Top 10 Reasons to Teach Students About Agriculture

In our rapidly evolving world, providing students with a foundational understanding of agriculture takes on a vital role. Beyond cultivating an appreciation for their food sources, agriculture literacy equips young minds with a diverse array of skills and provides a deeper connection to the environment and community that surrounds them. Agriculture is also one of the topics that students can easily connect to because they can apply concepts being learned. From the food we eat, clothes we wear, and even the fuel that powers the cars and busses we ride in, the resources for these materials come from plants and animals grown on the farm. Agriculture themes provide perfect real-world connections to STEM and make learning relevant to students.

Here are just a few reasons it’s important to teach agriculture literacy. 

1. Food Awareness. Teaching students about agriculture helps them better understand where their food comes from, which fosters a deeper appreciation for the sources of their nutrition.
2. Health and Nutrition. It connects students with fresh, locally grown produce and emphasizes the nutritional value of different foods.
3. Interdisciplinary Learning. Agriculture involves elements of science, technology, engineering, math, social studies, and even art. Teaching it offers cross-disciplinary learning opportunities.
4. Critical Thinking. Students can explore complex systems and challenges such as crop rotation, pest control, and soil health.
5. Career Opportunities. It introduces students to potential career paths in farming, agribusiness, research, food science, and more, broadening their future prospects.
6. Economic Impact. Agriculture is a significant contributor to the economy. Teaching students about it helps them grasp its importance in local and global economies.
7. Problem Solving. Agricultural challenges like climate change, food security, and resource scarcity require innovative solutions. Teaching about agriculture encourages creative and problem-solving thinking and skills.
8. Hands-on Learning. Agriculture education often involves practical, hands-on experiences like gardening, which can engage students in active learning and foster a sense of responsibility.
9. Sustainability. It instills an understanding of sustainable farming practices, promoting responsible use of resources and conservation.
10. Future Challenges. As the world faces challenges related to food production, and population growth (among others), informed citizens with agricultural knowledge can contribute to informed discussions and decisions. 

Want to connect your classroom to agriculture learning for the new school year? Here are a few ideas for the upcoming fall months to help tie-in to agriculture.

	Elementary	Middle School	High School	National Celebrations
September	Honey Bees: A Pollination Simulation Eggs From Hen to Home   Let’s Go Shopping	Flower Power   Eggs on the menu   Enlightened Concessions	Honey as a Biomolecule   Photoperiod Phenomena   My Agriculture Connections	Food Literacy Month Chicken Month Honey Month
October	Pork Production Then and Now   From Farm to Lunch Tray   PizzaThon	Iowa Hog Lift: International Diplomacy   What’s for Lunch?   FoodMASTERS Cheese	Pig Power: Creating Biogas and Renewable Energy   A Search for the Source   Enzymes and Bacteria are Whey Cool!	Pork Month Farm to School Month Pizza Month
November	It’s a MOO-stery!   Exploring Aquaponics   GobbleUp!	GobbleUp!   FoodMASTERS: Fats and Oils   Aeroponic Engineering & Vertical Farming	Blue’s the Clue: Souring Milk for Science   GobbleUp!   Urban Agriculture Innovation	Butter Day (17) STEM Day (8) Eat a Cranberry Day (23)

Other Resources to Check Out

Education Programs Calendar           

Bushel of Stories                  

Iowa Ag Today Elem & MS

Be sure to also check out our 2023-2024 School Programs Calendar! It includes information and deadlines for our various teacher and student programs throughout the year.

Please reach out to anyone on the Iowa Agriculture Literacy Foundation team to learn more about how you can easily incorporate agriculture into your classroom or how you can fund agriculture in the classroom efforts throughout Iowa or locally.

~IALF Team

Science 101: Seeds

A seed’s sole mission is to produce another plant. Without seeds, most plant species would not continue and our food, fiber, and fuel choices would be very limited.

Seeds are made up of several components that work together to keep the plant embryo inside alive until conditions are right for the seed to germinate and develop into a seedling that will survive.  Let’s take a look at some of the parts of a seed.

Structure and function of seeds Source: lumenlearning.com

Seeds are protected by a seed coat. This coat can be thin and papery or thick and hard. Thick coats help the embryo to survive through challenging conditions, such as extreme weather or even being eaten by an animal.

The embryo is the part of the seed that develops into a plant. It contains the embryonic root (radical), embryonic stem (epicotyl and hypocotyl), and one or two seed leaves (cotyledons).

