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20225
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Subject: Botany × End date: 2022 × Start date: 2022 × Type: Thesis ×
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    Evaluation of morpho-physiological and metal accumulation potential of Salix alba L. and Toona ciliata M. Roemer grown on heavy metal contaminated soils
    (Punjab Agricultural University, 2022) Ravneet Kaur; Sharma, Rajni
    The present investigations were carried out to study the effect of lead (Pb), cadmium (Cd) and their combinations (Pb+Cd) on morpho-physiological and metal accumulation potential of Salix alba and Toona ciliata during 2020 and 2021. Heavy metals induce negative effect on morphological and biomass attributes of both species, but Toona showed better survival percentage (>95%) than Salix (<55%) even at higher concentrations of Pb300 and Cd25. The accumulation of proline, total soluble sugars, total soluble proteins along with increased antioxidant enzyme activities are responsible to enhance tolerance in both species. On the basis of phytoremediation efficiency evaluation factors such as bioconcentration factor (BCF) and translocation factor (TF), Salix alba can be categorized as excluder plant for Pb and Cd with higher metal accumulation in roots than shoots (BCF>1, TF<1), while Toona ciliata can be categorized as hyperaccumulator with more Pb and Cd accumulation in the shoots than roots (BCF>1 and TF>1). Further, heavy metal translocation and accumulation decreased in combinations as compared to single element application suggesting the antagonistic relationship among both metals. Pb and Cd negatively affect the plant nutrient content either by affecting their translocation or by decreasing nutrient availability in soils. Anatomical studies showed significant alterations in stomatal pore size, stomatal density and trichome density due to heavy metal toxicity in both Salix and Toona. Field emission scanning electron microscopy and energy dispersive x-ray spectroscopy (FESEM-EDS) results confirmed the Pb and Cd accumulation sites in the leaves and root tissues of plants. Fourier transformed infrared (FTIR) spectroscopy analysis revealed that Pb and Cd accumulation in plants induced changes in carboxy, amino, hydroxyl and phosphate groups that ultimately caused alteration in physiological functioning in plants. Conclusively, both Salix alba and Toona ciliata have potential to be used as remediation species for Pb and Cd contaminated soils.
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    EVALUATION OF MORPHO-PHYSIOLOGICAL AND METAL ACCUMULATION POTENTIAL OF Salix alba L. AND Toona ciliata M. Roemer GROWN ON HEAVY METAL CONTAMINATED SOILS
    (Punjab Agricultural University, Ludhiana, 2022) Ravneet Kaur; Sharma, Rajni
    The present investigations were carried out to study the effect of lead (Pb), cadmium (Cd) and their combinations (Pb+Cd) on morpho-physiological and metal ccumulation potential of Salix alba and Toona ciliata during 2020 and 2021. Heavy metals induce negative effect on morphological and biomass attributes of both species, but Toona showed better survival percentage (>95%) than Salix (1, TF1 and TF>1). Further, heavy metal translocation and accumulation decreased in combinations as compared to single element application suggesting the antagonistic relationship among both metals. Pb and Cd negatively affect the plant nutrient content either by affecting their translocation or by decreasing nutrient availability in soils. Anatomical studies showed significant alterations in stomatal pore size, stomatal density and trichome density due to heavy metal toxicity in both Salix and Toona. Field emission scanning electron microscopy and energy dispersive x-ray spectroscopy (FESEM-EDS) results confirmed the Pb and Cd accumulation sites in the leaves and root tissues of plants. Fourier transformed infrared (FTIR) spectroscopy analysis revealed that Pb and Cd accumulation in plants induced changes in carboxy, amino, hydroxyl and phosphate groups that ultimately caused alteration in physiological functioning in plants. Conclusively, both Salix alba and Toona ciliata have potential to be used as remediation species for Pb and Cd contaminated soils.
