Phosphate-Solubilizing Microbes and Biocontrol Agent for Plant Nutrition and Protection: Current Perspective

ABSTRACT

Phosphate-solubilizing microbes (PSM) are widely distributed in the rhizosphere and helps plant to acquire phosphates from soil. The availability of phosphates in soil are governed by several factors among which the proton exchange capacity has been regarded to be the most important factor involved in cation complex formations with soluble phosphates making them unavailable to plants, thereby disturbing the phosphorus cycling events found in arable soils. PSM solubilizes the cation complexes and thereby improves the functioning of phosphorus cycle in soil. In addition to involvement in biogeochemical cycling events, PSM have been also found to have antagonistic potential against several plant phytopathogens. These biocontrol microbes represent the most abundant groups of soil microflora. Among which some nutrient solubilizers have been used for effective biocontrol of important plant diseases. This review article shows contributions of different plant growth promoters used in nutrient and disease management practices in agriculture.

Abbreviations: P (phosphorus), PSM (phosphate-solubilizing microbes), PSB (phosphate-solubilizing bacteria), PSF (phosphate-solubilizing fungi), PGPM (plant growth-promoting microbes), PGPB (plant growth-promoting bacteria), SAR (systemic acquired resistance), ISR (induced systemic resistance), TCP (tri-calcium phosphate), HCN (hydrogen cyanide), IAA (indole-3-acetic acid), ^aPhosphorus [(SSP) single super phosphate, RP (rock phosphate), PM (poultry manure) and FYM (farm yard manure)], PAL (phenylalanine ammonia lyase), ESI-MS (electrospray ionization mass spectrometry), DAPG (2,4-diacetylphloroglucinol) and NMR (¹H nuclear magnetic resonance).     

Effect of nutrient management and straw mulching on crop yield,uptake and soil fertility in rapeseed (Brassica campestris)–greengram (Vigna radiata)–rice (Oryza sativa) cropping system under Gangetic plains of India

An experiment was conducted at Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India during 2001–2003 to study the effect of levels of fertility and straw mulch on a rapeseed (Brassica campestris var yellow sarson)–greengram (Vigna radiata)–rice (Oryza sativa) cropping system under a rainfed upland ecosystem. The experiment was laid out in a split-plot design having 14 treatment combinations of organic and inorganic nutrients along with straw mulch in three replicates. The results revealed that conjunctive use of organic and inorganic nutrients as well as paddy straw mulch resulted higher yield in both rapeseed and greengram, and the residual effects of different levels of fertilization and mulching also gave rise to higher grain yield in the succeeding rice crop. The uptake of nutrients, by the cropping system as a whole, to the tune of 204.29 and 183.00 kg ha^?1 of N, 72.84 and 74.07 kg ha^?1 of P and 179.95 and 175.41 kg ha^?1 of K took place, with the treatment receiving 10 t ha^?1 of farmyard manure (FYM) applied (to rapeseed) along with 50% recommended dose (RD) of NPK to all the crops in the sequence in two consecutive years, respectively. The same treatment resulted in a higher percentage of porosity vis-à-vis lower bulk density. Soil physico-chemical properties were superior in mulch-treated plots compared with no mulch treatment. Application of organic and inorganic nutrients along with proper moisture conservation practices can enhance the yields maintaining a good soil health.     

Anti-Alzheimer’s Molecules Derived from Marine Life: Understanding Molecular Mechanisms and Therapeutic Potential

Alzheimer’s disease (AD) is a devastating neurodegenerative disease and the most common cause of dementia. It has been confirmed that the pathological processes that intervene in AD development are linked with oxidative damage to neurons, neuroinflammation, tau phosphorylation, amyloid beta (Aβ) aggregation, glutamate excitotoxicity, and cholinergic deficit. Still, there is no available therapy that can cure AD. Available therapies only manage some of the AD symptoms at the early stages of AD. Various studies have revealed that bioactive compounds derived from marine organisms and plants can exert neuroprotective activities with fewer adverse events, as compared with synthetic drugs. Furthermore, marine organisms have been identified as a source of novel compounds with therapeutic potential. Thus, there is a growing interest regarding bioactive compounds derived from marine sources that have anti-AD potentials. Various marine drugs including bryostatin-1, homotaurine, anabaseine and its derivative, rifampicins, anhydroexfoliamycin, undecylprodigioisin, gracilins, 13-desmethyl spirolide-C, and dictyostatin displayed excellent bioavailability and efficacy against AD. Most of these marine drugs were found to be well-tolerated in AD patients, along with no significant drug-associated adverse events. In this review, we focus on the drugs derived from marine life that can be useful in AD treatment and also summarize the therapeutic agents that are currently used to treat AD.     

