Abdul Qayyum

Water stress causes differential effects on germination indices, total soluble sugar and proline content in wheat (Triticum aestivum L.) genotypes

Different cultivars differ inherently in their response to drought and those cultivars best adapted to growth in arid and semiarid conditions form the most uniform and vigorous stands when grown under water deficits. The seeds of five wheat cultivars (GA-2002, Chakwal-97, Uqab-2000, Chakwal-50 and Wafaq-2001) were subjected to five different levels of osmotic stress; 0 bars (distilled water, control), -2, -4, -6 and -8 bars to assess the effect of osmotic stress on germination percentage, mean germination time, coleoptile length, proline and sugar amounts. The investigations were performed as factorial experiments under complete randomized design (CRD). Germination percentage, mean germination time and coleoptile length were shown to decrease with increasing osmotic stress, whereas a progressive increase in proline and sugar content were observed with increasing osmotic stress. The response of five cultivars examined under various levels of osmotic stress differed dramatically. Chakwal-50 and GA-2002 were amongst best performers, showing high germination rate, longest coleoptile length, highest proline values and sugar contents when compared with other cultivars under stress conditions. These were proven to be the most tolerant cultivars. Performance ofxa0 Wafaq-2001 and Uqab-2000 were poor when compared to the other cultivars under limited water stress conditions. Key words : Wheat, Triticum aestivum, water stress, osmotic stress, proline, sugar, seedling, germination.

Sugar-Starch Metabolism and Antioxidant Potential in Potato Tubers in Response to Different Antisprouting Agents During Storage

Single applications of different antisprouting agents like hot water treatment, spearmint oil and clove oil were carried out on potato cultivar “Lady Rosetta” to compare their efficacy with that of synthetic chloro isopropyl N-phenyl carbamate (CIPC). The tubers were stored at ambient storage conditions (25u2009±u20092xa0°C) for 81xa0days to assess changes in their sugar-starch concentrations and antioxidant potential. Antioxidant potential in the tubers was assessed as their total phenolic concentrations and radical scavenging activities. In addition, the enzymatic activities were also determined in order to evaluate the possible depletion of these antioxidants as substrate during storage. Results revealed significant response of stored potatoes to all antisprouting agents compared with the control (Pu2009≤u20090.05). CIPC and clove oil applications maintained tuber dormancy almost twice as long (81xa0days) as observed in the control (45xa0days). Application of spearmint oil and hot water treatment maintained tuber dormancy for almost 2xa0months. However, it was associated with an increased percentage sprouting during the last weeks of storage. At the end of storage, the highest starch (16.83%) and lowest sugar (0.99%) concentrations were estimated after CIPC application and maximum total phenolic concentration (143.57xa0mg gallic acid equivalent (GAE)/100xa0g), and highest antioxidant activity (39.73%) were found after clove oil application. Enzymatic activities were not statistically different between CIPC and clove oil application during most of the storage period. Results showed that efficient replacement of CIPC with clove oil in the premium potato cultivar might be useful; this may avert related food safety and environmental issues and would also ensure organic potato storage.

Water stress effects on biochemical traits and antioxidant activities of wheat (Triticum aestivum L.) under In vitro conditions

ABSTRACT Water stress is one of the major environmental stresses that affect agricultural production worldwide, especially in arid and semi-arid regions. This research investigated the effect of water deficit, induced by PEG-6000 on wheat genotypes (GA-2002, Chakwal-97, Uqab-2000, Chakwal-50 and Wafaq-2001) grown in modified MS medium solution. Osmotic stress caused a more pronounced inhibition in leaf relative water content and leaf membrane stability more sensitive (index in Wafaq-2001 and Uqab-2000) genotypes compared with the tolerant (Chakwal-50, GA-2002 and Chakwal-97) genotypes. Upon dehydration, an incline in proline, total soluble sugar, total soluble protein, superoxide dismutase, peroxidase, catalase and malondialdehyde activity content were evident in all genotypes, especially at osmotic stress of −8 bars. The observed data showed that status of biochemical attributes and antioxidant enzymes could provide a meaningful tool for depicting drought tolerance of wheat genotypes. The present study shows that genotypic differences in drought tolerance could be likely attributed to the ability of wheat plants to induce antioxidant defense under drought conditions. In order to develop genotypes with stable, higher yields in dry farming conditions, it is necessary to characterise genetic resources based on drought adaptation, determine suitable genotypes, and then use them in breeding programmes.

