Days After Incubation Research Articles

Pengaruh Hormon Asam Indol Asetat yang Dihasilkan Azospirillum sp. terhadap Perkembangan Akar Padi

<p>Free-living bacteria of the<br />genus Azospirillum live in close association with rice roots.<br />This bacteria produced indole acetic acid (IAA), a plant<br />growth hormon, to the environment. IAA was isolated from<br />cultures of Azospirillum strains and investigated for its effect<br />on root development and plant height of rice variety IR64 in<br />vitro. Rice cultures of variety IR64 were grown in vitro and<br />inoculated with cultures of Azospirilllum. Production of IAA<br />by the bacterium during its growth period in rice culture medium<br />containing different levels of nitrogen was observed.<br />Results of the experiment showed that strains Azospirillum<br />Az15 and Az44 had a high ability to produce IAA, i.e., 57.93<br />μg/ml at 12 days after incubation (DAI) and 40.42 μg/ml at 7<br />DAI, respectively. The IAA production pattern of Azospirillum<br />Az15 and Az44 in the liquid medium were fluctuative<br />until the end of the incubation period, while that of the strain<br />Az7 was linier. Strain Az7 gave a better effect on the root<br />development and plant height than strains Az15 and Az44.<br />Treatment combination of strain Az7 and 100% nitrogen gave<br />highest root development. High level of nitrogen increased<br />IAA content in the uninoculated culture, while low IAA<br />content on the inoculated one. Inoculation the culture with<br />strain Az7 together with 50% nitrogen application resulted in<br />the IAA content, root dry weight, root length, fiber root number,<br />and plant height as high as those on cultures containing<br />100% nitrogen (1 mM NH4NO3) without inoculation. Inoculation<br />of rice culture with Azospirillum is expected to reduce<br />nitrogen application on rice IR64 by the IAA production as<br />indicated by significant changes in the root growth and<br />development. A higher concentrations of IAA tend to give<br />better effects on the root growth and development of rice<br />IR64.</p>

Influence of Inorganic Fertilizers and Organic Amendments on Plant Nutrients and Soil Enzyme Activities under Incubation

An incubation experiment was carried out in the department of Soil Science and Agricultural Chemistry, ANGRAU, Hyderabad, India during 2013−14 with 12 treatments including control to study the mineralization pattern and timely release of nutrients (N, P, K and soil enzymes) to plant from different sources and periods. Mineralization of nitrogen (NH4+-N and NO3−-N), phosphorus (P2O5) potassium (K2O) and soil enzymes (urease, acid and alkaline phosphatase and dehydrogenase) activities from different treatments were evaluated. During initial period 7 to 21 days after incubation (DAI), the recommended dose of fertilizer (RDF) had maximum release of NH4+-N and NO3−-N and later on decreased in the succeeding days but manures combination treatment has taken lead to release the N from 1 DAI to 70 DAI than control. Similar trends were followed in available P2O5 and K2O. The maximum quantity of urease and DHA were reached 203 to 227 μg NH4+-N g−1 soil h−1 and 10.6 to12.4 μg TPF g−1 soil h−1 from combination of poultry manure and neem cake at 70 DAI, respectively. Maximum released of acid and alkaline phosphatase were observed in 21 DAI and 35 DAI in RDF respectively. Among the manures treatment, PM+NC had superior in releasing of alkaline phosphatase over other, followed by poultry manure and FYM+PM. Correlation study between nutrients (N, P and K) and enzymes activity showed that a significant (p<0.05) positive relationship with each others.

Identification and characterization of potassium solubilizing bacteria (KSB) from Indo-Gangetic Plains of India

Abstract The present investigation comprises a total of fifty potassium solubilizing bacterial (KSB) strains which were isolated from Oryza sativa, Musa paradisiaca, Zea mays, Sorghum bicolor and Triticum aestivum L. These strains were evaluated for their ability to solubilize the fixed K from waste biotite (WB). On the basis of K-solublization, the seven most efficient KSB strains were evaluated for K-solublizing dynamics from the WB at 7, 14 and 21 DAI (days after incubation) on MAMs (Modified Solid Aleksandrov Medium). Further, these screened seven KSB strains were used for their morphological, physiological and molecular chacterization. The KSB strains Bacillus licheniformis BHU18 and Pseudomonas azotoformans BHU21 showed significantly higher K-solublization 7.22 and 6.03 µg mL −1 at 30 °C and pH 7.0, respectively. A significantely higher zone of solubilization significantly higher was recorded with Pseudomonas azotoformans BHU21 (3.61 cm). Bacillus licheniformis BHU18 produced significantly higher (~23 µg mL −1 ) concentrations of indole-3-acetic acid. The diversity of KSB as bioinoculants to release potassium provides a win-win situation. Therefore, it is crucial to adopt efficient KSB strain interventions for the judicious use of chemical and biological resources for maximizing food production while reducing pollution and rejuvenating degraded land for agricultural benefit.

