Genetic improvement of cashew is important to increase yields, resistance to diseases and pests, and adaptability to different environmental conditions. The key methods of genetic improvement discussed are controlling the mating system through techniques like cross-pollination and hybridization to generate genetic variability, followed by selection of desirable traits through artificial and natural selection. Selection criteria important for cashew include increased yield, tolerance to diseases and pests, and improved fruit quality. Sri Lanka has introduced several improved cashew varieties developed through these genetic improvement methods that have higher yields and other desirable traits compared to traditional varieties.

2. Increased Yield: Developing cashew varieties with higher yields can increase
production and help meet the growing global demand for cashew nuts.
Disease Resistance: Creating disease-resistant cashew varieties can help protect
crops from common diseases and reduce the need for chemical pesticides.
Drought Resistance: Developing cashew trees that are more resistant to drought
can help ensure a stable cashew nut supply in regions with irregular rainfall.
Environmental Adaptability: Cashew is grown in various climates and soil types.
Developing cashew varieties that are adaptable to different environmental
conditions.
Key reasons for the genetic development of cashew

3. Food Security: Ensuring a stable supply of cashews can contribute
to food security, as cashews are an important source of nutrition
and income in many regions.
Reduced Harvesting Time: Some genetic improvements aim to
reduce the time it takes for cashew trees to reach maturity and start
producing nuts, which can lead to quicker returns for farmers.
Quality Improvement: Genetic development can focus on
improving the quality of cashew nuts in terms of size, shape, taste,
and nutritional content. High-quality nuts can fetch better prices in
the market.

4. a. Crop stabilization (reducing the year-to-year variability in crop
production)
Can be described under two heading
Scope of crop improvement of cashew
Climate-Resilient Varieties: Drought-resistant or heat-tolerant cultivars, can help mitigate the impact of extreme
weather events on crop yields.
Climate Monitoring and Forecasting: Using weather data and climate models to predict adverse weather
conditions allows farmers to take proactive measures, such as adjusting planting dates or selecting appropriate
crops.
Pesticides: Integrated Pest Management (IPM) strategies combine pesticide use with other pest control methods
to reduce risks to the environment and human health.
Resistant Varieties: Planting crop varieties that are naturally resistant or tolerant to specific pests and diseases
can reduce the need for chemical pesticides.
Adapted Varieties: Planting crop varieties that are well-suited to local environmental conditions, including climate
and soil types, can help stabilize crop production.

5. Scope of crop improvement of cashew
b. Increase productivity- increase yield (Increasing productivity
in agriculture, particularly in crop production, is essential to meet
the growing global food demand)
Improved crop management -
• Proper crop management techniques, including optimal planting and harvesting times, and the
use of suitable cultivation practices, can maximize crop yields.
Use of genetically superior varieties -
• Selecting and cultivating high-yield crop varieties that have been developed through traditional
breeding or genetic modification.
• These varieties are often bred for traits like disease resistance, improved nutrient utilization,
and increased yield potential.

6. By changing genetic properties
desired change
Genetic improvement
Desired change can be obtained by
- controlling the mating system
- Selection
Cross-Pollination
Hybridization
Inbreeding
Gene Editing
Natural Selection
Artificial Selection
Phenotypic Selection
Marker-Assisted Selection (MAS)
Genomic Selection

7. Controlling the Mating System:
Controlling the mating system involves deliberately guiding the reproduction of plants to ensure
that desired genetic traits are passed on to the next generation. Here's how it works:
Cross-Pollination: By controlling the pollination process, plant breeders can mate two plants
with specific desirable traits to produce offspring that inherit these traits. This is often done by
isolating plants or using controlled pollination techniques.
Hybridization: Creating hybrids by crossbreeding two distinct parental lines can lead to
improved traits in the offspring, such as higher yield or disease resistance
Inbreeding and Selective Mating: In some cases, inbreeding is used to stabilize specific traits,
followed by selective mating to introduce genetic diversity and enhance the overall
characteristics of a crop.
Gene Editing: Advanced techniques like CRISPR-Cas9 can be used to precisely modify specific
genes in plants to achieve desired changes in their genetic properties.