Plants with one cotyledon, like corn and rice, are called monocots. If they have two cotyledons, like beans and sunflowers, they are called dicots. In dicots, the seed’s cotyledons form the first leaves of the plant. They are appropriately called cotyledon leaves or seed leaves.

The endosperm contains the starch or stored energy for the developing embryo. In monocots, the endosperm is the largest part of the seed and packed around the embryo.

Seeds are encased in fruit. The fruit protects the seed as it develops and aids in the dispersal of mature seeds. Seed shapes and sizes vary greatly from species to species.  Some, like orchid seeds, are as small as a speck of dust. Others are very large. The seeds of a coconut palm can grow up to 18 inches long.

There are many seeds that farmers grow for food, fiber, and other products. Here’s a look at a few products made from seeds.

Food. Of course, many seed crops are grown for food. Beans can be sold fresh, or dried, frozen, or canned for later use. Rice is a staple food around the world. Wheat is ground into flour for bread and pastries. Soybeans, almonds, and other high-protein seeds can be processed into dairy and meat substitutes. These are just a few examples of the many ways that seeds appear in our diet.

Cooking Oil. Almost all products sold as “vegetable oil” are made from soybeans. The seeds like soybeans are crushed and the oil is extracted and then clarified. Other popular cooking oils made from seeds include sunflower oil, canola oil, peanut oil, corn oil, and sesame oil.

Fuel. Ethanol, or grain alcohol, is derived from the fermentation of corn and other seeds with a high sugar content. Biodiesel is made from soybeans and other seeds with a high oil content.

Spices can come from any dried plant part, but many are derived from seeds. A few popular spices from seeds include black pepper, mustard, nutmeg, celery seed, cumin, paprika, and vanilla.

Livestock Feed. Soybeans are the most common protein source in animal feed worldwide. Just over 70% of the soybeans grown in the United States are used for animal feed. Poultry is the number one livestock consumer of soybeans, followed by hogs, dairy, beef, and aquaculture.

 

-Cindy

Note: This is the sixth post in a series about the science and agricultural importance of plant parts. Previous posts explore roots, stems, leaves, flowers, and fruit.

Science 101: Fruit

Fruits are the prized jewels of the plant and food worlds. They are essential for plant reproduction, as they protect the developing seed and aid in the dispersal of mature seed.  Fruits also provide an important and tasty food source for people and animals.

Botanists, farmers, nutritionists, chefs, and the general public often have different definitions of what makes a fruit a fruit, though. This is because botanical classification is determined by structure and function, while culinary classification considers taste.

Culinarily and nutritionally, a fruit is a sweet or sour-tasting plant part. They are generally eaten raw or made into sweet drinks and desserts. Cucumbers and peppers are not considered fruits in the food world, but rhubarb, which is a leaf stem, is.

Botanically, a fruit is the part of the plant that contains seeds. It is formed from the ovary after flowering. It includes traditional fruits (tree fruits and berries), but also seed-containing vegetables (i.e., squash, tomatoes, peppers, eggplant, etc.) and many nuts (i.e., chestnut, hazelnut, and acorns).

If you’re a self-proclaimed plant and science geek like me or just curious to learn more about plant classification, I highly recommend watching this SciShow video. It is four minutes of head-spinning and witty plant anatomy entertainment.

As stated before, fruits serve two important functions in plant reproduction: seed protection and seed dispersal. Fruits provide a physical barrier between the developing seed and the external environment. Their fleshy inside creates a moist environment for the embryo, or immature seed, and prevents it from drying out too soon. Fruits also provide protection from mammals, birds, and insects. Some have thick skin or shells, contain a toxic substance, or are covered with thorns for extra protection from herbivores.

After the seed is mature, a fruit’s purpose changes dramatically. Instead of protecting the seed, its job is to disperse the seed – or transport it to other locations to germinate and grow. How fruits transport seeds vary greatly from species to species.  Some fruits have wings or a parachute-like structure to carry the seeds by air. Coconut nuts float in water and can be transported miles downstream. Fruits of Impatiens and Viola species explode and catapult seeds onto the ground.

Animals play an important role in seed dispersal, and fruits play a key role in how this happens.  Many fruits are eaten by birds and mammals. The animal digests the fruit, but the seeds pass through the digestive tract and are dropped in other locations.  Some animals, like squirrels, bury nuts to save for later. If the squirrel does not return, the seeds germinate. Some fruits, like cockleburs, have hooks that stick to animal fur and are transported to another place.

