Abstract Background: Parthenium hysterophorus L., commonly known as parthenium weed, poses severe economic and environmental hazards to the agro-ecosystems of Pakistan. Objective: To estimate the yield loss and critical competition period of this weed in the spring sown maize crop. Method: Field studies were conducted at an agronomic research area in the College of Agriculture at the University of Sargodha in Punjab-Pakistan during two consecutive year spring seasons (2014 and 2015). Treatments were comprised of viz., control plots (weed free), and parthenium competition durations of 2, 3, 4, 5 and 6 weeks after crop emergence (WAE), as well as weedy check for the full growing season of the crop. Results: Study results showed that the prolongation in parthenium competition duration from 2 WAE to the full crop season resulted in an increase in dry weight up to 541% and 450% in the years 2014 and 2015, respectively. Plant height, stem diameter, biological yield, 1000 grain weight and grain yield decreased significantly at 2 or more WAE parthenium competition periods. The maximum reduction in plant height (8.8 and 11.3%), stem diameter (30.6 and 12.7%), cob number m-2 (35.8 and 33.9%), grain rows cob-1 (26.6 and 29.4%), 1000 grain weight (15 and 9.8%), grain (34.1 and 39.1%) and biological yield (31.4 and 27.9%) were recorded with the longest parthenium competition duration (6 WAE) during the years 2014 and 2015, respectively. Conclusion: Based upon the results above, it is concluded that the critical competition period of parthenium in spring maize, as determined by a three-parameter logistic model, is 17 to 28 and 16 to 26 days after crop emergence during the years 2014 and 2015, respectively. Therefore, this weed must be controlled during these periods in order to avoid significant grain yield loss.

In the present work, a yeast strain Pichia kudriavzevii was identified on the basis of 18S rDNA, showing maximum growth at 30°C and pH 7.0. Among all the complex polysaccharides used, wheat bran proved to be the best substrate as indicated by the maximum growth of the yeast strain. The yeast isolate was capable of producing xylanase both intra-and extra-cellularly, the dominant form being extracellular. The maximum enzyme activity was determined at pH 5.0 and at 50°C. Na+, Mg2+ and Fe2+ presence caused a substantial increase in enzyme activity while a slight decrease (4.5%) was observed in the presence of Mn2+, Zn2+ and Cu2+. Pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) activities were assayed to confirm the presence of the ethanol pathway and PDC activity was much more pronounced (73%) compared to ADH activity (51%). The yeast strain can be employed to utilize hemicellulose containing agroindustrial residues for ethanol production.

En el presente estudio se identificó en aguas residuales de una zona industrial de Pakistán una cepa de la levadura Pichia kudriavzevii sobre la base del 18S ADNr, dicha cepa mostró un crecimiento máximo a 30 °C y a pH 7. Entre todos los sustratos de crecimiento evaluados para esta cepa, que incluyeron residuos industriales y medios definidos, el salvado de trigo demostró ser el mejor en función del crecimiento máximo alcanzado. Este aislado de levadura fue capaz de producir xilanasa intracelular y extracelular, esta última fue la forma predominante. Dicha capacidad enzimàtica mostró ser óptima a un pH de 5 y a 50°C. La presencia de Na+, Mg2+ y Fe2+ causó un incremento sustancial de la actividad enzimática, y hubo un ligero descenso (4,5%) en presencia de Mn2+, Zn2+ y Cu2+. Se evaluaron también las actividades de piruvato descarboxilasa y alcohol deshidrogenasa para confirmar la presencia de la vía del etanol. La actividad de la piruvato descarboxilasa fue mucho más pronunciada (73%) en comparación con la de alcohol deshidrogenasa (51%). Esta cepa de levadura puede emplearse para aprovechar los materiales hemicelulósicos de los residuos agroindustriales en la producción de etanol.

ABSTRACT Trichosporon asahii and Rhodotorula mucilaginosa isolated from wastewater effluents were identified as chromium-resistant yeasts. Cr(VI) concentrations at 8 mM and 6 mM were inhibitory for R. mucilaginosa and T. asahii. Remarkably elevated GSH (69.88 ± 10.01) and GSSG (11.24 ± 0.96) was observed under metal stress in T. asahii as compared to R. mucilaginosa GSH (18.95 ± 3.19) and GSSG (3.7 ± 2.74) mM g-1 8 level. Statistical analysis revealed significantly higher GSH/GSSG ratio in both strains. NPSH (29.84 ± 0.54) level in T. asahii was much higher than in R. mucilaginosa (6.05 ± 0.24). Chromate reductase (ChR) was assayed and its activity was optimum at 50°C (pH 6) in T. asahii while R. mucilaginosa showed higher activity at 30°C (pH 7). Activity of both ChRs was enhanced in the presence of Mg, Na, Co and Ca but strongly inhibited by Hg cations. Cr(VI) uptake capabilities were ranged between 43-97% in R. mucilaginosa and 35-88% in T. asahii. One dimensional electrophoresis revealed enriched bands of cysteine rich metallothioneins suggesting some differential proteins could be overexpressed under Cr(VI) stress.

