Uday Burman

Influence of Water Stress on Water Relations, Photosynthetic Parameters and Nitrogen Metabolism of Moth Bean Genotypes

Effects of water stress at pre-flowering stage were studied in three genotypes (RMO-40, Maru moth and CZM-32 E) of moth bean [Vigna aconitifolia (Jacq.) Marechal]. Increasing water stress progressively decreased plant water potential, leaf area, net photosynthetic rate, starch and soluble protein contents and nitrate reductase activity while contents of reducing sugars, total soluble sugar, free amino acids and free proline progressively increased. Significant genotypic differences were observed and genotype CZM-32-E displayed a better drought tolerance than other genotypes.

Effect of zinc oxide nanoparticles on growth and antioxidant system of chickpea seedlings

Ten days old seedlings of chickpea (Cicer arietinum L var. HC-1) were foliar sprayed with 1.5 or 10 ppm aqueous solution of zinc oxide (ZnO) nanoparticles and effects were compared with corresponding concentration of zinc sulphate and ZnO of normal size. Maximum promontory response with respect to shoot dry weight was observed in seedlings treated with 1.5 ppm ZnO nanoparticles while at 10 ppm the nanoparticles exerted adverse effects on root growth. However, overall biomass accumulation improved in the ZnO nanoparticle treated seedlings. This response may be attributed to low reactive oxygen species (ROS) levels which resulted in less lipid peroxidation as evident from lower malondialdehyde (MDA) content. This was associated with lower activity of prominent antioxidant enzymes, superoxide dismutase (SOD), and peroxidase ZnO nanoparticle treated seedling compared to control. The study indicates importance in precise application of zinc, more so in deficient system, where plant response varies with concentration and is important in understanding the mechanism of action of specific nanomaterials.

Interactive effects of thiourea and phosphorus on clusterbean under water stress

Effects of phosphorus and thiourea application (either alone or in combination) were studied on clusterbean (Cyamopsis tetragonoloba Taub.) plants subjected to water stress by withholding irrigation at pre- and post-flowering stages in pot culture trial. Water stress significantly decreased shoot water potential, relative water content of leaves, net photosynthetic rate, contents of total chlorophyll, starch and soluble proteins as well as nitrate reductase activity at both the growth stages. Application of phosphorus and thiourea or combined application increased most of these parameters. Results revealed synergistic effects of P and thiourea in enhancing net photosynthesis, leaf area, chlorophyll content and nitrogen metabolism leading to significant improvement in plant growth and seed yield under water stress condition.

Influence of nitrogen fertilization on water relations, photosynthesis, carbohydrate and nitrogen metabolism of diverse pearl millet genotypes under arid conditions

Effects of nitrogen fertilization (80 kg N/ha) were studied on pearl millet (Pennisetum glaucum) genotypes including hybrids (MH-179 and HHB-67), composites (CZ-IC-923 and CZP-9604) and land races (Barmer population and CZ-IC-718) grown for 2 consecutive years (1997 and 1998) under rainfed conditions of the Indian arid zone. Nitrogen application significantly increased the grain and stover yields in all the genotypes, particularly in the hybrids during both the years but more so in 1997, characterized by late onset of rains followed by adequate precipitation (299.5 mm). Notwithstanding lower plant water potential and leaf relative water content, N fertilized plants displayed significantly higher photosynthetic rates, leaf area, levels of total chlorophyll, starch, reducing sugars, soluble protein and free amino acids and nitrate reductase activity as compared with unfertilized control plants in all the genotypes during both the years. Genotypes HHB-67 and Barmer population during 1997 and HHB-67 and CZ-IC-718 during 1998 provided significantly higher grain yields than other genotypes whereas dry matter production was highest in cv. Barmer population during both the years. These genotypes generally maintained higher rates of photosynthesis, more efficient carbohydrate metabolism and higher nitrate reductase activity leading to better performance. Relatively higher yields of land races than composites and comparable with those of hybrids indicated adaptation of these cultivars to arid conditions and maintenance of several characteristics for their superior performance which could be further augmented by N application. Fertility induced improvement of metabolic efficiency, coupled with higher photosynthesis and nitrate reductase activity for efficient N utilization seem to be the control mechanisms, for enhanced growth and yield of diverse pearl millet genotypes under limited water conditions.

