PPT Category: PPT Horticulture

This PPT deals with the physiology of dwarfism in fruit trees, explaining why and how dwarf growth occurs and how it can be deliberately induced and managed for efficient fruit production. It begins with the concept of dwarfism, defining dwarf fruit trees as plants that attain smaller size at full maturity due to genetic factors or horticultural manipulations. The presentation emphasizes the importance of dwarf trees in modern fruit cultivation, particularly for maximizing the use of vertical and horizontal space and increasing productivity per unit area and time.

The PPT explains that the physiology of dwarfism involves complex anatomical, physiological, and biochemical alterations that modify normal growth patterns. Various theories and postulations explaining dwarfing mechanisms are discussed. A major focus is placed on the role of dwarfing rootstocks, interstocks, and scion–stock interactions, which influence water and nutrient uptake, hydraulic conductivity, carbohydrate partitioning, canopy development, and hormonal balance.

Key physiological processes associated with dwarfing include reduced xylem vessel size, higher bark-to-wood ratio, restricted root systems, partial blockage at graft unions, and depletion of minerals and solutes in xylem sap. The role of phytohormones, especially reduced auxin transport, altered ABA:IAA ratio, reduced gibberellin activity, and variations in cytokinin levels, is explained in detail. Dwarfing is also associated with reduced net assimilation rate, early and heavy fruiting at the expense of vegetative growth, and restricted canopy architecture.

The PPT further discusses methods to achieve dwarfism, including the use of dwarfing and incompatible rootstocks, plant growth regulators (such as paclobutrazol and gibberellin inhibitors), pruning and training systems, nutrient management, phenolic compounds, in vitro techniques, viral induction, genetic engineering, and induced mutations. Each method is supported by physiological explanations and research findings.

Advantages of dwarf fruit trees highlighted include suitability for high-density planting (HDP), ultra-high-density planting (UHDP), and meadow orcharding, ease of management, reduced wind damage, early bearing, and improved fruit quality. Disadvantages such as shorter lifespan, higher technical requirements, and increased pest and disease pressure in intensive systems are also discussed.

The PPT concludes with extensive case studies demonstrating dwarfing effects of rootstocks, interstocks, training systems, growth retardants, virus inoculation, and in vitro techniques across fruit crops like apple, pear, citrus, mango, plum, and mandarin. Overall, the presentation provides a comprehensive understanding of the physiological basis of dwarfism and its practical application in modern orchard systems

This PPT focuses on the role of nano edible coatings as an advanced postharvest technology for improving the shelf life and quality of horticultural crops. It begins by highlighting the magnitude of postharvest losses in fruits and vegetables, particularly in India, where a significant proportion of produce is lost due to inadequate infrastructure, high respiration rate, moisture loss, and microbial spoilage. The presentation emphasizes the urgent need for innovative technologies to reduce postharvest losses and ensure food security.

The concept of nanotechnology is introduced, including its definition, historical background, and unique properties of nanoparticles such as high surface-to-volume ratio and enhanced physicochemical activity. The PPT explains why nanotechnology is increasingly important in postharvest management, especially as many conventional chemicals are costly, phytotoxic, or likely to be restricted due to environmental concerns.

The core of the PPT discusses nano edible coatings, which are ultra-thin layers formed by incorporating nanoparticles, nanoemulsions, or nanocomposites into edible coating materials. Conventional edible coatings based on polysaccharides, proteins, and lipids are described, along with their limitations such as excessive thickness, restricted gas exchange, rancidity, and development of off-flavours. Nano coatings overcome these limitations by providing better gas and moisture barriers while maintaining internal fruit physiology.

Various nano-based systems are explained, including nanoemulsions, nanocomposites, nanosensors, and antimicrobial nanoparticles such as nano silver, zinc oxide, and titanium dioxide. Their roles in controlling microbial growth, degrading ethylene, improving mechanical strength, and enhancing barrier properties are discussed. The PPT also covers coating application methods and highlights sprayable nano-coating technologies developed using plant-derived compounds.