ABSTRACTA lipase producing bacterium was isolated from oil contaminated effluents of various industries from Sheikhupura Road, Pakistan, and, on the basis of biochemical and 16S rRNA ribotyping, was identified asBacillus subtilis. The optimum temperature and pH for the growth of the culture were 37ºC and 7.0, respectively.B. subtilis I-4 had a lag phase of 4 h in LB medium while this phase prolonged to 6 h in oil containing medium. The optimum temperature and pH for the enzyme activity were 50ºC and 7.0, respectively. Maximum lipase activity was found in the presence of Ca ions. Olive oil and Tween 80 induced lipase gene in the bacterium while concentration of oil greater than 2% retarded the growth of the organism. In addition to lipaseB. subtilis I-4 also produced alkane hydroxylase and biosurfactant which could make this bacterium potential candidate for lipase production as well as bioremediation of oil-contaminated wastewater.

Finding more efficient ways to fertilize crops will reduce N losses and increase nutrient uptake. A field experiment was conducted at the Agronomic Research Farm, University of Agriculture, Faisalabad, Pakistan, during 2006 and repeated in 2007. The crop was planted in three different geometrical arrangements, viz. flat sowing (rows spaced 75 cm), ridge sowing (ridges spaced 75 cm), and strip planting (double row strips spaced 120 cm with 30 cm between rows in a strip); NPK was applied in four different combinations (0-0-0 control, 200-100-100 low dose,250-125-125 medium dose, and 300-150-150 high dose kg ha-1). Both fertilizer use efficiency (FUE) and N use efficiency (NUE) were significantly lower with the high fertilizer dose (300-150-150 kg NPK ha-1) than with the low or medium doses. The highest nitrogen uptake efficiency was with the medium fertilizer dose and proved to be a good indicator of grain yield. Among planting methods, ridge plantation resulted in higher FUE, NUE, and N uptake efficiency. The highest grain yield, net income, and benefit cost ratio were recorded when a crop was planted on ridges with the medium fertilizer dose. Sowing methods did not significantly affect grain quality parameters. Seed oil, protein, and starch contents were the lowest in the control. Thereafter, seed oil contents continued to decrease, while seed protein and seed starch increased with each NPK fertilizer increment.

Encontrando maneras más eficientes para fertilizar los cultivos se reducirán las pérdidas de N y aumentará la absorción de nutrientes. Un experimento de campo se llevó a cabo en la Granja de Investigación Agronómica de la Universidad de Agricultura, Faisalabad, Pakistán, durante 2006 y 2007. El cultivo fue sembrado en tres modalidades geométricas diferentes: siembra plana (filas separadas 75 cm), siembra en camellones (camellones separados 75 cm), y plantación en hileras (franjas de doble hilera separadas por 120 cm con espacio de 30 cm entre las hileras de una franja) y cuatro combinaciones de NPK (control 0-0-0; dosis baja 200-100-100; dosis media 250-125-125, y dosis alta 300-150-150 kg ha-1). La eficiencia de uso de fertilizantes (FUE), así como la eficiencia del uso del N (NUE) fue significativamente menor con la dosis más alta de fertilizante (300-150-150) que con las dosis baja o media. Eficiencia de absorción de N fue mayor con la dosis fertilizante media y demostró ser un buen indicador del rendimiento de grano. Entre los métodos de siembra, plantación en camellones resultó en una mayor extracción de unidades foliculares, NUE, y la eficiencia de absorción de N. El mayor rendimiento de grano, la utilidad neta y la relación costo-beneficio se registraron en el cultivo sembrado en camellones con dosis media de fertilizante. Métodos de siembra no afectaron significativamente los parámetros de calidad del grano. Contenido de aceite de semillas, proteína y almidón fueron los más bajos con el control. A partir de entonces, el contenido de aceite de semilla continuó disminuyendo, mientras que la proteína y el almidón de semillas aumentaron con cada incremento de fertilizantes NPK.