Magnesium and iron nanoparticles production using microorganisms and various salts

Response of five fungi and two bacteria to different salts of magnesium and iron for production of nanoparticles was studied. Pochonia chlamydosporium, and Aspergillus fumigatus were exposed to three salts of magnesium while Curvularia lunata, Chaetomium globosum, A. fumigatus, A. wentii and the bacteria Alcaligenes faecalis and Bacillus coagulans were exposed to two salts of iron for nanoparticle production. The results revealed that P. chlamydosporium induces development of extracellular nanoparticles in MgCl2 solution while A. fumigatus produces also intracellular nanoparticles when exposed to MgSO4 solution. C. globosum was found as the most effective in producing nanoparticles when exposed to Fe2O3 solution. The FTIR analysis of the nanoparticles obtained from Fe2O3 solution showed the peaks similar to iron (Fe). In general, the species of the tested microbes were selective to different chemicals in their response for synthesis of nanoparticles. Further studies on their characterization and improving the efficiency of promising species of fungi need to be undertaken before tapping their potential as nanonutrients for plants.

Effect of Phosphorus Application on Clusterbean under Different Intensities of Water Stress

ABSTRACT Response of clusterbean [Cyamopsis tetragonoloba (L.) Taub.] to phosphorus (P) application (0 and 40 kg ha−1) under different intensities of water stress at the critical pre-flowering stage was studied in a pot trial by withholding irrigation for 0, 3, 6, and 9 days. Increasing stress intensity progressively decreased plant water potential (Ψplant), relative water content, levels of different leaf metabolites, photosynthetic rate, and nitrate reductase activity under both phosphorus (P) treatments. However, P-fertilized plants displayed higher photosynthetic efficiency, leaf metabolism, and enzyme activity than unfertilized plants, though decrease in plant water status was more in P-fertilized plants. Recovery upon rewatering was also more in P-fertilized than unfertilized plants with respect to all the parameters studied. Consequently, P application significantly enhanced dry matter and seed yields at all stress intensities. The results indicate the possibility of alleviation of water stress effects by P nutrition in clusterbean, at least up to moderate stress level.

Water management of transplanted seedlings of Azadirachta indica in arid areas

Abstract Large mortality and general growth restriction of transplanted tree seedlings in the Indian arid zone prompted this study on the effects of different levels (1/4, 1/2, 3/4 and full field capacity (FC)) and intervals (1, 2, 4 and 6 weeks) of irrigation, during the first dry period (September to July), following transplantation. Results are expressed as increases in height and stem diameter over time in relation to soil moisture regime and plant water status under different treatments. Final measurements 450 days after starting irrigation treatments indicated that watering at FC at 1- and 2-week intervals brought about the maximum increase in height and stem diameter, which declined progressively with increasing intervals and decreasing level. Despite the similarity in trend, final biomass production and crown area were highest under watering at FC at a 2-week interval due to larger increase in stem and foliage weight. Limited data on root growth along a single vertical plane suggested that branching of root laterals was mostly confined to the 10–50-cm depth irrespective of irrigation treatments, while depth of rooting tended to increase at longer intervals of watering. Under the prevailing conditions, average application of 46 1 (FC) per plant at 2-week intervals led to maximum growth and biomass production with no mortality, while under the low-threshold average irrigation of 121 (1/4 FC) per plant at 2-week intervals could eliminate mortality although the biomass production was reduced by about 91%.