Case studies presented in the PPT demonstrate the practical application of nano edible coatings in crops such as okra and bell pepper. Results show improved shelf life, reduced physiological loss in weight, better texture retention, lower microbial decay, and improved marketability under ambient and cold storage conditions. The combined use of natural coatings (e.g., gum Arabic) with nanoparticles showed superior results compared to single-component coatings.

Finally, the PPT outlines the advantages, limitations, and future prospects of nano edible coatings. While they offer significant benefits such as controlled release of functional agents, reduced chemical usage, and environmental friendliness, concerns related to cost, measurement difficulties, and potential toxicity are highlighted. The presentation concludes that further research, standardization, and safety evaluation are essential for the sustainable adoption of nano edible coatings in horticulture

This PPT focuses on the concept of seed ageing, describing it as a natural, inevitable process in which seeds gradually lose quality, vigour, and germination capacity during storage. Since seeds are living entities, they undergo a series of physiological, biochemical, and structural changes soon after physiological maturity and during the storage phase. These changes collectively lead to seed deterioration, reduced field performance, poor stand establishment, and ultimately loss of germinability.

The presentation explains that seed ageing is both an inexorable and irreversible process. Although deterioration cannot be reversed once it has occurred, the rate of ageing can be slowed. Seed ageing varies among species, varieties, seed lots, and even among individual seeds within a lot. The PPT emphasizes that stored seeds are critical assets for growers, as uniform and successful establishment is essential for strong crop growth.

The mechanisms of seed ageing are discussed in detail, highlighting oxidative damage to macromolecules such as lipids, proteins, enzymes, and nucleic acids. Free radicals, formed through ionizing radiation, enzymatic reactions, transition metals, and normal metabolic processes, play a central role in oxidative degradation. One of the earliest effects of ageing is the loss of cellular membrane integrity, resulting in increased leakage of metabolites due to phospholipid hydrolysis and lipid autoxidation. Mitochondrial degradation, including swelling, loss of function, pigmentation, and fragmentation, further contributes to reduced seed viability.

The PPT also explains the activation of hydrolytic enzymes when seed moisture approaches levels required for germination. If germination does not proceed normally, continued enzyme activity leads to energy depletion and accumulation of breakdown products, accelerating deterioration. Additionally, the breakdown of mechanisms responsible for triggering germination contributes to ageing-related loss of viability.

Another major aspect covered is genetic degradation, where progressive fragmentation and oxidative damage of embryonic nuclear DNA occur during seed ageing. DNA damage may result from uncontrolled oxidation or programmed cell death–like processes.

Visible symptoms of seed ageing include morphological changes such as darkening of the seed coat, development of necrotic lesions in cotyledons, increased membrane leakage, and loss of enzyme activity. Enzymes commonly associated with seed deterioration include dehydrogenase, catalase, peroxidase, amylase, and cytochrome oxidase.

The PPT concludes that seed ageing affects multiple cellular systems simultaneously and that deterioration is not limited to a single function. Environmental storage factors such as seed moisture content, oxygen availability, relative humidity, and temperature play a decisive role in determining seed longevity and storability. Understanding these factors is essential for improving seed storage practices and maintaining seed quality over time

This PPT covers the concept and practical importance of canopy management in fruit crops through the use of rootstocks and scions. It begins with the definition of a rootstock and explains its historical development, particularly its early use in European vineyards to overcome phylloxera. The presentation highlights why rootstocks are essential in fruit propagation, especially for controlling tree size, improving precocity, and enabling efficient orchard management.

The material explains stock–scion relationships, detailing how rootstocks influence scion characteristics such as tree vigour, growth habit, flowering, fruiting, yield, fruit quality, nutrient uptake, and resistance to biotic and abiotic stresses. It also describes how scions can affect the rootstock, including impacts on root system development, cold hardiness, and longevity. The physiological and anatomical basis of dwarfing, including restricted water and solute transport, partial incompatibility, and altered hormone movement, is discussed.

