Lecture 9: Sources and Genetics of Crop Quality Traits Flashcards
Importance/ utility of crops and plants
Oxygen, cleansing air
Fuel and materials, industrial
Soil conservation
Food and nutrition
Biodiversity and ecosystem stability
Beauty, Health and wellbeing
Pharmaceuticals and drugs
Climate regulation and Carbon sequestration
Habitats, sanctuaries, supporting
wildlife / pollinators
Careers in plant biology
Research and development
Breeder
Entrepreneur
Scientific communication/ policy advisor
Molecular engineer/ biotechnologist
Teacher/Lecturer
Patent agent/Attorney
Lecture content
Quality traits in crops
Genetics of traits
Priorities for improving nutritional content
Breeding and transgenic approaches: Biofortification and the Golden rice project
Definition of ‘crops’
‘Plants that can be grown and harvested extensively for profit or subsistence.’
Definition of agronomy
Crop science; plant breeding, physiology, biochemistry, soil science, etc
Science and Economics of Crop Production
‘agros’=field;‘nomas’=manage
Synthesis of principles: Environmental science; meteorology, ecology Farm and field management, Economics
Johan Kroon’s Background is in metabolic study:
The chemical and physical processes
that allow organisms to build up and
break down molecules to grow,
develop, survive and reproduce.
· Synthesizing substances to create building
blocks and energy.
· Transforming substances into energy.
. Making energy available for use.
+he has worked in the engineering of metabolic pathways of oils and lipids
+bioderived chemicals and polymers
Classification of crops or plants
Provides valuable knowledge about optimal conditions necessary for successful cultivation:
Specific requirements; appropriate soil & water conditions, adaptability, growing habits, and climatic needs
Understand economical production & usage of crop plants and growing seasons
Classification can be based on:
Climate
The Growing Season
Ontogeny (‘life cycle / duration’)
Agronomic Classification of Crops (use and characteristics)
Photosynthesis
Reduction of Carbon Dioxide /Dark Reaction)
Cultural Method/Water
The Number of Cotyledons
Root System
Economic Importance
The Length of Photoperiod Required For Floral Initiation
Some plants will have multiple possible classifications
Classification based on climate
Tropical climate crops - warm and hot climate e.g. rice, and sugarcane
Temperate crops - cool climate e.g. wheat, oats, gram, and potatoes
Classification based on the growing season
Rainy crops. warm and wet weather during their growth period and short day lengths for flowering.
e.g. cotton and rice
Cold-season crops. winter season / cold and dry weather and longer day lengths for flowering.
e.g. wheat, gram, and sunflower
Summer crops. warm weather during the major growth periods and longer day lengths for flowering.
e.g. Groundnuts, watermelons, pumpkins, and gourds
Classification Based on Ontogeny
(‘life cycle /duration’)
Seasonal - complete their life cycle within a single season, typically summer. E.g. rice and wheat
Two-seasonal e.g. cotton, turmeric, and ginger
Annual require a full year to complete their life cycle. E.g. sugarcane
Biennial grow in one year and flower, fructify, and perish the next year.
e.g. radish, carrot, beet or cotton, turmeric, and ginger, bananas, papaya
Perennial live for more than one year. occupying land more than 30 months.
e.g. ginger, garlic, sweet potatoes, fruit crops such as mango, guava
Agronomic classification of crops
(by use and characteristics)
> Grain crops: refer to cultivated grasses grown for their edible starchy grains, cereals like millet
> Pulse/legume crops: are leguminous crops whose seeds are used as food. On splitting, they produce crops rich in protein, green gram, black gram, soybean, pea, and cowpeas
> Oil seed crops: are crops whose seeds are rich in fatty acids and are used to extract vegetable oil to meet various requirements. groundnut, mustard, sunflower, sesamum, and linseed
> Forage crops: refer to vegetative matter, fresh or preserved, utilized as food for animals. Crops are cultivated and used for fodder, hay, and silage, sorghum, elephant grass, guinea grass, and other pulses.
> Fiber crops: are grown for their fiber yield, which may be obtained from seeds, such as cotton
> Root crops: are crops whose economic production is in their roots, sweet potatoes and carrots
> Tuber crops: are crops whose edible portion is not a root but a short thickened underground stem, potatoes and yams
> Sugar crops: refer to the two important crops which are cultivated for the production of sugar, sugarcane and sugar beet
> Starch crops: are grown for the production of starch, tapioca and sweet potato
> Dreg crops: are used for the preparation of medicines, tobacco, mint, and pyrethrum
> Spices and condiments/spices crops: refer to crops whose products are used to flavor, taste, and sometimes color fresh preserved food. ginger, garlic, chili, cumin, onion, coriander, cardamom, pepper, and turmeric
> Vegetable crops: may refer to leafy or fruity vegetables, such as tomatoes
> Green manure crops: are grown and incorporated into the soil to increase soil fertility.