Sunflower (Helianthus annuus) Hybrids Evaluation for Oil Quality and Yield Attributes under Spring Planting Conditions of Haripur, Pakistan

Field experiment was conducted at the University of Haripur, Pakistan, to explore the role of photothermal units on oil contents, fatty acids profile, yield and yield traits of four sunflower hybrids viz SMH-0917, NK-S-278, SMH-0907 and Hysun33. These sunflower hybrids were selected because the farmers of that area are mostly relying on these hybrids for sunflower production. Sunflower hybrids were sown in spring and arranged under Randomized Complete Block Design with 3 replications under field conditions. Significant variation (p ≤ 0.05%) was found among the sunflower hybrids for photothermal unit requirements for flower completion and physiological maturity. Highest photothermal unit accumulation was found in Hysun33 followed by SMH-0917 and SMH-0907. Highest seed oil content and oil composition (linoleic and oleic acid were most abundant, whereas palmitic acid was least) was recorded in Hysun-33, SMH-0917 and SMH-0907. Overall Hysun-33, SMH-0917 and SMH-0907 performed better for plant height, head diameter, number of achenes per head and achene yield under field conditions. It was also observed that temperature and moisture availability positively influenced the oil quality of sunflower hybrids under spring planting conditions. The significant amount of variation within the sunflower population for photothermal unit accumulation, oil content, oil quality, and yield traits under these uniform field conditions reveals potential genetic variation that could be useful in breeding early maturing and high yielding local sunflower hybrids.

Changes in soil phosphorus fractions across a toposequence in the estuary plains of Pakistan

ABSTRACT Understanding the regional dynamics of soil phosphorus (P) chemistry is essential for developing the best fertilizer management practices aimed at enhancing P use efficiency in cropping systems. The soil content of apatite, an important P-containing lithogenic mineral, can be influenced by its position in the local relief of a landscape. The objective of this study was to determine quantitative distribution of various P-forms in estuary plains of southern Pakistan in relation to soil genesis. Soils at different positions within the estuary plain were sampled at various genetic horizons. Apatite-P was the most abundant inorganic P constituent (380-590 mg kg−1) in all cases, followed in decreasing abundance by iron oxides surfaces adsorbed phosphorus (Fe-P), octacalcium phosphates (Ca8-P), aluminum oxides with surface bound P (Al-P) and the least abundant was the phosphorus occluded in iron oxides mineral (Occl-P). The abundance of apatite-P and these other forms of secondary phosphate varied for the soils at different relief positions in these estuary plain landscapes.

Photo-induced changes in quality attributes of potato tubers during storage

The retail display of potato tubers is carried out in supermarkets under additional light sources to impart aesthetic value and consumer’s attention, however, is associated with potato greening and associated disorders. The objective of this study was to identify a most appropriate light source for potato variety ’Lady Rosetta‘ along with photo-induced changes in different quality parameters. Potato tubers were placed for 27 days at ambient storage (25 ± 2 °C) under different light sources i.e. blue, fluorescent, green, mercury and red along with dark storage, which also served as normal control. In general, quality parameters, such as sugars, chlorophyll, total glycoalkaloids, increase while attributes, such as starch and ascorbic acid decrease during the storage period. The initial increase followed by final decline has been observed in parameters, such as total phenolic contents and radical scavenging activity. The results showed maximum retention of different quality attributes in dark potato storage. Amongst different light sources mercury and green light retained appreciable retention of different quality parameters with non-significant difference estimated between them in most of the studied parameters. Storage of potato under fluorescent, red and blue light proved to be precarious due to skin discoloration. Overall results revealed tuber sensitivity to different colored light along with their potential storage stability in the retail markets.

Transition in quality attributes of potato under different packaging systems during storage

The suitability of different packaging materials i.e. jute, nylon, polypropylene, cotton, low density polyethylene, medium density polyethylene and high density polyethylene were studied along with the control on the premium potato variety “Lady Rosetta”. After the harvest potato tubers were washed, sorted, graded, cured and subsequently stored in different packaging materials at ambient temperature (25±2 o C). Transition in quality attributes of potato tubers under different packaging materials were studied on the basis of their physico-chemical and functional parameters. Overall results revealed that packaging materials had significant (p ≤ 0.05) effect on most of the quality attributes studied. In general weight loss, glucose, glycoalkaloids, polyphenol oxidase, peroxidase, increased while ascorbic acid contents decreased with the increase of storage time. Total phenolic contents and radical scavenging activity showed a sort of parabolic trend during the storage period. Amongst different packaging employed potato stored in polypropylene and low density polyethylene packaging presented best overall retention of vital quality attributes during 63 days storage however, tensile strength of polypropylene packaging made it advantageous for prolonged potato storage coupled with easy transit operations during marketing.

