Muhammad Arshad

Thermal stress impacts reproductive development and grain yield in rice

Rice is highly sensitive to temperature stress (cold and heat), particularly during the reproductive and grain-filling stages. In this review, we discuss the effects of low- and high-temperature sensitivity in rice at various reproductive stages (from meiosis to grain development) and propose strategies for improving the tolerance of rice to terminal thermal stress. Cold stress impacts reproductive development through (i) delayed heading, due to its effect on anther respiration, which increases sucrose accumulation, protein denaturation and asparagine levels, and decreases proline accumulation, (ii) pollen sterility owing to tapetal hypertrophy and related nutrient imbalances, (iii) reduced activity of cell wall bound invertase in the tapetum of rice anthers, (iv) impaired fertilization due to inhibited anther dehiscence, stigma receptivity and ability of the pollen tube to germinate through the style towards the ovary, and (v) floret sterility, which increases grain abortion, restricts grain size, and thus reduces grain yield. Heat stress affects grain formation and development through (i) poor anther dehiscence due to restricted closure of the locules, leading to reduced pollen dispersal and fewer pollen on the stigma, (ii) changes in pollen proteins resulting in significant reductions in pollen viability and pollen tube growth, leading to spikelet sterility, (iii) delay in heading, (iv) reduced starch biosynthesis in developing grain, which reduces starch accumulation, (v) increased chalkiness of grain with irregular and round-shaped starch granules, and (vi) a shortened grain-filling period resulting in low grain weight. However, physiological and biotechnological tools, along with integrated management and adaptation options, as well as conventional breeding, can help to develop new rice genotypes possessing better grain yield under thermal stress during reproductive and grain-filling phases.

Immunopotentiation of outer membrane protein through anti-idiotype Pasteurella multocida vaccine in rabbits.

Pasteurella multocida was isolated from cattle affected with haemorrhagic septicaemia and characterized on the basis of morphological, cultural and biochemical tests. Bacterial outer membrane proteins (OMPs) were extracted with 1% Sarkosyl method. P. multocida anti-idiotype vaccine prepared from OMPs (21.3 mg per 100 ml), was evaluated and compared with bacterin supplemented with 10% OMPs and plain alum-adsorbed bacterin in rabbit models. It was observed that OMPs-anti-idiotype vaccine induced high levels of antibody titres (geomean titres -GMT) detected using indirect haemagglutination (IHA) test. The OMPs anti-idiotype antibody titres of 168.9 GMT were obtained to 42.2 GMT in OMPs supplemented bacterin on 21 days post vaccination, while the plain bacterin had the least titre of 27.9 GMT. The OMPs-anti-idiotype vaccine provoked better immunogenic response in terms of highest GMT titres and long lasting effect in rabbits and 100% protection against the challenge with homologous strain of P. multocida,while 88% protection was obtained in rabbits, given OMPs supplemented bacterin.

Comparative Evaluation of Leukotoxic Activities of Indigenous Staphylococcus aureus Isolates from Subclinical and Clinical Mastitic Milk Samples of Buffalo and Cattle

The present study was conducted for the comparative evaluation of leukotoxic activities of indigenous Staphylococcus aureus isolates issued from Institute of Microbiology University of Agriculture Faisalabad Pakistan. A total of 200 milk samples 100 each of buffalos (Nili Ravi) and cattle (Sahiwal) with subclinical and clinical mastitis were collected. Staphylococcus aureus isolates recovered were used for extraction of leukotoxins. Leukotoxic activities were determined against bovine Polymorphonuclear cells (PMNs) through Toxin Limit Concentration (TLC) assay. Overall positive percentage of mastitis was more important in cattle (32%) than for buffalos (22%). Overall and quarter based prevalence of subclinical mastitis were higher than clinical cases in both buffalos and cattle. In TLC assay, PMNs remained normal in control wells without leukotoxins after incubation at 37 0 C for 30 minutes, whereas, under the influence of leukotoxins, PMNs flattened and spread on the gelatin coated plastic surface. TLC titers in subclinical mastitis ranged from 4 to 16 with Geometric Mean Titer (GMT) at 6 in buffalos and 8 in cattle whereas, in clinical cases it ranged from 32 to 128 with GMT of 64 in buffalo and cattle.