The PPT further outlines the abilities and desirable traits of rootstocks, such as nursery performance, soil adaptability, climatic hardiness, and resistance to soil-borne diseases. The importance of rootstocks in imparting stress tolerance, regulating moisture and nutrient uptake, controlling tree size, improving yield and fruit quality, and ensuring early bearing is emphasized.

Problems associated with rootstock use, particularly graft incompatibility, are explained along with their symptoms, causes (anatomical, physiological, pathological), and types. Detailed sections describe rootstocks used in major fruit crops such as apple, pear, peach, plum, cherry, walnut, and several tropical and subtropical fruits. Clonal and seedling rootstocks, their characteristics, and major rootstock series (Malling, Malling Merton, Geneva, Budagovsky, etc.) are discussed with examples.

Finally, the PPT covers propagation methods used for different fruit crops and concludes that the use of dwarfing rootstocks under high-density planting systems can significantly increase productivity per unit area. It also highlights the role of modern techniques like tissue culture for rapid multiplication and production of virus-free planting material

This PPT provides a comprehensive overview of crop modelling in fruit crops, emphasizing the use of quantitative mathematical models to describe, analyze, and predict growth, development, and productivity of perennial fruit trees. It introduces crop modelling as a multidisciplinary subject integrating bioclimatology, soil science, botany, agronomy, applied mathematics, and computer science. The presentation highlights the importance of carbon-based productivity models and plant growth simulation, particularly for understanding fruit tree growth, phenology, and yield under varying environmental and management conditions.

The PPT explains how fruit tree models differ from annual crop models due to their perennial nature, multi-year growth, complex plant architecture, carry-over of physiological status, and strong influence of management practices such as pruning, training, crop load regulation, and grafting on rootstocks. Key differences among fruit tree species, including root system size, reproductive abscission, and bioenergetic cost of fruit production, are discussed.

Various types of crop models are described, including morphological models, process-based models, statistical and empirical models, mechanistic models, deterministic and stochastic models, as well as static and dynamic simulation models. Special emphasis is placed on photosynthesis-based models and functional–structural plant models that combine biomass acquisition and biomass partitioning with plant architecture.

The PPT outlines the prerequisites and steps in crop modelling, such as defining system boundaries, identifying state, rate, driving, and auxiliary variables, quantifying relationships, calibration, validation, and sensitivity analysis. Examples of widely used crop models in fruit crops, including SUCROS, WOFOST, STELLA®, DSSAT, APSIM, and SUGAR, are presented to illustrate practical applications.

Applications of crop models are highlighted in areas such as yield forecasting, phenology prediction, water and nutrient use efficiency, precision farming, on-farm decision making, weather-based agro-advisory services, and evaluation of climate change impacts. Case studies demonstrate the use of simulation models in citrus, apple, peach, and other fruit crops. The PPT also discusses limitations of crop models, including data dependency, complexity, and challenges in representing climatic variability.

Finally, the role of national initiatives such as CHAMAN (Coordinated Horticulture Assessment and Management using Geoinformatics) is described, highlighting the use of remote sensing, GIS, and modelling for horticultural assessment and development. The PPT concludes that although crop models are not universal, they are valuable tools for crop growth prediction, yield analysis, and improved management in fruit crop production

SLIDE 1 – STRESS AND STRAIN

STRESS
When some factor of the environment interferes with the complete expression of genotypic potential of plant is called stress.

STRAIN
The effect of stress on plant condition is called strain.

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SLIDE 2 – PLANT RESPONSE TO STRESS

PLANT RESPONSE TO STRESS
Extreme temperature
Flooding
Drought
Salt

Stress recognition
Stress transduction
Altered cellular metabolism
Physiological and developmental event

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SLIDE 3 – DROUGHT

DROUGHT
The inadequacy of water availability, including precipitation and soil moisture storage capacity in quantity and distribution during the life cycle of a crop to restrict its yield potential.

