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: 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: Pollination

The goal of every living organism, including plants, is to create offspring for the next generation. Flowering plants reproduce by seed, and to produce seed, pollination must occur.

So, what is pollination?  It is the transfer of pollen from the male flower part of the plant, the stamen, to the female part of the plant, the pistil.  Both of these parts are contained in flowers, sometimes the same flowers and sometimes different flowers.  I’ll go into more detail about types of flowers and their parts in a future blog post.

Most plants rely on wind or pollinators to transfer pollen, but some plants can pollinate themselves.

Soybean plants are self-pollinated. This means that pollen produced within a flower fertilizes the ovary of the same flower on the same plant. Because soybeans plants do not need to attract pollinators, their flowers are not showy. Soybean flowers are hidden under the leaves near the plant’s main stem. Each flower is only about the size of your pinky fingernail, but there can be 50 to 75 flowers on one plant.  Other self-pollinating crops include lima beans, green beans, peas, and peanuts.

Corn and other cereal grains, including wheat and rice, are pollinated by wind.  Corn plants have two types of flowers.  The ear is the female flower. The tassel at the top of the corn plant is the male flower. Wind carries pollen from the tassel to the silks at the end of each immature ear. Pollen grains attach to the sticky end of each silk, and travel down the silks to fertilize each ovary. After pollination, the ovary develops into a kernel of corn at the other end of each strand of silk.

Wind pollinated plants usually have long stamens and pistils with small or no petals. They also have very lightweight and smooth pollen that is easily carried by the wind from one plant to another.

Approximately 35 percent of the food and fiber crops grown throughout the world depend upon pollinators for reproduction. While bees are the most well-known, moths, butterflies, beetles, ants, bats, and hummingbirds are also pollinators. In fact, there are more than 200,000 different species of pollinators, and 1,000 of those are small birds and mammals.

Plants that rely on pollinators tend to have showy or fragrant flowers to lure insects, birds and other pollinators to them.  Food, in the form of energy-rich nectar and/or protein-rich pollen, also entices pollinators to visit flowers. Pollen grains stick to the pollinator’s body and hitchhike a ride to another flower. There, the pollen comes off on the top of the pistil and pollination occurs.

Our world is filled with flowers of many shapes, sizes, and colors, thanks to the many ways that flowers are pollinated.

-Cindy

An Introduction to Herbicides

 

herbicides.1

Are you fearful, intrigued, confused, or simply curious about herbicides? If so, you’re in the right place! Let’s dig a little deeper into the science of how herbicides function.

To start off with, what is a herbicide? A herbicide is a chemical that can manage and control unwanted plant vegetation. The most common types of herbicides are synthetic, but there are also organic options. These chemicals are typically used to effectively eliminate weeds in order to maximize the growth of more desirable plants. Herbicides can be utilized anywhere from your favorite golf course to a neighbor’s garden, and everywhere in-between! It’s important to understand the different ways these chemicals are applied as well as how they physiologically effect plants.

Categories of Herbicides

The two largest categories of herbicides are selective and non-selective. Non-selective herbicides are designed to harm just about any plant species that comes into contact with it. Selective herbicides are formulated to target specific plants and leave others unaffected.

Herbicides can be further classified by their method of application. Some are formulated to be absorbed through leaf and green material, and are spread in a foliar application. These are commonly called “post-emergent herbicides“. Others can be applied to the soil as a preventative measure. These are commonly called “pre-emergent herbicides“. The timing of application is also crucial, since different chemicals work the best when applied before, during, or after a crop has been planted.

waterhemp seeds

One tall waterhemp weed that’s allowed to seed can produce 440,000 seeds or more.

Now that we know how herbicides are used, it’s good to understand that they aren’t the sole solution in the war against weeds. Herbicides are only one of the tools found in the producer’s weed-fighting toolbox. Other methods of weed control include cultural, biological, and mechanical tactics.  It’s recommended that farmers utilize an Integrated Weed Management plan to best control weed population. If the same type of herbicide is used in fields repeatedly, agriculturists face the fear of weeds developing a resistance to the chemical. A herbicide resistant plant develops through slight mutations in the plant’s seed, which occurs due to the large quantity of seed produced by a single weed. It seems to be a never-ending fight of producers against weed’s continuous adaptability.

