Indicators of soil quality and crop productivity assessment at a long-term experiment site in the lower Indo-Gangetic plains

Deterioration of soil quality under resource-intensive modern agriculture in the face of global climate change poses a huge risk to food security. Because of the complex nature, estimators of soil quality often rely upon a limited set of soil attributes, along with statistical data reduction techniques, for developing quality indices, whilst overlooking biological aspects and regional climatic variability. This study screened the most suitable soil quality indexing approaches for a rice-oilseed-based cropping system in the lower Indo-Gangetic plains (IGP). For this, surface soil samples (0–15 cm) were collected from an ongoing long-term fertilizer experiment with a rice-mustard-sesame cropping system in the IGP. The following treatments were assessed for their effect on soil quality: T₁-control, T₂-NPK (recommended NPK doses), T₃-NPKG (NPK + in situ green manuring), T₄-NPKGB (NPK + in situ green manuring + biofertilizer) and T₅-NPKF (NPK + farm yard manure FYM). We found that total organic carbon (TOC), β-glucosidase, CaCl₂ extractable S, alkaline KMnO₄ oxidizable N, activity of urease, amidase enzyme and mean weight diameter (MWD) were sensitive key indicators of soil quality. The NPKF treatment maintained the highest soil quality status (0.80–0.91), both under productivity and environmental protection goals, owing to the availability of decomposable carbon. Regression analysis showed a better agreement of equivalent rice yield with expert opinion (EO; R² = 0.89) than principal component analysis (PCA; R² = 0.76). Finally, we found that the expert opinion approach with the nonlinear scoring function was the best tool for soil quality assessment of the region.     

Tillage and nitrogen management effects with sequential and ready-mix herbicides on weed diversity and wheat productivity

In this experiment, weed management was studied in zero tillage (ZT) and conventional tillage (CT) wheat with and without crop residue and nitrogen (N). The treatment ZT with crop residue retention (R) and 75% of required N plus GreenSeeker? (GS)-aided N management (ZTRNGS) resulted in a reduction of density and dry weight of weeds compared to CT and ZT without residue. Sequential application of pendimethalin and sulfosulfuron (PMT-SSF) reduced the weed density and dry weight compared to the weedy check (WC). Importantly, the richness and diversity indices were high in ZTRNGS and in WC treatments. Greater wheat grain (5.11 t/ha) and biomass yield (13.31 t/ha) were observed in ZTRNGS than CT without residue and blanket split application of N (CTN). The treatment ZTRNGS recorded 14.1% and 16.9% higher gross and net returns, respectively, over CTN. This study demonstrates that surface retention of crop residue in ZT is more useful than residue incorporation under CT for effective weed control, improving crop yield and profitability.     

Using chemical seed dormancy breakers with herbicides for weed management in soyabean and wheat

Variable dormancies result in periodicity in the germination of weeds and make weed control a repetitive practice. Under some conditions, repeated applications of selective herbicides can lead to the dominance of perennial weeds like Cyperus rotundus . Our hypothesis was that applying a chemical dormancy breaker (DB ) plus herbicide mixture would better control a mixture of weed species. Three experiments were designed to develop a cost‐effective DB treatment and to evaluate its dose with herbicides tank‐mixtures for effective weed management. KNO ₃ and gibberellic acid GA ₃ as dormancy breakers offered comparable effects, but KNO ₃ was more economical than GA ₃. KNO ₃ at a 6% concentration was more effective in promoting weed germination than a 3% concentration in soyabean. A combination of KNO ₃ (6%) and pre‐emergence pendimethalin 0.75 kg a.i. ha^?1 + imazethapyr 0.10 kg a.i. ha^?1 controlled annual weeds by 99% and reduced C. rotundus growth by 83%. This treatment gave significantly higher soyabean yield and net returns. Similarly, a tank‐mixture comprising of clodinafop 0.06 kg a.i. ha^?1 + metsulfuron 0.006 kga.i. ha^?1 was more effective against weeds than pre‐emergence tank‐mix application of pendimethalin 0.75 kg a.i. ha^?1 + carfentrazone‐ethyl 0.02 kg a.i. ha^?1 and isoproturon 0.75 kg a.i. ha^?1. The use of pre‐emergence tank‐mixture of pendimethalin 0.75 kg a.i. ha^?1 + imazethapyr 0.10 kg a.i. ha^?1 should exhaust seed/tuber bank if repeated and reduce the application cost of herbicides by 50% and the dose, residue and cost of pendimethalin by 25%.     

