eChapters

1. Nucleus seed: It is the handful of original seed obtained from selected individual plants of a particular variety. It has the highest genetic purity and physical purity.

Seed Testing
1.    Sampling

2.    Determination of Heterogeneity

3.    Purity analysis

4.    Germination Test

5.    Seedling Evaluation

6.    Quick Test for Viability

7.    Estimation of Seed Moisture

8.    Grow Out Test

9.    Seed Health Test

Seed testing

No matter how good processed seed may look, the actual value is the number of seedlings it will produce. Testing of seeds is therefore imperative to determine and identify the changes that have occurred from the time of collection until the seeds are sold or sown at one time. The critical step in evaluating a seed lot is the drawing of representative sample. Place all the test samples in a bucket, mix them thoroughly and subdivide to obtain sample size. Improvements in seed processing can only be obtained with quality control. These evaluations should be made in the processing plant and at a seed testing laboratory. The National Tree Seed Laboratories offers a free service to evaluate processing machinery. You need only collect a small sample of seed after it has been processed by each machine and send it to the laboratory. Be sure all the seed comes from the same lot so all samples are related. Each machine must be adjusted for efficient operation, and proper adjustment requires monitoring of the operation.

Objective: To study the seed treatment methods and equipments A key factor in achieving the few potential of good quality seed is the blanket treatment of the seeds with agrochemical in order to control or prevent diseases in the  crops.

Objectives

1. To know about the seed treatment of spices and condiments.
2. To know the sowing method and time of spices and condiments.

Seed treatments or seed dressing: Seed treatment refers to the application of fungicide, insecticide, or a combination of both, to seeds so as to disinfect and disinfect them from seed-borne or soil-borne pathogenic organisms and storage insects. It also refers to the subjecting of seeds to solar energy exposure, immersion in conditioned water, etc. The seed treatment is done to achieve the following benefits.

Advantages of seed treatment

1. Protects germinating seeds and seedlings against soil and seed borne pathogens/insects.
2. Seed germination enhancement.
3. Early and uniform establishment and growth
4. Enhances nodulation in legume crop.
5. Better than soil and foliar application.
6. Uniform crop stand, even in adverse conditions (less/high moisture)

Seed is the basic input of agriculture, and its importance has now well recognized in the food supply chain since the warranty for production could be succeeded only based on the availability of seed. Seed becomes the quality seed, on possession of specific characters, viz. germination, vigour, purity and health status, hence, seed production becomes the specified scientific technology with the foreseeing of quality and storability in addition to productivity. From time immemorial, seeds are being imposed with some management techniques for improvement in seed quality and thereby the productivity. These seed management techniques are known as seed treatments. Generally, seed treatment is the application of biological, chemical agents and physical techniques to the seed in order to obtain the benefit of plant protection, production and invigouration. Basically, seed treatments are intended to improve the quality of seeds since nothing can substitute poor quality seed, no matter how lavishly other inputs are spent on the crop established from such seeds. Even for a resource poor farmer, high quality seed would be a great advantage because it ensures the best utility of all inputs in addition to the augmentation of yield increase by 15 to 20%.

In general, seed treatment could broadly be classified into physical and physiological treatment. Physical treatment is external seed treatment, while physiological is impregnation of needy substances into the seed through various seed management techniques. Some of the germination augmenting physiological seed treatments are seed fortification, seed hardening, seed priming, dry permeation and pre-germination. In addition, some of the seeds are imposed with special treatments such as dormancy breaking treatment such as soaking in water, mechanical scarification, acid scarification, bio-scarification, scorching, warm stratification, cold stratification and electrical seed treatment. The common physical seed treatments are seed pelleting, seed coating/film coating and seed colouring. Seeds are also imposed with some other physical treatments that can act on the physiology of the seed such as irradiation, magnetic and electrical seed treatment. In addition, irrespective of seed, seeds are given with protective treatment when they are taken for storage, which are commonly termed as pesticide seed treatment. Seeds are also given with corrective treatment at their initiation reduction with seed quality characters during storage, which are termed as mid storage correction.