Modes of Action

Mode of Action (1)

Herbicides can be further arranged with the various methods of how they target the anatomy of plants. Mode of action states the effect on the plant, and site of action specifies where the herbicide targets the process. Most herbicides are designed to interfere with an enzyme used to carry out an essential function to plant life (photosynthesis, amino acid production, lipid production, etc.).

Roundup is a common herbicide that belongs to group 9. This means it targets the enzyme  referred to as EPSP Synthase. This messes up the shikimate pathway, which would normally help produce molecules such as amino acids. This completely ruins the plant’s physiology, leading to its soon demise. If the chemical was formulated correctly, the plant will exhibit yellow and deformed leaves before necrosis, or plant tissue death.

Another common herbicide is 2,4-D which belongs to group 4 and is a growth regulator. All growth regulators effect the levels of auxin within plants, which is a hormone that facilitates plant growth. When applied correctly, the effected plant will exhibit twisting, abnormal growth, and structural deformity before necrosis.

I could go on for pages describing in detail why each group is unique, but this PDF is a useful and condensed resource. Long story short, it’s important for producers to choose a treatment plan that implements various modes of action to further prevent weeds from becoming resistant.

Real-life Application

Genetic modification has allowed producers to use a wider range of herbicides on their crops, the most recent scenario being dicamba. Dicamba is a group 4 growth regulator that targets broadleaf plants. This chemical used to be more common in residential areas (such as golf courses) than in row crop fields. It’s been around in the US since the 1960’s, and up until 2016 farmers only used it to eliminate broadleaf weeds before the growing season began. Dicamba is seen as one of the more dangerous herbicides due to its ability to volatilize and move post-application. This is why it’s now classified as a restricted use pesticide, which means there are increased rules and regulations surrounding application methods and timing. With the commercialization of dicamba-tolerant soybeans, these farmers are now able to use dicamba on their beans (which are broadleaves) without damaging them. When producers utilize biotechnology such as dicamba-tolerant soybeans and Roundup Ready corn, they are given another tool to fight the persistent army of weeds.

soda can

Photo from cheetsheet.com

The last thought I’d like to leave you with regards the rate of application of herbicides. Let’s talk a bit more about the herbicide commonly referred to as Roundup. Roundup (also known as Touchdown) contains glyphosate as the active ingredient. All applicators must follow the product label to properly calculate application rates. When using Roundup it’s recommended to use 32 fluid ounces per acre, up until the weed is one foot tall. Putting that into a bit of perspective – one aluminum can of soda holds 12 fluid ounces, so this rate calls for less than 3 cans. Now spread that out over an acre, which is approximately one football field. Additionally rates and various chemicals mixed together vary upon the species and maturity of weeds in the field. Simply put, these chemical applications are highly technical, tightly regulated, and extensively researched before ever reaching a field.

-Rosie

Macronutrients in Crop Production

elements in the environment

When growing crops of any type, it’s important to understand the required inputs in order to receive the desired yields. One of these inputs, arguably the most important and critical one, revolves around nutrient management. All plants have these requirements, whether it be crops grown for biofuels, fruit production, or landscape ornamentals. Each plant needs various amounts of nutrients, which can be used to classify them (by quantity) into macro or micro nutrients. It’s important to remember that each one is vital for plant growth, simply required in different doses. As a sidenote – this blog is going to be mainly focused upon corn production, but all of these elements are necessary for any plant you’re trying to grow! First I have a couple questions to spark your curiosity about nutrients in plants…    

  • A plant can be deficient in oxygen, how is that possible?
  • Plants need calcium just like humans do. If it doesn’t go towards bone and teeth strength, then what’s its purpose?

