Management of purple blotch and Stemphylium blight of onion in Tarai and Bhabar regions of Uttarakhand, India

Purple blotch [Alternaria porri] (Ellis) Cif.) and Stemphylium blight [Stemphylium vesicarium] (Wallr.) E. Simmons) of onion cause serious problems in onion seed crop in Tarai and Bhabar region of Uttarakhand. In present study different bio agents and fungicides have been evaluated in vivo against both the diseases. The severity of both purple blotch and Stemphylium blight varied in both Tarai and Bhabar region and even more pronounced in Tarai region than in Bhabar region. A correlation was observed in between the severity of both the diseases with the yield in seed crop. The minimum disease severity of purple blotch and stemphylium blight with the foliar spray of mancozeb (@ 0.3%) + monochrotophos (@ 0.05%) were observed 2.67% and 2.57% respectively with the total yield of seed was1844.44 kg/ha over check 893.33 kg/ha in 2011. While with the foliar spray of neembicidine (@ 0.3%) disease severity of both the diseases were 5.57% and 4.78% respectively providing a yield of 1827.78kg/ha in seed crop of onion in 2011. Amongst the applied bio-agents, the foliar spray of Trichoderma harzianum (@ 1%) the disease severity of purple blotch and stemphylium blight were recorded 15.44% and 13.11% respectively which was found to be most effective in delaying the disease appearance and providing a yield of 1134.44kg/ha in 2011. However, all the treatments helped to reduce both the diseases in comparison with check

Rhizospheric bacteria: the key to sustainable heavy metal detoxification strategies

The increasing rate of industrialization, anthropogenic, and geological activities have expedited the release of heavy metals (HMs) at higher concentration in environment. HM contamination resulting due to its persistent nature, injudicious use poses a potential threat by causing metal toxicities in humans and animals as well as severe damage to aquatic organisms. Bioremediation is an emerging and reliable solution for mitigation of these contaminants using rhizospheric microorganisms in an environmentally safe manner. The strategies are based on exploiting microbial metabolism and various approaches developed by plant growth promoting bacteria (PGPB) to minimize the toxicity concentration of HM at optimum levels for the environmental clean-up. Rhizospheric bacteria are employed for significant growth of plants in soil contaminated with HM. Exploitation of bacteria possessing plant-beneficial traits as well as metal detoxifying property is an economical and promising approach for bioremediation of HM. Microbial cells exhibit different mechanisms of HM resistance such as active transport, extra cellular barrier, extracellular and intracellular sequestration, and reduction of HM. Tolerance of HM in microorganisms may be chromosomal or plasmid originated. Proteins such as MerT and MerA of mer operon and czcCBA, ArsR, ArsA, ArsD, ArsB, and ArsC genes are responsible for metal detoxification in bacterial cell. This review gives insights about the potential of rhizospheric bacteria in HM removal from various polluted areas. In addition, it also gives deep insights about different mechanism of action expressed by microorganisms for HM detoxification. The dual-purpose use of biological agent as plant growth enhancement and remediation of HM contaminated site is the most significant future prospect of this article