I. FILL UPS

1. _____ refers to the application of pesticides to seeds before sowing or storage to protect the seeds.
2. The chemical gases as fumes are used to control the pests in seed lots is called as _____.
3. The treatments given to the seeds prior to or during storage to protect the seed are called _____ treatment.

Seed treatment is one of the important activities of the shop floor. The seed should be treated with various insecticides, fungicides and additives to protect it up to establishment. Some timesenhance quality parameters like vigour which is critical for better establishment. Since vegetable seeds are of very high value and low volume, investment on seed treatment will yield better not only for the seed seller but to the grower also. More number of plants in a field brings moreincome per unit area. Hence the farmer or grower who buys seed is ready to bear the cost of seed treatment making it an important aspect of seed processing.

Seed treatment refers to the application of fungicide, insecticide or both to the seeds to disinfect(deep seated) and disinfest (over seed coat) them from seed borne or soil borne pathogenic organisms and storage insects. It also refers treating seed for enhancing quality by subjecting the seed to solar energy exposure or immersion in hot water or dry heat treatment or priming also.

Definition

Seed treatment is the process by which seeds are treated with physical, chemical or biological agents to prevent the infection of seedlings and the subsequent development of the crops.

Advantages of Seed Treatments

Increased seed germination.

Ensures uniform seedling emergence.

Protect seeds or seedling from early season diseases and insect pests improving crop emergence and its growth.

Lower seedling mortality.

Improved plant population and thus higher productivity.

Reduces the cost and the potential environmental impact.

Also reduces the probability of chemical residues in harvested grain.

Relatively easy and cheap to apply compared to broadcast sprays.

1. SEED TREATMENT

It refers to the application of pesticides (fungicides, insecticides or a combination of both) to seeds before sowing and/or storage in order to protect the seeds and young seedlings from soil borne pathogens and/or storage pathogens and insects. Seeds are thoroughly mixed with required quantities of chemicals namely bavistin (carbendezim) @ 2-4 g/kg of seeds.

Seed viability tests

Only two methods, the Topographical tetrazolium (TZ) test and the embryo excision test were previously accepted by the International Seed Testing Association as official methods for some species of seeds. ISTA has recently accepted the X-ray method as a valid alternative to the cutting test for the detection of empty and insect-damaged seeds. The following tests can be applied depending on the circumstances.

Seed Viability Test

Germination test for a seed lot is a pre-requisite to know its potential of emergence under field condition. However, this test requires few days to weeks and a month in some cases. Tetrazolium test gives quick information on seed viability or germinability. It makes possible to distinguish red coloured living parts of seeds from the colourless dead ones. Staining of seeds determines  viability.  Completely  stained  seeds  are  viable  while,  partially and comparatively unstained seeds are non-viable. This test is not valid as compared to seed germination test.

I. FILL UPS

1. _____ is the measure of how many seeds are alive and could develop into plants which will reproduce themselves.
2. _____ method is useful for determining viability of forest tree seeds.

Introduction

Seed vigour is an important quality parameter, which needs to be assessed to supplement germination and viability tests to gain insight into the performance of a seed lot in the field or in storage. Several definitions have been offered to explain seed vigour. Isley (1957) defined vigour as “the sum total of all seed attributes, which favour stand establishment under unfavourable field conditions”. While, AOSA (2005) defined seed vigour as the sum total of all those properties in seed, which upon planting, result in rapid and uniform production of healthy seedlings under a wide range of environments, including both favourable and stress conditions and ISTA (1985) stated that seed vigour is the sum total of those properties of the seed, which determine the potential level of performance and activity of a non-dormant seed or seed lot during germination and seedling emergence.

I. FILL UPS

1. Rapid and uniform production of healthy seedling and stand establishment under a wide range of field condition is considered as _____.
2. The sum of those properties of seed which determine the potential level of activity and performance of the seed lot is called _____.
3. Vigour index = _____.

1. DEFINITION

Sum of those properties of seed, which determine the potential level of activity and performance of the seed or seed lot during germination and seedling emergence. i.e., rapid and uniform production of healthy seedling and stand establishment under a wide range of field conditions is considered as seed vigour.

In a vigour test, the seed is introduced to a stressful environment unfavorable to seedling development. This environment can be cool, cold or warm, or a combination of either high humidity and high temperatures, or heavy moisture at low temperatures. A vigor test cannot replace a germination test, but rather supplements it with more information about seed quality.