Macronutrients

Let’s start with the big three: carbon, hydrogen, and oxygen. If you’re reading a fertilizer label, they don’t typically advertise for these elements. So, where do plants take them from? Why are they necessary for plant life? Should I be worried that my garden isn’t receiving enough hydrogen? The simple answer is that no one should be concerned about their plants being nutrient deficient in C, H, or O, as long as the plants are surrounded by air!

Carbon (C) – Thanks to many fields of science, we know that carbon is the base for life on Earth! This means that if plants are going to continue to be alive, they must obtain and maintain C. In more direct terms, plants produce and uses chains of carbon with other atoms called carbohydrates, lipids, proteins, and nucleic acids. But what happens if the plant is unable to take in carbon? This would be a very unfavorable scenario for the plant, especially since carbon is essential to photosynthesis. More specifically, without carbon (in the carbon dioxide form) the Calvin cycle wouldn’t occur. This means there’s no G3P, which helps make glucose, and without energy the plant cannot continue to live.

calvin cycle.png

This depicts the Calvin cycle in photosynthesis. Diagram from Khan Academy

Hydrogen (H) – Whenever I think of elemental hydrogen, I don’t normally think of it as a nutrient. I don’t directly eat anything that is marketed as “high in hydrogen”, so how could a plant use it? To start off with, every living organism on Earth needs water (H₂O) to live. Plants use water to obtain hydrogen atoms when splitting H₂O molecules through the light reaction of photosynthesis. The hydrogen ion is then used to create NADPH, which is a crucial ingredient in the Calvin cycle. If a plant is missing this chemical compound, then photosynthesis would cease and the plant would die.

z scheme.png

This shows the light-dependent reactions in photosynthesis, commonly referred to as the z scheme. Image from LibreTexts

Oxygen (O) – Wait a minute – oxygen is a product of photosynthesis, why would a plant need to take in oxygen too? In order to break down food through aerobic respiration, there must be oxygen present. Yes that’s right, plants respire just like humans do! Cells within leaves and stems obtain oxygen atoms that are a product of photosynthesis. However, cells found in areas that aren’t photosynthetically active must find oxygen elsewhere. To solve this issue, roots are able to take in O₂ from the air between soil particles. If the ground is saturated to capacity, then the roots cannot take up oxygen in the gas state. If the area is flooded for longer than 72 hours, it’s likely the plant will run out of oxygen and not recover.

photosynthesis.JPG

The chemical equation for photosynthesis.

Nitrogen (N) – This is a much more commonly discussed nutrient, especially since it has a huge correlation to high yields in corn production. If you were to walk into a farmer’s field, you would be surrounded by nitrogen in many forms! N₂ is a gas found in the air, whereas NO₃⁻, NH₄⁺, and NH₃ are compounds found in the soil. But if nitrogen is found in the air, why can’t corn absorb it like carbon or oxygen? This is because corn can only take up nitrogen when it’s in a nitrate form, which can be found in solutions and attached to soil particles! When taking a closer look at NO₃⁻, it’s more prone to being lost to the environment due to its negative charge. Soil naturally has a negative charge, which means that a nitrate is more likely to move elsewhere in the environment than wait around to be absorbed by a plant. This is why many agriculturists use anhydrous  ammonia as a N fertilizer, because it contains NH₃ and not NO₃⁻. Overtime soil microorganisms will convert ammonia to a plant available nitrate. Why is nitrogen so important in corn physiology? N is essential to grain fill and development. This means that if the plant is deficient in nitrogen, the kernels and ear won’t fill to their genetic potential. A common symptom of N deficiency is a yellowing midrib on a lower leaf.