Coating of essential oils onto prilled urea retards its nitrification in soil

ABSTRACTIncreased use of nitrogenous fertilizers in agriculture has led to the increased pollution of ground water and atmosphere. Certain plant products can be used as coating materials onto urea to reduce the N losses. We evaluated the effectiveness of citronella and palmarosa grass oils as nitrification inhibitors in a soil incubation study. The treatments (14) were combinations of 4 N sources (neem, citronella and palmarosa oil coated prilled ureas, and uncoated prilled urea), 2 coating thicknesses of oils (500 and 1000 mg kg−1) and 2 N levels (75 and 150 kg N ha−1), replicated thrice in a randomized block design. N levels at 75 and 150 kg ha−1 were equivalent to 34 and 68 mg N kg−1 soil, respectively. Results showed that N sources citronella (CCPU1000) and neem oil (NCPU1000) coated prilled ureas at 1000 mg kg−1 coating thickness with 75 kg ha−1 released similar amount of ammonical-N to uncoated prilled urea at 150 kg N ha−1, suggesting the beneficial effect of coated ureas. The highest nitrification inhibition (%) was recorded with NCPU1000, the reference nitrification inhibitor, which was significantly greater to all the other N sources at 7 days after incubation (DAI), and at par to CCPU1000 at 14 and 21 DAI.

Characteristics and mechanisms of acrylate polymer damage to maize seedlings

Superabsorbent acrylate polymers (SAPs) have been widely used to maintain soil moisture in agricultural management, but they may cause damage to plants, and the mechanisms are not well understood. In this study, seed germination, soil pot culture, hydroponic experiments, and SAPs degradation were conducted to investigate damage characteristics and mechanisms associated with SAPs application. The Results showed that SAPs inhibited maize growth and altered root morphology (irregular and loose arrangement of cells and breakage of cortex parenchyma), and the inhibitory effects were enhanced at higher SAPs rates. After 1h SAP hydrogels treatment, root malondialdehyde (MDA) content was significantly increased, while superoxide dismutase (SOD) and catalase (CAT) content were significantly decreased. Hydroponics experiment indicated that root and shoot growth was inhibited at 2.5mgL−1 acrylic acid (AA), and the inhibition was enhanced with increasing AA rates. This effect was exacerbated by the presence of Na+ at a high concentration in the hydrogels. Release and degradation of AA were enhanced at higher soil moisture levels. A complete degradation of AA occurred between 15 and 20 days after incubation (DAI), but it took longer for Na+ concentration to decrease to a safe level. These results indicate that high concentration of both AA and Na+ present in the SAPs inhibits plant growth. The finding of this study may provide a guideline for appropriate application of SAPs in agriculture.

Behaviour of Different Levels and Grades of Diatomite as Silicon Source in Acidic and Alkaline Soils

Diatomite or Diatomaceous earth (DE) is a sedimentary rock that results from the deposition of Si rich unicellular life forms (diatoms) found in both salt and fresh water. The cell walls of these dead diatoms consist of amorphous silica. Amorphous silica is more easily solubilised than crystalline silica and is expected to release more PAS (Plant available silicon). Information on use of DE as the source of Si in different crops is very limited and hence there is a need to know the effect of different levels and grades of DE on availability of nutrients in acidic and alkaline soil under field capacity and submergence level. An incubation study was conducted by using acidic and alkaline soil in a plastic pot with different levels (0, 150, 300 and 600 kg ha −1) of diatomite under field capacity and submergence. In another study, five different grades of diatomite at different levels (0, 250, 500, 750, 1000 and 1500 kg ha −1) were incubated under the field capacity moisture regime alone. During the incubation studies, soil samples were periodically analyzed for pH and PAS at 7, 15, 30, 60, 90 and 120 days after incubation (DAI). Increase in pH of acidic and decrease in pH of alkaline soil was recorded irrespective of application rates of diatomite under both the moisture regimes. Increase in PAS was observed at 30 DAI in both types of soil. Among the different grades, diatomite-3 and diatomite-4 recorded significantly higher PAS in acidic soil under the field capacity moisture regime.

