Monitoring of Phytotoxicity of Lead and Mercury from Germination and Early Seedling Growth Indices in Two Rice Cultivars

Treatment of seeds of two rice (Oryza sativa L.) cultivars (Ratna and IR36) separately with 10^-5and 10^-4M PbCl²and HgCl²decreased germination percentage, germination index (GI), shoot and root length, tolerance index (TI), vigour index (VI) and dry mass of shoot and root but increased percentage difference from control (% DFC) of germination and percentage phytotoxicity in both the cultivars. It was observed from these indices that the phytotoxic effect of mercury was greater than lead at identical concentrations and that IR36 appeared more tolerant than Ratna to these metals. Among the monitoring indices examined, TI, VI, and % phytotoxicity seemed to serve as good biological monitoring methods for evaluating the relative toxicity of lead and mercury to rice cultivars.

     

Influence of gibberellic acid on the sporulation of Azolla caroliniana, Azolla microphylla and Azolla pinnata

strains used in the study sporulate throughout the year while Azolla caroliniana and Azolla pinnata strains show sporulation only during November–March, the favourable period for sporulation. Application of gibberellic acid (GA) at a concentration of 2.5–100.0 μg ml^–1 substantially enhanced the sporulation frequency and number of sporocarps (mega plus micro) per plant in Azolla microphylla (two strains) during the unfavourable period (September–October) by 77.3–200.0%. The increase in the number of microsporocarps was more than that of the megasporocarps. The sporulation frequency and number of sporocarps in Azolla pinnata (two strains) and Azolla caroliniana during the favourable season also increased considerably due to GA (2.5–10.0 μg ml^–1) application. The optimum GA concentration for the sporulation of the three Azolla species was 2.5 μg ml^–1, which was used in the subsequent investigations. Efficacy of GA for enhancing sporulation was tested across 20 Azolla pinnata strains. A significant positive response was observed in all the strains. Of them, 17 strains for the sporulation frequency and 15 strains for the sporocarp number showed a >25% increase due to GA treatment. Under field conditions, Azolla microphylla (two strains), Azolla caroliniana and Azolla pinnata exhibited 66.0–88.1% higher sporulation frequency and 42.8–52.6% higher sporocarp number due to GA application. However, the proportion of megasporocarps to total sporocarps did not change. Received: 4 August 1998     

Changes in ovary and testis and breeding fitness of the climbing perch,Anabas testudineus (Bloch, 1792), exposed to sub‐lethal concentrations of monocrotophos

Monocrotophos (MCP) is one of the organophosphate pesticides extensively used in agriculture and animal husbandry. The present study reports the effects of sub‐lethal concentrations of MCP on gonadosomatic index (GSI), gonadal histology and breeding fitness of the fish Anabas testudineus. The fish were exposed to three sub‐lethal concentrations of monocrotophos (T1: 3.5 mg/L, T2: 5.3 mg/L and T3: 10.6 mg/L) for 45 days with 12 fish (males and females in equal numbers) in each tank, and one group was kept as control (C) without any treatment. GSI decreased in all treatment groups in comparison with control. Significant decrease in fertilization and hatching rate was observed at all concentrations in comparison with control on 15, 30 and 45 days of monocrotophos exposure. The decreased vitellogenesis, disruption of follicular wall and oocyte atresia were observed in all the treated females at 30 and 45 days of exposure. Rupture of seminiferous tubules was noticed in all the treated males irrespective of exposure periods. The results thus indicated that monocrotophos could deleteriously impact the gonadal structure and function in A. testudineus, which could seriously impact the reproductive success of the animal.     

Rehabilitation of degraded sodic lands during a decade of Dalbergia sissoo plantation in Sultanpur District of Uttar Pradesh,India

The ameliorative effect of Dalbergia sissoo, planted on sodic land at Sultanpur (26° 10′–26° 40′N, 81° 45′–82° 30′E), India, in a tropical environment, was studied at 3, 6 and 9 years of age. The soil properties of the sites improved significantly, showing marked reduction in pH, electrical conductivity (EC) and exchangeable sodium percentage (ESP) and an increase in organic carbon, nitrogen and availability of nutrients in the soil. The significant reduction in Na ion was found in all the age groups. Results showed an improvement in the soil moisture regime due to increased infiltration rate (cm hr⁻¹), soil permeability (cm²), water‐holding capacity, field capacity and pore space whereas, the bulk density decreased significantly after successive years of planting. The effect on soil attributes was confined to surface soil in the young plantation and deeper in older plantation. Therefore, the study clearly indicated that the sodic soil could be desodified by growing D. sissoo plantations on these degraded sites. Copyright © 2002 John Wiley & Sons, Ltd.     

Identification of potential sources of mungbean yellow mosaic India virus resistance in black gram (Vigna mungo) and expression of antioxidants and R-genes modulating resistance response in cultivated and its two wild relatives

Black gram is one of the most important short duration grain legume, which contributes significantly towards nutritional security and environmental sustainability. The virus specific primers confirms the presence of mungbean yellow mosaic India virus (MYMIV) in representative samples. A total of 27 cultivated and two wild species were found as highly resistant (HR) to MYMIV and validated through molecular markers. The start codon target (SCoT) markers analysis revealed that the SCoT loci, namely, SCoT-4 (2200 bp), SCot-9 (1150/ 1200 bp), SCoT-15 (1150/1100 bp), SCoT-16 (700 bp), SCoT-24 (2500 bp), SCoT-25 (700 bp), SCoT-33 (900/1000 bp), and SCoT-34 (600 bp), were found unique, able to distinguish HR and highly susceptible (HS) genotypes. Biochemical characterization and gene expression profiling revealed the higher expression of antioxidants and R-genes just after pathogen inoculation indicated the activation of defence mechanism in both cultivated and its wild relatives, which modulates the resistant responses in cultivated and wild accessions. These information will be really helpful in accelerating resistance breeding in black gram.     