5.1. Seed village

Compact area approach in which the whole village is involved in seed production.

Concept is a win-win model (Deepak Mullick)

INTRODUCTION

High crop productivity depends on quality of seed as without good quality seed even if we apply manure, Plant protection measure and other cultural practices it is not possible to produce good quality seed. So the basic seed used for sowing must be healthy and good in quality. It is different from commercial production as it need proper care, good quality basic seed, timely cultural operations, thinning, roguing, timely application of pesticides and fertilizers and maintenance of seed quality through inspections. 
Seed production requires technical skill to achieve all the above advantages for which the best approaches Compact Area Approach or Seed Village Concept.
It is selection of compact area by organizing the seed farmers in the selected area. The selected area must be fertile and suitable for reproduction of good quality seed such areas can be organized for self and cross pollinated crops (Groundnut, Paddy, Pulses, Sorghum) especially for the varietal seed production. But the variety should be one another for whole of the selected area.

Advantages of Seed Village Concepts

1. Isolation and Roguing

For maintenance of genetic purity of the crop it requires isolation and proper rouging. This can be achieved in the compact area programme, as it will be the mutual benefit to the farmers who are concentrating growing on single variety on compact area.

I. FILL UPS

1. Seed village is also known as _____.
2. ITC with Zeneca stands for _____.
3. ITC Zeneca has recently changed name to _____.
4. CENSAR stands for _____.
5. _____ is a compact area approach in which the whole village involved in seed production.
6. The concept of seed village is a _____.
7. Seed village concept was started in_____.
8. _____ has guided the experiment in wheat.
9. _____ is a milestone in green revolution.
10. CAPART stands for _____.

1. DEFINITION

Seed village definition is to see that the aim right from the start is to make a holistic transformation in the village. Seed village concept is a “Win-Win model”, says Deepak Mullick, one of India’s foremost professionals in agribusiness. It is also known as “Compact area approach”. Seed village area should be suitable for crop or varieties. Seed in compact area, whole village should be involved. The whole farmers in the village cultivate same crop, same variety and follow same cultivation practices.

“The light of unconditional love awakens the dormant seed potential of the soul helping them ripen, blossom and bear fruit, allowing us to bring the unique gifts that are ours to offer in this life”

–John Wehwood

Introduction

In nature and in humans, seeds are vehicles for spreading new life from place to place. In plants, it refers to the unit of dispersal that survives between seed maturation and its establishment as a seedling. A seed, like a fortress, protects and sustains life as they are well-stocked with special food supplies to endure long sieges. There are many things that seeds are, but above all else, they are the means of survival of their species. It is a way of suspending embryonic development and then resuming it years later after the parents have passed away.

Technically, seed is the sexually produced matured ovule consisting of an intact embryo, endosperm and or cotyledon with protective covering (seed coat). A true seed consist of an embryonic plant, a store of food which consists of cotyledons and endosperm and a protective seed coat. Seed can also be considered as any material that is used for planting or regeneration purpose. Rather than seed, propagating materials like healthy seedlings, tuber, bulbs, rhizome, roots, cuttings, setts, slips, all types of grafts and vegetatively propagating materials used for production purpose is also referred to as seed. Thus, seeds are of two types namely sexual or botanical seed and asexual seed. Both can be used for raising the crops thus forms the agricultural seeds.

Based on the moisture content present, seeds are of two types, orthodox seeds and recalcitrant seeds. Orthodox seeds are the botanical seeds which contain moisture content less than 20%. Such seeds do not germinate even if the moisture content is more than 20% unless artificially forced to germinate. Recalcitrant seeds contain moisture content more than 20% and such seeds will not germinate if moisture content is less than 20%. These seeds cannot be stored for long and for long storage, special structures or conditions are required. Mostly perennial plant species produce this type of seeds.

Seeding /Sowing

Seeding is the process of planting seeds in soil to grow crops, plants, or grass. It is a fundamental step in the cultivation of plants and is essential for agricultural production, landscaping, and reforestation. The goal of seeding is to establish and promote the growth of desirable plants, allowing them to germinate, develop, and eventually mature into a full-grown plant, tree, or crop.

