Decomposition of pea and maize straw in Pakistani soils along a gradient in salinity     

S. Muhammad  T. Müller  R. G. Joergensen 《Biology and Fertility of Soils》2006,43(1):93-101

Maize straw and pea straw were added to five Pakistani soils from a gradient in salinity to test the following hypotheses: Increasing salinity at high pH decreases proportionally (1) the decomposition of added straw and (2) the resulting net increase in microbial biomass. In the non-amended control soils, salinity had depressive effects on microbial biomass C, biomass N, but not on biomass P and ergosterol. The ratios microbial biomass C-to-N and biomass C-to-P decreased consistently with increasing salinity. In contrast, the ergosterol-to-microbial biomass C ratio was constant in the four soils at pH>8.9, but nearly doubled in the most saline, but least alkaline, soil (pH 8.2). The addition of the maize and pea straw always increased the contents of microbial biomass C, biomass N, biomass P and ergosterol, but without clear effects of salinity. Highest mean contents of microbial biomass C and biomass N were measured at day 0, immediately after the straw was added. Straw amendments increased the CO₂ evolution rates of all five soils without any effect of salinity. The same was true for total C and total N in the two fractions of particulate organic matter (POM) 63–400 μm and >400 μm. Lowest percentage of straw-derived CO₂-C and highest recoveries of POM-C and POM-N were observed in the maize straw treatment and the reverse in the pea straw treatment. Yield coefficients were calculated for maize and pea straw based on the assumption that the balance gap between CO₂ and the amount of POM can be fully assigned to microbial products.  相似文献   

Clay amendment to sandy soil—effect of clay concentration and ped size on nutrient dynamics after residue addition     

Shermeen Tahir  Petra Marschner 《Journal of Soils and Sediments》2016,16(8):2072-2080

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Subcellular compartmentation of sugars in wheat leaves under the influence of salinity and boron toxicity     

Sajid Masood  Muhammad Iqbal  Hassan Javed Chaudhary  M. Farooq Hussain Munis 《Journal of plant nutrition》2016,39(14):2100-2105

In this study, long-term effects of salinity and high boron (B) on subcellular distribution of sugars in wheat leaves were investigated. Four treatments with three replications of each; control, high B, sodium chloride (NaCl) and NaCl + high B, respectively were established according to completely randomized design. Plants were grown hydroponically and harvested after 6 weeks onset of experiment. NaCl treatment markedly decreased the shoot fresh and dry weight compared to high B or NaCl + high Boron. It increased the sugar concentrations in subcellular compartments, whereas decreased in NaCl + high B. Contrary, NaCl either alone or in combination with high B decreased the sugar contents in whole leaf compared to control or high B. Overall, higher concentrations of sugars were observed in symplast compared to apoplast indicating the symplast as major compartment for sugar transport. Furthermore, wheat plants accumulate sugars in subcellular compartments to maintain their growth under stress conditions.  相似文献   

Salt‐resistant and salt‐sensitive wheat genotypes show similar biochemical reaction at protein level in the first phase of salt stress     

Muhammad Saqib  Christian Zrb  Sven Schubert 《植物养料与土壤学杂志》2006,169(4):542-548

Salinity has a two‐phase effect on plant growth, an osmotic effect due to salts in the outside solution and ion toxicity in a second phase due to salt build‐up in transpiring leaves. To elucidate salt‐resistance mechanisms in the first phase of salt stress, we studied the biochemical reaction of salt‐resistant and salt‐sensitive wheat (Triticum aestivum L.) genotypes at protein level after 10 d exposure to 125 mM–NaCl salinity (first phase of salt stress) and the variation of salt resistance among the genotypes after 30 d exposure to 125 mM–NaCl salinity (second phase of salt stress) in solution culture experiments in a growth chamber. The three genotypes differed significantly in absolute and relative shoot and root dry weights after 30 d exposure to NaCl salinity. SARC‐1 produced the maximum and 7‐Cerros the minimum shoot dry weights under salinity relative to control. A highly significant negative correlation (r² = –0.99) was observed between salt resistance (% shoot dry weight under salinity relative to control) and shoot Na⁺ concentration of the wheat genotypes studied. However, the salt‐resistant and salt‐sensitive genotypes showed a similar biochemical reaction at the level of proteins after 10 d exposure to 125 mM NaCl. In both genotypes, the expression of more than 50% proteins was changed, but the difference between the genotypes in various categories of protein change (up‐regulated, down‐regulated, disappeared, and new‐appeared) was only 1%–8%. It is concluded that the initial biochemical reaction to salinity at protein level in wheat is an unspecific response and not a specific adaptation to salinity.  相似文献   