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    Histological and physiological changes in developing seeds and fruit pericarp of pumpkin (Cucurbita pepo L.) grown during different seasons
    (Punjab Agricultural University, 2022) Bhavna; Chahal, Gagandeep Kaur
    The histological and biochemical changes in developing seeds and pericarp of pumpkin genotypes (hulled and hull-less) in different growing seasons were evaluated in the present study. Biochemical analysis of seed coat revealed that the proteins, lipids and starch content were decreased in the seed coat with advancement of seed development due to translocation of these components towards the seed cotyledon since cotyledon acting as dominant sink. The proteins, lipids and starch content were observed to be more in the seed cotyledon in season II (low temperature) which improved the seed quality and also increased the thickness of seed cotyledon. Further, histological studies of developing seeds also depicted that the seed cotyledon thickness was more in season II as the low temperature slowed the seed development and gave more time to seed for accumulation of biomolecules into seed cotyledon. The seed coat thickness was also found to be more in season II in both the genotypes due to increased content of primary wall components like cellulose, hemicellulose and pectin and their deposition is responsible for increasing the seed coat thickness. The seed length, diameter and hundred seed weight were also more in season II and might be caused by increased seed coat and cotyledon contents. The pectin, cellulose, hemicellulose and lignin contents were observed to be increased with development in the pericarp.The development of pumpkin seeds and fruits hastened in high temperature which decreased the seed quality, while the low temperature slowed the maturity process and enhanced the seed quality.
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    Mitigation of salt stress by γ-amino butyric acid (GABA) and proline in maize (Zea mays L.)
    (Punjab Agricultural University, Ludhiana, 2022) Sharma, Sakshi; Gupta, Namarta
    The present investigation was conducted to study the effect of proline and GABA on physiological and biochemical parameters at different on different salt stress levels in two varieties of J-1006 and J-1007 maize (Zea mays). The salt stress negatively affected the seed germination and seed vigour parameters. Seeds of both the varieties were subjected to different treatments viz. Proline (10mM and 20 mM) and GABA (100ppm and 500ppm) at salt stress level of 50mM, 75mM and 100mM NaCl. Various parameters were recorded from seedlings after 10 days of germination. The seed treatments positively affected the physiological parameters (percentage germination, seedling length, seedling biomass, seed vigour I and seed vigour II) and biochemical parameters (total soluble sugars, total soluble protein and activities of antioxidant enzymes viz. Catalase, peroxidase and superoxide dismutase) of treated seedlings as compared to control. However, a reduction was observed in malondialdehyde content continue to decreased with seed treatments at all salinity levels. The results recoded that proline 20mM and GABA 500 ppm were more effective than proline 10mM and GABA 500ppm respectively. Therefore, the application of seed treatments viz, proline and GABA could play an important role in mitigating the effect of salt stress.
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    Effect of residue mulch and irrigation regimes on physiological and biochemical attributes of onion (Allium cepa L.)
    (Punjab Agricultural University, Ludhiana, 2022) Shinedeep Kaur; Dhingra, Madhu
    A field experiment was conducted during rabi season of 2020-21 to examine the effect of residue mulch on physiological, biochemical and yield attributes of onion under different irrigation levels in a split plot design with three irrigation regimes based on IW/CPE 0.8 (I0.8), 1.4 (I1.4), 2.0 (I2.0) in main plots and two mulch rates i.e. M0 (no mulch) and M6 (paddy straw mulch @ 6 t ha-1) in sub-plots. Mulching with paddy straw moderated the soil hydrothermal regime by significantly improving the soil moisture storage and lowering the soil temperature. Plant growth in terms of plant height, biomass, number and size of leaves was significantly better in most frequent irrigation regime and further enhanced with the application of mulch under all irrigation levels at all stages. Both the factors exerted a significant effect on plant water status with 19.21-26.54% and 6-14% increase in relative water content with irrigation and mulch, respectively. Amongst biochemical traits, total chlorophyll and total protein content were highest in I2.0 while total soluble sugars and total proline content were maximum in I0.8. Mulch application increased total soluble sugar and protein content in onion leaves under all irrigation regimes but decreased proline content. Weed infestation was lowered by 34.69% in mulched plots but increased with irrigation frequency. Mulch application also reduced the profile water use and total water use by 44.74 and 3.31%, respectively. Higher percentage of large sized bulbs was obtained in I2.0M6. Both irrigation and mulching significantly affected bulb quality with respect to total soluble solids. Water productivity was highest in I0.8 and mulched plots. Application of paddy straw mulch improved the bulb yield with more pronounced effect in least frequent irrigation regime. Higher bulb yield with mulch in I1.4 than no mulch in I2.0 indicated the saving of three irrigations.