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SLIDE 4 – EFFECTS OF DROUGHT ON PLANT GROWTH AND DEVELOPMENT

Structures of membranes and organelles damaged
Hydration status decreased
Structures of macromolecules like proteins and nucleic acids damaged
Reduced cell division and expansion
Reduced osmoregulation
Increased root/shoot ratio
Reduced leaf area
Reduced photosynthetic rate

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SLIDE 5 – EFFECTS OF DROUGHT ON MANGO

Vegetative flush greatly reduced
Reduction in number of leaves, flush length and leaf water content
Advancement of floral bud break by 2 weeks
Postponement in development of vegetative buds

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SLIDE 6 – EFFECTS OF DROUGHT ON GRAPE

Tolerant crop due to large xylem vessels
Enhanced root length and reduced shoot growth

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SLIDE 7 – EFFECTS OF DROUGHT ON BANANA

Sensitive crop
Carbon assimilation is affected
Flowering stage is most sensitive
Reduction in bunch weight and yield
Robusta, Karpuravalli and Rasthalli are sensitive varieties

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SLIDE 8 – EFFECTS OF DROUGHT ON PAPAYA

50 % reduction in leaves
Reduction in number of flowers by 86 %
Reduction in fruits by 58 %
Growth and development of fruit retarded

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SLIDE 9 – DROUGHT RESISTANCE

The mechanism causing minimum loss of yield in a drought environment relative to the maximum yield in a constraint free environment.

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SLIDE 10 – MECHANISMS OF DROUGHT RESISTANCE

Drought escape – avoiding the period of drought by early maturity
Dehydration avoidance – retaining higher hydration under water stress

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SLIDE 11 – DEHYDRATION AVOIDANCE

Reduced transpiration
Osmotic adjustment
ABA synthesis leading to stomatal closure
Cuticular wax
Leaf pubescence
Deep root system and large root length density

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SLIDE 12 – DEHYDRATION TOLERANCE

Lower level of changes in chemical activity of water and solute concentration
Maintenance of membrane integrity
Synthesis of mannitol and polyethylene glycol
Proline accumulation

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SLIDE 13 – SALINITY

Accumulation of soluble salts in the root zone causing detrimental effects on plant growth and development.
Area under salt affected soils in India is 6.74 M ha.

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SLIDE 14 – TYPES OF SALT AFFECTED SOILS

Saline soils – chlorides and sulphates of sodium, calcium, magnesium and potassium
Alkali or sodic soils – sodium carbonate is the dominant salt

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SLIDE 15 – EFFECT OF SALINITY STRESS IN FRUIT CROPS

Osmotic stress to roots
Nutrient imbalance and reduced uptake
Leaf injury
Growth inhibition
Poor fruit bearing and reduced yield

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SLIDE 16 – SALINITY EFFECT ON MANGO

Increase in irrigation water salinity reduces N, K, Ca and Mg content in leaves without affecting P and S.

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SLIDE 17 – SALINITY EFFECT ON PAPAYA

Growth reduced by 50 % at 4 dS m⁻²
Mortality occurs above 6 dS m⁻²

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SLIDE 18 – SALINITY EFFECT ON BANANA

Leaf necrosis
Reduced pseudostem thickness
Delayed flowering
Reduced finger size
Low quality bunches

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SLIDE 19 – SALINITY RESISTANCE

Resistance to salinity induced water stress through osmoregulation
Resistance to salinity induced ion toxicity by maintaining low salt concentration in cytoplasm

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SLIDE 20 – ION EXCLUSION AND SALT TOLERANCE

Reduced uptake of Na⁺ and Cl⁻ ions
Example: Citrus – Rangapur lime and Cleopatra mandarin
Excretion of excess salts through salt glands or cellular compartmentation

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SLIDE 21 – HEAT / HIGH TEMPERATURE STRESS

Adverse effects on plants of temperature higher than the optimal temperature.

