Authors:R. Kundu, K. Bhattacharyya, A. Majumder and S. Pal
Arsenic, the toxic metalloid, widely available in the natural ecosystem, poses serious problem through contaminated groundwater and drinking water. The emerging areas of arsenic hazards in agricultural systems through use of contaminated irrigation water and entry of toxin in crops has been largely overlooked. Arsenic accumulation by plants and its translocation to edible parts were observed to vary within crops and also across the cultivars. Wheat is an alternative choice of summer rice, due to low water requirement. With this background, the current experiment was conducted with four popular wheat cultivars to study the arsenic accumulation and varietal tolerance under different soils and groundwater. The arsenic content was determined by using atomic absorption spectrophotometer (AAS). Result revealed that, wheat cultivars differed in their grain arsenic concentration (0.23–1.22 mg kg−1), which differed across the sites and year of experiment. The arsenic translocation in wheat grains usually least, and accumulation by different tissues followed the order root > stem > leaf > grain across the cultivars. The cultivar UP-262 was found to accumulate least arsenic in grains and cultivar Kalyansona the highest under same growing condition, due to phyto-extraction or phyto-morphological potential of the varieties.
Authors:K.G. Mandal, K. Kannan, A.K. Thakur, D.K. Kundu, P.S. Brahmanand and A. Kumar
Three-year (2007/2008–2009/2010) field experiment was conducted at the Directorate of Water Management Research Farm under Deras command in Odisha, India to assess the crop yield, irrigation water use efficiency (WUE), sustainable yield index (SYI), land utilization index (LUI) and changes in soil organic carbon (SOC) for dominant rice systems, viz. rice-maize-rice, rice-cowpea-rice, rice-sunflower-rice, rice-tomato-okra and rice-fallow-rice. Results revealed that crop yield, in terms of total system productivity (TSP) increased by 273, 113, 106 and 58% in rice-tomato-okra, rice-sunflower-rice, rice-maize-rice and rice-cowpea-rice, respectively, when compared to rice-fallow-rice. Irrigation WUE was 49–414% greater in rice-based diversified systems than the existing rice-fallow-rice (2.98 kg ha−1 mm−1). The SYI ranged from 0.65 to 0.75 indicating greater sustainability of the systems. Three crops in a sequence resulted in greater LUI and production efficiency compared to rice-fallow-rice. The gross economic return and benefit-cost ratio was in the order: rice-tomato-okra > rice-maize-rice > rice-sunflower-rice > rice-cowpea-rice > rice-fallow-rice. The SOC storage ranged from 40.55 Mg ha−1 in rice-fallow-rice to 46.23 Mg ha−1 in rice-maize-rice system. The other systems had also very close values of SOC storage with the rice-maize-rice system; there was a positive change of SOC (7.20 to 12.52 Mg ha−1) for every system, with highest in rice-maize-rice system and the lowest in rice-fallow-rice. It is concluded that the appropriate rice-based system would be rice-tomato-okra followed by rice-maize-rice, rice-sunflower-rice and rice-cowpea-rice. Rice-fallow-rice is not advisable because of its lower productivity, lower LUI and economic return.
Authors:S. Dutta, A. Kundu, M. R. Chakraborty, S. Ojha, J. Chakrabarti and N. C. Chatterjee
Siderophores are low molecular weight
(<1000 D) iron chelating compounds produced by microorganisms. Production of
siderophore is a device of antagonism as by virtue of the capacity of
siderophore production, a microorganism competes for Fe (III) with the others.
Production of siderophores by 9 different soil fungi and wood-decay fungi was
studied following CAS - assay and CAS - agar plate assay. Optimization for the production of
siderophores was done by varying the levels of pH and Fe (III) concentrations
in the low nutrient medium. All the test fungi could produce siderophores,
though the degree of production recorded to be very low both in Botryodiplodia
theobromae and in Fusarium spp. On the other hand, all the species of
Trichoderma showed their excellency in siderophore production. The optimum pH
for production of siderophores remained at neutral pH level though the range
varied from pH 6.0-8.0. The optimum range of the
concentration of Fe (III) required for siderophore production was recorded to
be 1.5-21.0 µM. However, the stress condition of
iron might be a decisive factor for siderophore production.