Effect of efficient pectinolytic bacterial isolates on retting and fibre quality of jute

Four bacterial strains with high balanced polygalacturonase (PG) and pectin lyase (PNL), and xylanase with minimal cellulase activity were used in jute retting. The 16S rDNA analysis revealed that the organisms were: Bacillus sp. L6 (GQ891097), Bacillus pumilus strain EK-17 (GQ891098), B. pumilus strain Geo-03-422 (GQ891103) and B. pumilus strain IK-MB12-518F (GQ891105). The microorganisms in different combinations of consortia showed synergistic effect resulting in increased PG (35.52-46.61 IU/g cell wet weight), PNL (39.79-72.12 U/ml), xylanase (0.705-0.840 μmol/ml/min) and little cellulase (0-0.153 μmol/ml/min) activities. The organisms in different combinations of consortia reduced the retting period from 11 to 13 days as compared to 19 days in the control. Microbial inoculation produced remarkable improvement in jute fibre strength (26.62-28.91 g/tex) and fineness (2.76-2.92 tex) over control. The pH of the post-retting water samples became acidic, and the electrical conductivity (Ec), chemical oxygen demand (COD) and hardness increased. The organisms could be adopted in industrial application for extraction of jute fibre.     

Induction,purification and partial characterization of vitellogenin in an Indian major carp Catla catla (Ham.)

Vitellogenin was purified from the serum of 17‐β estradiol (E₂)‐induced juvenile Catla catla using a simple two‐step purification procedure i.e. selective chemical precipitation followed by gel filtration chromatography. Purified protein migrated as single band in a native gradient PAGE which indicated the purity of the sample. The molecular weight of the native catla vitellogenin (~440 kDa) was determined using gel filtration chromatography. In SDS‐PAGE under reducing conditions catla vitellogenin dissociated into three major sub units at 115 kDa, 102 kDa and 73 kDa along with a few faint bands. Confirmation of purified protein as catla vitellogenin was supported by multiple physiological evidences, e.g. absence in male as well as juvenile sera and presence in matured female fish, ability to be synthesized upon estradiol injection in immature fish and certain unique biochemical properties like high molecular weight, phospholipoglycoprotein nature of the molecule. Western blot analysis showed that polyclonal antibody raised against purified protein detected vitellogenin in the sera of catla and in a few species selected from Cyprinidae family. These antisera were used to detect vitellogenin in liver tissue of hormone‐induced catla using immunohistochemistry and its applicability in other immunoassays is discussed.     

An assessment of benzimidazole resistance against caprine nematodes in Central India

Current status of resistance to benzimidazole (BZ) group of anthelmintic drugs against caprine nematodes in Central India at Amanala goat farm, Jabalpur, Madhya Pradesh (M. P.), was systematically investigated using faecal egg count reduction (FECR) test and egg hatch test (EHT). Besides, allele-specific PCR (AS-PCR) was deployed to ascertain the susceptible genotype (alleles) especially of the Haemonchus contortus. Randomly selected 30 goats, irrespective of age and sex, were divided into three groups of 10 each, to serve as treated and untreated controls. It was ensured that the animals were not administered with an anthelmintic drug for the past 3 months prior to undertaking the study, and faecal egg counts were estimated. FECR test evidenced fenbendazole resistance by partial elimination (24.90%) copro-egg counts in the treated group of animals vis-à-vis controls with a lower confidence interval of ?26%. Further, EHT revealed ED-50 value of 0.335 μg of thiabendazole/ml, confirming benzimidazole resistance in the animals of that farm. AS-PCR showed that 62% of H. contortus larvae were homozygous resistant (rr), 24% heterozygous (rS) and 14% homozygous susceptible (SS). The genotypic frequencies of three genotypes (rr, rS and SS) were significantly (P < 0.01) different. The prevalence of benzimidazole resistance allele (r) was also significantly (P < 0.01) higher (74%) as compared to susceptible allele (S) (26%). The resistance to benzimidazole has been discussed while emphasizing improved managemental practices designed to reduce exposure of the goat population to parasites, minimize frequency of anthelmintic use at optimum dose and rotational use of different chemical groups of medicines with different mode of action, so as to overcome and combat the upcoming problem in the field.     

Physio-biochemical parameters: a potential tool for target-selective treatment of haemonchosis in the small ruminants

