Short-Term Response of Soil Microbial Community to Field Conversion from Dryland to Paddy under the Land Consolidation Process in North China

Land consolidation of dryland-to-paddy conversion for improving tillage conditions and grain production capacity is widely implemented throughout the world. The conversion affects soil ecological stability, especially the most active soil microorganisms. However, the impacts of the dryland-to-paddy conversion has paid little attention in recent decades. In this study, a pot experiment was used to explore the responses of the microbial community and their interactions with soil properties after rice in the first season (five months). The results indicated that a significant decrease in the topsoil pH, organic matter content, nitrate nitrogen, and ammonical nitrogen, and an increase in soil electrical conductivity (EC) was observed (p < 0.05) after the dryland-to-paddy conversion. The richness and diversity of bacteria and fungi decreased in the short term. The composition of the soil microbial community and the soil microbial dominant bacteria had considerably changed after the conversion. Actinobacteria, Firmicutes, and Olpidiomycota were found to be highly sensitive to the dryland-to-paddy conversion. The soil microbial community structure had extremely significant positive correlations with soil pH, EC, organic matter, nitrate nitrogen, and ammonical nitrogen (p < 0.05). Microorganisms are the most important component of soil nutrient cycling. Converting a large area of dryland to paddy may lead to an imbalance in the soil carbonitride cycle and should be further examined in North China.

GROWTH OF INVASIVE AQUATIC MACROPHYTES OVER TAPI RIVER

<p><strong>Abstract.</strong> Aquatic macrophytes are important elements of freshwater ecosystems, fulfilling a pivotal role in the ecological functions of these environments and biogeochemical cycles. Although aquatic macrophytes are beneficial, some species can hinder human activity. They can clog reservoirs and reduce water availability for human needs. Surveys of macrophytes are hindered by logistic problems, and remote sensing represents a powerful alternative, allowing comprehensive assessment and monitoring. The objectives of this study was to map temporal changes in the macrophytes using time series multispectral dataset over Tapi River, Surat. The field trip was conducted over the Tapi River on 22nd June 2018, where <i>in-situ</i> spectral response dataset were acquired using ASD Spectroradiometer. Water samples were also collected over three locations, one before entering the city (Kamrej), second at the Sarthana water treatment plant and third at the outer end (causeway). The nutrient concentration was less before entering the city (Ammonical Nitrogen 0.056<span class="thinspace"></span>mg/L and phosphate 0.0145<span class="thinspace"></span>mg/l), while higher concentration (Ammonical Nitrogen 0.448<span class="thinspace"></span>mg/l and phosphate 0.05<span class="thinspace"></span>mg/l) was observed within the city. Maps of aquatic macrophytes fractional cover were produced using Resourcesat-2/2A (LISS-III) dataset covering a period of 2012&amp;ndash;2018. Maximum extent was observed in February-March of every year. Although during monsoon, lot of agriculture run-off and nutrients will come into the river, but main flow of water will dilute its concentration. During summer, the same nutrient concentration will boost these macrophytes due to less availability of stream water. Within the area of 16<span class="thinspace"></span>km² between Kamrej and causeway, 3.35<span class="thinspace"></span>% was covered by macrophytes during March 2013. This area coverage increase to 36.41<span class="thinspace"></span>% in March 2018. Based on these maps, we discuss how remote sensing could support monitoring strategies and provide insight into spatial variability, and by identifying hotspot areas where invasive species could become a threat to ecosystem functioning.</p>

EFFECT OF PHOTOPERIOD ON GROWTH PERFORMANCE, FEED UTILIZATION AND CARCASS COMPOSITION IN CHANNA PUNCTATUS

To study the effect of photoperiod on growth performance in C. punctatus, the fish were exposed to three combinations of day length i.e. LD 14:10, LD 12:12 and LD 9:15 at 25°C. Variables tested were weight gain, length gain, condition factor, FCR, body composition, VSI and HSI. Fish exposed to long photoperiod showed high growth performance followed by equal and short photoperiod. Significantly low concentration of ammonical nitrogen and orthophosphate in holding water were observed in fish exposed to LD 14:10 as compared to LD 12:12 and LD 9:15. VSI values were significantly high (P0.05) in group of fish exposed to LD 14:10, followed by LD 12:12 and LD 9:15. On the other hand, HSI was significantly decreased in fish exposed to LD 9:15, while HSI values under LD 14:10 and LD 12:12 were equal.

Bioremediation Potential of Bacterial Isolates for Municipal Wastewater Treatment

The potential of bacteria for the treatment of municipal wastewater was investigated in present study. Total eight bacterial isolates were used for this study that showed growth on wastewater agar medium. These isolates were identified on the basis of morphological and biochemical test and identified as Bacillus licheniformis NW16, Pseudomonas aeruginosa NS19, Pseudomonas sp. NS20, Planococcus salinarum NS23, Stenotrophomonas maltophilia NS21, Paenibacillus sp. NW9, Paenibacillus borealis NS3 and Aeromonas hydrophilia NS17. The B. licheniformis NW16 showed highest potential to reduce all parameter under study than other isolates except Ammonical nitrogen. B. licheniformis NW16 and Aeromonas hydrophilia NS17 showed maximum reduction (42.86%) in BOD each. B. licheniformis NW16 and Paenibacillus sp. NW9 showed 82.76% and 81.61% reduction in COD respectively. B. licheniformis NW16, P. salinarum NS23 and Aeromonas hydrophilia NS17 showed reduction in nitrate ranging from 17.36%-63.64%. All the isolates have potential to reduced phosphate from 17.55% -72.3%. B. licheniformis NW16, Ps. aeruginosa NS19, Pseudomonas sp. NS20, Paenibacillus sp. NW9 and Aeromonas hydrophilia NS17 showed reduction in TSS ranging from 42.69%-79.94%. B. licheniformis NW16, Ps. aeruginosa NS19, Pseudomonas sp. NS20, S. maltophilia NS21 and Paenibacillus sp. NW9 showed reduction in TDS ranging from 14%-81.4%.

Bromatological and fermentative characteristics of elephant grass silages with the addition of annato by-product

The objective of the present study was to evaluate the nutritional value of elephant grass (Pennisetum purpureum, Schum.) silages with the addition of 0; 4; 8; 12 and 16% of the by-product from SPU annato (Bixa orellana, L.) based on natural matter. A complete random design was used with four replications. The nutritional composition, pH, ammonical nitrogen and lactic, acetic, propyonic and butyric acids were determined. Levels of annato by-product had an increasingly linear effect on contents of dry matter, organic matter, crude protein, ether extract, non-fibrous carbohydrates, propionic acid and ammonical nitrogen. The insoluble nitrogen contents in detergent and acid detergent, calculated on the percentage of total nitrogen and lactic, acetic and butyric acids were not altered by adding the annato by product. The annatto by-product improves the bromatological characteristics of the silages and it can be added in levels up to 16% of the natural matter at the moment of elephant grass ensilage.