abcd assignment seminar presentation.pptx

presentation.pptx

1. Contour farming and terracing Contour farming involves planting crops along the contour lines of the land, reducing water runoff and soil erosion. Terracing, commonly used in hilly or sloping terrain, creates level platforms on which crops are grown, allowing rainwater to infiltrate and be retained within each terrace.

2. Soil cover Maintaining ground cover through cover crops or permanent vegetation reduces soil erosion and water evaporation. Cover crops not only protect the soil from erosion but also contribute organic matter when incorporated into the soil, improving its water retention capacity.

3. Soil moisture and monitoring Regular monitoring of soil moisture levels helps optimize irrigation scheduling, ensuring that water is applied only when necessary. Various tools such as soil moisture sensors or tensiometers can be used to measure soil moisture content at different depths.

4. Concept of increasing water holding capacity Water holding refers to the ability of soil to retain water against the force of gravity making it available for plant uptake. Methods to increase water holding capacity : Organic matter addition : Incorporating organic matter such as compost, manure, or cover crops into the soil increases its water holding capacity. Cover crops : Cover crops, also known as green manure, protect the soil surface from erosion and water evaporation. Mulching : Applying a layer of mulch on the soil surface reduces water evaporation, suppresses weed growth, and maintains soil moisture . Soil ammendment : : Adding soil amendments like gypsum or clay can improve soil structure and increase water holding capacity, especially in sandy soils.

5. Hydrogels Hydrogels are fascinating materials with a wide range of applications, thanks to their unique properties. Essentially, hydrogels are three-dimensional networks of hydrophilic polymer chains that can absorb and retain a significant amount of water. They're like sponges, but on a microscopic scale. These gels are used in various fields, including biomedical engineering, drug delivery systems, wound healing, contact lenses, tissue engineering, and even in agriculture for soil conditioning and water retention .

6. M ost notable features of hydrogels is their ability to mimic the natural environment of living tissues due to their high water content . Hydrogels can be engineered to respond to external stimuli like temperature, pH, or light, which opens up opportunities for controlled drug release systems. For instance, a temperature-responsive hydrogel might release a drug when exposed to body heat, ensuring targeted and controlled delivery.

7. The water and nutrient release principles in hydrogels : Swelling and Porosity : Hydrogels have the ability to absorb and retain water within their structure. When immersed in a solution containing water and nutrients, the hydrogel swells as it absorbs the liquid. The extent of swelling depends on factors like the degree of crosslinking within the polymer network and the concentration of the solution . Diffusion : Water and nutrients within the hydrogel can diffuse through the polymer network. The rate of diffusion is influenced by factors such as the size and charge of the molecules, the mesh size of the polymer network, and the presence of any chemical interactions between the polymer and the molecules being transported. Degradation : Some hydrogels are designed to degrade over time, either through enzymatic or hydrolytic mechanisms. As the hydrogel degrades, it releases any entrapped water and nutrients into the surrounding environment. The degradation rate can be controlled by adjusting the chemical composition of the hydrogel or by incorporating specific degradation triggers .

8. Stimuli-Responsive Release : Certain hydrogels are engineered to respond to external stimuli such as changes in pH, temperature, or light. These stimuli can trigger changes in the hydrogel's structure, leading to the release of water and nutrients. For example, a temperature-responsive hydrogel might undergo a phase transition in response to body heat, causing it to release any encapsulated molecules. Controlled Release Systems : Hydrogels are often used as matrices for controlled release systems, where the release of water and nutrients is regulated over time. This can be achieved by incorporating molecules with specific affinity for the desired nutrients, or by modifying the hydrogel's structure to create diffusion barriers.

9. Approaches to improve transpiration over evapotranspiration Improving transpiration while reducing evapotranspiration can be a valuable strategy in agriculture, particularly in water-stressed environments. Here are some approaches to achieve this : Plant Selection and Breeding : Choose or develop crop varieties that are more efficient in water use. This includes selecting plants with deep root systems that can access water deeper in the soil profile, as well as those with traits such as smaller leaf size, reduced stomatal density, and higher water use efficiency . Precision Mulching : Applying organic or synthetic mulches on the soil surface helps to reduce evaporation by creating a barrier between the soil and the atmosphere. This can also help to regulate soil temperature and moisture content, reducing the need for frequent irrigation . Soil Management : Improving soil structure and organic matter content can enhance water retention and infiltration, reducing the amount of water lost to evaporation. Practices such as conservation tillage, cover cropping, and compost application can help improve soil health and water holding capacity. Planting Density and Spacing : Adjusting planting density and spacing can optimize water use efficiency by reducing competition among plants for water and nutrients. Proper spacing allows for better air circulation and light penetration, which can help reduce transpiration rates while maintaining adequate crop yields.