Micronutrient seed priming improves stand establishment, grain yield and biofortification of bread wheat

Agronomic biofortification by seed treatments is a convenient way to harvest improved yields of micronutrient-enriched grains. This 2-year field study was conducted to evaluate the effects of seed priming with zinc (Zn), boron (B) and manganese (Mn) alone and in combinations on stand establishment, grain yield and biofortification of bread wheat (Triticum aestivum L.). Seeds of wheat cv. Faisalabad-2008 were soaked in aerated solutions of 0.5u2009m Zn, 0.01u2009m B and 0.1u2009m Mn, alone and in different combinations, for 12u2009h. Seed priming with the micronutrients was quite effective in improving stand establishment, yield-contributing traits, grain yield, and straw and grain micronutrient contents during both years. Best stand establishment was achieved from seed priming with Zn+B, followed by seed priming with Zn+Mn. Grain yield improvement from different seed priming treatments was in the order Zn+Bu2009>u2009Zn+Mnu2009>u2009Znu2009>u2009Bu2009>u2009Mnu2009>u2009Zn+B+Mn, with respective increases of 34%, 33%, 21%, 19%, 18% and 8% relative to untreated seeds. Seed priming with Zn, B and Mn alone and in combinations also improved the contents of the respective micronutrients in straw and grain. All seed priming treatments were economically profitable except Zn+B+Mn, which was not cost-effective. The highest benefitu2009:u2009cost ratio accrued from seed priming with Zn+B. In conclusion, seed priming with micronutrients was generally cost-effective in meeting the crop micronutrient requirements, and in improving crop stand, grain yield and grain micronutrient contents in bread wheat. Seed priming with Zn+B was the most effective in this regard.

Microwave-Assisted Catalytic Synthesis of Bio-Based Copolymers from Waste Cooking Oil

Solvent-free copolymerization of epoxides derived from fatty esters of waste cooking oil with phthalic anhydride using (salen)CrIIICl as catalyst and n-Bu4NCl/DMAP (tetrabutylammonium chloride/4-(dimethylamino)pyridine) as co-catalysts was carried out for the first time under microwave irradiation, where reaction time was reduced from a number of hours to minutes. The polyesters were obtained with molecular weight (Mw = 3100–6750 g/mol) and dispersity values (D = 1.18–1.92) when (salen)CrIIICl/n-Bu4NCl was used as catalysts. Moreover, in the case of DMAP as a co-catalyst, polyesters with improved molecular weight (Mw = 5500–6950 g/mol) and narrow dispersity values (D = 1.07–1.28) were obtained even at reduced concentrations of (salen)CrIIICl and DMAP. The obtained products were characterized and evaluated by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), proton nuclear magnetic resonance (1H-NMR) spectroscopy, gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) Techniques.

Soil Carbon Sequestration in Dryland Agriculture

Drylands are the part of terrestrial ecosystem characterized by low water and spans over an area of about 6.15 billion hectares. About 57–65 % of this area is desertified or prone to desertification. In spite of low soil organic carbon (SOC), the total SOC stock in dryland soils is 241 Pg (1 Pg = petagram =1015 g) which is 15.5 % of the global SOC pool (1550 Pg). Significant C losses (~20–30 Pg) occur due to low C input as a result of desertification. About two third of this loss can be sequestered through better management practices in the period of next 50 years. In this chapter, our major focus is to discuss the biophysical aspects of soil C sequestration and their impact on global climate change and food security in dryland areas. Management and other land use practices for SOC sequestration to combat land degradation in drylands, such as afforestation using suitable species, management of pasture on grazing lands, management of cultivated lands, and restorative land use to reestablish the degraded soils and the ecosystems. In drylands, tree species suited for afforestation are Acacia, Mesquite and Neem etc. Grazing management practices such as controlled grazing at an optimal carrying capacity, fire management, and the cultivation of improved species. Suitable practices for soil management are application of biosolids (manure, sludge) to improve the macrofauna (termites) of the soil, water harvesting, use of vegetative mulches, and wise irrigation structures.