ISOLATION STUDIES FROM STEM EXTRACT OF PISTACIA INTEGERRIMA STEW. EX BRAND

Plants have been source of fantastic natural compounds that range in complexity. Chemical studies on traditional medicinal plants have led to discovery of potent bioactive components . Pistacia integerrima belonging to family Anacardiaceae has been traditionally effective for rheumatic pain, analgesic and antipyretic effects and used in treatment of coughs, phthisis, asthma and dysentery. Natural products have served as basis for compounds to be utilized in drug discovery. Stem extract of Pistacia integerrima was investigated with the aim to find some novel components that can later be used as drugs or active pharmaceutical intermediates. Plant material was collected from Margalla Hills Islamabad, shade dried and subjected to cold maceration technique for extraction. Crude extract was partitioned into different fractions on polarity basis. Repeated normal and reverse phase column chromatography of ethyl acetate fraction supported by Thin Layer Chromatography have led to the isolation of pure single compound. Isolated compound was further analyzed towards structural elucidation using LC-MS, IR and NMR spectroscopy. Present finding will be a useful and novel addition in already known chemical components from Pistacia integerrima.

Exogenously applied gibberellic acid, indole acetic acid and kinetin as potential regulators of source-sink relationship, physiological and yield attributes in rice (Oryza sativa) genotypes under water deficit conditions.

Rice is one of the important cereal crops drastically affected by water scarcity in rice ecosystems. In a pot study, the impact of externally applied gibberellic acid (GA3), indole acetic acid (IAA) and kinetin was investigated on assimilates mobilization and yield parameters of rice under water stress. Twenty five days seedlings of two rice genotypes KS-133 and Basmati-2000 were transplanted in soil filled pots and sprayed with GA3, IAA and kinetin each of 10 M concentration at panicle initiation stage. Water stress was imposed to plants 80 days after transplanting for 10 days. Water stress (p≤ 0.05) reduced leaf chlorophyll content and yield of rice but increased the concentration of proline, leaf soluble protein and enhanced mobility of assimilates from leaves to grains. Application of GA3 and kinetin significantly (p≤ 0.05) increased chlorophyll content, growth and yield attributes in both genotypes under water stress conditions. However, IAA application did not improve the grain yield in rice genotypes under water stress. The positive impact of GA3 and kinetin spray was imitated in the form of enhanced solute accumulation; enhanced growth and greater grain assimilate deposition. This may be concluded that GA3 and kinetin can be applied exogenously prior to flower initiation in rice to reduce panicle sterility by increasing assimilates mobility under water deficit for optimal economic yield.

Evaluation of potential morpho-physiological and biochemical indicators in selecting heat-tolerant tomato (Solanum lycopersicum Mill.) genotypes

A few degrees in temperature above the optimum can cause a considerable yield loss in tomatoes. A research experiment was conducted in which three tomato genotypes of (Solanum lycopersicum Mill.), ‘Suncherry Extra Sweet’ (Suncherry), ‘Walter’, and ‘CLN-2498d’, were evaluated for response to moderate high temperature at the reproductive stage. High temperature reduced the total number of fruits per plant, fruit size, number of seeds per fruit, seed setting, and relative ovule viability. However, high temperature increased proline accumulation and membrane thermo-stability in plant parts of the investigated genotypes. Fruit size and the number of seeds per fruit were reduced in all the genotypes, with the greatest reduction occurring in Suncherry. Similarly, viability of male and female gametes was also reduced in all of the investigated genotypes due to high temperature injury. The reduction in seed setting due to high temperature was greatest in ‘Suncherry’ and ‘Walter’, and least in ‘CLN-2498d’. Likewise, ovule viability was least reduced in ‘CLN-2498d’. The genotypes accumulating higher proline concentrations in reproductive parts and with enhanced membrane thermo-stability under high temperature likewise produced the highest fruit yield, and hence, exhibited high temperature tolerance.