10. Plant Growth Regulators : Application of plant growth regulators can modulate stomatal conductance and transpiration rates, helping to optimize water use efficiency without compromising crop productivity. However, this approach requires careful management to avoid negative impacts on plant growth and development.

11. Biological and Chemical Amendments : Certain biological amendments, such as mycorrhizal fungi, can improve plant water uptake efficiency by extending the root system and enhancing nutrient uptake. Additionally, the use of hydrogel -based soil amendments or soil conditioners can improve water retention and availability to plants. Crop Rotation and Diversification : Implementing crop rotation and diversification practices can help break pest and disease cycles, reduce soil compaction, and improve soil structure, all of which contribute to better water infiltration and retention.

12. Stomatal and Non- stomatal regulation of water loss Stomata : These are tiny pores on the surface of leaves and stems that allow gas exchange, including the intake of carbon dioxide (CO2) for photosynthesis and the release of oxygen (O2) and water vapor. Stomata are bordered by guard cells which control their opening and closing . Transpiration : This is the process by which water vapor is released from the stomata into the atmosphere. When stomata are open, transpiration rates increase, leading to higher water loss. Conversely, when stomata are closed, transpiration decreases, conserving water . Regulation factors Light : Stomata generally open in response to light to facilitate photosynthesis. Carbon dioxide concentration : High concentrations of CO2 can lead to stomatal closure. Plant hormones : Hormones like abscisic acid (ABA) induce stomatal closure during drought stress.

13. Non- stomatal Regulation : Cuticle : The waxy cuticle covering the epidermis of leaves reduces water loss by creating a barrier to water vapor diffusion. Trichomes : These are hair-like structures on leaf surfaces that can reduce water loss by creating a microclimate around the leaf, reducing transpiration rates. Root architecture : Plants may alter their root systems in response to water availability, with deeper roots accessing groundwater during drought. Metabolic adjustments : Some plants undergo metabolic changes to conserve water, such as altering the composition of cell membranes or adjusting biochemical pathways to minimize water loss. Crassulacean Acid Metabolism (CAM) : CAM plants, such as succulents, have adapted to arid conditions by conducting most of their gas exchange and water uptake at night when temperatures are lower and humidity is higher, reducing daytime water loss through stomata.

14. Antitranspirants Antitranspirants are substances or materials applied to plant surfaces to reduce transpiration, thereby minimizing water loss from the plant. They are commonly used in agriculture and horticulture to help plants cope with water stress, particularly during drought conditions or in arid environments. Antitranspirants work through various mechanisms to achieve their effects:

15. 1.Film forming antitranspirants These antitranspirants create a thin, transparent film or coating on the surface of leaves, which reduces the rate of water loss through transpiration. The film helps to minimize water loss by reducing the surface area available for evaporation and by providing a physical barrier to water vapor diffusion. Common film-forming antitranspirants include products containing materials like latex, polyvinyl acetate, or acrylic polymers.

16. 2.Stomatal Closure Inducers : Some antitranspirants contain compounds that induce stomatal closure, thereby reducing the rate of transpiration. These compounds may mimic the effects of plant hormones such as abscisic acid (ABA), which naturally trigger stomatal closure in response to water stress. Stomatal closure inducers can help conserve water during periods of drought or water scarcity.

17. 3.Reflective Antitranspirants : Reflective antitranspirants contain substances that reflect or scatter sunlight, reducing the amount of solar radiation absorbed by the plant. By reducing the amount of heat absorbed by leaves, these antitranspirants help to lower leaf temperatures and minimize water loss through transpiration.

