Effect of conservation agriculture on soil organic and inorganic carbon sequestration and lability: A study from a rice–wheat cropping system on a calcareous soil of the eastern Indo-Gangetic Plains

Increasing soil carbon (C) in arable soils is an important strategy to achieve sustainable yields and mitigate climate change. We investigated changes in soil organic and inorganic carbon (SOC and SIC) under conservation agriculture (CA) in a calcareous soil of the eastern Indo-Gangetic Plains of India. The treatments were as follows: conventional-till rice and wheat (CT-CT), CT rice and zero-till wheat (CT-ZT), ZT direct seeded rice (DSR) and CT wheat (ZT-CT), ZTDSR and ZT wheat without crop residue retention (ZT-ZT), ZT-ZT with residue (ZT-ZT+R), and DSR and wheat both on permanent beds with residue (PB-PB+R). The ZT-ZT+R had the highest total SOC in both 0–15 and 15–30 cm soil layers (20% and 40% higher (p < .05) than CT-CT, respectively), whereas total SIC decreased by 11% and 15% in the respective layers under ZT-ZT+R compared with CT-CT. Non-labile SOC was the largest pool, followed by very labile, labile and less labile SOC. The benefits of ZT and residue retention were greatest for very labile SOC, which showed a significant (p < .05) increase (~50%) under ZT-ZT+R compared with CT-CT. The ZT-ZT+R sequestered ~2 Mg ha⁻¹ total SOC in the 0–15 cm soil layer in 6 years, where CT registered significant losses. Thus, the adoption of CA should be recommended in calcareous soils, for C sequestration, and also as a reclamation technique.     

Physiological responses of dietary tryptophan fed Labeo rohita to temperature and salinity stress

Two experiments were conducted to elucidate the possible effects of dietary L‐tryptophan (TRP) in Labeo rohita based on growth performance and physio‐biochemical responses. In the experiment I, a 60‐day feeding trial was carried out to elucidate the effects of dietary TRP enrichment on growth performance and physio‐biochemical responses. In the experiment II, the TRP pre‐fed L. rohita, from experiment I, was exposed to temperature and salinity stress to evaluate stress‐mitigating efficacy of TRP. In L. rohita, dietary supplementation of TRP showed significant effect on weight gain percentage and feed conversion ratio but not on blood glucose. A significant increase in RNA content and RNA/DNA ratio upon TRP supplementation was observed and was positively correlated with growth performance. The results of experiment II indicated that weight gain percentage, serum T3 and T4 levels were significantly reduced in groups that were exposed to temperature and salinity stress and fed diets without TRP supplementation. However, dietary supplementation of TRP significantly augmented weight gain percentage in stress‐exposed groups. Tryptophan supplementation helped in bringing back T3 and T4 levels comparable with control. A significant increase in superoxide dismutase, catalase, Adenosine triphosphatase, blood glucose and serum cortisol was observed in temperature‐ and salinity‐exposed groups fed without TRP‐supplemented diets. However, TRP supplementation was found to be effective in restoring the above parameters. The results of these experiments suggest that dietary TRP supplementation augments growth, lowers energy demand and helps in mitigating thermal and salinity stress in L. rohita.     

Responses of aerobically grown iron chlorosis tolerant and susceptible rice (Oryza sativa L.) genotypes to soil iron management in an Inceptisol

Iron deficiency is a serious nutritional disorder in aerobic rice, causing chlorosis, poor yields and reduced grain nutritional quality. The problem can be managed by complementing the use of Fe-efficient plant type with a suitable Fe management strategy. In the present paper, we report the effect of eight iron management practices to resolve the problem of iron (Fe) chlorosis through the use of an iron deficiency tolerant (IDTR) and iron deficiency susceptible (IDSR) rice genotype, i.e. Pusa 33 and ADT 39, respectively. Fe deficiency tolerance of these genotypes was related to the root release of PS which enabled a higher uptake of Fe in the IDTR than the IDSR under Fe deficiency. In general, IDTR performed better than the IDSR as evident from a significant increase in total iron, active iron, chlorophyll content and grain and straw yield. IDSR produced the highest grain and straw yield under slow iron release nano clay complex source. Grain Fe content of the IDTR and IDSR increased by 18.9 and 13.4%, respectively, under recommended dose of Fe. The results identified the most effective soil management strategies for the alleviating Fe deficiency chlorosis and improving Fe nutrition of both IDTR and IDSR genotypes.     