There are many fruits that farmers grow for food, fiber, and other products. Here’s a look at a few products made from fruit.

Cooking Oil:  Many cooking oils, including avocado oil, coconut oil, and olive oil are made from fruit with high oil content.  Avocado and olive flesh can contain up to 30% oil.

Juice: This is an obvious, but important use of fruit. In its early days, the juice industry primarily relied on salvaged fruit, which was unsuitable for regular sales because it was misshapen, badly colored, or blemished. Advancement in juice processing, canning and bottling technologies, and cold storage led to increased production and demand for juice.  Now, specific cultivars of apples, citrus, and tomatoes are often are grown specifically for juice.

Pectin is a starch found in the cell walls of fruits and vegetables. When cooked with sugar and acid, it is a gelling agent used to thicken processed food, including jams, jellies, and gummy candies. Commercial pectin is usually made from citrus rinds.

Feed and Silage:  Fruit crops are not usually grown for animal feed, but significant quantities of substandard fruits, peels, cores, seeds, and other by-products of the fruit processing are fed to animals directly or used to make silage. Silage is a fermented feed made by tightly storing green plant material in a silo, silage bag, or silage pit. In parts of the country where seed corn is grown, farmers purchase truckloads of husks, cobs, and discarded grain leftover from seed corn processing. This material has a high sugar and protein content and is perfect for making silage.

– Cindy

Note: This is the fifth post in a series about the science and agricultural importance of plant parts. Previous posts explore roots, stems, leaves, and flowers.

 

 

 

 

 

 

 

Science 101: Flowers

Flowers are probably the most celebrated plant part. We prize them for their beauty, enjoy their fragrance, and use their likeness to adorn our walls and clothing. Flowers get such attention because they are beautiful, but it’s also important to celebrate the critical role they play in our world. Without flowers, most plants wouldn’t be able to reproduce.

The primary role of flowers is reproduction, and reproduction starts with pollination. Flowers have evolved over millions of years to ensure that tiny grains of pollen are carried from the male flower part to the female flower part. Without this transfer, fertilization does not happen, and seeds are not produced. I encourage you to check out our Science 101: Pollination blog post to learn more about how pollination works.

The four main parts of a flower are the sepals, petals, stamen, and pistil. If a flower has all four of these key parts, it is considered to be a complete flower. If any one of these elements is missing, it is an incomplete flower.

Photo Credit: Michigan State University Extension

The sepals are the first part of the flower to form. They protect the petals and other flower parts as they grow and prevent them from drying out.

Petals draw pollinators to the flower and serve as a place for them to land. They are often brightly colored and showy to attract pollinators. Some have several layers of petals, creating a rounded shape, while others are flat.

The stamen is the male reproductive organ of a flower. Each stamen contains two main parts. The anther is at the top and contains the pollen. The filament is the long skinny part of the stamen that holds the anther up for pollinators or wind to reach.

The pistil is the female reproductive organ of a flower. Pistils are generally shaped like a vase or bowling pin and contain three parts – the stigma, the style, and the ovary. The enlarged bottom of the pistil holds the ovary that produces and contains developing seeds. The style is the tube-like structure that connects the ovary to the stigma at the very top of the pistil. The stigma has a sticky texture to capture pollen transported by wind, insects, or birds.

Floriculture is the aspect of agriculture that focuses on growing flowers for decorative use, both inside and outside. Floriculture crops include annual and perennial garden plants for landscape use, potted flowering plants such as orchids, poinsettias, and Easter lilies, and cut flowers used for flower arrangements, corsages, and more.

There are quite a few other flowers that farmers grow for food, fiber, and other products. Here’s a look at a few products made from flowers.

Artichokes are spiny and tough flowers of the plant that usually grow during the fall. Both the wild forms and the cultivated forms of artichokes are consumed all over the world. People in Mediterranean countries including Egypt, Italy, and Spain are the greatest consumers and producers of artichokes today.

Cauliflower. As the name suggests, the cauliflower is also a flower. It is a cool season crop that thrives in a moist atmosphere. It is available year-round, although especially plentiful in the spring and fall. Cauliflower is a low-calorie vegetable, high in fiber, folacin, potassium, and vitamin C.

Broccoli. The edible portion of the broccoli plant is its unopened flower buds and tender stems. If not harvested, the green buds will open to form small yellow flowers. Broccoli is a cool season crop, closely related to cabbage, cauliflower, and Brussels sprouts. Cool season crops are often planted before the last frost and must mature while the weather is still cool. Hot weather and warm soil cause broccoli to flower too quickly, or bolt. Once the plant begins to bolt, anything harvested will be bitter.