18. 4.Desiccation Retardants : These antitranspirants contain compounds that help to retain moisture within plant tissues, reducing the rate of water loss through transpiration. Desiccation retardants may include substances such as humectants or osmoprotectants , which help to maintain cellular hydration and prevent dehydration of plant tissues.

19. Osmoprotectants Osmoprotectants , also known as compatible solutes or osmolytes , are small organic molecules that accumulate in cells in response to osmotic stress, such as drought, salinity, or extreme temperatures. These compounds help to maintain cell turgor pressure, stabilize proteins and membranes, and protect cellular structures from damage caused by dehydration or high salt concentrations. Osmoprotectants play a crucial role in the ability of plants, microorganisms, and some animals to survive and thrive in challenging environmental conditions .

20. common osmoprotectants found in plants : 1.Proline: Proline is a non-essential amino acid that accumulates in large quantities in response to various stress conditions. It acts as a compatible solute, helping to maintain cell turgor and stabilize proteins and membranes.Proline also plays a role in scavenging reactive oxygen species (ROS) and protecting cells from oxidative damage.

21. 3.Glycine betaine : is a quaternary ammonium compound that accumulates in response to osmotic stress in many plant species. It helps to maintain cellular osmotic balance, stabilize membranes, and protect enzymes and proteins from denaturation.Glycine betaine also acts as an osmoprotectant in some bacteria and other organisms.

22. 3.Trehalose: its is a disaccharide sugar composed of two glucose molecules linked together. 4.sugars : Sugars such as sucrose, glucose, and fructose can act as osmoprotectants when they accumulate to high concentrations in plant cells. 5.polyols: Polyols are sugar alcohols that accumulate in response to osmotic stress in many plants . They help to maintain cell turgor pressure, stabilize membranes, and scavenge ROS to protect cells from oxidative damage.

23. ROS scavengers Reactive oxygen species (ROS) scavengers are molecules or enzymes that help neutralize and remove harmful ROS generated within cells under various stress conditions. ROS, including superoxide radicals (O2•−), hydrogen peroxide (H2O2), hydroxyl radicals (•OH), and singlet oxygen (^1O2), are highly reactive molecules that can cause oxidative damage to proteins, lipids, nucleic acids, and other cellular components if their levels become excessive.

24. Enzymatic ROS Scavengers : 1.Superoxide Dismutase 2.Catalase 3. Glutathione Peroxidase

25. Non-enzymatic ROS Scavengers : Ascorbic Acid (Vitamin C) : Ascorbic acid is a potent water-soluble antioxidant that scavenges various ROS, including superoxide radicals (O2•−) and hydroxyl radicals (•OH), through its reducing properties . α- Tocopherol (Vitamin E) : α- Tocopherol is a lipophilic antioxidant that protects cellular membranes from lipid peroxidation by scavenging lipid-derived radicals and terminating chain reactions . Glutathione (GSH) : Glutathione is a tripeptide ( γ- glutamyl-cysteinyl-glycine ) that acts as a major intracellular antioxidant and cofactor for glutathione peroxidase (GPX). It directly scavenges ROS and regenerates other antioxidants, such as ascorbic acid and α- tocopherol .

26. Polyphenols : Polyphenolic compounds found in fruits, vegetables, and plant-based foods possess antioxidant properties and can scavenge ROS through their ability to donate hydrogen atoms or electrons.

27. Rootstocks Rootstocks play a crucial role in improving tolerance to various environmental stresses and biotic factors in horticultural crops, particularly in fruit trees like apples, grapes, citrus, and stone fruits. Here's how rootstocks contribute to enhancing tolerance: 1. Drought tolerance : Rootstocks with deep and extensive root systems can access water from deeper soil layers, enhancing drought tolerance by improving water uptake efficiency. 2.salinity tolerance : Certain rootstocks are tolerant to saline soils, enabling crops to thrive in areas with high soil salinity.Salinity -tolerant rootstocks can exclude sodium and chloride ions from uptake, maintain ion homeostasis, and prevent the accumulation of toxic ions in aerial plant parts.

28. 3. Soil pH and Nutrient Tolerance :Some rootstocks are adapted to specific soil conditions, such as alkaline or acidic soils, and can thrive under adverse pH conditions. 4. Biological Stress Resistance : Rootstocks can confer resistance to soil-borne pathogens, nematodes, and pests through mechanisms such as secretion of allelochemicals , induction of systemic resistance, or formation of physical barriers against pathogens.