This study aims to evaluate the conjunctiva colour-based FAMACHA score (FS) coupled with a body condition score (BCS), haemogram and stressor hormone level estimation, in identifying post-mortem (PM)/coproscopically proven individuals wanting therapy for economically important gastrointestinal (GI) helminths, Haemonchus contortus, in the small ruminants. The incidence of haemonchosis was significantly (p < 0.05) higher (60.81%) in the ruminants with FS = 3. The H. contortus count in the animals with FS 2, 3 and 4 was 23.2 ± 0.37, 62 ± 2.5 and 74 ± 3.2 (p < 0.05) [positive correlation (r = 0.841 in goats; r = 0.828 in sheep, p < 0.05)], respectively, with corresponding 2.8 ± 0.15, 2 ± 0.3 and 2 ± 0.16 BCS (negative correlation, p > 0.05). The infected animals of FS 2, 3 and 4 measured 8.2 ± 0.0, 7.5 ± 0.23 and 6.7 ± 0.34 g/dl Hb (r = ?0.452, p = 0.01) in goats/9.3 ± 0.8, 8.6 ± 0.5 and 7.6 ± 0.3 g/dl Hb (r = ?0.511, p = 0.05) in sheep with 21.2, 19.8 ± 1.8 and 17.8 ± 0.2% PCV (r = ?0.369, p = 0.05) in goats/26.7 ± 1.2, 22.2 ± 0.2 and 20.9 ± 0.6% PCV (r = ?0.251, p = 0.03) in sheep, respectively. The FS 2, 3 and 4 infected goats/sheep measured 6.1 ± 0, 7.9 ± 1.0 and 9.5 ± 0.9 (p < 0.05)/5.8 ± 2.3, 6.9 ± 1.2 and 7.8 ± 0.2% (p < 0.05) mid-granulocyte [(r = 0.928 (goats)/0.834 (sheep), p < 0.05], while the cortisol level was 15.6, 23 ± 4.5 and 42 ± 2.3 (p = 0.23)/12.1 ± 0, 15.9 ± 1.2 and 24 ± 3.4 (p = 0.29) μg/dl, respectively. The infected ruminants recorded low (p < 0.05) level of Hb/PCV while high level of mid-granulocytes/cortisol. Specificity of FAMACHA test was maximized (100%) when FS = 4 was considered anaemic, but sensitivity was low (35.29% in goats; 25% in sheep). The false negatives was 5.9 (goat)/12.5 (sheep)% when FS ≥ 3 was considered anaemic. The small ruminants with FS ≥ 3, BCS ≤ 2.5, Hb ≤ 7.5 g/dl (goats)/8.6 g/dl (sheep), PCV ≤ 19.8% (goats)/22.2% (sheep) and mid-granulocyte ≥7.9% (goats)/6.9 ± 1.2% (sheep) can be subjected to target-selective treatment for haemonchosis in the field simultaneously maximizing the economic benefit to the farmers.     

Suppression of Botryosphaeria canker of apple by arbuscular mycorrhizal fungi

Stem brown canker or Botryosphaeria canker disease impairs the growth and kills the shoots, limbs and even trunks of infected apple trees. Apple roots are usually colonized by arbuscular mycorrhizal fungi, which may have a positive influence on plant growth and suppression of diseases. In order to assess the efficacy of AM to suppress the disease severity and plant growth enhancement, nine AMF inoculation treatments (Sclerocystis dussi, Glomus intraradices, G. fasciculatum, G. bagyaraji, G. leptotichum, G. monosporum, Gigaspora margarita, a mixed AM culture and a non-mycorrhizal control treatment) were used in this present study. Two-year-old potted apple plants, maintained under glasshouse conditions, were either pre-inoculated with AMF followed by stem inoculation with Botryosphaeria ribis or simultaneously inoculated with Botryosphaeria ribis and AM. The results indicated that the incidence of canker was less severe in plants inoculated with AMF in comparison to non-mycorrhizal control. Timing of inoculation also had a significant effect on disease development and plant survival. Plants pre-inoculated with mycorrhiza performed better over those inoculated simultaneously with Botryosphaeria ribis and AM fungi. Furthermore, AM inoculation resulted in improved survival and growth of AMF-colonized plants; though, it varied by species of AM fungi utilized.     

Factors affecting sporulation of Pestalotiopsis disseminata causing grey blight disease of Persea bombycina Kost., the primary food plant of muga silkworm

The effect of inoculum concentrations, temperature, relative humidity (RH), incubation period and leaf age on sporulation of Pestalotiopsis disseminata and the development of grey blight disease on som (Persea bombycina Kost.) were studied in controlled environmental conditions. These factors had a significant role on spore germination and germ tube development of P. disseminata, the causal organism of the disease. The optimum inoculum concentration of the pathogen were found to be 1 × 10⁷ spores ml⁻¹ for maximum infection percentage. A nonlinear relationship was found between temperature and germination percentage of spores at a given relative humidity (RH). However, 25 °C (±2) temperature and 70% RH were the optimum parameters for better spore germination of the pathogen. Young leaves (leaf no. 1–4 from the top) were more susceptible for development of the diseases in a controlled environment than the older leaves. The germination of spores started at 8 h of incubation and gradually increased up to 20 h (maximum). The disease severity was favoured in the optimum range of temperature (25 ± 2 °C) and RH (70%) which had a combined effect. These epidemiological parameters could help in the management practices of the disease.