Methane consumption from ambient atmosphere by a Typic Ustochrept soil as influenced by urea and two nitrification inhibitors

The effect of urea and urea mixed with different doses of two nitrification inhibitors, dicyandiamide (DCD) and karanjin [a furanoflavonoid, extracted from seeds of the karanja (Pongamia glabra Vent.) tree], on methane (CH₄) consumption was examined in a Typic Ustochrept (alluvial inceptisol) soil, collected from a field under rice-wheat rotation. The soil, fertilized with urea (100 mg N kg^-1 soil) and urea combined with different doses of the two inhibitors, DCD and karanjin (each added at 5%, 10%, 15%, 20% and 25% of applied N), was incubated at 25°C, at field capacity moisture content for 35 days. The methane consumption rate ranged between 0.2 and 1.7 µg CH₄ kg^-1 soil day^-1 with little temporal variation (CV =10–31%). It was significantly higher in the control (no fertilizer-N) than other treatments except for a few cases, while total CH₄ consumption in the incubation period was significantly higher in the control than other treatments. Methane consumption rate was found to be negatively and positively correlated with soil NH₄ ⁺ and NO₂ ^- + NO₃ ^- content, respectively. Mean CH₄ consumption rate, as well as total CH₄ consumption, was lower on the addition of karanjin due to slower nitrification and higher conservation of NH₄ ⁺ released from applied urea. Addition of urea led to a 17% reduction of total CH₄ consumption while urea combined with karanjin and DCD had 50–64% and 19–34% reduction, respectively. Karanjin was a more effective nitrification inhibitor than DCD during the incubation period.     

Arsenic speciation in food and estimation of the dietary intake of inorganic arsenic in a rural village of West Bengal, India

Arsenic (As) species were quantified by HPLC-HG-AFS in water and vegetables from a rural area of West Bengal (India). Inorganic species predominated in vegetables (including rice) and drinking water; in fact, inorganic arsenic (i-As) represented more than 80% of the total arsenic (t-As) content. To evaluate i-As intake in an arsenic affected rural village, a food survey was carried out on 129 people (69 men and 60 women). The data from the survey showed that the basic diet, of this rural population, was mainly rice and vegetables, representing more than 50% of their total daily food intake. During the periods when nonvegetarian foods (fish and meat) were scarce, the importance of rice increased, and rice alone represented more than 70% of the total daily food intake. The food analysis and the food questionnaires administrated led us to establish a daily intake of i-As of about 170 microg i-As day (-1), which was above the tolerable daily intake of 150 microg i-As day (-1), generally admitted. Our results clearly demonstrated that food is a very important source of i-As and that this source should never be forgotten in populations depending heavily on vegetables (mainly rice) for their diet.     

Anti-inflammatory and antinociceptive activity of Thymus pubescens extract

Thymus pubescens is an aromatic and medicinal plant, which has been widely distributed in Iran. The anti-inflammatory and analgesic effects of the T. pubescens aerial parts methanol extract were studied at doses of 50-400 mg/kg i.p. using carrageenan-induced edema, formalin, hot plate and writhing tests. The extract produced a significant decrease in the degree of swelling, 3 h after carrageenan injection and caused graded inhibition of both phases of formalin-induced pain. Moreover, in the hot plate test, it significantly raised the pain threshold. While in the writhing test produced a significant decrease in the number of writhing in comparison with the control group (P<0.001). The results of pharmacological tests performed in the present study suggest that the extract of T. pubescens presents analgesic and anti-inflammatory effects.     

Momordica charantia L. (Cucurbitaceae) floral volatiles causing attraction of Epilachna dodecastigma (Coleoptera: Coccinellidae)

Epilachna dodecastigma (Wied.) (Coleoptera: Coccinellidae) causes economic losses to bitter gourd, Momordica charantia L. (Cucurbitaceae) production in India and Bangladesh because adults feed on the leaves and flowers resulting death of the plant. This insect is currently controlled by insecticides, which are harmful to human health and environment. We studied the behavioral responses of E. dodecastigma females to floral volatiles and synthetic compounds comparable to floral volatiles in a Y-tube olfactometer to determine their potential for monitoring this pest. The gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detector (GC-FID) analyses of M. charantia floral volatiles revealed the presence of 20 compounds. Myrcene was predominant followed by methyl jasmonate and 1-octadecanol in floral volatiles. Epilachna dodecastigma females were attracted to floral volatiles by a Y-tube olfactometer bioassay. Females were attracted to individual synthetic 1-heptanol, sabinene, myrcene and ocimene at 16, 1, 20, and 8 µg/25 mL methylene chloride in a dose response bioassay, respectively, and hence, these compounds might be used for insect pest management strategies such as baited traps.     

Spontaneous Colibacillosis in Infectious Bursal Disease-affected Broiler Flocks

Tropical Animal Health and Production -     

Seed treatment for viability,vigour and productivity of tomato

Soaking—drying treatment of stored tomato seeds greatly reduced their deterioration under accelerated and natural ageing conditions. Hydration by moisture equilibration at 100% RH for 24 hours followed by drying-back was also very effective. Treatment of harvest-fresh seed was ineffective. The beneficial effects of the soaking—drying treatments were reflected in the productivity of the crop. Treatment with dilute solutions of sodium chloride (10^?3 M) or sodium phosphate (dibasic, 10^?4 M) proved better than water for field performance and productivity.