Insecticides. Although most flowers attract insects, some repel them. Pyrethrin, also known as pyrethrum, is a chemical compound produced by certain types of chrysanthemum flowers. It is commonly used in pesticide products that control mosquitos, fleas, flies, moths, ants, and other pests. Some species of marigolds are also used to make nematode repellents.

Fragrances. Roses, violets, jasmine, and lavender are just a few of the flowers commonly used in the perfume industry to make traditional perfumes and add a pleasing fragrance to lotions, soaps, candles, and more.

Medicines & supplements. Digitalis is derived from Foxglove (Digitalis purpurea) flowers and are used to treat heart arrhythmia. Chamomile flowers are used to make teas other types of supplements that calm anxiety, settle stomachs, and even relieve mouth sores caused by cancer treatments.

Note: This is the fourth post in a series exploring the science and agricultural importance of plant parts.

-Cindy

 

 

 

 

 

Science 101: Leaves

Leaves are the workhorse of plant parts. They produce the food plants need to grow and reproduce. Leaves protect plants from predators. They remove carbon dioxide from the air and produce oxygen for humans and animals to breathe. In addition to all of these important functions, leaves also serve as an important food source for animals, insects, and people.

Leaves convert energy from the sun into chemical energy through photosynthesis that the plant can use as food. This important process happens in chloroplast cells. Chlorophyll within these cells absorbs sunlight to turn water (H₂O) and carbon dioxide gas (CO₂) into sugar and oxygen gas (O₂). Chlorophyll pigment absorbs red and blue light from the sun. Green light is reflected, which makes the leaves appear green.

 

A leaf is made of many layers that are sandwiched between two outer layers of tightly packed cells, called the epidermis. The epidermis is coated with a waxy substance called the cuticle. The epidermis and cuticle protect the leaf from insects, bacteria, and other pests and help keep moisture in the plant from evaporating too quickly.

Among the epidermal cells are pairs of sausage-shaped guard cells. Each pair of guard cells forms a pore called stoma. Carbon dioxide enters and oxygen exits through these pores. They also regulate water movement and cool the plant through the process of transpiration.

Veins support the leaf and are filled with vessels that transport food, water, and minerals to the plant. Monocot plants, like corn, wheat, and rice have long narrow leaves with veins that run parallel to each other across the length of the leaf. Beans, peas, and other dicot plants have wider leaves with veins arranged in a branched or webbed pattern. The petiole, or leaf stem, attaches the leaf to the plant’s stem.

Cabbage, lettuce, kale, and other leafy greens are some of the most well-known leaf crops, but there are quite a few other leaves that farmers grow for food and fiber. Here’s a look at a few products that wouldn’t be possible without leaves.

Medicine: Some leaves have important medicinal properties. Digitoxin from the leaves of the digitalis plant (i.e. foxglove) strengthens contractions of the heart muscle and is used in medicines to treat heart failure. Vincristine from the periwinkle plant (catharanthus rosea) is a chemotherapy medication used to treat many types of cancer.

Aloe. If you’ve ever had a sunburn, I’m sure you are familiar with the cooling and healing properties of aloe vera. The leaf sap of this succulent has a long history of being used for medicinal purposes dating back to ancient Egypt. Today, aloe vera is grown in tropical climates worldwide.   

Tea. Leaves of the tea plant (Camellia sinensis) are used to make most traditional caffeinated teas, including black tea, white tea, oolong tea, and green tea. The types are differentiated by how the leaves are processed after they are harvested. Generally speaking, white teas are plucked and dried, green teas are steamed and then dried, oolong teas are lightly roasted and then dried, and black teas are roasted and then dried.

Tequila. This popular distilled beverage is made from the blue agave plant, primarily grown in the area surrounding the city of Tequila in western Mexico. The region’s red volcanic soils are well suited to growing blue agave. More than 300 million plants are harvested there each year.

Herbs. The leaves of rosemary, thyme, oregano, basil, cilantro, parsley, mint and others can be harvested and used fresh or dried, packaged, and sold to use in flavoring food.

Essential Oils. Many popular essential oils including lavender, eucalyptus, and rosemary oil are derived from the leaves of their namesake plants through steam distillation and other methods.