A framework for refining soil microbial indices as bioindicators during decomposition of various organic residues in a sandy loam soil

Assessment of soil quality is an invaluable tool in determining the sustainability and environmental impact of agricultural ecosystems. Soil microbial indices like microbial biomass and microbial activity are important criteria for the determination of soil quality. Laboratory incubation study was undertaken to examine the influence of eight crop residues widely varying in biochemical composition on the periodic changes in important soil microbial indices {(microbial (Cmic: Corg), metabolic (qCO2), carbon mineralization (qC) and microbial biomass change rate (qM) quotients)} at 28 days and 63 days after incubation (DAI) in a sandy loam soil. A. sativa amended soil showed maximum soil respiration rate (14.23 mg CO2-C g-1 soil day-1) whereas T. aestivum amended soil showed maximum microbial biomass C (790 µg/g). The metabolic quotient among different crop residues ranged from 11.1 to 19.8 ?g CO2-C ?g-biomass-C-1 h-1 at 63 DAI. The results indicate that incorporation of different crop residues has positive effect on microbial flora and their activity. Microbial quotient (Cmic:Corg) was significantly positively correlated with microbial biomass carbon (MBC), qC and qM. The study suggests that the biochemical composition of different crop residues seems to be of better option for long term sustainable crop production with maintenance of soil quality in a sandy loam soil.

Bio activity of some botanicals on Helminthosporium infestans L. and Solanum aethiopicum L. (host)

Some botanicals were assayed in two laboratory trials for their relative toxicities to African eggplant (Solanum aethiopicum L.) and Helminthosporium infestans causing leaf spots disease at the Department of Crop Science, University of Nigeria, Nsukka. In the first experiment on the toxicity of the protectants to S. aethiopicum, three concentrations (10, 20 and 30 g/ml) were used. Four concentrations (0.03, 0.06, 0.12 and 0.25 g/ml) were used in the second experiment on the toxicity of the botanicals (Azadirachta indica leaves, Gongronema latifolia leaves, Garcinia kola seeds, Zingiber officinale stems and Carica papaya leaves) to H. Infestans. Distilled water served as control in each case. Solanum seeds dressed with G. kola germinated faster and attained 100% germination 14 days after incubation (DAI). On the other hand, Z. officinale inhibited the seed germination most, resulting in the least germination being recorded on seeds treated with Z. officinale. Similarly, all the plant extracts assayed inhibited the growth of H. Infestans to varying degrees relative to check at 3 days after inoculation. Anti-fungal activity of extracts on H. Infestans decreased in the following order: G. kola at 0.12 g/ml (90.00%) > C. papaya at 0.25 g/ml (59.54%) > G. kola at 0.06 g/ml (59.15%) > G. kola at 0.03 g/ml (55.15%) > A. Indica at 0.06 g/ml (53.67%) > Z. officinale at 0.03 g/ml (52.65%) > control (7.71%). The seeds extracts of G. kola at 0.12 g/ml therefore proved more effective in the suppression of H. infestans relative to other botanicals and concentrations and were be recommended as a good alternative in its control in the field. Key word: African eggplant anti-fungal, inhibition, protectants, toxicity.

Plant growth promoting activities of rhizobacteria associated with tomato in semi-arid region

