Samiullah Khan

Influence of lead and cadmium on the growth and nutrient concentration of tomato (Lycopersicum esculentum) and egg-plant (Solanum melongena)

SummaryThe effect of lead and cadmium on the dry matter yield and nutrient concentration of tomato (Lycopersicum esculentum) and egg-plant (Solanum melongena) was studied in a greenhouse experiment. The results showed some benificial effects of Pb and Cd at their lower doses and toxicity at higher levels. The threshold concentration (C10), toxicity index (T10) and loading rate to produce C10 were also calculated. These values suggested the tomato to be more tolerant than egg-plant for heavy metals whose toxicity was found in the order of Cd>Pb in both the plants.The application of the heavy metals was found to effect the nutrient concentration and their uptake by plants. The results have been explained on the basis of their complexation and translocation through the plant sap.

The mobility of some heavy metals through Indian Red Soil

Abstract An investigation was undertaken to study the mobilities of Cr, Ni, Pb, Ag and Cd through Indian Red Soil using soil thin layer chromatography. Different soil constituents such as organic matter, pH, anions of the soluble salts—i.e. Cl − , HCO 3 − , CO 3 −− , SO 4 −− , PO 4 −−− and MoO 4 −− —and some exchangeable cations were examined as mobility factors. It was found that the decomposition of soil organic matter greatly increased the mobility of heavy metals whereas a rise in pH of the soil water system caused a decrease. Initial addition of all anions apparently enhanced the mobility but high levels of added SO 4 −− , PO 4 −−− and MoO 4 −− caused a reduction. The mobility of heavy metals tested in soils saturated with different cations was found to be in the order H-soil > Na-soil > K-soil > Mg-soil > Ca-soil.

The mobility of some organophosphorus pesticides in soils as affected by some soil parameters

Using soil thin layer chromatography (soil TLC), we conducted laboratory experiments to evaluate the mobility (R1) of four organophosphorus pesticides—dimethoate, malathion, phosphamidon, and dich-lorvos—in soils. The effects of soil organic matter (SOM) and fractions, i.e., humic (HA) and fulvic acids (FA), clay content, sesquioxides (A12O3 and Fe2O3), soil pH, and exchangeable cations and anions were investigated. We observed that, except for sakit sandy loam soil, the mobility of these pesticides followed the order: dimethoate ≥ phosphamidon > malathion > dichlorvos, which was attributed to their adsorption over soil colloids. The SOM; HA; FA; clay content; sesquioxides; acidic and alakline pH; exchangeable cations, i.e., H+, K+, Ca2+ and Mg2+; and anions, i.e., CO32-, SO42-, and H2PO4- were all found to decrease the pesticide mobility in soils, except for HA, which increased the malathion and phosphamidon mobility. However, the C1- caused an increase in the mobility of all the pesticides. The order of exchangeable cations to affect the mobility was: H+ > CA2+ > Mg2+ > K+. The results have been explained on the basis of their adsorption/complexation, the nature of soil colloids, and the molecular structure of pesticides.

Studies on the effects of some organic pollutants on the heavy metal transport in an Indian soil

The translocation of some heavy metals, such as Hg, Cd, Cu, Co, Ni and Zn, as affected by organic pollutants, i.e. methanol, ethanol, propanol, formaldehyde, acetaldehyde, benzaldehyde, acetone, ethyl methyl ketone and cyclo-hexanone, was studied in an Indian red soil using soil thin layer chromatography. It was observed that an increase in the concentration of organic compounds in developer enhances the heavy metal mobility, except in the case of Cu and Hg which show a decreasing trend. The results are discussed in relation to the physico-chemical characteristics of the soil and adsorption/desorption phenomena.

Studies on the thermodynamics of exchange in clays—IV: Nickel exchange on Ca-illite

Abstract The thermodynamics of the exchange of Ni 2+ ions with Ca-illite have been investigated. The exchange at pH 5.0 and an equilibrium time of 3 hr yielded isotherms, K and ΔG ° values, which were indicative of a strong preference for Ni 2+ ions on the illite surface. The surface phase activity coefficients of the cations pointed to a more homogeneous distribution of Ni 2+ ions on the illite surface and a heterogeneity of the calcium distribution. The excess thermodynamic functions showed that the mixed system was more stable, more tightly bound and tended to deviate from ideal behaviour.