Plant Response to Engineered Nanoparticles

Abstract Nanoparticles possess unique properties such as a large specific surface area and consequently greater reactivity than macro-sized particles. Therefore questions concerning their potential adverse effects on human and environmental health have often been raised. They are being widely used in consumer products and are thus expected to find their way into aquatic, terrestrial, and atmospheric environments, where their fate and behavior are unpredictable. Therefore plants that interact strongly with their immediate environments are expected to be affected as a result of exposure to the nanoparticles. Factors influencing the entry of nanoparticles into a plant cell are shape and size of the nanoparticles in addition to size of the cell wall pore. Selective permeability exercised by the cell membrane also influences the entry as well as surface characteristics, charge, and configuration of nanoparticles. After entering through the cell wall they move from cell to cell either apoplastically or symplastically and in that process they may reach locations that are far from the application point. Aggregation of metallic nanoparticles can be further guided by external magnetic forces and this forms the basis of their target delivery, which could also be achieved in the case of nonmetallic nanoparticles by surface characteristics that facilitate specific conjugate bonding. Dissolution potential of the nanoparticle, relative proportion of endocytosis and exocytosis, and characteristics of reaction environment are other factors that regulate the entry of nanoparticles in plants. Because nanoparticles of varying characteristics are able to enter the plant because of one or more factors enumerated in the preceding paragraph, they reflect both positive and negative effects on plant growth. However, the response of plants to nanomaterials varies with the type of plant species, their growth stages, and the nature of nanomaterials. Furthermore, the situation becomes more complex because of variation in the characteristics of the medium in which the plant grows, and even more so in soil. These effects stem from their potential to differentially influence a proportion of free radicals and plant hormones in addition to regulation of transmembrane transport. A positive effect on specific enzyme conjugate formation, nucleic acid synthesis coupled with improved carbon and nitrogen metabolism results in biomass accumulation, while enhanced oxidative stress and membrane damage induce ion leakage resulting in reduced growth. There are many gaps in our knowledge and there are many unresolved problems and new challenges concerning the biological effects of these nanoparticles. This, coupled with lack of proper legislation related to the use of nanomaterials, their confinement, and disposal, further aggravates the problem of ecotoxicity of nanoparticles. However, the development of nanomaterials that are biodegradable in soil and the environment, in addition to being less toxic, would be ideal for agricultural production. This chapter enumerates the details related to the response of plants to the exposure of nanoparticles, and clearly elucidates the intricacies of the different facets of their interaction at cellular, organ, and whole plant levels.

Ecological Risks of Nanoparticles: Effect on Soil Microorganisms

Abstract A large part of the more than 11 million tons of nanomaterials produced every year are metal and metal oxide nanoparticles (NPs), which ultimately end up in soil. NPs could enter into microbial cells either through endocytosis or by penetrating cells, and many of them, especially silver, copper, and zinc, have antimicrobial properties. Thus after entering the soil, NPs could adversely affect microorganisms present and disrupt essential functions of the soil. The effect of NPs on microorganisms and the mechanisms of their toxicity are comprehensively reviewed and discussed in this chapter. Both physical characteristics and chemical interactions of NPs at the nano–bio interface could elicit toxic effects, depending on their physical structure and chemical composition. Physical interactions, depending on size and surface properties of NPs at the nano–bio interface, could cause membrane disintegration and interference in transport processes. NPs, which are the same size as a protein molecule, interact with proteins and change their configuration, thus obstructing signaling processes in cells. Their shape can also affect toxicity by influencing uptake efficiency (rod-shaped NPs show maximum uptake and cubes minimum uptake), subsequently causing physical disintegration of membranes (truncated triangular silver nanoplates display the strongest biocidal action against Escherichia coli ). Once inside the cells, NPs affect the catalytic activity of enzymes and stability of protein structures. Release of metal ions and the generation of reactive oxygen species restrict normal physiological redox-regulated functions of cells and lead to oxidative modification of proteins, which causes mortality of cells. Carbon-based NPs are less toxic than metal or metal oxide NPs but generation of reactive oxygen remains a major mechanism behind their toxicity.

Utilizing Geo-information Tools for Mapping Spatio-temporal Changes in Population of Prosopis cineraria (khejri) in Agroforestry System of Arid Western Rajasthan

The present study is an attempt to assess the spatial variability and the changes in the population of Prosopis cineraia (khejri) trees in the agroforestry systems of arid part of western Rajasthan. This tree is regarded as an important natural resource for the rural livelihood of desert dwellers because of its multifarious uses. The tree populations were mapped in a geographical information system using available information from aerial photographs, google earth images and IRS-LISS-III satellite images to compare their populations between the past and the very recent period. Mapping carried out in a part of Nagaur district in western part of Rajasthan, indicated increase in khejri trees in the region in 2013–2014 compared to 1960s. The number and tree density were higher under irrigated croplands than under rainfed. Increase in rainfall, multiple uses of the tree, societal and scientific support are the key reasons for the observed changes in their population.