The present investigation was designed to evaluate the plant growth promoting activities of rhizobacteria associated with tomato. Twenty six rhizosphere soil samples of tomato were randomly collected from tomato cultivating areas of district Faridabad, Haryana, India and a total of 56 strains of rhizobacteria were isolated on three different selective and non-selective medium i.e. nutrient agar, King’s B agar and glycerol-arginine agar at 300C. Pseudomonas was identified as the predominant bacterial genus with almost 34% of the isolated strains belonging to this genus. All isolated strains were evaluated for indole acetic acid (IAA) production and phosphate solubilization. In vitro IAA production was observed in 76.8% isolates and phosphate solubilizing activity was given by 41.1% isolates. Isolates varied significantly (P < 0.05) for IAA production as well as phosphate solubilization. The average IAA concentration recorded for these isolates was 6.32 μg/ml and the inorganic phosphate (Pi) released in Pikovskaya’s broth at 15 days after incubation (DAI) was 18.80 μg/ml. The average pH of Pikovskaya’s broth at fifteen DAI dropped to 5.20 from 7.00 at 0 DAI. Leading IAA producing genera were Flavobacterium and Azotobacter while maximum P-solubilization activity was shown by the genus Pseudomonas. The isolate TNAM22 gave the highest IAA concentration of 9.81 μg/ml while the isolate TKB14 released maximum Pi i.e. 22.7 μg/ml.

Different Forms of Soil Zinc - their Relationship with Selected Soil Properties and Contribution towards Plant Availability and Uptake in Maize Growing Soils of Erode District, Tamil Nadu

Information on soil zinc (Zn) distribution is essential for understanding its chemical reactions and bioavailability. A study was conducted on the distribution of different forms of soil Zn and response of maize to native soil Zn content at four locations (L1, L2, L3 and L4) having very low, low, medium and high soil available Zn status. The results revealed that various chemical pools of Zn under incubation condition treated with graded levels of Zn fertilizer application (0, 1.25, 2.50, 5.0, 7.5, 10.0 Zn as ZnSO4 kg ha-1) showed significant variation in almost all the locations and similar trends were noticed for all the soil studied, where the highest amount of added Zn (10 kg Zn ha-1) always produced greater Zn release than the lower doses. Among the fractions, the higher release of water soluble plus exchangeable zinc (WSEX-Zn), organically bound zinc (OM- Zn) and crystalline bound zinc (CFeOX-Zn) were observed at 15 days after incubation(DAI) and gradually declined at the end of the experiment upto 30DAI whereas other forms such as manganese oxide bound zinc (MNOX- Zn), amorphous sesquioxide bound zinc (AFeOX- Zn), residual zinc (RES- Zn) and TOTAL- Zn showed a prolonged release upto 30 DAI. Also from the study it is evident that the content of different fractions varied between the soils of all locations, the order of preponderance of different zinc fractions viz. WS and EX < OM < AFe-OX < CFe-OX) < MN-OX < RES and it remained same for all the locations. More than 95 % of the total Zn content occurred in the relatively inactive and mineral-bound residual form (RES), whereas only a small fraction occurred in WS and EX, OM, AFe-OX, and CFe-OX fractions. The pot culture experiment conducted with similar set of treatments with maize crop responded well to Zn fertilizer application and the location with very low Zn status with 7.50 kg Zn ha-1 showed higher value for the dry matter production (76.4 g plant- 1) and Zn - uptake (3.34 mg plant-1). Correlation data indicated that those fractions are in a state of dynamic equilibrium among different fractions and were influenced by pH, EC, CEC, organic carbon, DTPA- Zn and also revealed that almost all the fractions contributed to the plant availability. In all the cases it is noted that the release of various forms of Zn and response of maize crop to Zn fertilizer application always higher for the soil having very low Zn followed by low, medium and high Zn status.

Phythonematoxic properties and nematicidal potential of Tithonia diversifolia extract and residue on Meloidogyne incognita infecting yam (Discoria rotundata)

A laboratory study and a screen house experiment were conducted to determine the phythonematoxic properties and nematicidal potential of extract and residue of Tithonia diversifolia (Hemsl.) A. Gray on Meloidogyne incognita, (Kofoid and White) Chitwood infecting yam. Alkaloids and saponins were found to be present in the constituents of Tithonia ethanol extract. Also, Tithonia water extract significantly (P ≤ 0.05) inhibits M. incognita egg hatch by 98% from 2 days after incubation (DAI) and was more evidenced with 100% inhibition at 9 DAI in the in vitro studies. M. incognita (5000 eggs/plant) reproduction, number of eggs and juveniles and galling were significantly (P ≤ 0.05) suppressed by Tithonia residue treatment at a rate of 30 tons/ha on yam (Discoria rotundata) in the screen house. The extract and residue of T. diversifolia have potential for the control of root-knot nematodes.

