Mohammad Tariq Jan

Potential role of phytohormones and plant growth-promoting rhizobacteria in abiotic stresses: consequences for changing environment

Plants are sessile beings, so the need of mechanisms to flee from unfavorable circumstances has provided the development of unique and sophisticated responses to environmental stresses. Depending on the degree of plasticity, many morphological, cellular, anatomical, and physiological changes occur in plants in response to abiotic stress. Phytohormones are small molecules that play critical roles in regulating plant growth and development, as well as stress tolerance to promote survival and acclimatize to varying environments. To congregate the challenges of salinity, temperature extremes, and osmotic stress, plants use their genetic mechanism and different adaptive and biological approaches for survival and high production. In the present attempt, we review the potential role of different phytohormones and plant growth-promoting rhizobacteria in abiotic stresses and summarize the research progress in plant responses to abiotic stresses at physiological and molecular levels. We emphasized the regulatory circuits of abscisic acid, indole acetic acid, cytokinins, gibberellic acid, salicylic acid, brassinosteroids, jasmonates, ethylene, and triazole on exposure to abiotic stresses. Current progress is exemplified by the identification and validation of several significant genes that enhanced crop tolerance to stress in the field. These findings will make the modification of hormone biosynthetic pathways for the transgenic plant generation with augmented abiotic stress tolerance and boosting crop productivity in the coming decades possible.

Influence of nitrogen and sulfur fertilization on quality of canola (Brassica napus L.) under rainfed conditions

Field experiments were conducted at Cereal Crops Research Institute, Pirsabak, Nowshera, Pakistan, during winter 2003∼2004 and 2004∼2005 to evaluate the effect of nitrogen and sulfur levels and methods of nitrogen application on canola (Brassica napus L. cv. Bulbul-98) under rainfed conditions. Four levels of S (0, 10, 20, and 30 kg/ha) and three levels of N (40, 60, and 80 kg/ha) and a control treatment with both nutrients at zero level were included in the experiments. Sulfur levels were applied at sowing while N levels were applied by three methods (100% soil application, 90% soil+10% foliar application, and 80% soil +20% foliar application). The experiments were laid out in randomized complete block (RCB) design having four replications. Oil content increased significantly up to 20 kg S/ha but further increase in S level did not enhance oil content. Glucosinolate content increased from 13.6 to 24.6 μmol/g as S rate was increased from 0 to 30 kg/ha. Protein content increased from 22.4% to 23.2% as S rate was increased from 0 to 20 kg/ha. Oil content responded negatively to the increasing N levels. The highest N level resulted in the highest values for protein (23.5%) and glucosinolate (19.9 μmol/g) contents. Methods of N application had no significant impact on any parameters under study.

Recent developments in therapeutic protein expression technologies in plants

Infectious diseases and cancers are some of the commonest causes of deaths throughout the world. The previous two decades have witnessed a combined endeavor across various biological sciences to address this issue in novel ways. The advent of recombinant DNA technologies has provided the tools for producing recombinant proteins that can be used as therapeutic agents. A number of expression systems have been developed for the production of pharmaceutical products. Recently, advances have been made using plants as bioreactors to produce therapeutic proteins directed against infectious diseases and cancers. This review highlights the recent progress in therapeutic protein expression in plants (stable and transient), the factors affecting heterologous protein expression, vector systems and recent developments in existing technologies and steps towards the industrial production of plant-made vaccines, antibodies, and biopharmaceuticals.

EFFECT OF NITROGEN AND SULFUR FERTILIZATION ON YIELD COMPONENTS, SEED AND OIL YIELDS OF CANOLA

Field experiments were conducted to evaluate the effects of nitrogen (N) and sulfur (S) levels and their methods of application on canola. Branches plant−1, pods plant−1 and biological yield significantly increased with increase in nitrogen level and no significant increase in seed pod−1 and seed and oil yields occurred beyond 120 kg N ha−1. However, thousand seed weight consistently decreased with increasing level of nitrogen. Pods plant−1 and biological yield continually increased with increase in sulfur level. Alternatively, significant increase in branches plant−1, seed pod−1, seed weight, seed and oil yields was noted with increase in sulfur level up to 40 kg ha−1. Applications of sulfur and nitrogen in split significantly decreased seed yield as compared to sole applications. It is concluded that sulfur and nitrogen application as sole at the rate of 40 and 120 kg ha−1, respectively performed better than the rest of their levels and method of application.

