Assessment of growth and yield losses in two Zea mays L. cultivars (quality protein maize and nonquality protein maize) under projected levels of ozone

Rapid industrialization and economic developments have increased the tropospheric ozone (O₃) budget since preindustrial times, and presently, it is supposed to be a major threat to crop productivity. Maize (Zea mays L.), a C4 plant is the third most important staple crop at global level with a great deal of economic importance. The present study was conducted to evaluate the performance of two maize cultivars [HQPM1: quality protein maize (QPM)] and [DHM117: nonquality protein maize (NQPM)] to variable O₃ doses. Experimental setup included filtered chambers, nonfiltered chambers (NFC), and two elevated doses of O₃ viz. NFC+15 ppb O₃ (NFC+15) and NFC+30 ppb O₃ (NFC+30). During initial growth period, both QPM and NQPM plants showed hormetic effect that is beneficial due to exposure of low doses of a toxicant (NFC and NFC+15 ppb O₃), but at later stages, growth attributes were negatively affected by O₃. Growth indices showed the variable pattern of photosynthate translocation under O₃ stress. Foliar injury in the form of interveinal chlorosis and reddening of leaves due to increased production of anthocyanin pigments was observed at higher concentrations of O₃. One-dimensional gel electrophoresis of leaves taken from NFC+30 showed reductions of major photosynthetic proteins, and differential response was observed between the two test cultivars. Decline in the number of male flowers at elevated O₃ doses suggested damaging effect of O₃ on reproductive structures which might be a cause of productivity losses. Variable carbon allocation pattern particularly to husk leaves, foliar injury, and damage of photosynthetic proteins led to significant reductions in economic yield at higher O₃ doses. PCA showed that both the cultivars responded more or less similarly to O₃ stress in their respective groupings of growth and yield parameters, but magnitude of their response was variable. It is further supported by difference in the significance of correlations between variables of yield and AOT40. Cultivar response reflects that QPM performed better than NQPM against elevated O₃.     

Differences in responses of summer and winter spinach to elevated UV-B at varying soil NPK levels

Seasonal variations in response of spinach to elevated ultraviolet-B (UV-B) during summer and winter were assessed with respect to growth, biomass, yield, NPK uptake and NPK use efficiencies at varying NPK levels. The nutrient amendments were recommended NPK (RNPK) and 1.5 times recommended NPK (1.5 RNPK). Season significantly affected the measured parameters except the number of leaves. Under ambient UV-B, the growth performance of summer spinach was better in both the NPK levels, higher being at 1.5 RNPK leading to higher nutrient uptake. However, more reduction in biomass under elevated UV-B in 1.5 RNPK was recorded during summer, while during winter in RNPK. Reduction in biomass under elevated UV-B was accompanied by the modification in its partitioning with more biomass allocation to root during summer compared to winter at both the NPK levels. NPK uptake was higher in summer, while NPK use efficiencies were higher during winter. At higher than recommended NPK level, better NPK use efficiencies were displayed during both the seasons. Increased NPK supply during winter enabled spinach to capitalize light more efficiently and hence increased biomass accumulation. Strategies for surviving elevated UV-B in winter differ from those that provided protection from the same stress when it occurs in summer.     

The evolutionary consequences of mate copying on male traits

In some species, a female's mating preference can be influenced by the matings she observes. Mate copying occurs when a female alters her mating preference in favor of the type of males she has observed mating with other females. Here I present a model that explores the consequences of mate copying on the evolution of male traits. In contrast to previous work, I show that mate copying can have diverse evolutionary consequences. Mate copying can cause (positive or negative) directional selection on male traits or (positive or negative) frequency-dependent selection on male traits. The type of selection generated by mate copying depends on the details of how females are influenced by the matings that they observe. I discuss my results in relation to previous theoretical work that posits that mate copying can only hamper the spread of novel male traits.     

Impact assessment of a hydroelectric project on the flora in the Western Himalayan region based on vegetation analysis and socio-economic studies

This study provides an overview of the impacts of a proposed hydroelectric power project in the Western Himalayan region in India, using a primary database on floristic diversity and vegetation analysis. The remote sensing data revealed that in the submergence zone only mixed deciduous forest that occupies 807.5 ha area and has a wood biomass volume of 4,027,503 m³ is likely to be lost due to impoundment. A total of 165 plant species found in the submergence zone also occur in the influence and free draining catchment area of the project. In the influence zone of the project area only one tree species (Acer oblongum) is found under conservation threat category, which is also present in the free draining catchment of the project. The project affected population (6716 people) residing in the submergence and influence zone depend upon the surrounding forests for fuel wood, fodder, wild edibles etc., and most likely they will settle in the nearby areas, thus mounting more pressure on residual forests of the influence zone for various forest products. Further, from the vegetation analysis it is evident that several tree species (e.g. Lannea coromandelica, Terminalia alata, T. bellerica etc.), may face more pressure from exploitation as they provide a number of useful products and are represented in lower numbers in the forests of the project area. To compensate for the loss of various goods and services provided by the forests falling in the submergence zone and to offset the increased pressure of the project affected families on the forests of influence zone, a biodiversity management plan is suggested incorporating socio-economic considerations.     

