Modification in spinach response to UV-B radiation by nutrient management: Pigments, antioxidants and metabolites

Fertilizers are extensively used essentially to meet the food demand of increasing population. Further, they help the plants in alleviating the deleterious effects of UV-B radiation. In this study, we explored this in spinach (Spinacia oleracea L.). S. oleracea plants were grown under ambient and elevated UV-B at different combinations and concentrations of NPK: (i) recommended level of NPK (RNPK); (ii) 1.5 times recommended level of NPK (1.5 × NPK); (iii) 1.25 times recommended level of N plus recommended PK (1.25N+PK); and (iv) 1.25 times recommended level of NPK (1.25 × NPK) to assess the amelioration potential of nutrient combination. Higher availability of NPK provided more protection to plants against oxidative stress as is obvious from reduction in MDA content under elevated UV-B which can be attributed to low oxidative stress due to higher induction of antioxidants. Protection provided to chlorophyll by nitrogen was enhanced by phosphorus and potassium in 1.5 × NPK and 1.25 × NPK compared to RNPK and 1.25 × N+ PK. Maximum increase in PAL activity in plants at 1.5 × NPK did not translate into flavonoid accumulation in same at initial age of observation. Maximum alleviation against UV-B radiation was observed at 1.5 × NPK which can be attributed to better ROS scavenging capacity, more metabolite production and maintaining photochemical efficiency.

Effects of municipal waste water irrigation on availability of heavy metals and morpho-physiological characteristics of Beta vulgaris L.

In the present study physiological, biochemical and growth characteristics of a leafy vegetable palak (Beta vulgaris L. var All green H1) grown in suburban areas irrigated by wastewater were compared with those irrigated by ground water. Continuous use of wastewater for irrigation led to the enrichment of micronutrients including heavy metals in the soil. Wastewater irrigation favorably affected the physiological, biochemical and growth characteristics of plants, but biomass and yield did not differ significantly between the sites. Uptake and translocation ratio of heavy metals were higher in plants grown at wastewater irrigated site. Mn showed maximum uptake followed by Zn, Cu, Pb, Ni Cr and Cd. Plants produced more secondary metabolites and antioxidants to tolerate against the negative impact of heavy metals at wastewater irrigated sites. Plants produced more metabolites to compensate the toxicity of metals in the area and thus did not enhance the yield and biomass potential. The study suggests that plants growing in wastewater irrigated area have potentially developed the defense strategy to combat against heavy metal toxicity.

Acid rain and its ecological consequences.

Acidification of rain-water is identified as one of the most serious environmental problems of transboundary nature. Acid rain is mainly a mixture of sulphuric and nitric acids depending upon the relative quantities of oxides of sulphur and nitrogen emissions. Due to the interaction of these acids with other constituents of the atmosphere, protons are released causing increase in the soil acidity Lowering of soil pH mobilizes and leaches away nutrient cations and increases availability of toxic heavy metals. Such changes in the soil chemical characteristics reduce the soil fertility which ultimately causes the negative impact on growth and productivity of forest trees and crop plants. Acidification of water bodies causes large scale negative impact on aquatic organisms including fishes. Acidification has some indirect effects on human health also. Acid rain affects each and every components of ecosystem. Acid rain also damages man-made materials and structures. By reducing the emission of the precursors of acid rain and to some extent by liming, the problem of acidification of terrestrial and aquatic ecosystem has been reduced during last two decades.

Development of ground vegetation under exotic tree plantations on restored coal mine spoil land in a dry tropical region of India.

Restoration of mine spoil is a prime need for coal industry. The study of ground cover vegetation provides essential information about the species diversity and their successional trends during the restoration. The present study was conducted to analyze the structure and biomass accumulation of ground vegetation developing in different plantation stands of an opencast coal mine spoil in a dry tropical region. Different plantation stands showed variations in species diversities. Exotic herbs were more dominant in comparison to native herbs. Pennisetum pedicillatum, an exotic herb showed maximum Importance Value Index in most of the plantation stands. Total number of species varied between 12-18 in different plantation stands. Speces richness and evenness increased with increasing age of the plantations. Variations in total biomass accumulation of ground vegetation were also significant among different plantations. These results suggest that reforestation programme with exotic species on coal mine spoil has been successful in colonization of ground vegetation under different plantations. Gravellia pteridifolia plantations showed most successful ground cover among different plantation stands.

Biological effects of heavy metals: an overview.

Heavy metals constitute a very heterogeneous group of elements widely varied in their chemical properties and biological functions. Heavy metals are kept under environmental pollutant category due to their toxic effects on plants, animals and human being. Heavy metal contamination of soil results from anthropogenic as well as natural activities. Anthropogenic activities such as mining, smelting operation and agriculture have locally increased the levels of heavy metals such as Cd, Co, Cr, Pb, As and Ni in soil up to dangerous levels. Heavy metals are persistent in nature, therefore get accumulated in soils and plants. Heavy metals interfere with physiological activities of plants such as photosynthesis, gaseous exchange and nutrient absorption, and cause reductions in plant growth, dry matter accumulation and yield. Heavy metals also interfere with the levels of antioxidants in plants, and reduce the nutritive value of the produce. Dietary intake of many heavy metals through consumption of plants has long term detrimental effects on human health.