Fiber. Although stems and seeds more commonly used as fiber, the leaves of sisal (Agave sisalana) and a few other plants provide good quality fiber for manufacturing rope, twine, rugs, and other fiber products.  

Celery. A celery stalk, the part that we eat, is a special part of the leaf called a petiole. The petiole, or leaf stem, attaches the leaf blade to the plant’s stem.

-Cindy

Note: This is the third post in a series exploring the science and agricultural importance of plant parts.

Science 101: Stems

Stems. They may not be as showy or as talked about as other plant parts, but they are important. Stems are the glue that keeps all of the parts together and working as a team.

Stems provide support and elevation for leaves, flowers, and fruits. They arrange leaves in a way that they can get adequate sunlight to perform photosynthesis, a process necessary for life. They position flowers to attract pollination and ensure that fruits have room to grow and ripen in the sun.

Stems transport fluids throughout the plant. They move water and nutrients taken up by the roots to the leaves. This upward movement happens in specialized cells in the stem called xylem. Stems also move the food produced by the leaves to other parts of the plant. The cells that do this work are called the phloem. Unlike xylem cells, phloem moves food up and down.

Stems can also store water or nutrients. Cacti are the best example of water-storing stems.  Their thick, hard-walled, succulent stem stores water, which is infrequent in the dry, arid, locations they thrive.  The inside of a cactus stem can be spongy or hollow. The outside is covered with a thick, waxy coating, which keeps the water from evaporating like it would in other plants.

Not all stems are found above ground. Nutrient-storing stems are located underground. Potatoes and sweet potatoes, for example, store excess energy in underground modified stems called tubers. These plants produce more energy than the growing plant can use at one time. Excess energy in the tubers and provide the plant energy to regrow in the spring.

There are quite a few other stems that farmers grow for food and fiber. Here’s a look at a few products that wouldn’t be possible without stems.

Wood and wood products, like paper, rank just behind food plants in overall value to society. Like all stems, a tree’s trunk is made up of xylem and phloem cells. Each year, the tree forms new cells, arranged in concentric circles called annual rings. Early in the growing season, the cambium produces numerous large cells that form the light-colored springwood. Towards the end of the summer, growth slows down and the cells produced are small with thick walls. These cells form the darker-colored summerwood. This process repeats each year, increasing the diameter of the tree and producing a valuable agricultural product.

Sugar. Sugar cane is a tall perennial grass grown in tropical environments like Florida and South America. The plant stores excess energy as sugar in a sweet juice found in the plant’s fibrous stalks (stems). To produce table sugar, the stalks are harvested, the juice is extracted, excess water is evaporated, and the sugar crystals are dried. While sugar cane is the number one source of sugar, it is important to note that it can also be made from sugar beets, a root crop.

Cinnamon comes from the inner bark of the trunk (stem) of cinnamon tree. Farmers will shave off the outside bark of the tree to get to the cinnamon layer that is harvested and dried. Cinnamon has a natural tendency to curl as it dries, which gives cinnamon sticks their curled appearance.

Straw is a byproduct of cereal grains like wheat, barley, and oats. When the seeds of these crops are harvested the stems, or stalks, are left behind. Most of the stalks’ nutrients were depleted while producing seed, leaving little nutritional value as a feed source. The stalks can, however, be baled and used for straw.

Maple Syrup. Pure maple syrup begins as sap from the xylem of a Sugar Maple tree. The sap is harvested in the spring when days are warm and nights cool below the freezing point. Trees are tapped, and the sap either drips into a bucket or flows down a special tube to a holding tank. Maple sap is clear, slightly sweet, and very thin. The distinctive maple flavor and thick consistency of syrup is developed through careful heating to evaporate most of the water. It takes 40 gallons of sap to make one gallon of syrup.

Onions & garlic. Although usually referred to as root crops, onions and garlic are both underground stems, called bulbs. Like tubers, these modified stems hold nutrient reserves for the following season – and provide a tasty food crop for us!

-Cindy

Note: This is the second post in a series exploring the science and agricultural importance of plant parts.

Science 101: Roots

Roots. They are the hidden heroes of plants. We rarely see them, but they provide the foundation from which all plants grow. Without them, we would not have fruits, vegetables, grains, wood products or beautiful flowers to enjoy.

Roots have two primary functions. They collect water and nutrients, and they provide anchorage and support for the plant. Both of these functions are essential. Plants cannot grow and produce flowers and fruit without water and nutrients, and plants would blow away without being anchored in the ground by roots.