The process of seeding typically involves placing seeds at a specific depth in the soil, providing the necessary conditions for germination (such as water, light, and temperature), and ensuring proper spacing between seeds to allow for healthy plant growth. The choice of seeding method and the timing of seeding can vary depending on the type of plant or crop being grown and the specific environmental conditions of the planting area.

Seeding can be done manually by hand; using specialized seeding tools and equipment, or through mechanized methods, such as using tractors and seed drills for larger agricultural operations. The success of seeding is crucial for the establishment of healthy and productive plants, making it a critical step in agriculture and horticulture.

4.1 Seeding equipment

Sowing is an art of placing seeds in the soil to have good germination in the field and thereby gives better productivity. Seeding is one of the most important farm operations after soil preparation because the time of sowing and the way in which it is done decisively influence germination of the seed and growth of the seedling during its early stages. This in turn affects the subsequent time of weeding and inter-culture, harvesting and threshing and finally the yield. Seed needs an adequate supply of moisture, temperature, air and protected environment for good germination.

Crop sowing refers to broadcasting seeds on the surface of soil, placement of seeds in the soil or transplanting seedlings in the soil, under optimum conditions. The primary functions of any planting operation are to establish an optimum plant population and spacing, the ultimate goal being to obtain the maximum net return per unit area. Plant population and spacing requirements are affected by various factors such as the crop type and variety, soil type, soil fertility level, soil moisture and row spacing upon the cost and convenience of operations such as thinning, weed control etc. In order to get better returns, the right amount of seed should be placed at the right time and at a predetermined depth and spacing in the soil. Usually the depth of sowing depends upon the moisture availability and seed emergence capacity. The amount of seeds to be sown varies according to the size of seeds, percentage germination etc.

The seed drills and planters developed and manufactured in advanced countries are designed to meet the requirements of farmers for the different crops and agro-climatic conditions. These machines are capable of operating at high working speed, cover the large area per unit time and provide the desired plant emergence and stand in the fields. The machines are available to handle the seeds of cereals, pulses, oil seeds and other crops widely grown in the developed countries. In developing countries even though these machines can be made available but they are beyond the reach of small farmers. The level of mechanization of sowing and planting is at a very low level.

Seedling:A seedling is a very young plant that grows from a seed. When the moisture, light, and temperature conditions are correct, the seedling’s development begins with seed germination and the formation of three main parts:

1.Radicle - Embryonic root

2.Hypocotyl - Embryonic shoot

3.Cotyledons - Seed leaves.

In vegetables and annual ornamental crops where generally seed size is small they are germinated in nursery beds or in plug trays indoor (greenhouse) or outdoor(field), hardened before transplanting.

Sapling: A sapling is a young tree, say more than 1 year and less than 3 years’ old. In the life cycle of trees, a seedling converts into a sapling as the next stage of development. It is nearly one-meter tall and generally remains to be known as a sampling until its stem reaches 7 centimetre in diameter. The time period of this stage depends upon the particular species of a tree. In vegetable and annual ornamental crops seedlings generally are one month to 40 days old. Older than this, seedlings do not give better yields on transplanting. Very young seedlings exhibit larger mortality on transplanting.

Transplanting: Transplanting or replanting is the technique of moving a plant by uplifting from one location to another. From nursery beds seedlings or saplings are shifted and planted either in the field or greenhouses for commercial growing. Seedlings are uprooted if grown in soil medium. They are transplanted with growing medium. Uprooted seedlings take time to establish at a new place and face transplanting shock- time taken by roots to establish contact with the soil or growing medium.

It is said that “Success of any production system depends on the kind of seed which are sowing”. It is true for the seedlings also beacause healthy seedlings grown in a well managed nursery will decide the yield and consequently the profit.

Definition of Vegetable Nursery

A vegetable nursery is a place or an establishment for raising or handling of young vegetable seedlings until they are ready for more permanent planting.