8. Two basic principles of selection
operate on existing
genetic variability
(Natural selection)
Thus before selection the breeder has to
generate
Genetic variability
In cashew breeding too this is must
Acts on existing genetic
variability(Artificial selection)
Selection

9. Selection
• Natural Selection: In natural settings, certain plants may naturally possess beneficial traits that enable
them to thrive and reproduce. These individuals contribute their genes to the next generation, gradually
improving the overall population.
• Artificial Selection: Plant breeders can accelerate the process by artificially selecting and
breeding plants with desirable traits. This is a common practice in crop improvement.
Others
• Phenotypic Selection: Traits are selected based on observable characteristics, such as plant height, fruit
size, or disease resistance. Over successive generations, breeding lines with these traits are favored.
• Marker-Assisted Selection (MAS): Molecular techniques, such as DNA markers, are used to identify specific
genes or genetic markers associated with desired traits. This allows for more precise and efficient selection.
• Genomic Selection: Utilizing information from the entire genome of a plant, genomic selection helps
predict the genetic potential of plants for various traits and aids in selecting the best candidates for
breeding

10. Selection described as
- retention of desirable individuals
- breeding objective depends on
correspondence between phenotype
and genotype

11. Cashew varieties used in the past in SL
Kondachchi
Mannar
Trinidad
Shanthigudu,
Ulal
Vital
and indigenous type

12. Nature of cashew planting material
• Prior to 1997 not any attempt to breed cashew variety
• Hence, either seedlings or bud grafted plants
lost their genetic identity

13. Genetic improvement of cashew
 In SL - Average yield 260kg/ha
Very low compared to other countries
eg. India 694 kg/ha
 The main reason is highly variable seedling with low
genetic potential

14. This could be overcome by
- Use of genetically improved seedlings
- Use of VP clone (Vegetative Propagation Clones) in order to
achieve homogenetic stands
Genetic improvement of cashew could be achieved by
1. Collection and conservation
2. Evaluation of germplasm
3. introduction of new varieties
by hybridization
Biotechnology

15. 1. Collection and conservation of Genetic variability
- VP leads to erosion of genetic variability
- Collection and conservation of existing
variability in the seedling population is needed
- Introduction from other country is difficult

16. 2. Evaluation of Germplasm collection
- Future breeding programmes
- promising accessions released as varieties
3. Introduction of varieties
- Needed to test under local condition for
yield and pest and disease
-conditions

17. Creation of new genetic variation
- Involves hybridization from promising genotype
- Artificial pollination techniques used by other countries
- SL not having a collection of prone clone for hybridization
Biotechnology
Gene transfer techniques used in cashew

18. Important selection criteria
-Yield/plant/year
-Morphological characters
-Tolerance to P & D
-Grade and quality parameters

19. Yield- selection criteria
- Number of inflorescence per unit area of tree
- Ratio of male to hermaphrodite
- Number of nuts/ inflorescence
- Mean nut weight per tree
- High shelling %.

20. Morphological characters
- Dwarf habit
- compact canopy
- intensive branching with a high proportion of
flowers/unit area

21. Tolerance to pests and diseases
Two major serious pests in Sri Lanka
- Tea mosquito bug - Helopeltis antonii
- stem and root borer- Placaederous ferrugineus

22. Introduced for planting in 2012. The nut size of this variety
is large and the average nut weight is 9 grams. Shelling
percentage is around 30%. Colour of the mature apple is
yellowish red or orange. Kernel weight is >2.5 grams. Under
good management practices, this variety has a yield potential
of 10 kg/tree/yr when it reaches to the maturity stage. This
variety is recommended for all cashew growing areas of the
country.
WUCC 1
WUCC 2
Introduced for planting in 2020. The nut size of this
variety is Medium and the average nut weight is 9 grams.
Shelling percentage is around 30%. Colour of the mature
apple is reddish yellow. Kernel weight is >2.5 grams.
Under good management practices, this variety has a
yield potential of 15 kg/tree/yr when it reaches to the
maturity stage. This variety is recommended for all cashe
w growing areas of the country.
Cashew Varieties – Sri Lanka