29. Chemical regulation of flower drop due to temperature Chemical regulation of flower drop due to temperature involves the use of plant growth regulators (PGRs) to mitigate the adverse effects of high or low temperatures on flower development and retention. Flower drop, also known as flower abscission, can occur when temperature stress disrupts hormonal balance, metabolic processes, and cellular signaling pathways involved in flower development and retention. Here are some strategies for chemical regulation of flower drop due to temperature:

30. Gibberellins (GA) : Gibberellins are a class of plant hormones that regulate various aspects of plant growth and development, including flower initiation, development, and abscission. Application of gibberellin formulations, such as GA3, can promote flower retention by stimulating cell elongation, delaying senescence, and enhancing fruit set under suboptimal temperature conditions.

31. Cytokinins : Cytokinins are plant hormones that play roles in cell division, shoot growth, and reproductive development. Application of synthetic cytokinin formulations, such as 6-benzylaminopurine (6-BA) or kinetin, can promote flower retention by stimulating cell division, delaying senescence, and enhancing flower and fruit development under temperature stress conditions.

32. Auxins Auxins are phytohormones involved in various aspects of plant growth and development, including flower induction, differentiation, and abscission . Application of synthetic auxin formulations, such as indole-3-acetic acid (IAA) or naphthaleneacetic acid (NAA), can promote flower retention by inhibiting abscission zone formation, suppressing ethylene synthesis, and promoting fruit set under temperature stress conditions.

33. Ethylene Inhibitors : Ethylene is a plant hormone involved in senescence, fruit ripening, and abscission processes, including flower drop. Application of ethylene inhibitors, such as 1-methylcyclopropene (1-MCP) or silver thiosulfate (STS), can suppress ethylene synthesis or perception, thereby delaying flower senescence and abscission under high temperature conditions.

34. Abscisic Acid (ABA) Modulators : Abscisic acid is a plant hormone involved in various stress responses, including drought and temperature stress, and can influence flower abscission. Modulating ABA levels using inhibitors or analogs can regulate flower development and abscission responses to temperature stress, although the effects may vary depending on the species and environmental conditions.

35. Combined PGR Treatments : Integrated applications of multiple PGRs, such as combinations of gibberellins, cytokinins , auxins , and ethylene inhibitors, may provide synergistic effects in regulating flower development and abscission under temperature stress conditions.

36. Chemicals to improve pollen viability during abiotic stress Polyamines : Polyamines such as spermidine and spermine have been reported to enhance pollen viability and tolerance to abiotic stress in various plant species. They help in stabilizing cellular structures and protecting membranes under stress conditions. Calcium : Calcium is an essential element for pollen germination and pollen tube growth. It plays a crucial role in regulating various signaling pathways involved in stress responses. Calcium can be applied exogenously to enhance pollen viability during stress.

37. Boron : Boron is known to play a role in pollen germination and pollen tube elongation. Boron deficiency can lead to reduced pollen viability. Therefore, applying boron can help improve pollen viability under stress conditions. Salicylic acid (SA) : SA is a signaling molecule involved in plant defense responses. It has been shown to enhance pollen viability and pollen tube growth under stress conditions. SA treatment can improve stress tolerance in plants by inducing antioxidant defense mechanisms.

38. Polyethylene glycol (PEG) : PEG is often used to simulate water stress in plants. It can induce osmotic stress, which mimics drought conditions. While PEG itself may not directly induce pollen viability, it can be used in experiments to study the effects of drought stress on pollen viability and to screen for compounds that mitigate the stress. Antioxidants : Antioxidants such as ascorbic acid (vitamin C), tocopherols (vitamin E), and glutathione can help scavenge reactive oxygen species (ROS) generated under stress conditions. ROS accumulation can lead to pollen damage and reduced viability. Therefore, exogenous application of antioxidants can improve pollen viability during stress.

39. Plant growth regulators : Plant hormones like cytokinins , auxins , and gibberellins can regulate pollen development and pollen tube growth. Exogenous application of these hormones, especially cytokinins , has been reported to improve pollen viability under stress conditions.