Seema Mahmood

Germination and seedling growth of corn (Zea mays l.) under varying levels of copper and zinc

The heavy metal tolerance in corn (Zea mays L.) var. ‘Neelum’ was assessed at germination and seedling growth after having subjected it to different concentrations of CuSO4 and ZnSO4. Germination was not affected by any of the metal tested, whereas initial growth was strongly inhibited by increasing concentrations of ZnSO4. Seedlings developed toxicity symptoms in the presence of both metals but more chlorotic and necrotic regions were observed at varying levels of ZnSO4 than CuSO4. The metal accumulation was concentration dependent. Z. mays seedlings accumulated more copper in roots but greater contents of zinc in their shoots. On the basis of results presented here, it can be concluded that the cultivar of the species tested has shown a marked sensitivity to the presence of small amounts of metals present in the growth medium. The data support the assumption that metal sensitivity is probably due to strong tendency of the species to accumulate them. This justifies that the corn variety ‘Neelum’ is not suitable for the cultivation under situations where water and soil suffer from occasional and/ or transitory metal pollution.

Biochar affects growth and biochemical activities of fenugreek ( Trigonella corniculata ) in cadmium polluted soil

Cadmium (Cd) has no defined biological role and may enter the food chain from polluted soils. Biochar has been proposed as an organic amendment to minimize the toxic effects of Cd for plants grown on contaminated soils. In this study, biometric and biochemical attributes of fenugreek (Trigonella corniculata) grown on artificially cadmium (Cd) contaminated soil (0, 25, 50, 75 and 100 mg Cd/kg soil) at three levels of cotton-sticks derived biochar (CSB; 0, 3 and 5 %) were studied. Data show significant decline in the growth, photosynthetic pigments (chlorophyll a, b and total, carotenoids, anthocyanin and lycopene), and physiological attributes (sub-stomatal CO2 concentrations, photosynthetic and transpiration rate) in the presence of high Cd concentrations (50 and 100 mg Cd/kg soil). However, the decline was reduced in the presence of CSB. A steady amplification in lipid peroxidation (assessed via Malondialdihyde (MDA)) and ascorbic-acid assembly was noted with increasing Cd. The concentration of Cd in the root and shoot also decreased with increasing CSB application rates from 3 % - 5 %. Overall, the greater production of protein, amino acids and sugar contents in response to higher application rates of CSB seems to be due to alleviation in Cd toxicity. Thus, cotton-sticks can be safely utilized in the form of biochar as amendment with additional benefit of reducing Cd bioavailability and toxicity to crop plants.

Dose dependent rhizospheric Ni toxicity evaluation: Membrane stability and antioxidant potential of Vigna species

8 CHILEAN JOURNAL OF AGRICULTURAL RESEARCH 76(1) JANUARY-MARCH 2016 3 ULY-SEPTEMBER Different concentrations of Ni are found in agricultural soil released from various environmental sources. The responses of plants grown in such soil-substratum vary accordingly depending upon the concentration of metal present and plant species. To assess the toxic effects of Ni and extent of plant defensive strategies, increasing Ni doses (50, 100, and 150 mg kg-1) were used in sandy-loam soil-substratum at pH 7.9 to evaluate the performance of Vigna species (V. cylindrica [L.] Skeels, V. mungo [L.] Hepper, and V. radiata [L.] R. Wilczek). The experiment was conducted in a complete randomized design. Nickel stress was induced by adding various concentrations of Ni chloride in soil substratum. Malondialdehyde (MDA) and antioxidant levels were determined in roots and leaves. Escalating levels of Ni in soil resulted in an affirmative relationship between MDA with that of antioxidants. A dose-dependent increase in the activity of Superoxide Dismutases (SOD), Catalase (CAT), and peroxidases (POD) suggested the existence of a sequence response of these enzymes to scavenge oxidative stress in the roots. However, inadequate production of SOD and CAT appeared to be compensated by the enhanced activity of POD, which acted as potent quencher to reactive oxygen species (ROS) in leaves. At the most elevated Ni dose, SOD, CAT and POD activities were insufficient to counteract ROS generated that led to membrane damage manifested by elevated MDA levels. Nevertheless, SOD and CAT alleviated Ni toxicity in roots while SOD, CAT and POD acted in a concurrent manner to protect leaves from oxidative damage in V. cylindrica. The study clearly indicated a Ni dependent antioxidant enzymes defense system in V. cylindrica.

Dust Interception Capacity And Alteration Of Various Biometric And Biochemical Attributes In Cultivated Population Of Ficus Carica L.