The shape, size, and structure of roots vary greatly from species to species, but they are generally categorized into two main types – fibrous and taproot. Most dicots, or broad-leaf plants have a taproot system, and most monocots, like corn, wheat, asparagus, and rice have a fibrous root system.

Credit: United Soybean Board

Plants with taproots have a thick, main root that grows deep into the soil and smaller lateral roots growing from it. Some plants, like radish, have relatively shallow taproots with very small lateral roots. Others have a very deep primary root and an extensive system of lateral roots growing from it. The taproot system of soybeans, for example, can reach 6 feet deep with lateral roots that spread 1-2 feet wide in favorable conditions.

Some plants, like carrots, parsnips, and beets, have an extra thick taproot that hold large quantities of nutrients. These enlarged roots store extra sugars and other carbohydrates for the plant and provide a valuable food crop for us!

In contrast, a fibrous root system is usually formed by a network of thin, branching roots of about equal diameter. Plants with fibrous root systems often form a mat of roots underground. While they do not have a large taproot as an anchor, their many small roots firmly secure them in the ground.

Plants with shallow fibrous roots, like grasses, are also great at stabilizing the soil and preventing erosion. This makes them a good choice for cover crops, terraces, buffer strips, and other conservation practices.

Not all fibrous root systems are shallow. Corn roots, for example, often grow three to five feet deep. Some have even been found extending more than 10 feet!

Roots grow from their tips and are thin at first. New and rapidly growing portions of a root system are the most permeable and have the greatest ability to absorb water and nutrients. These thin roots are often covered with even smaller roots called root hairs. They may be small, but root hairs are numerous and mighty! Their large surface area to volume ratio makes them very efficient in absorbing minerals and water.

A common feature of almost all root systems is mycorrhizae, a symbiotic relationship that forms between fungi and plants. Plant roots secrete compounds that interact with microorganisms in the soil. In exchange for a bit of sugar, the fungus helps the roots pull in more nutrients and water than the plant could on its own. Mycorrhizal fungi occur naturally in soil and can be added as a seed treatment before planting.

Roots are influenced by the soil in which they live and are good indicators of soil health If the soil is compact, is low in nutrients or water, includes high populations of root pathogens, or has other problems, plants will not develop a healthy root system. On the other hand, roots also benefit the soil in which they grow. Roots help keep soil in place, add organic matter, and feed beneficial bacteria and fungi.

Healthy plants are essential for good crop yields…and healthy plants have healthy roots.

– Cindy

Science 101: Plant Classification

Plants are pretty amazing. They provide us with oxygen, food, fiber, and medicine. They grow in all regions of the world. Each species has leaves, stems, flowers, roots, fruit and seeds adapted to its habitat. These specialized plant parts ensure they can acquire their basic needs, protect themselves against predators, and reproduce.

In future posts, we will explore the function, specialized features, and agricultural importance of each of the basic parts of plants – roots, stems, leaves, flowers, and fruit. But before I dive into these topics, we need to take a step back and review some terminology – particularly in regard to how plants are classified.

Do you remember learning about Carl Linnaeus in high school biology? Linneaus is known as the father of taxonomy – a system for organizing the natural world. He brought order and structure into the previously chaotic realm of naming plants and animals. His system was based on morphology, a fancy word for grouping organisms based on their physical form and structure.

Today’s taxonomic system includes three domains: Archaea, Bacteria, and Eukarya. The Eukarya domain is divided into four kingdoms: Animalia (animals), Plantae (plants), Protista (slime molds, algae, and protozoans), and Fungi. Each kingdom is further divided into phyla (also called divisions), classes, orders, families, genera, and species. My biology teacher taught us to remember the order of classification with this mnemonic device: Did King Phillip Come Over For Good Soup?

Using corn as an example, the chart above illustrates how groups become smaller as you move down classification levels from domain to species. Two plants within the same group have more in common and are more closely related than they are to plants in another group. Just like humans are more closely related to gorillas and chimpanzees than other mammals.

Taxonomic classification is not just useful for plant identification. Understanding the common characteristics of plants within a group helps plant breeders, chemists, and others improve agricultural practices. For example, herbicides have been developed to kill broad-leaf weeds (dicots), without harming monocot crops like corn, wheat, and rice.

Since plants within the same family have similar roots, reproductive structures, or other characteristics, they tend to have similar growth characteristics, nutritional needs, and pests. Knowing this, farmers often rotate crops from different plant families to interrupt pest life cycles and reduce yield loss.

