Muhammad Ijaz

Potential plant growth-promoting strain Bacillus sp. SR-2-1/1 decolorized azo dyes through NADH-ubiquinone:oxidoreductase activity

In this study, a bacterial strain SR-2-1/1 was isolated from textile wastewater-irrigated soil for its concurrent potential of plant growth promotion and azo-dye decolorization. Analysis of 16S rRNA gene sequence confirmed its identity as Bacillus sp. The strain tolerated high concentrations (i.e. up to 1000mgL-1) of metals (Ni2+, Cd2+, Co2+, Zn2+, and Cr6+) and efficiently decolorized the azo dyes (i.e. reactive black-5, reactive red-120, direct blue-1 and congo red). It also demonstrated considerable in vitro phosphate solubilizing and 1-aminocyclopropane-1-carboxylic acid deaminase abilities at high metal and salt levels. Bioinformatics analysis of its 537bp azoreductase gene and deduced protein revealed that it decolorized azo dyes through NADH-ubiquinone:oxidoreductase enzyme activity. The deduced protein was predicted structurally and functionally different to those of its closely related database proteins. Thus, the strain SR-2-1/1 is a powerful bioinoculant for bioremediation of textile wastewater contaminated soils in addition to stimulation of plant growth.

Separate and combined effects of silicon and selenium on salt tolerance of wheat plants

Soil salinity is the leading global abiotic stress which limits agricultural production with an annual increment of 10%. Therefore; a pot experiment was conducted with the aim to alleviate the salinity effects on wheat seedlings through exogenous application of silicon (Si) and selenium (Se). Treatments included in the study were viz. (Ck) control (no NaCl nor Si and Se added), only salinity (50 mM NaCl), salinity + Si (50 mM NaCl with 40 mM Si), salinity + Se (50 mM NaCl with 40 mM Se) and salinity + Si + Se (50 mM NaCl + 40 mM Si + 40 mM Si). The salt stress impaired the growth (root and shoot dry weight, root: shoot ratio, seedlings biomass), water relations, photosynthetic attributes, transpiration rate and chlorophyll contents of wheat seedlings. Nonetheless, the foliar application of Si and Se alone and in combination improved the growth, water relations, photosynthetic attributes, transpiration rate and chlorophyll contents of wheat seedlings under stressed conditions. Moreover, an increase in antioxidant enzyme activity and accumulation of osmo-protectants (proline, soluble protein and soluble sugar) was noted under stressed conditions, which was more pronounced in wheat seedling which experienced combined application of Si and Se. To conclude that, foliar application of Si alone mitigated the adverse effect of salinity, while the combined application of Si and Se was proved to be even more effective in alleviating the toxic effects of salinity stress on wheat seedlings.

Allelopathic Effects of Winter Legumes on Germination and Seedling Indicators of Various Summer Cereals

Abstract In the present study, the putative allelopathic potential of aqueous extracts (10 % w/v) of three legumes, i.e. alfalfa, berseem and brassica spp., including distilled water treatments as check were evaluated on germination and early seedling growth indicators of rice, sorghum and millet under laboratory conditions. The treatments were compared in completely randomized design with factorial arrangements in four replications. The recorded observations clearly indicated that the germination process and seedling growth of receptor plants were negatively affected in the presence of legume extracts. The extract of Brassica had the strongtest inhibitory effect on germination process in form of increased mean germination time (MGT) and lowered the coefficient of velocity of germination (CVG), germination % age and germination index (GI) as compared to other extracts. Likewise, the lowest root and shoot length, their fresh and dry weight was also noted in petri dishes with Brassica extracts. Among the receptor crops, rice was the most susceptible in term of both seedling growth and germination attributes. The interaction between test crops and legume extracts was found to be significant for most of studied parameters except germination % age, fresh and dry weight of root and shoot. The presence of allelochemicals in the studied legumes entitled them to be used in weed management programme and is also signal for designing specific production technologies able to reduce their effects on succeeding crops.

Combined application of bio-organic phosphate and phosphorus solubilizing bacteria (Bacillus strain MWT 14) improve the performance of bread wheat with low fertilizer input under an arid climate

This study was aimed to investigate the effect of bio-organic phosphate either alone or in combination with phosphorus solubilizing bacteria strain (Bacillus MWT-14) on the growth and productivity of two wheat cultivars (Galaxy-2013 and Punjab-2011) along with recommended (150–100 NP kg ha−1) and half dose (75–50 NP kg ha−1) of fertilizers. The combined application of bio-organic phosphate and the phosphorous solubilizing bacteria strain at either fertilizer level significantly improved the growth, yield parameters and productivity of both wheat cultivars compared to non-inoculated control treatments. The cultivar Punjab-2011 produced the higher chlorophyll contents, crop growth rate, and the straw yield at half dose of NP fertilizer; while Galaxy-2013, with the combined application of bio-organic phosphate and phosphorous solubilizing bacteria under recommended NP fertilizer dose. Combined over both NP fertilizer levels, the combined use of bio-organic phosphate and phosphorous solubilizing bacteria enhanced the grain yield of cultivar Galaxy-2013 by 54.3% and that of cultivar Punjab-2011 by 83.3%. The combined application of bio-organic phosphate and phosphorous solubilizing bacteria also increased the population of phosphorous solubilizing bacteria, the soil organic matter and phosphorous contents in the soil. In conclusion, the combined application of bio-organic phosphate and phosphorous solubilizing bacteria offers an eco-friendly option to harvest the better wheat yield with low fertilizer input under arid climate.