The dust accumulation capacity of Ficus carica L. was evaluated from eight different sites in and around Multan. The impact of dust accumulation was observed via various biometric attributes (leaf area, leaf fresh and dry weights) and biochemical attributes (chlorophyll contents, carotenoids & ascorbic acid) from leaves of F. carica. The maximum dust accumulation was occurred in the plants growing at Road sides while, the minimum dust was found on plants growing at Bahauddin Zakariya University. Dust accumulation has caused a significant effect on almost all foliage and biochemical attributes of F. carica. A positive correlation was found between dust accumulation and biometric attributes in F. carica. Biochemical responses had shown an inconsistency as chlorophylls (a, b & total), carotenoids decreased and ascorbic acid contents increased with an increase in dust accumulation. A negative correlation was found between dust deposition and chlorophyll contents. Whereas, accumulation of ascorbic acid was associated with

Spatial pattern of variation in populations of Acacia nilotica in semi-arid environment

Variability among populations was analyzed in five provenances of Acacia nilotica from spatially variable habitats. Populations of A. nilotica developed in response to their habitat conditions. The level of variability was significantly high among the populations. Phenotypic variability was extremely high for leaf and stipular spine characteristics. The nature of morphological variability for vegetative traits appeared environmentally controlled. The differentiation of leaf and stipular spine expression seems to have an adaptive significance for the species in terms of water economy. Although, seed and pod characteristics are genetically controlled showing a lower proportion of variability but these traits supported r and k-selection that may allow the species to survive under a wide array of contrasting habitats. The study suggested that populations of A. nilotica are differentiated in relation to the heterogeneity of environment. These populations became adapted to their habitat through the variability of morphological expressions. The morphologically differentiated populations of the species had allowed them to maintain themselves in a wide array of environmental situations enabling A. nilotica to occupy ample ecological ranges.

Influence of urea application on growth, yield and mineral uptake in two corn (Zea mays L.) cultivars

A pot experiment was conducted in a wire netting green house in order to assess the beneficial effect of urea on corn cultivars (C-20 and C-79) differing in yield production. Corn plants were grown in loam soil with alkaline in reaction. Application of varying urea levels did not change the physico-chemical properties of soil. Four weeks-old corn plants were subjected to varying levels of urea (0, 50, 100, 175 and 225 kg/ha urea) for 8 (mid-season harvest) and 15 weeks (final harvest). After which, plants growth, yield and mineral nutrient status of the two corn cultivars were assessed for both mid-season and final harvest. It was observed that cv. C-20 showed higher (P<0.1) growth and yield. Addition of varying levels of urea enhanced the growth and yield of both the corn cultivars. However, 175 kg urea /ha was found to be more effective (P<0.1) in enhancing growth and yield of both the cultivars. The rate of urea application at a rate of 175 kg/ha had greater beneficial effect on cv. C-20 due to improved mineral nutrient (N, P, K, Cu, Fe, Mn and Zn) status of the cultivar. Keywords: Corn cultivars, fertilizer treatment, urea, mineral nutrition, plant growth

Computational modeling and functional characterization of a GgChi: A class III chitinase from corms of Gladiolus grandiflorus

The present study describes the predicted model and functional characterization of an endochitinase (30 kDa) from corms of Gladiolus grandiflorus. ESI‐QTOF‐MS generated peptide showed 96% sequence homology with family 18, Class III acidic endochitinase of Gladiolus gandavensis. Purified G. grandiflorus chitinase (GgChi) hydrolyzed 4‐methylumbelliferyl β‐d‐N,N′,N′′‐triacetylchitotriose substrate showing specific endochitinase activity. Since no structural details of GgChi were available in the Protein Data Bank (PDB), a homology model was predicted using the coordinate information of Crocus vernus chitinase (PDB ID: 3SIM). Ramachandran plot indicated 84.5% in most favored region, 14.8% in additional and 0.6% in generously allowed region while no residue in disallowed region. The predicted structure indicated a highly conserved (β/α)8 (TIM barrel) structure similar to the family 18, class III chitinases. The GgChi also showed sequence and structural homologies with other active chitinases. The GgChi (50 μg/disc) showed no antibacterial activity, but did provide mild growth inhibition of phytopathogenic fungus Fusarium oxysporum at a concentration of 500 μg/well Similarly, insect toxicity bioassays of GgChi (50 μg) against nymphs of Bemisia tabaci showed 14% reduction in adult emergence and 14% increase in mortality rate in comparison to control values. The GgChi (1.5 mg) protein showed significant reduction in a population of flour beetle (Tribolium castaneum) after 35 days, but lower reactivity against rice weevil (Sitophilus oryzae). The results of this study provide detai.led insight on functional characterization of a family 18 class III acidic plant endochitinase.