Effect of Silkworm Pupae Compost on Soil N mineralization, Nutrient Uptake, Crop Yield and Plant Nutrient Contents of French Bean (&lt;i&gt;Phaseolus vulgaris&lt;/i&gt; L.)

A field experiment was conducted during the period of December 2007 to March 2008 on a sandy clay loam soil in Bangalore, India to study the effect of silkworm pupae compost as a nutrient source for French bean. Four different mixtures of seri-compost were prepared using raw pupae wastes of silkworm and evaluated for soil N mineralization, plant nutrient content, nutrient uptake and yield of French bean. Soil incubation and a field experiment was conducted using 11 treatment combinations containing different ratios of inorganic fertilizers, farm yard manure and seri-compost. The NH₄⁺-N release in soil increased rapidly up to 28 days after incubation (DAI) and thereafter, it decreased. At 0-28 days after incubation, the highest increase in NH₄⁺-N was recorded in treatment 8 (T8) which contained 50% N RDF (Recommended dose of fertilizer) + 50% N seri-compost 3(C3) prepared with silkworm pupae waste and 10% cowdung slurry (5.6 to 92.2 mg kg^-1). The lowest increase was in treatment 5 (T5) in which 100 % N supplied through Seri-compost 4 (C4) prepared with silkworm pupae waste with 10% cow dung slurry, 5% rock phosphate and microbial inoculant (14 to 28 mg kg^-1). At 0-21 days after incubation, the highest increase in NO₃^--N release was recorded in treatment 2 (T2); 100% N through seri-compost 1 (C1) prepared with silk worm pupae waste and farm yard manure (16.8 to 112 mg kg^-1) and lowest in treatment 4 (T4);100% N through seri-compost 3 (C3) (50.4 to 92 mg kg^-1). The NO₃^-- N release in soil increased rapidly up to 21 DAI and thereafter it decreased. All the silkworm pupae compost treatments incorporated with 50% N RDF improved yield and highest bean yield of 5793 kg ha^-1 was in treatment 7 (T7) which contained 50% N RDF + 50% N Seri-compost 2. The highest N, P and K content of French bean plants at maturity was noticed in T6 (50% N RDF + 50% N silkworm pupae compost 1), T7 (50% N RDF + 50% N seri-compost 2) and T3 (100%N through Seri-compost 2) treatments respectively. Application of seri-compost increased available N, P₂O₅ and K₂O status of the postharvest soil. Highest N, P and K uptake was recorded from 50% N RDF with seri-compost 2 (T3), seri-compost 3(T8) and 100% N through seri-compost 3(T4) respectively. Therefore sericompost could be used to obtain higher yields of French bean than the recommended package of practices with inorganic fertilizer. DOI: http://dx.doi.org/10.4038/tar.v21i4.3315 TAR 2010; 21(3): 391-397

In vitro Assay of Factors Affecting the Growth of Pathogens Associated with Diseases on Dragon Fruit (Hylocereus spp.) in Peninsular Malaysia

Knowing the unfavorable environment for the growth of a pathogen can be utilized as the basic information in developing appropriate strategies to prevent disease occurrence on dragon fruit. Several environmental factors including temperature, pH and salinity, as well as biotic factor including three antagonistic bacteria species, namely Bukholderia cepacia, B. multivorans and Pseudomonas aeruginosa against Bipolaris sp., Colletotrichum gloeosporioides, Botryosphaeria sp. and Monilinia sp., were investigated. Mycelial growth of all tested fungi was constantly inhibited by a temperature of 35°C, while a temperature of 25°C was quite suitable for their growth. A temperature of 30°C was favorable for the growth of Colletotrichum gloeosporioides. Under different pH condition, the growth of tested fungi was mostly inhibited by extreme pH of 4 and 10. The salinity assay showed that Monilinia sp. was not affected by all treatments among tested fungi. Only concentration 100 ppm could reduce the growth of Bipolaris sp., though its inhibition statistically affected on 4 and 6 Days after Incubation (DAI). Meanwhile, the in vitro examination of antagonistic bacteria resulted in Bukholderia multivorans which was highly effective in inhibiting the growth of examined fungi, except Monilinia sp., which was more significantly influenced by B. multivorans and B. cepacia. The proper combination of environmental modification may be useful for the growth of crop in the field as well as the storage life of the fruit at postharvest preservation.