If this piqued your interest, be sure to check out our other Science 101 posts and subscribe so you don’t miss future posts.

– Cindy

Science 101: Photoperiodism

Saturday is the Winter Solstice, the shortest day of the year in the Northern Hemisphere. Since June 21, the Summer Solstice, the days have been getting shorter. As a parent, I look forward shorter days and longer nights for one reason. My kids go to bed easier. They are cranky and do not function well unless they get 10-12 hours of sleep, and they sleep better when their room is dark. Many plants are similar.

Poinsettias, strawberries, cotton, and soybeans may not seem to have a lot in common, but the plants they come from sure do. They set flowers in response to shorter days and longer nights.  And without flowers, they will not produce what we want – beautiful red bracts for the Christmas season; fiber for clothes; sweet berries to eat; and beans for biodiesel, livestock feed, vegetable oil and more.

There is a key science phenomenon behind this seasonal response to day-length.  Photoperiodism is the ability of plants and animals to use the length of daylight or darkness to trigger development or a modification of activities. In many organisms, photoperiodism causes seasonal activities like growth, flowering, reproduction, migration and dormancy in some organisms. Temperature and moisture affect growth and other seasonal activities too, but they are much less regular in timing. Consequently, they are less effective “clocks” to trigger activities needed for organisms to survive and reproduce.

In the plant world, flowering is the most common and significant activity affected by photoperiodism. Plants are divided into three categories: short-day, long-day, and day-neutral. While these names suggest that the length of daylight triggers flowering, it is actually the night length that is most critical to development.

Short-day plants bloom when the length of day drops below a critical threshold. This threshold varies by species, but short-day plants generally require greater than 12 hours of uninterrupted darkness to flower. Other short-day plants include the chrysanthemum, Christmas cactus, rice, green onion, and sugarcane.

Conversely, flowering in long-day plants is triggered when daylight lasts longer than their critical threshold, typically in spring or early summer, after the spring equinox.  Examples of agriculturally significant long-day plants include lettuce, spinach, turnip, radish, sugar beet, and potato.

You might be wondering; how do plants sense light? Unlike my kids, plants do not have eyes to tell night from day. Instead they have photoreceptors, specialized proteins bonded to light absorbing pigment within cells. When the pigment receives certain wavelengths of light, the photoreceptor protein is altered and causes changes in hormone production, gene expression, and growth.

So, why does photoperiodism matter and how does it affect farmers?

Day-length influences a wide range of plant responses in the crops farmers grow across the country and around the world. Flowering in soybeans, bulb formation in onions and garlic, runner development versus flower bud initiation in strawberries, and even seed germination of some plants are affected by the amount of daylight and darkness.  Because of this day-length plays a big factor in what farmers grow when and where.

Some crop’s critical day -length differs among varieties. Soybeans, for example, are classified into maturity groups according to their response to photoperiod. Maturity group zones were developed to define where a soybean cultivar is best suited.

Some crops’ critical day-length differs among varieties. Onions, for example, can be short-day, long-day, or day-neutral. Farmers choose varieties best suited to their part of the country. In the South, winter temperatures are milder and summer and winter days do not vary much in length. Because of this, southern farmers plant short-day varieties in the fall for a late-spring harvest. Short-day varieties can be grown in northern states, but the bulbs will not grow as large.

All soybean varieties are short-day plants, but there is still some variance in the critical day-length threshold required for flowering. Therefore, photoperiod response is one of the primary factors used to classify soybeans into maturity groups. Plant breeders use maturity groups to define where a soybean variety is best suited. Soybean maturity groups range from earliest (000), to latest (10). There are gradations within maturity groups formed by adding a decimal to the number. For example, a seed company may offer a soybean variety with a 3.6 relative maturity.

Soybean yield is a product of the number of days seeds have to develop and the rate at which they develop. Later maturing varieties have more days for seeds to develop, which helps increase yield.

Earlier maturing varieties, on the other hand, produce more leaves before flowering starts. Leaves are the plant’s energy factory, and energy is needed for seed development. So, as you go up the maturity group scale, the signal to start flowering is delayed. This gives the plant more time to develop a bigger factory, thus increasing the rate of seed development and yield potential.

If a late-maturing soybean is planted too far north, frost may occur before the seeds are fully mature. If an early variety is planted too far south, seed development may take place when the plant is stressed from summer heat or drought. Either scenario can result in lower yields.