Assessment of Awareness about Antibiotic Resistance and Practices Followed by Veterinarians for Judicious Prescription of Antibiotics: An Exploratory Study in Eastern Haryana Region of India

Tropical Animal Health and Production - The rise of antibiotic resistance and its global outreach has recently become a subject of increasing importance in veterinary research with an objective to...     

A Seasonal Assessment of the Impact of Coal Fly Ash Disposal on the River Yamuna,Delhi. I. Chemistry

The impact of fly ash on the chemistry of the River Yamuna was studied. By-products from a 200 MW capacity I.P. thermal power station on the west bank of the River Yamuna, Delhi are largely from coal combustion (fly ash) and are disposed of as a slurry to off-site ash ponds. Many elements associated with fly ash are soluble and become available to the biota. A two-year survey was made of the seasonal variations in limnochemical features in the non-impacted and the impacted segments of the river receiving fly ash effluent and the ash treatment ponds. Conductivity, TDS, DO, hardness, sulphate and nitrate increased significantly in the receiving waters over background values. The reverse was noticed for free CO₂, alkalinity and phosphate. Changes in some other parameters were insignificant. Fly ash effluents from the ash ponds significantly increased the concentration of some elements, viz., Al, Sb, Bi, Cd, Cr, Co, Li, Mn, Mo, K, Si, and Zn in river water. Generally, the highest concentration of most parameters were recorded in the ash ponds. This investigation was helpful in assessing the effect of wet ash disposal on the river limnology and understanding the solubility of various elements in the ash ponds.     

Comparative efficiency of acid phosphatase originated from plant and fungal sources

A study was conducted to demonstrate the comparative efficiency of acid phosphatase generated by plants or fungi towards the hydrolysis of different organic P compounds present in soil. The results revealed that acid phosphatases were most efficient in the hydrolysis of glycerophosphate followed by lecithin and phytin. The P release increased with increase in enzyme concentration. Acid phosphatase generated from fungal sources showed three times greater efficiency in the hydrolysis of phytin, two times greater efficiency in hydrolysis of lecithin than plant phosphatase. Both sources were at par in hydrolyzing glycerophosphate. The results suggest that acid phosphatase generated from plant and fungal sources is different and microbial acid phosphatase to be more efficient than that from plant sources.     

Physiological and biochemical effects of boron toxicity in mustard during the seedling stage

A study was conducted to determine the physiological and biochemical effects of boron in seedlings of mustard (Brassica juncea L. var Varuna). For this seeds were sown in petridishes with varying concentrations of boron (0, 0.33, 3.3, 33, 330 mM) in seed germinator. Seed germination and vigor index was found to be decreased and percentage phytotoxicity was increased in seeds with increase in the concentration of boron in germinating solution. There was accumulation of sugars and decreased starch concentration in cotyledons and embryonic axes of growing seedling with increasing boron stress. For the estimation of oxidative damage in cotyledons and embryonic axes of mustard seedlings, hydrogen peroxide (H₂O₂), thiobarbituric acid reactive substances (TBARS), phenols and activities of antioxidative enzymes- polyphenoloxydase (PPO), superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were determined. Boron toxicity caused accumulation of H₂O₂, TBARS and phenols and affected the antioxidative enzyme activity in growing seedling components.     

Cryptic species composition and genetic diversity within Bemisia tabaci complex in soybean in India revealed by mtCOI DNA sequence

Bemisia tabaci is a cryptic species complex, causing significant loss on many agriculturally important crops worldwide. Knowledge on species composition and diversity within B. tabaci complex is critical for evolving sustainable pest management strategies. Here we investigate the whitefly species complex in soybean in major soybean growing states of India. The mitochondrial cytochrome oxidase gene subunit-1(mt COI) based phylogenetic relationships established using Bayesian methods indicated the existence of three cryptic species namely AsiaⅠ, AsiaⅡ1, and AsiaⅡ7. All the haplotypes detected in the study could be assigned to these three cryptic species following the species demarcation criteria of 3.5% divergence threshold. Of these, AsiaⅡ1 was found to be predominant with wide spread distribution across the surveyed regions from cool temperate zones to hot and humid tropical plains. On the contrary, cryptic species AsiaⅡ7 showed localized distribution. The AsiaⅡ1 exhibited the highest haplotype diversity and AsiaⅠ showed high level of nucleotide diversity. There was a significantly high genetic differentiation among these three cryptic species. The MEAM 1, a dreadful invasive species was not detected in the specimens tested in the current study. The diversity and distribution of three cryptic species is discussed in the light of current knowledge on distribution of whitefly species in India and yellow mosaic disease observed during sampling survey.