QUALITY PARAMETERS OF CANOLA AS AFFECTED BY NITROGEN AND SULFUR FERTILIZATION

Field experiments were conducted at Cereal Crops Research Institute Pirsabak Nowshera, Pakistan, for two years (2003–2004 and 2004–2005) to evaluate the effects of nitrogen (N) and sulfur (S) levels and their methods of application on quality parameters of canola (Brassica napus L. cv. ‘Bulbul-98’). Four levels of S (0, 20, 40, and 60 kg ha−1) and three levels of N (80, 120, and 160 kg ha−1) and a control treatment (with both nutrients at zero level) were applied as a sole dose at sowing, in two split applications (half each at sowing and leaf rosette stages) and three split applications (one third each at sowing, leaf rosette stage, and early flowering). Large increases in oil and protein concentrations were measured at 40 kg S ha−1 while no further significant increase was observed at 60 kg S ha−1. However, increasing level of S consistently increased glucosinolate concentrations to the highest level of 60 kg S ha−1. Nitrogen significantly increased protein concentrations up to the maximum level of 160 kg N ha−1 while glucosinolate concentrations were increased up to 120 kg N ha−1. However, oil concentrations showed negative trend to increasing level of N.

Incorporation of Biochar and Legumes into the Summer Gap: Improving Productivity of Cereal-Based Cropping Systems in Pakistan

Biochar can improve soil quality, increase crop production and sequester C in agricultural systems; however, this now needs critical evaluation in a sustainable agricultural context. In Pakistan, there is a gap in cereal-based wheat–maize–wheat cropping systems that lasts between 70–80 days. This “summer gap” can be used for growing short duration legume crops, which can provide valuable grain, fodder, or green manure and can provide a sustainable input of N into agricultural systems. We have used a field-based study to determine the effect of biochar application to an alkaline, nutrient poor, soil on the productivity of legume crops grown during the summer gap. Overall, biochar application (50 t ha−1) increased the productivity and yield of cowpea, mungbean and Sesbania over two cropping seasons compared to unamended non-biochar controls. The integration of biochar and legumes could be a useful strategy for improving the overall farm productivity of cereal-based cropping systems in Pakistan, by delivering a sustainable input of N to soil and providing increased yields from this additional summer gap crop.

Efficiency of Dry Matter and Nitrogen Accumulation and Redistribution in Wheat as Affected by Tillage and Nitrogen Management

Field experiments were conducted over 2 years with the hypothesis that farmyard manure (FYM), soybean residue (SR) as sole and/or in combination with urea under different tillage practices has similar effects on crop nitrogen (N) status and accumulation of dry matter (DM). Conventional ploughed plots had higher DM than other. Post anthesis accumulation of DM for minimum tillage (MT) was 4% higher than DT. Incorporation of 20 tons FYM ha−1 combined with 30 or 60 kg ha−1 had higher DM and N partitioned to leaves, stem, and spike than control. Leaves accumulated more DM at anthesis stage than other, whereas stem and spike at maturity than earlier stages. Fertilized plots had higher DM and N redistribution efficiency than control. However, N remobilization increased linearly with increasing DM accumulation (r2 = 22%). It was concluded that FYM coupled with N under MT showed marked variations for DM partition and N status in wheat than other treatments.

Response of Tillage, Nitrogen and Stubble Management on Phenology and Crop Establishment of Wheat