Farmers choose maturity groups based on their location, weather, and other factors. If spring planting is delayed by weather, they may choose a maturity on the earlier side of the range suitable for their location. Some farmers choose to plant a variety of maturities so their crop matures at different time.  This helps to spread risk and time planting and harvest around other farm activities.

-Cindy

 

 

 

 

Science 101: Germination

Seeds are amazing. Although they might appear to be tiny lifeless objects, seeds are powerful living things just waiting for the right conditions to do their thing! Each seed contains exactly what it needs and is designed specifically for the job it must do. All seeds have the same mission. To germinate and grow into a plant that will produce more seeds.

It is important for farmers, and gardeners, to understand the science of seed germination so they can maximize yields while efficiently using resources.

So, what exactly is germination? And how does it work? Let’s explore these questions and others.

What is germination?

In simple terms, it is the process of a seed developing into a plant. Germination occurs below ground, before the stem and leaves appear above the soil.

How does germination work?

To understand the process, you’ll need know the main parts of a seed and their function.

All fully developed seeds contain three basic parts, the embryo, endosperm and seed coat. The embryo is the part of the seed that develops into a plant. It contains the embryonic root (radical), embryonic stem (epicotyl and hypocotyl), and one or two seed leaves (cotyledons).

Structure of Seeds (Source: Lumen Learning)

The endosperm contains the starch or stored energy for the developing embryo. The endosperm is the largest part of the seed and packed around the embryo. The seed coat is the outer layer that protects the seed’s internal structures.

The first stage of germination, called imbibition, occurs when the seed is exposed to water. The seed absorbs water though its seed coat. As this happens, the seed coat softens.

Next, water triggers the seed to begin converting starch to sugar. This provides energy for the embryo during germination.

More water is then absorbed and the seed’s cells start to elongate and divide. The radicle, or primary root, is usually the first part of embryo to break through the seed coat. It grows downwards to anchor the seed in place and absorb water and nutrients from the soil.

Next, the shoot and seed leaves emerge from the seed coat. The process and order depends on type of seed. Monocot and dicot seeds are structurally different, which affects how they germinate.

Soon the shoot will emerge from the soil. The seed tissue will diminish as the plant’s roots, stems, and leaves develop.

What do seeds need to germinate?

All seeds need water, oxygen, and the proper temperature to germinate.

The soil temperature must be warm enough so seeds can germinate, but not so hot as to damage the seed. Cold soil temperatures can cause seeds to remain dormant, increasing their vulnerability to diseases and insect damage. Temperature requirements vary between species. Soybeans, for example, need a minimum soil temperature of 50 °F for germination, but 77°F is optimum.

Water triggers germination to start and is needed throughout the germination process. Soil should be moist, but not saturated with water. Some seeds require more water than others. The critical soil moisture level for corn is 30%, while soybeans need soil that it at least 50% moist in order for germination to occur. That’s because beans absorb more water. Beans take in two to five times their weight in water, while corn only absorbs about 1.5 times its weight.

Oxygen is found in the air we breathe, and in soil too! Oxygen is usually on the list of things plants need to grow. However, it’s not always included when discussing germination.

When a seed is exposed to the proper conditions, water and oxygen are absorbed through the seed coat and cause the embryo cells to enlarge. If there is not enough oxygen present, germination may not occur. The most common reason for a lack of oxygen is too much water in the soil due to over-watering or flooding.

Do seeds need light to germinate?

Sometimes, not usually. Most seeds do not require light for germination and germinate best in dark conditions. However, some seeds like carrots & some lettuce varities need light to germinate. The stimulus of light causes them to break dormancy and start germination once exposed to water and proper warmth. These seeds germinate best when planted on the soil surface or just barely covered with soil.

Why does planting depth matter?

Although it may be tempting to plant seeds shallow so they emerge sooner, it is important to follow the recommended planting depth. Planting too shallow can result in insufficient soil moisture for germination or a weak root system. Planting seeds too deeply causes them to use all of their stored energy before reaching the soil surface. Like temperature and moisture, ideal planting depth varies by plant species. As a general rule of thumb, larger seeds can be planted deeper because they contain more stored energy to reach the soil surface than smaller seeds. Farmers consider other factors like soil type, planting time, and temperature when deciding how deep to plant.

Nearly everything we eat and most of what we use would not be possible without germination. Vegetables, grains and fiber crops are grown from seed. Meat, eggs, and dairy products come from animals that were fed seeds or plants that grew from seeds.

As you drive past fields of emerging crops this spring, think about the amazing science phenomenon happening before you.

– Cindy