> Medicinal and aromatic crops: refer to medicinal plants, such as cinchona, and aromatic plants, such as lemon grass, citronella grass, cannabis, mint, peppermint, rose, jasmine, and henna
Classification Based on Cultural Method/Water
e.g. Rainwater, Irrigated. Chili, sugarcane, Banana, and papaya
Classification Based on Root System
A taproot system; a main root that grows deep into the soil. E.g. grapes and cotton
Adventitious or fiber-rooted; shallow, fibrous roots that spread into the soil.
E.g. cereal crops, such as wheat and rice
Classification based on The Length of Photoperiod Required For Floral Initiation
Length of day and night - floral initiation = photoperiodism.
Three categories:
Short-day plants initiate flowering when days are shorter than ten hours
e.g rice, green gram, and black gram
Long-day plants require longer days, more than ten hours, for floral ignition
e.g. wheat and barley
Day-neutral plants are not influenced by photoperiod and their rate of flowering initiation depends on the duration of the photoperiod e.g. cotton and sunflower
Classification Based on Photosynthesis (Reduction of Carbon Dioxide /Dark Reaction)
(Classification: C3, C4 & Cam plants)
C3 Plants: use the C3 cycle to fix carbon from carbon dioxide into 3 carbon sugars.
Enzyme involved in primary carboxylation is ribulose-1,-biophosphate carboxylase.
Photorespiration is high in C3 plants, which results in lower water use efficiency
e.g. rice, soybeans, wheat, oats, rye, or hardgrass, barley, cotton, and potatoes
C4 Plants: fix carbon by producing four-carbon compounds such as malic acid or acerbic acid.
Phosphoenol pyruvic acid carboxylase - carboxylation and has a high affinity for carbon dioxide
= negligible photorespiration.
Higher photosynthetic rates than C3 plants for same amount of stomatal opening
= drought-resistant
e.g. Corn, sorghum, sugarcane, millet, and switchgrass
Cam Plants: Crassulacean acid metabolism; periodic water supply
open their stomata at night (air temperature lower) to fix a large amount of carbon dioxide as malic acid which is stored in vacuoles.
e.g. sedum, kalanchoe, pineapple, opuntia, and snake plants
In the day, stomata are closed, and carbon dioxide stored as malic acid is broken down and released
Negligible transpiration and are highly drought-resistant e.g. pineapple, sisal, and agave
Classification Based on The Number of Cotyledons:
Monocots or monocotyledons are crops with one cotyledon in the seed
= all cereals and millet (grass type)
Dicots or dicotyledonous are crops having two cotyledons in the seed
= all legumes and pulses
Classification Based on Economic Importance
Cash crops are grown for the purpose of earning money e.g. sugarcane, cotton, cannabis
Food crops are grown to produce food grain for the population and fodder for cattle.
e.g. wheat and rice
Quality traits
‘A property or aspect with association to one or more key performance characteristics in target environments’
Each crop or ‘cultivar’ has its own specific set of quality traits *.
e.g. yield, lodging (risk of falling over), disease or pest resistance, grain retention, thresh-ability, photoperiod sensitivity, end use quality, nutritional value
Climactic and environmental adaptations
Repeatability, genetic variation
Concept of quality
Crop dependent – based on what we need to do with the crop:
*Varies from crop consumption to food consumption
*Market – nutritional and or industrial qualities
*Degree of Excellence/Suitability/Fitness of plant product for end use
Aspect of growth at any stage:
- Nutritional worth
*Market quality
*Seeds
*Processing
*Transport & Storage
Classification of quality traits
Morphological - shape and appearance
Organoleptic - sensory
Nutritional – food, feed and health
Biological – technofunctionality
Morphological traits
& organoleptic traits
Morphological:
Easily observable – appearance related
Size and colour
Consumer acceptance e.g. ‘wonky’ produce fetches lower market value
Defines the market value of products
Organoleptic:
‘Being that which stimulates the senses’
Sensory qualities: Easily determined
Palatability of the produce: taste, aroma, smell, juiciness, texture, etc
Influences consumer acceptance
Nutritional traits
Determine the value of the produce in human / animal nutrition
Paramount in human/animal health: but not easily appreciated/observed
Nutritional factors
Protein content & quality
Oil content & quality
Vitamin & mineral content
Also important: Presence of anti-nutritional factors e.g. in pulses
Biological traits – technofunctionality
Technical and specific per crop – determines utility of crop for consumption
^ Not always directly obvious to producer or consumer
Examples:
*cooking quality of rice
*fibre strength of cotton
*Pathogen resistance
*Keep/storage/transportability of fruits and vegetables
*Protein efficiency ratio (PER) - biological value and body weight gain
Genetic variability in plant breeding
Variation in the genetic makeup of individuals within a population:
different individual genetic traits present in a group of plants mutations, genetic recombination during sexual reproduction, etc
Raw material for selection and foundation for plant breeding programs:
*Adaptation changing environments
*Disease/Pest resistance
*Yield improvement
*Quality traits
Sources of Genetic Variability:
*Transgene / Biotechnology
*Wild species and relatives (of cultivars)
*Somaclonal variants
*Spontaneous / Induced Mutations
*Germplasm - Instrumental in Agri biodiversity Total of ALL the genes crop & related species
*Cultivated crop varieties - Most preferred! Maintained living genetic resource