Why vegetable nursery is needed

Some vegetable crops require special cares during their early growth period. There are some vegetables with very small sized seeds. Seedlings of many seed propagated vegetable crops like, tomato, brinjal, chillies, sweet pepper, cauliflower, cabbage, knolkhol, broccoli, Brussels sprout, kale, endive, chicory, celery, lettuce, parsley, onion, etc. are first raised in the nursery beds before transplanted in the main field. Many seed propagated vegetable crops viz., okra, peas, beans, radish, carrot, beet, turnip and all the cucurbits (e.g. bitter gourd, bottle gourd, pumpkin, cucumber, watermelon, muskmelon, snake gourd, sponge gourd, ridge gourd, etc.) are conventionally grown through direct seeding in the main field. However, many cucurbits, particularly in the early season are also grown in India using the seedlings raised in polythene packets.

The success of mechanized transplanting largely depends on the quality of seedlings used, making seedling raising an essential component of the process. This chapter revolves around the techniques and practices involved in raising seedlings that are optimized for transplanters. Proper seedling raising ensures that the plants are healthy, uniform, and robust, thereby improving the efficiency of the transplanting process and enhancing crop yields. We will explore various methods for preparing seedlings, including the use of specialized nurseries, seedling trays, and appropriate handling techniques to prevent damage. Understanding these techniques is important for achieving optimal performance from transplanters, reducing labor costs, and promoting sustainable agricultural practices. Transplanting is a common method for controlling weeds in wet or puddled fields. It uses less seed than direct seeding but requires significantly more labor. Additionally, transplanted crops tend to take longer to mature due to transplanting shock.
TECHNIQUES OF MANUAL TRANSPLANTING
Manual transplanting can be performed using two different methods:
Random Method
In the random method, seedlings are transplanted without maintaining a set distance or spacing between plants. While it’s difficult to establish equal distances between each hill in this method, it is crucial that the estimated distances are neither too close nor too wide. The spacing should range between 10 cm and 25 cm to ensure effective weed control through early shading from the rice canopies.

Seed is a fertilized ripened ovule consisting of three main parts namely seed coat, endosperm and embryo which in due course gives rise to a new plant. Seed is the nucleus of life. Endosperm is the storage organ for food substance that nourishes the embryo during its development. Seed coat is the outer cover that protects or shields the embryo and endosperm.

Importance

Plants reproduce sexually by seeds and asexually by vegetative parts. Grains which are used for multiplication are called seeds while those used for human or animal consumption are called grains. Good stalks of planting materials are basic to profitable crop production. The seed or planting material largely determines the quality and quantity of the produce. A good seed or stalk of planting material is genetically satisfactory and true to type, fully developed and free from contamination, deformities, diseases and pests.

Seed is the living link between plant and progeny and biologically seed is ripe fertilized ovule and a unit of reproduction of flowering plant. Agronomically, a seed material or propagule is the living organ of crop in rudimentary form used for propogation.

Propagation Asexual Sexual Seed Stem cutting Ex: Sugarcane Grafting Rooted slips Ex: Grasses Tubers Ex: Potato Budding Corms Rhizomes Layering

Plants perpetuate / multiply either sexually or asexually. Sexual methods are through seeds and asexually through vegetative parts. Most of the crop plants produce viable seeds which are used for sowing. Those used for multiplication are called seeds and those which used for human consumption are called grains.

Seed consisting of intact embryo, stored food and seed coat which is viable and has got a capacity to germinate. Embryo has two parts:

A seed consists of a plant embryo, stored food material surrounded by a seed coat. Seeds of cereals and grasses consist of embryo or germ, endosperm and the pericarp.

Seeds of legumes contain no endosperm, the bulk of the seed being made up of the two cotyledons. The cotyledons constitute the food storage portion.

The embryo of the grass seed is made of epicotyl, hypocotyl and scutellum- the single cotyledon of monocots, the epicotyl gives rise to the shoot and the hypocotyl produces the roots.

Part A

Counting of Seeds in a Seed Lot

Counting of seeds is essential in order to estimate the number of seeds required for planting in a nursery or direct sowing or where seeds are valuable and are sold or purchased on number basis. However, in practice, it is difficult to count the seeds in the entire lot. Alternately, the whole lot is weighed accurately. From the whole lot, 5-6 small seed samples of 100 g each are randomly selected. The number of seeds in these samples are counted. The average of these samples is then applied to the whole seed lot in order to calculate the number of seeds.