Studies on the thermodynamics of exchange in clays—III Nickel exchange on Na-, Ca- and Mg-Montmorillonites

Abstract Exchange equilibria involving Ni ions on Na-, Ca- and Mg-montmorillonites were studied with the help of the thermodynamic models of earlier workers. The exchange isotherms and free energy changes were indicative of a lower preference of Ni for the base saturated montmorillonites. The exchange was in accordance with the Hofmeister series. Enthalpy changes indicated a stronger binding of Ni on Ca- and Mg-montmorillonites than on Na-clay. Entropy findings were indicative of a dehydrated and disordered arrangement of Ni ions during their adsorption on Na-montmorillonite. The effect of dehydration on the entropy was the reverse in the case of Ca- and Mg-montmorillonites. The diversity of the exchange equilibria involving Ni, Na, Ca and Mg ions on the montmorillonite surface was further confirmed from our observations on the activity coefficients and the values of ΔGmx, ΔHmx and ΔSmx.

Assessment of genetic response and character association for yield and yield components in Lentil (Lens culinaris L.) population developed through chemical mutagenesis

Abstract Genetic variation is imperative to any plant improvement program. Therefore, this study was primarily based on this aspect of inducing desirable genetic variation for enhancement of the available lentil genetic diversity. The lentil seeds were treated with methyl methanesulfonate (MMS) alone and in combination with dimethyl sulfoxide (DMSO) for inducing polygenic variation as well as determining the impact of DMSO on mutagenecity of MMS. Comparative observations were recorded for bio-physiological damages, morphological variation, and quantitative traits to assess the genetic response of the lentil cultivar L 4076 toward the different concentrations of chemicals. Significant statistics suggested that the DMSO interfere with the extent of mutagenecity of MMS in lentil which could be attributed to either synergistic action of both or variation in MMS uptake. The outcome of mutagenesis on the character association study revealed that mutagenic treatments can modify significantly the manner of association between any two traits in lentil. The moderate doses of MMS in combination with 2% DMSO showed notable diminution in the biological damages while accelerating the rate of desirable high-yielding mutants had proved to be economical. The segregate of the selected mutants in future generations will definitely contribute to the improvement of Lentil genotype.

Assessment on induced genetic variability and divergence in the mutagenized lentil populations of microsperma and macrosperma cultivars developed using physical and chemical mutagenesis

Induced mutagenesis was employed to create genetic variation in the lentil cultivars for yield improvement. The assessments were made on genetic variability, character association, and genetic divergence among the twelve mutagenized populations and one parent population of each of the two lentil cultivars, developed by single and combination treatments with gamma rays and hydrazine hydrates. Analysis of variance revealed significant inter-population differences for the observed quantitative phenotypic traits. The sample mean of six treatment populations in each of the cultivar exhibited highly superior quantitative phenotypic traits compared to their parent cultivars. The higher values of heritability and genetic advance with a high genotypic coefficient of variation for most of the yield attributing traits confirmed the possibilities of lentil yield improvement through phenotypic selection. The number of pods and seeds per plant appeared to be priority traits in selection for higher yield due to their strong direct association with yield. The cluster analysis divided the total populations into three divergent groups in each lentil cultivar with parent genotypes in an independent group showing the high efficacy of the mutagens. Considering the highest contribution of yield trait to the genetic divergence among the clustered population, it was confirmed that the mutagenic treatments created a wide heritable variation for the trait in the mutant populations. The selection of high yielding mutants from the mutant populations of DPL 62 (100 Gy) and Pant L 406 (100Gy + 0.1% HZ) in the subsequent generation is expected to give elite lentil cultivars. Also, hybridization between members of the divergent group would produce diverse segregants for crop improvement. Apart from this, the induced mutations at loci controlling economically important traits in the selected high yielding mutants have successfully contributed in diversifying the accessible lentil genetic base and will definitely be of immense value to the future lentil breeding programmes in India.

The influence of Bavistin and Calixin on CO2-evolution and the major nutrient status (NPK) of the soil.

An application of Bavistin (5 mg kilogram of soil) and Calixin (1.5 mg per kilogram of soil) significantly enhanced the microbial activity, as well as availability, of NH(4)(+)-N and P in the soil, while NO(2)(-)-NO(3)(-)-N and available K were found to decrease. During incubation, decreases in CO(2)-evolution were observed initially up to 21 days, with an increase up to 42 days, and, thereafter, a fall in both treatments.

Adsorption and interaction of oxamyl with acid and base saturated illites

Abstract The adsorptive behavior and reaction mechanism of oxamyl with acid and base saturated illites were investigated with the help of adsorption isotherms, Freundlich constants, thermodynamic parameters, infrared and X-ray spectroscopy. A qualitative assessment of the nature of the reaction was made with these. Effects of temperature, concentration, and different cations were also studied. All the above data indicate the existence of protonation and/or coordination between exchangeable cations of the illite and oxygen of the amide group of the pesticide (oxamyl).