The adsorption characteristics of soils and removal of cadmium and nickel from wastewaters     

Muhammad Sadiq  Tahir H. Zaidi 《Water, air, and soil pollution》1981,16(3):293-299

The interactions between the adsorption characteristics of 27 experimental soils and the sorption of Cd and Ni from the municipal wastewaters were investigated in this study. The removal of these elements from soil solution was followed for 50 days. All the adsorption characteristics, except cation exchange capacity and organic matter, were significantly correlated to the sorption of Cd after one day shaking. After 7 days of shaking, none of the soil adsorption characteristics except free CaCO₃ was significantly correlated to Cd removal from wastewater. The soil saturated paste pH and suspension pH were strongly correlated to Cd sorption throughout this experiment. The behavior of Ni in soils was different from that of Cd. Surface area, total Fe, and total Al were significantly correlated to Ni sorption. The correlation between Ni removal and pH was the strongest than any other parameter studied. After 7 days shaking, clay content and total Ca were not significantly correlated to Ni sorption. The cation exchange capacity of the soils was not significantly correlated to Cd or Ni sorption in this experiment. It seems that in the experimental soils, concentration of Cd and Ni were probably not controlled by adsorption process. The precipitation process was probably playing a major role in the removal of these elements from the municipal wastewaters. As observed in this experiment, the cation exchange capacity of experimental soils was a poor parameter to define sorption capacity of these soils for Cd and Ni. The guidelines for determining the soil sludge load, which are mainly based on the cation exchange capacity of soils, should be revised.  相似文献   

New alkamides from maca (Lepidium meyenii)     

Zhao J  Muhammad I  Dunbar DC  Mustafa J  Khan IA 《Journal of agricultural and food chemistry》2005,53(3):690-693

Maca (Lepidium meyenii) has been used as a food in Peru for thousands of years. More recently a wide array of commercial maca products have gained popularity as dietary supplements, with claims of anabolic and aphrodisiac effects, although the biologically active principles are not fully known. In an earlier chemical investigation, two new alkamides and a novel fatty acid, as well as the N-hydroxypyridine derivative, macaridine, were isolated from L. meyenii. Further examination has led to the isolation of five additional new alkamides, namely, N-benzyl-9-oxo-12Z-octadecenamide (1), N-benzyl-9-oxo-12Z,15Z-octadecadienamide (2), N-benzyl-13-oxo-9E,11E-octadecadienamide (3), N-benzyl-15Z-tetracosenamide (4), and N-(m-methoxybenzyl)hexadecanamide (5). Their structures were established by spectrometric and spectroscopic methods including ESI-HRMS, EI-MS, (1)H, (13)C, and 2D NMR, as well as (1)H-(15)N 2D HMBC experiments. In addition, the identity of N-benzyl-15Z-tetracosenamide (4) was confirmed by synthesis. These compounds have been found from only L. meyenii and could be used as markers for authentication and standardization.  相似文献   

Management of human health risk in the context of kitchen gardens polluted by lead and cadmium near a lead recycling company     

Stéphane Mombo  Yann Foucault  Frédéric Deola  Irène Gaillard  Sylvaine Goix  Muhammad Shahid  Eva Schreck  Antoine Pierart  Camille Dumat 《Journal of Soils and Sediments》2016,16(4):1214-1224