23. WUCC 5
This variety was introduced for planting in 2007. The
nut size is of the variety is large and average weight of a
nut is high (10.8g). Shelling percentage is around 30%.
Colour of the mature apple is red. Kernel weight is > 2.5
grams. Under good management practices, this variety
has a yield potential of 10 kg/tree/yr when it reaches to
the maturity stage. This variety is recommended for all
cashew growing areas of the country.
WUCC 7
Introduced for planting in 2020. The nut size of this
variety is Medium and the average nut weight is 9 grams.
Shelling percentage is around 30%. Colour of the mature
apple is yellow. Kernel weight is >2.5 grams. Under good
management practices, this variety has a yield potential of
15 kg/tree/yr when it reaches to the maturity stage. This
variety is recommended for all cashew growing areas of
the country.

24. WUCC 8
This variety was introduced for planting in 2007. The
nut size of the variety is medium and weight of a nut is
intermediate (5 - 8g). Shelling percentage is around
30%. Colour of the mature apple is red. Kernel weight is
1.6 - 2.5 grams. Under good management practices, this
variety has a yield potential of 10 kg/tree/yr when it
reaches to the maturity stage. This variety is
recommended for all cashew growing areas of the
country.
WUCC 9
This variety was introduced for planting in 2005. The
nut size of the variety is medium and weight of a nut is
intermediate (5 -8 g). Shelling percentage is around
30%. Colour of the mature apple is red. Kernel weight is
1.6 - 2.5 grams. Under good management practices, this
variety has a yield potential of 10 kg/tree/yr when it
reaches to the maturity stage. This variety can be
recommended for all cashew growing areas of the
country.

25. WUCC 13
This variety was introduced for planting in 2007. The
nut size of the variety is large and weight of a nut is high
(8 -10.8g). Shelling percentage is around 30%. Colour of
the mature apple is red. Kernel weight is 1.6 - 2.5grams.
Under good management practices, this variety has a
yield potential of 10 kg/tree/yr. This variety is
recommended for all cashew growing areas of the
country.
WUCC 16
Introduced for planting in 2020. The nut size of this
variety is medium and the average nut weight is 9 grams.
Shelling percentage is around 24%. Colour of the mature
apple is yellowish red. Kernel weight is >2.5 grams. Under
good management practices, this variety has a yield
potential of 15 kg/tree/yr when it reaches to the maturity
stage. This variety is recommended for all cashew
growing areas of the country.

26. WUCC 19
This variety was introduced for planting in 2005. The
nut size is of the variety is large and weight of a nut is
high (8 – 10.8 g). Shelling percentage is around 30%.
Colour of the mature apple is yellowish red. Kernel
weight is >2.5 g. Under good management practices,
this variety has a yield potential is10 kg/tree/yr. This
variety is recommended for all cashew growing areas of
the country.
This variety was introduced for planting in 2005. The nut
size of the variety is large and weight of a nut is high (8 –
10.8g). Shelling percentage is around 30%. Colour of the
mature apple is yellow. Kernel weight is 1.6 - 2.5 grams.
Under good management practices, this variety has a
yield potential of 10 kg/tree/yr. This variety is
recommended for all cashew growing areas of the
country.
WUCC 21

27. WUCC 23
Introduced for planting in 2012. The nut size of the
variety is large in size and average weight of a nut is very
high (> 10.8 g). Shelling percentage is around 30%.
Colour of the mature apple is yellow. Kernel weight is >2.5
grams. Under good management practices, this variety
has a yield potential of 10 kg/tree/yr. This variety is
recommended for all cashew growing areas of the
country.

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