Multi-environment testing for reduced incidence of peanut bud necrosis disease in India.

Forty groundnut genotypes were tested for field resistance (reduced incidence) to peanut bud necrosis disease during 3 years at four locations in India. The 40 genotypes were grouped into seven clusters using the average linkage cluster analysis. Clusters 1 and 2 contained highly susceptible genotypes (JL 24 and TMV 2). Susceptible to moderately susceptible genotypes formed clusters 3,4, and 5. Cluster 6 represented 29 fairly resistant genotypes, and cluster 7 had the most resistant genotypes [ICGV 86430, 2192- 8(50), and2169-5(9)]. Genotype x environment interaction variance was significant but small. The field resistance of the genotypes studied was equally effective in all environments. Selection in any of these environments is possible, but is more effective in environments which are favorable for disease development

Studies on the settlement and succession of macrofouling organisms in the Kalpakkam coastal waters, southeast coast of India

747-761<span style="font-size:11.0pt;font-family: " times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";mso-bidi-font-family:="" mangal;letter-spacing:.1pt;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:hi"="" lang="EN-GB">Study was carried out to evaluate the fouling pattern, dominant species and their seasonal succession in waters of east coast of India. Three series (weekly, monthly and cumulative) of teak wood panels were exposed to coastal waters.<span style="font-size:10.0pt;mso-bidi-font-size: 11.0pt;font-family:" times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";="" mso-bidi-font-family:mangal;letter-spacing:.1pt;mso-ansi-language:en-gb;="" mso-fareast-language:en-us;mso-bidi-language:hi"="" lang="EN-GB"> There is wide variation in the colonization of the biofoulers on the weekly panels.&nbsp;&nbsp; The lowest and the highest numbers of organisms observed were between 1 and 136 per cm2, respectively. Dominance of barnacles (12.4-99%) on weekly panels was found throughout the year. Sizeable contribution (~7% of the total density) of oyster settlement was observed for the first time from this locality. Pattern of ecological succession observed was barnacles - hydroids - sea anemones - ascidians and finally green mussels. Weekly results, available for the first time for this locality, form the baseline data for future reference and impact assessment studies. Biofouling biomass (g. per 100 cm2) of weekly panels varied between 1 and 11, however, a steep increase in biomass was observed in cumulative panels. These biomass values compared well with earlier results. Total number of fouling taxa observed was only 30. A shift in the peak settlement period of green mussels, was observed as compared to the earlier report. Environmental parameters such as salinity, chlorophyll and phytoplankton density appeared to have significant (p≥ 0.01) contribution on biofouling settlement.</span

Assessing heavy metal toxicity in sediments of Chennai Coast of Tamil Nadu using Energy Dispersive X-Ray Fluorescence Spectroscopy (EDXRF) with statistical approach

The concentration of some heavy metals: Al, Ca, K, Fe, Ti, Mg, Mn, V, Cr, Zn, Ni and Co in sediments from Pulicat Lake to Vadanemmeli along Chennai Coast, Tamil Nadu has been determined using EDXRF technique. The mean concentrations of Mg, Al, K, Ca, Ti, Fe, V, Cr, Mn, Co, Ni, and Zn were found to be 1918, 25436, 9832, 9859, 2109, 8209, 41.58, 34.14, 160.80, 2.85. 18.79 and 29.12 mg kg−1 respectively. These mean concentrations do not exceed the world crustal average. The level of pollution attributed to heavy metals was evaluated using several pollution indicators in order to determine anthropogenically derived contaminations. Enrichment Factor (EF), Geoaccumulation Index (Igeo), Contamination Factor (CF) and Pollution Load Index (PLI) were used in evaluating the contamination status of sediments. Enrichment Factors (EF) reveal the anthropogenic sources of V, Cr, Ni and Zn Geoaccumulation Index (Igeo) results reveal that the study area is not contaminated by the heavy metals. Similar results were also obtained by using pollution load index (PLI). The results of pollution indices indicates that most of the locations were not polluted by heavy metals. Multivariate statistical analysis performed using principal components and clustering techniques were used to identify the source of the heavy metals. The result of statistical procedures indicate that heavy metals in sediments are mainly of natural origin. This study provides a relatively novel technique for identifying and mapping the distribution of metal pollutants and their sources in sediment. Keywords: Sediments, EDXRF, Heavy metals, Pollution indices, Multivariate statistical method

Geochemical distribution of forms of phosphorus in marine sediment of Bay of Bengal, southeast coast of India

1132-1141Sediment samples were collected from three transects in the continental shelf region (up to 30km offshore) between Chennai to Marakkanam. Sedimentary parameters such as sand, silt, clay and organic carbon percentage were analyzed in order to find out their relation with various phosphorus fractions.  Sediment was found to be predominantly sandy in nature with low silt and clay content. Among all the fractions (loosely bound- Lo-P, calcium bound- Ca-P, iron bound- Fe-P, aluminum bound- Al-P and organically bound- OP), Ca-P fraction constituted the largest portion (71.38%) followed by OP (16.16%). Bioavailable fractions of phosphorus ranged from 9.3 to 36.2% (avg. 20.9%) of the total phosphorus (TP) during the present study. Total phosphorus content in the offshore sediments ranged between 469.35 and 1219.34 mg/kg with an average of 824.66 mg/kg. The abundance of the major forms of P in the surface sediments of Kalpakkam coast followed the order: Ca-P > OP > Al-P > Lo-P > Fe-P. Cluster analysis clearly showed that all the three transects were different from each other as they formed three different clusters