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SLIDE 22 – EFFECTS OF HIGH TEMPERATURE STRESS

Sunburn on leaves, branches and stems
Leaf senescence and abscission
Inhibition of shoot and root growth
Fruit discoloration and damage
Reduced photosynthesis
Impaired reproductive processes

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SLIDE 23 – HEAT STRESS EFFECT ON MANGO

Floral induction at 15°C day and 10°C night
Vegetative induction at 30°C day and 25°C night
Low temperature increases male flowers
High temperature increases hermaphrodite flowers

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SLIDE 24 – HEAT STRESS EFFECT ON GRAPE

Advanced harvest
Higher sugar concentration
Low acidity
Alteration in aroma compounds

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SLIDE 25 – HEAT STRESS EFFECT ON BANANA

Growth and production affected
Leaf production and growth affected
Growth sustained up to 39.2°C

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SLIDE 26 – HEAT STRESS RESISTANCE

Heat avoidance through transpirational cooling
Heat tolerance by withstanding high internal temperatures

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SLIDE 27 – CHILLING STRESS

Tropical fruit crops are chilling sensitive.

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SLIDE 28 – CHILLING STRESS AT PLANT LEVEL

Reduced germination
Poor seedling growth
Stunted growth
Wilting
Chlorosis and necrosis
Poor fruit set
Pollen sterility

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SLIDE 29 – CHILLING STRESS AT CELLULAR LEVEL

Membrane damage
Protein changes
Decline in photosynthesis
Reduced chlorophyll synthesis
Increased respiration
Toxicity injuries

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SLIDE 30 – CHILLING TOLERANCE

Chill hardening by prior exposure to low temperature
Improved chlorophyll accumulation
Better germination, fruit set and pollen fertility

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SLIDE 31 – MANAGEMENT PRACTICES OF ABIOTIC STRESSES

Modification of cultural practices
Irrigation during post fruit set
Application of rice husk ash or composted coir pith
Incorporation of crop residues and green manures
Farm ponds for runoff harvesting
Potassium amendment to maintain K:Na ratio
Micro irrigation techniques
Partial root zone drying
Deficit irrigation
Subsurface irrigation

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SLIDE 32 – TOLERANT FRUIT CROPS

Ber, Aonla, Guava, Grape, Karonda, Jamun, Phalsa

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SLIDE 33 – TOLERANT ROOTSTOCKS

Grape – 110R, 99R, 1103P, Dogridge, Salt Creek, B2-56
Mango – Starch, Peach, Kensington, Mylepelian, Olur, Kurukkan, 13-1, Gomera-1

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SLIDE 34 – BIOTIC STRESS

Disease is the series of invisible and visible responses of plant cells and tissues to pathogenic microorganisms leading to impairment or death.

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SLIDE 35 – HOST, PATHOGEN AND DISEASE TRIANGLE

Host – Plant affected by disease
Pathogen – Organism producing disease
Environment – Influences disease development

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SLIDE 36 – RESISTANCE AND TOLERANCE

Vertical resistance – race specific
Horizontal resistance – race non-specific
Tolerance – infection occurs with little or no yield loss

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SLIDE 37 – PESTS

Sucking pests – aphids, jassids, thrips, white fly, mites
Tissue feeders – stem borers, fruit borers, weevils, beetles

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SLIDE 38 – MECHANISMS OF PEST RESISTANCE

Non-preference (antixenosis)
Antibiosis
Tolerance

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SLIDE 39 – CONCLUSION

Climate change intensifies biotic and abiotic stresses causing morphological, physiological and biochemical changes. Adoption of improved cultural practices, irrigation methods and tolerant crops is essential.

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SLIDE 40 – FUTURE LINE OF WORK

Enhancement of genetic diversity
Collection of tolerant genotypes
Identification of tolerance traits
Development of tolerant and transgenic cultivars and rootstocks