Seepage is the movement of water through the soil body and foundation of a hydraulic structure. In an earthen dam, uncontrolled seepage may produce excessive water loss, high pore-water pressure, slope instability, internal erosion, piping, or complete structural failure. Seepage analysis therefore determines the quantity and path of water movement and helps engineers design filters, drains, impervious cores, cut-offs, and other protective components. This chapter explains the objectives and importance of seepage analysis, Darcy’s law, permeability, seepage velocity, phreatic lines, flow nets, equipotential lines, and flow channels. It also examines seepage forces, piping conditions, exit gradients, and methods for improving dam safety.

Key Points

• Seizures are common in dogs and cats but uncommon in larger animals.

• Animal seizures can be induced by several circumstances.

• Idiopathic epilepsy is the leading cause of seizures.

• Rapidly rising core body temperature and metabolic alterations lead to fatal outcomes.

Introduction

A seizure is defined as any rapid and uncontrollable movement of the body induced by aberrant neuronal activity in the brain. Seizures are common in dogs and cats, but uncommon in larger animals. Seizures can be severe, affecting the entire body, or moderate, affecting only a section of the body. The pet may or may not be conscious or responsive, and it may urinate.

Seizures are usually brief (1-2 minutes) and self-limiting; however, some animals may experience protracted activity (more than 5 minutes). Seizures that persist longer than 3 to 5 minutes might cause serious complications such as pulmonary or brain edema. Death is caused by a sudden rise in body temperature and metabolic alterations that reach a life-threatening threshold.

INTRODUCTION

The origin of fish culture in India probably dates back to 2000 years. Possibly, fishery activity started when the human settlement moved away from the riverbanks to the hinterland. As the days went by, the Indian fish farmers practice their own indigenous technology as a common practice through natural resource management (National Commission on Agriculture, Gov. of India, 1976). The close and intimate observation of farmers through their age-old practices has developed the expertise of acquiring knowledge in aquatic ecosystem in particular. Admittedly, the multifarious knowledge and skill possessed by local people can substantially contribute to productive efforts and endeavors (Dasgupta, 1993).

Asia-Pacific Association of Agricultural Research Institutions (APAARI) Maliwan Mansion, 39 Phra Atit Road, Phra Nakorn, Bangkok 10200, Thailand

Selected ICT-enabled Agricultural Development Initiatives

• International Initiatives
• National Initiatives

Success Stories on Agricultural Information Systems

• South Korea’s Agricultural Information Service – A NARS Initiative
• ITC’s e-Choupal – A Private Sector Initiative

Lessons Learned on Secrets of Success

Extent of Adoption of Technology

Benefits and Impact at National and Regional Levels

Selection is an important tool for changing gene frequencies to better fit individuals for a particular purpose. It may be defined as a process in which certain individuals in a population are preferred to others for the production of the next generation. Selection is of two kinds

Buck can be mated to several does not gives many young ones. So quality of buck will be passed on to many number of young one. Choose bucks whose relatives have good commercial character performance can be known by looking at breeding record should have too well development testicle, have good growth, good healthy condition, not be too fat, good physical condition.

Best time is when animal is 2 kgs of body weight and age of 3-4 months.

It is advisable to purchase buck from good reliable source since it brings new characteristics and avoid inbreeding.

The mating of the buck of particular breed with die of another breed is cross breeding usually cross breeding has better commercial value → Hybrids which has hybrid vigour → grow faster, better litter size.

Usually breeding of 2 hybrid is not advisable because we will not be sure which hybrid characteristics will be passed on to young ones.

The back yard rabbitry has mixed breeding programme of low quality with reference to commercial characteristics. To improve back yard rabbitry, good well known breeding buck should be introduced to have better performance.

Rationally selected and contextually defined research problem is the foundation to the successful research project. If the selected research problem is not in line with the interests of the researcher, available time, resources, infrastructure & knowledge base then achieving success in research process remains highly uncertain. Consequently, in addition to hindering of professional growth of the researcher, it also results in wastage of time, money and human effort. Most importantly, it may sometimes add up incorrect knowledge into scientific base, hindering the process of scientific progress. Hence the identification of the research problem and designing the problem statement is the most important step in the research process.