Comparative evaluation of MCP gene in worldwide strains of Megalocytivirus (Iridoviridae family) for early diagnostic marker

Members of the Iridoviridae family have been considered as aetiological agents of iridovirus diseases, causing fish mortalities and economic losses all over the world. Virus identification based on candidate gene sequencing is faster, more accurate and more reliable than other traditional phenotype methodologies. Iridoviridae viruses are covered by a protein shell (capsid) encoded by the important candidate gene, major capsid protein (MCP). In this study, we investigated the potential of the MCP gene for use in the diagnosis and identification of infections caused Megalocytivirus of the Iridoviridae family. We selected data of 66 Iridoviridae family isolates (53 strains of Megalocytivirus, eight strains of iridoviruses and five strains of Ranavirus) infecting various species of fish distributed all over the world. A total of 53 strains of Megalocytivirus were used for designing the complete primer sets for identifying the most hypervariable region of the MCP gene. Further, our in silico analysis of 102 sequences of related and unrelated viruses reconfirms that primer sets could identify strains more specifically and offers a useful and fast alternative for routine clinical laboratory testing. Our findings suggest that phenotype observation along with diagnosis using universal primer sets can help detect infection or carriers at an early stage.     

Mechanical,thermal and interfacial properties of green composites from basalt and hybrid woven fabrics

Composites based on pure Basalt and Basalt/Jute fabrics were fabricated. The mechanical properties of the composites such as flexural modulus, tensile modulus and impact strength were measured depending upon weave, fiber contents and resin. Dynamic mechanical analysis of all composites were done. From the results it is found that pure basalt fiber combination maintains higher values in all mechanical tests. Thermo-gravimetric (TG/DTG) composites showed that thermal degradation temperatures of composites shifted to higher temperature regions compared to pure jute fabrics. Addition of basalt fiber improved the thermal stability of the composite considerably. Scanning electron microscopic images of tensile fractured composite samples illustrated that better fiber-matrix interfacial interaction occurred in hybrid composites. The thermal conductivity of composites are also investigated and thermal model is used to check their correlation.     

Effects of water exchange protocols on water quality,sedimentation rate and production performance of Penaeus monodon in earthen ponds

This study was carried out in farmers' fields to quantify the total water and consumptive water use in grow‐out culture of Penaeus monodon under recommended package of practice with two different water management protocols: T₁, with no water exchange and T₂, with regulated water exchange. Treatment‐wise estimated total water use, was 2.09 and 2.43 ha‐m 122 day^?1, while the computed consumptive water use index (m³ kg^?1 biomass) was 5.35 and 6.02 in T₁ and T₂ respectively. Lower rates of water exchange (T₂) showed significantly improved (P < 0.05) crop performance in terms of performance index (19.75 ± 0.75), production‐size index (74.1 ± 3.4), survival rate (80.13 ± 1.7%) and productivity (2.44 ± 0.08 t) over the zero water exchange. The shrimp pond water quality suitability index (WQSI) infers that regulated water exchange (T₂) improved the overall suitability of water quality for shrimp culture. WQSI up to 90 days of culture ranged between 7.5–9.0 in T₂, needs little management while in the last month of rearing, it was good with moderate management requirements. Treatment‐wise sediment load ranged between 50.4–56.3 m³ t^?1 shrimp biomass. High intensity of water exchange and low apparent feed conversion ratio influenced in lowering the sedimentation rate. Regulated water exchange protocol (T₂) performed well (higher net total water productivity and net consumptive water productivity) against no water exchange (T₁). A higher OV:CC ratio (ratio of the output value to the cost of cultivation) indicated that T₂ had a distinct edge over the T₁ protocol.     

Evaluation of genetic architecture and mutation drift equilibrium of Marathwada buffalo population in Central India

In the present study, microsatellite data on 24 loci were generated and utilized to evaluate the genetic architecture and mutation drift equilibrium of Marathwada buffaloes, a Central Indian population maintained under low input system. Sufficient allelic diversity was observed with a total of 109 alleles across different loci. The genetic diversity analysis of Marathwada buffaloes displayed moderate level of within breed variability in terms of mean number of alleles per locus (4.48) and heterozygosity values (Ho = 0.532, He = 0.624). The studied Indian buffalo population showed considerable heterozygote deficiency (F_IS = 0.138) and deviation from HWE at many investigated loci. Three quantitative tests viz. sign test, standardized difference test and Wilcoxon sign rank test and a qualitative test for mode shift distortion of allelic frequencies were employed to evaluate mutation drift equilibrium under three different models of microsatellite evolution. The population was found to deviate significantly under IAM and TPM, while it was reverse under SMM. The qualitative test for mode shift supported the results under SMM indicating the absence of genetic bottleneck in the recent past in Marathwada buffaloes.