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Effectiveness of potassium in mitigating the salt-induced oxidative stress in contrasting tomato genotypes     

Muhammad Amjad  Javaid Akhtar  Muhammad Anwar-ul-Haq  Muhmmad Atif Riaz  Zulfiqar Ahmad Saqib  Behzad Murtaza 《Journal of plant nutrition》2016,39(13):1926-1935

To check the efficacy of potassium in alleviating oxidative stress under salt stress, salt-tolerant (Indent-1) and salt-sensitive (Red Ball) tomato (Lycopersicon esculentum Mill.) genotypes were exposed to three levels of sodium chloride (NaCl) (0, 75, 150 mM) and two levels of potassium (4.5 and 9 mM) in solution and foliar form. Thirty days of treatments revealed that increasing NaCl stress increased lipid peroxidation (malondialdehyde, MDA) and correspondingly the activity of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; and glutathione reductase GR) in both genotypes. However, higher potassium (K) level in solution or foliar spray during the salt-induced stress decreased MDA and antioxidant activity and increased the growth in salt-tolerant genotype than in the salt-sensitive genotype. Decrease in MDA concentration, activity of antioxidant enzymes, and increase in the growth of tomato plants by the application of potassium under salt stress suggest that potassium is an effective ameliorating agent against salt-induced oxidative damage.  相似文献   

Laboratory Observations Regarding Different Instars ofCyclosain-sulana (Costa, 1834) (Araneidae) During Developmental Stages     

Muhammad Saleem Khan  Muhammad Saleem Asghar  Iram Maqsood  Mohsin Bukhari  Lemeng Han  Tang Li-jie  Li Yi-jing  Shahla A  Khalil U R 《东北农业大学学报(英文版)》2015,(2):52-59

The current experiment was conducted to find out the optimal conditions for mass rearing and developmental changes of Cyclosainsulana. The lab. conditions were maintained at(27±2)℃ and(65±5)% RH. The clear perplex cages and natural diet consisting of the aphids, larvae of the house fly and larvae of drosophila were used for rearing. C. insulana took(123.12±7.26) days to develop from eggs to adults passing through eight instars under prevailing vivo conditions. The eggs were greenish white in color with average size of 0.57 mm ±0.034. The eggs spent(7.52±1.64) days in emergence. Maximum number of spiderlings survived at the 5th instar(84%) and minimum at the 1st instar(34%). The measurements of different body parts including the total body length, cephalothorax and pedipalps of the both male and female C. insulana were done with the help of micrometer and presented as mean±SD. The measurements varied in the each developing instar. It was concluded that spiders were difficult to rear in the lab. conditions and each developing stage which was regarded as instars showed variations in size colors and body characteristics.  相似文献   

Where Pakistan Stands Among Top Rice Exporting Countries,an Analysis of Competitiveness     

Muhammad Abdullah  Jia Li  Sidra Ghazanfar  Jaleel Ahmed  Imran Khan  Mazhir Nadeem Ishaq 《东北农业大学学报(英文版)》2015,(2):80-86

Under the umbrella of WTO, the reduction in trade barriers has forced the policy makers to focus on the export competitiveness. Rice is an important source for foreign exchange earnings for the economy of Pakistan, keeping in mind of this fact, the competitiveness of Pakistan’s rice with other major exporters was examined by applying revealed competitive advantage. The domestic consumption trends of rice among the major rice exporting countries were also analyzed in the current study. The results revealed that as compare to other major exporters of rice in the world, Pakistan had high competitive and comparative advantage in the production of rice. The comparison of the movements in comparative advantage indices for Pakistan with the major world rice competitors/exporters showed that Pakistan possessed relatively high comparative and competitive advantages in rice production. The declining domestic per capita consumption of rice and increasing trends in competitiveness for Pakistan clearly revealed the expected potential of higher growth which meant that rice exports from Pakistan could continue to play an important role for the earnings of foreign exchange. In order to exploit the potential benefits of rice exports, we need to strengthen the competitiveness in rice sector of Pakistan.  相似文献