not reveal much difference. However, Southern hybridization revealed certain differences between submergence tolerant and susceptible cultivars. Although we did not notice major difference with regard to Sub1 genes when tried with EcoRI and BamHI, differences were noticed with adh1 and RAmy3C genes. Representative, Southern analysis showed the genetic variation among the deep-water cultivars as compared to Swarna and Sub1-Swarna. It is possible that deep-water rice cultivars may not differ in their genome at Sub1 locus but they respond through SNORKEL genes under submergence.