Field study was conducted at Cereal Crops Research Institute Pirsabak Nowshera, Khyber Pakhtunkhwa, Pakistan during 2009-2011 in a randomized complete block design with split plot arrangement having four replications. Three tillage systems (TS) [minimum, conventional and deep] were laid out in main plots, whereas the subplots were six maize stubble management (SM) practices such as removal, burning and incorporation with and without nitrogen (N; 120 kg ha -1 ) application. The objective of the study was to examine the treatment effects on phenology, establishment and yield of succeeding wheat crop. Result showed that wheat phenology except days to emergence was not affected by different TS however; early emergence (10 days) was observed in minimum tillage rather than conventional and deep tillage system. Nitrogen fertilization (120 kg N ha -1 ) enhanced days to phenological observations, while no significant variation in days to emergence and physiological maturity were recorded among SM practices, however; stubble incorporation delayed the booting and anthesis stage compared to burning and removing. Minimum tillage improved emergence, tillers and grain yield (3134 kg ha -1 ) compared to deep tillage systems. Nitrogen fertilization at the rate of 120 kg ha -1 and maize stubble incorporation prior to wheat sowing also improved emergence, tillers, plant height and grain yield compared to control and stubble removal or burning. It is concluded from current study that maize stubble incorporation with recommended dose of fertilizer N (120 kg ha -1 ) prior to wheat sowing delayed phenology, and improved wheat establishment and yield under minimum tillage in a continuous cereal based cropping system instead of stubble burning and removal.

Effect of Nitrogen Application Timing and Cutting Treatments on Phenology and Leaf Area of Three Brassica Cultivars

Brassica has potential as a grain and grazing option for mixed farming operations. The objectives of this experiment were to determine suitable nitrogen (N) application timing and Brassica cultivar for use as a dual-purpose crop. The field experiment was conducted at the Agricultural Research Farm of the Agricultural University, Peshawar, Pakistan, during winter 2009–2010 in a randomized complete block design with split-plot arrangement. The experiment consisted of three cultivars, three N application timings, and cutting treatments. Plant height and leaf area were greater at two and three split N applications. Likewise, leaf area was greater for N when applied in two split applications. Brassica cultivar Abasin-95 quickly emerged and attained more leaf area and leaf area index when compared to NIFA Raya and Dure-e-NIFA. Abasin-95 and Dure-e-NIFA took fewer days to mature when compared to NIFA Raya. NIFA Raya produced taller plants. Cutting significantly affected all parameters except days to maturity. Early flowering, taller plants, and greater leaf number, area, and leaf area index were noted for no-cut plots when compared to cut plots.

Effect of salinity and seed priming on growth and biochemical parameters of different barely genotypes

An experiment was conducted to investigate the interactive effect of salinity and seed priming on barely genotypes at the Institute of Biotechnology and Genetic Engineering (IBGE), Khyber Pakhtun Khwa Agricultural University Peshawar Pakistan. The experiment was carried out in completely randomized design (CRD) with three replications consisting of twelve barely genotypes (Haider-93, Soorab-96, Arabic Asward, NRB-37, Frontier-87, Jau-83, Balochistan-Local, NRB-31, KPK-Local, Sanober-96, Awarn-2002 and AZ-2006) at two seed conditions (seed priming with 30 mM NaCl or no seed priming) under four salinity levels (0, 50, 100 and 150 mM). The results revealed that seed priming and salinity had significantly (p≤0.05) affected all the parameters under study. However, the effect of seed priming was non significant (p>0.05) on shoot chlorophyll a content (mg g -1 fresh weight) and root sugar content (mg g -1 dry weight). Salinity stress had adversely affected growth and biochemical parameters of barley genotypes, however, seed priming with NaCl had diminished the negative impact of salt stress. Maximum shoot dry weight plant -1 (1.81 g), root dry weight plant -1 (0.42 g), shoot K + content (1.41 mg g -1 dry weight), root sugar content (7.55 mg g -1 dry weight) were recorded in Balochistan-Local. Similarly, Haider-93 produced highest root K + content (0.67 mg g -1 dry weight), shoot sugar content (16.36 mg g -1 dry weight), shoot chlorophyll a content (3.44 mg g -1 fresh weight) and shoot chlorophyll b content (1.78 mg g -1 fresh weight). Maximum shoot Na + content (1.20 mg g -1 ) and root Na + content (1.47 mg g -1 ) was recorded in Frontier-87. Seed priming had significantly (P<0.05) enhanced all the aforementioned parameters. The positive effect of seed priming was more profound in Balochistan-Local followed by Haider-93 as compared to other genotypes. Key words : Barely, salinity, seed priming, Na + , K + , chlorophyll a and b.