21.1 Introduction

There are a number of field, vegetable, fruit and ornamental crops that are cultivated using asexual or vegetative parts such as stems, roots, modified flower etc. This is a heterogeneous group of plants and can be further categorized into four groups for ease in understanding the breeding methods applied to them. They are:

Group 1: Flowerless or Sterile

This group either does not bear flowers or if bears, they are sterile and do not set seed, e.g., ginger, mango ginger, turmeric, garlic, betel, many yams, etc.

Group 2: Apomicts

Apomixis has been reported in over 300 genera. But stable apomixis has been reported only in a few cultivated plants like meadow grass, citrus, mango, raspberry, etc.

Group 3: Flowers but Seed-Set Rare

In this group flowering takes place under specific situations but seed-set is limited, e.g., potato, sweet potato, sugarcane, etc.

6.1 INTRODUCTION

The ultimate success of an orchard enterprise largely depends upon the quality and genuineness of planting materials as nursery plants are the foundation of the orchard. Fruit crops, mostly being perennial in nature, call for utmost care in selection of cultivar, quality planting material and adoption of right technology for mass multiplication of planting material. Mistakes committed during the initial establishment of orchards cannot be corrected and will cause serious damage to production and productivity. The variation of scion-wood and rootstock has great bearing on the productivity of an orchard. Thus, it is of immense importance having all plants carefully labelled or otherwise marked. Cuttings taken from the mother plant will grow to have the same genetic qualities as the original plant. This is why the plants resulting from these cuttings are called “clones”. When a stem cutting is taken from a mother plant, the piece of stem will produce new roots if it is properly hydrated. Additionally, some plants can be grown from leaf pieces, or leaf cuttings and these will produce both stems and roots.

Thus, the progeny trees are the basic component for the multiplication of fruit plants and ultimately deciding the quality and productivity of the fruit crops. Hence, it is necessary to stock the true to type and best quality progeny trees.

In asexual methods of plant propagation, plant parts are being used as propagating materials. The plant from which the plant parts are collected is known as mother plant. There is every possibility of transmission of disease or pest which is present in the mother plant to the progeny. The mother plants have to be maintained properly to obtain disease free planting materials so that multiplication of disease/pest can be prevented. Thus, there is a need for the establishment of mother plant block/scion banks.

Principle

Cloning experiments would be very difficult if we do not screen those very few cells that took up the recombinant plasmid DNA, as the transformation efficiency is very low as stated before (usually less than 1 in 10⁵ cells). Hence it is necessary that there should be a selection mechanism (i.e. conditions where cells grow if they express a gene, but die if they do not) to sort out which are transformed cells and which are not make the job easy.

A commonly used selection mechanism is antibiotic resistance. If the E. coli strain used is not resistant to the antibiotic, but the plasmid DNA contains a gene coding for resistance, then only the cells that have taken up the plasmid will be able to grow. Most commonly used plasmids contain a gene for resistance to ampicillin; only cells that have taken up the plasmid will be able to grow and form colonies.

Note: Uptake of plasmid DNA is rare; hence each group of cells visible on a plate represents the offspring of a single cell that will contain a single molecule of plasmid DNA.

Selecting and adding fish to an aquarium is a crucial process that directly affects the tank’s ecological stability, visual harmony, and long-term success. Effective fishkeeping involves more than just choosing attractive species—it requires a thoughtful understanding of each fish’s behavior, tank needs, dietary preferences, and environmental compatibility.
When choosing fish, consider the aquarium type—whether it’s a community setup, a biotope, or a species-specific tank. Factors such as tank size and water conditions (including pH, temperature, and hardness) should guide your selection. It’s essential to know which species are peaceful (like mollies, tetras, and guppies) and which are known to be aggressive or territorial (such as bettas or cichlids), and
avoid housing incompatible fish together.
Proper stocking density is vital for tank health. Overcrowding can lead to water pollution, increased stress, and disease outbreaks, while too few fish may destabilize the biological balance. The general guideline of “1 inch of fish per gallon” works for small freshwater aquariums, but must be adjusted for fish size, waste production, and swimming habits. New fish should be introduced gradually, particularly in newly cycled tanks, to avoid overloading the filtration system. Quarantining newcomers is also advised to reduce the risk of introducing illnesses.
A well-planned fish selection and stocking strategy promotes a thriving, visually appealing aquarium that is stable, easier to care for, and more enjoyable to watch.
CRITERIA FOR SELECTION: COMPATIBILITY, SIZE, ACTIVITY
When choosing and stocking fish for an aquarium, it’s essential to consider compatibility, adult size, and behavioral traits. Compatibility ensures that fish can coexist peacefully, while size and activity level help prevent overcrowding and stress, contributing to a stable and healthy aquatic environment.