Analytical modelling of residual stresses in orthogonal machining of AISI4340 steel

Residual stress profile in a component is often considered as the critical characteristic as it directly affects the fatigue life of a machined component. This work presents an analytical model for the prediction of residual stresses in orthogonal machining of AISI4340 steel. The novelty of the model lies in the physics-based approach focusing on the nature of contact stresses in various machining zones and the effect of machining temperature. The model incorporates: (i) stresses in three contact regions viz. shear, tool-nose-work piece and tool flank and machined surface, (ii) machining temperature, (iii) strain, strain rate and temperature dependent work material properties, (iv) plastic stresses evaluation by two algorithms, S-J and hybrid, (v) relaxation procedure and (iv) cutting conditions. The model benchmarking shows (86–88%) agreement between the experimental and predicted residual stresses in the X- and Y-directions. On the machined surface, the tensile residual stresses decrease with an increase the edge radius and increase with an increase the cutting speed. However, below the surface, the compressive residual stresses increase with an increase the depth of cut. Further, it is observed that the proposed model with hybrid algorithm gives better results at a lower feed rate, whereas with the S-J algorithm, at a higher feed rate.     

Physiological and biochemical responses of two cultivars of wheat to elevated levels of CO2 and SO2, singly and in combination

In view of the present increasing trends of anthropogenic emissions of carbon dioxide (CO2) and sulphur dioxide (SO2) throughout the world, the present study was aimed at investigating the long-term influence of elevated concentrations of CO2 and SO2, singly and in combination on the physiological and biochemical characteristics of two cultivars of wheat (Triticum aestivum L. cv. Malviya 234 and HP1209). For this purpose, the plants were grown in open top chambers under field conditions and were fumigated with 600 ppm CO2, 0.06 ppm SO2 and 600 ppm CO2 + 0.06 ppm SO2 separately for 8 h daily (0800-1600 h) from germination to grain maturity. The individual treatment of SO2 advers#ely affected both the cultivars of wheat by reducing protein and starch contents. The respiration rate, total soluble sugars and total phenolics, however, increased in response to SO2. Stimulation of photosynthesis rate and reduction in stomatal conductance and transpiration rate were observed under CO2 treatment. Concentrations of total soluble sugars, starch and total phenolics increased in response to CO2 and CO2 + SO2 treatments. In combined treatment, CO2 modified the plant response to SO2 in both the cultivars. Elevated CO2 increased the photosynthesis rate under combined treatment. Higher levels of starch and soluble sugars under combined treatment provided extra carbon for SO2 detoxification. The pattern of intraspecific response of wheat to different treatments was more or less similar, but the magnitude of response differed significantly.     

Effect of air pollution on peri-urban agriculture: a case study

Peri-urban agriculture is vital for the urban populations of many developing countries. Increases in both industrialization and urbanization, and associated air pollution threaten urban food production and its quality. Six hour mean concentrations were monitored for SO(2), NO(2) and O(3) and plant responses were measured in terms of physiological characteristics, pigment, biomass and yield. Parameter reductions in mung bean (Vigna radiata), palak (Beta vulgaris), wheat (Triticum aestivum) and mustard (Brassica compestris) grown within the urban fringes of Varanasi, India correlated directly with the gaseous pollutants levels. The magnitude of response involved all three gaseous pollutants at peri-urban sites; O(3) had more influence at a rural site. The study concluded that air pollution in Varanasi could negatively influence crop yield.     

Recent trends and current practices for secondary processing of zinc and lead. Part I: lead recovery from secondary sources.

Implementation of stricter environmental laws and economic reasons has forced all the metallurgical industries to go for eco-friendly technologies to produce metal and other related products. However, generation of wastes is an integral part of metallurgical industries. If the wastes/residues are hazardous in nature, they generally have to be treated or/and disposed of in safe and designated dumping sites. If these wastes/residues are non-hazardous in nature, then they may be suitable for use as secondary raw material to recover metals such as lead, copper etc., which are in growing demand all over the world. The processing of lead secondaries is important because of their relative high metal content, as well as the low energy and cost involved in recovering the metal. This paper mainly focuses on the current practices and recent trends in the secondary processing of lead. Various processes, particularly hydrometallurgical ones, already developed or in the development stages, are discussed. Attempts made by various Council of Scientific and Industrial Research (CSIR) Laboratories including the National Metallurgical Laboratory (NML) and industries such as Binani Zinc to develop eco-friendly processes for the recovery of lead from secondary raw materials are also described.     

Assessment of six Indian cultivars of mung bean against ozone by using foliar injury index and changes in carbon assimilation, gas exchange, chlorophyll fluorescence and photosynthetic pigments

Six Indian cultivars of Vigna radiata L. (HUM-1, HUM-2, HUM-6, HUM-23, HUM-24 and HUM-26) were exposed with ambient and elevated (ambient + 10 ppb ozone (O₃) for 6 h?day^?1) level of O₃ in open top chambers. Ozone sensitivity was assessed by recording the magnitude of foliar visible injury and changes in various physiological parameters. All the six cultivars showed visible foliar symptoms due to O₃, ranging 7.4 to 55.7 % injured leaf area. O₃ significantly depressed total chlorophyll, photosynthetic rate (Ps), quantum yield (F _v/F _m) and total biomass although the extent of variation was cultivar specific. Cultivar HUM-1 showed maximum reduction in Ps and stomatal conductance. The fluorescence parameters also indicated maximum damage to PSII reaction centres of HUM-1. Injury percentage, chlorophyll loss, Ps, F _v/F _m and total biomass reduced least in HUM-23 depicting highest O₃ resistance (R%).