Improving the performance of bread wheat genotypes by managing irrigation and nitrogen under semi-arid conditions

ABSTRACT Wheat (Triticum aestivum L.) productivity is generally affected by water limitation and inadequate nitrogen supply especially under semi-arid environment. The current study was conducted to determine whether the crop yield and irrigation water use efficiency (IWUE) could be manipulated through alteration of nitrogen and irrigation application. To meet the desired objectives, a two-year field study was carried out in 2013–2014 and 2014–2015, in a split-split plot arrangement with three factors i) irrigation in main plots, ii) nitrogen in sub-plots, and iii) twenty genotypes in sub-sub plots on a sandy loam soil. The analysis of variance revealed that the wheat performance was affected by genotypes and alteration of irrigation and nitrogen application with respect to IWUE and final grain yield. IWUE under water stress conditions was observed 56% higher than normal irrigated. Much higher values of IWUE under water stress indicated that the existing optimum water requirements of the crop needs to be revaluated. The regression model indicated that addition of nitrogen and irrigation patterns along with morphological traits cannot explain variation in yield related traits more than 65% under semi-arid conditions. Therefore, for better crop yields in semi-arid environment, more physiological parameters should be considered in evaluation of yield.

Plant-Microbe Interactions: Current Perspectives of Mechanisms Behind Symbiotic and Pathogenic Associations

The phyllosphere and rhizosphere of plants have been a reservoir of microorganisms of both symbiotic and pathogenic nature. The interplay between plants and associated microbes involves complex and dynamic mechanisms, many of which are unexplored. The unraveling of these mechanisms is a big challenge for plant biologists. The consequence of such interactions may be beneficial, detrimental, or neutral for the hosts. There are many known mechanisms through which microorganisms especially bacteria support plant growth, i.e., fixation of atmospheric nitrogen, solubilization of inorganic phosphate, modulated phytohormones synthesis, production of stress-responsive enzymes like 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, and biocontrol of many plant diseases. Both above- and underground plant organs are frequently exposed to a plethora of microorganisms, including viruses, bacteria, oomycetes, fungi, and eukaryotic protozoans. Phytopathogens defend their habitat and infect plants by a variety of compounds (toxins) that are broad spectrum in their activity. In response, plants initiate defensive mechanisms that resist pathogen penetration and subsequent infection. Thus, various events of molecular crosstalk take place between plants, and both friendly and hostile microbes trigger a series of highly dynamic plant cellular responses. Such mechanisms are very crucial for pathogen recognition and induction of adequate defense signal transduction cascades in the plant. More research insights are required to unravel the molecular basis behind these mechanisms. Also, to support the plant life, many complex mechanisms initiated after the association of symbiotic or pathogenic microorganisms need to be explored.

Physiological response of late sown wheat to exogenous application of silicon

Late planting of wheat in rice-wheat cropping system is perhaps one of the major factors responsible for low crop yield. The main cause of reduction in yield is due to supra-optimal conditions during the reproductive growth. High temperature during reproductive phase induces changes in water relations, decreases photosynthetic rate, and transpiration rate, stomatal conductance and antioxidative defence system. Silicon (Si), being a beneficial nutrient not only provides significant benefits to plants growth and development but may also mitigate the adversities of high temperature. A field study was conducted at Agronomic Research Area of University of Agriculture; Faisalabad, Pakistan to assess the performance of late sown wheat with the soil applied Si. Experiment was comprised of three sowing dates; 10th Nov (normal), 10th Dec (late), 10th Jan (very late) with two wheat varieties (Sehar-2006 and Faisalabad-2008), and an optimized dose of Si (100 mg per kg soil), applied at different growth stages (control, crown root, booting and heading). Results indicated that 100 mg Si per kg soil at heading stage offset the negative impact of high temperature and induced heat tolerance in late sown wheat. Silicon application improved 34% relative water contents (RWC), 30% water potential, 26% osmotic potential, 23% turgor potential and 21% photosynthetic rate, and 32% transpiration rate and 20% stomatal conductance in wheat flag leaf than control treatment. Further it was observed that Si application preventing the oxidative membrane damage due to enhanced activity of antioxidant enzymes, i.e. 35% superoxide dismutase (SOD) and 38% catalase (CAT). In conclusion results of this field study demonstrated that soil applied Si (100 mg per kg soil) at heading stage enhanced all physiological attributes of wheat flag leaf. Which in turn ameliorated the adverse effects of high temperature in late sown wheat. Study depicted that Si can be used as a potential nutrient in order to mitigate the losses induced by high temperature stress.