A primary objective of extension and development workers is to deliver presentations that are engaging, dynamic, and memorable for their audience. This objective can be most effectively achieved through the use of audio visual aids, which enhance the communication of knowledge and the teaching of skills. Extension teaching methods are defined as the tools and techniques that create environments conducive to the exchange of knowledge and skills between extension workers and their audience. Similarly, audio-visual aids play a significant role in enhancing the effectiveness of learning by facilitating the communication of knowledge and the teaching of skills.

People predominantly learn through seeing, hearing, and doing by looking, listening, and acting. Audio-visual aids provide extension workers with unique opportunities to enhance the effectiveness and clarity of the developmental concepts being conveyed. These aids allow learners to engage more fully with the material by seeing and hearing, thus fostering a deeper understanding. The success of extension workers and the progress made by their learners are largely dependent on the workers' ability to effectively communicate ideas. For progress and development to occur, it is essential that extension workers communicate clearly and that their learners comprehend the information. Audio-visual aids are crucial in this communication process, guiding learners through the steps of the teaching-learning process.

In light of this, the current unit discusses the important audio-visual aids that are beneficial in extension teaching, aiming to enhance your understanding of their application and impact.

Understanding Audio-Visual Aids

People's attention is captured by various senses in the following proportions: seeing (87.0%), hearing (7.0%), smell (3.5%), touch (1.5%), and taste (1.0%). Consequently, seeing and hearing are the primary senses involved in attracting attention and enhancing learning.

12.1 Introduction

Allowing certain plants from the population to reproduce, while barring others, comprises selection. This permission for reproduction may be granted by nature or by the plant breeder. In the other words, both nature and breeder exert selection pressure. Natural selection operates through differences of fertility among the adult individuals of parent generation as well as through differences of viability among the individuals of offspring generation. Artificial selection, i.e., the selection from action of the plant breeder in the choice of parents, produces its change of gene frequency by separating the adult individuals of parent generation into two groups, viz., the selected and the discarded, that differ in gene frequency. So, selection simply implies the retaining of desirable types or culling of unwanted or undesirable types.

Combining Ability Estimation
Crosses made in a definite fashion are a prerequisite for combining ability estimation. Estimated by half-sib (GCA) and full-sib (SCA) mating. Various steps like parent selection for crosses, performing crosses, their evaluation, and interpretation are involved while estimating of combining ability. For analysis of crosses, biometrical techniques like diallel analysis, partial diallel, and Line x tester analysis are used. If GCA variance is higher than SCA variance the importance of AGA & parent selection will be effective for the improvement of such traits. If SCA variance is higher than GCA variance there is importance of NAGA( dominance & epistasis) & Heterosis breeding may be rewarding. If GCA=SCA variance then AGA & NAGA are equally important in the expression of character, In this situation reciprocal recurrent selection may be adopted for population improvement.
Selection for GCA
General combining ability (GCA) is the average value of the inbred line based on its behavior in crosses with other lines. The mean performance of the line is expressed as deviation from the mean of all crosses.GCA is owing to the activity of genes which are largely additive in their effects as well as additive × additive interactions.

The selection of individual animals from a group is very important in a livestock farming business. While creating a herd, every farmer should buy animals from a trustworthy disease-free herd and learn as much as they can about the animals. Once the herd is established, the selection of gilts and boars for replacement in the breeding herd should be based on type and performance. The following are important criteria to consider while creating a healthy sow herd:

• Size of litters
• Strength and vigour of litters
• Milking ability
• Temperament