nitrogen d.jpg

Nitrogen deficiency in corn. Photo from SDSU Extension

Phosphorus (P) – This is another very important macronutrient! In a similar respect to nitrogen, plants are unable to absorb and utilize the elemental form of P. This creates a problem in fields, because P is most commonly found in a plant unavailable form! Luckily, roots have a symbiotic relationship with Mycorrhizal fungi which are able to turn P into a more usable form. Corn can easily uptake phosphates, and the most common compounds are H₂PO₄⁻ and HPO₄²⁻. Since phosphates have negative charges, they are more prone to leaving the soil than the elemental form (similar to nitrates). This is why synthetic fertilizers that contain significant amounts of phosphorus are delivered in a P₂O₅ compound. Why is phosphorus so important in corn physiology? P is directly correlated to crop maturity, yields, and overall plant growth. More specifically phosphorus is a huge makeup of sugar phosphates, which directly affects ATP. Energy transfer with ATP is crucial, due to it’s role in both RNA and DNA. A lack in P will affect the overall efficiency of any plant. Phosphorus deficiency in corn appears in older leaves and starts as a purple hue. An increase in severity will turn leaf margins brown.

phosphorus d

Phosphorus deficiency in corn. Image from Channel.

Potassium (K) – When applying synthetic fertilizers, it’s common to see potassium in the K₂O form. However, this form is not immediately available to plants. Plants can only take up K+ when it’s in a solution. This form differs from the available compounds of N and P, since potassium is a cationWhy is potassium so important in corn physiology? A deficiency in K can have a multitude of negative affects upon the plant. This could be seen as an increase in susceptibility to drought, temperature stressors, and pests. Agronomists refer to K as “the quality nutrient”, meaning there’s a direct connection to traits like seed vigor, size, color, and shape. To be more specific, potassium helps build cellulose, increase protein content, maintain turgor, and move sugars and starches throughout the plant’s vascular system. K deficiency symptoms start as a yellowing of leaf margins on older leaves, and an increase in severity turns the pale color to a brown necrosis.

K d.jpg

Potassium deficiency in corn. Photo from Thompsons.

Secondary Macronutrients

There are three elements that fall under this category, as they’re needed in higher quantities than micronutrients but lesser amounts than N, P, and K.

Calcium (Ca) – Calcium deficiencies are most common in sandy and/or acidic soils, since the Ca ions can be leached through the soil profile. Similarly to potassium, Ca²⁺ can only be imbibed by plants when in a soil solution. Why is calcium so important in corn physiology? Ca holds a vital role in the creation of cell walls and membranes. Calcium deficiency symptoms are visible in new growth, so in corn this would be around the growing point. It typically appears as a yellowing color, slowed growth, and leaf tips sticking together.

Ca d.jpg

Calcium deficiency in corn. Image from Crop Nutrition.

Magnesium (Mg) – Without Mg, a plant would not be able to photosynthesize. This element is a sizable component within chlorophyll molecules, which is 100% necessary for capturing the sunlight’s energy! Additionally, Mg serves as a phosphorus carrier. Simply put –  if there’s not enough Magnesium then the plant would be unable to uptake P, even if it was available in the soil! Mg²⁺ is the plant available form, and can be heavily affected by the pH and sandiness of soils. Mg deficiencies are first seen in older and lower leaves, starting as a purple interveinal discoloration.

Mg deficiency.jpg

Magnesium deficiency in corn. Photo from The Mosaic Company.

Sulfur (S) – The last, but certainly not least, macronutrient can be absorbed both through the roots and stomata openings. In the environment, sulfur is commonly found in the air as SO₂ and within soil solutions as SO₄²⁻. Unlike the previous secondary macronutrients, this one is taken up as an anion as opposed to a cation. Due to the negative charge on a sulfate molecule, it is mobile in the ground (just like nitrate or phosphate) and can be leached through the soil profile. Why is sulfur so important in corn physiology? Without adequate S, some amino acids and proteins would be unable to synthesize. Sulfur also has a connection to winter hardiness, which is a major trait in certain crops. S deficiency in corn appears as a general yellowing of younger leaves, starting between veins but widening to encompass the entire leaf with increasing severity.

SulfurDef_SF.jpg

Sulfur deficiency in corn. Image from Successful Farming.

This is merely a glimpse into some of the chemical factors and management systems that a row crop grower oversees each and every year. If you liked this blog or learned something new from it, let us know! Or maybe if you’d like to see a similar breakdown of micronutrients too? Either way I love writing about agronomic science and can’t wait to share another blog with you all!

-Rosie

 

Benefits of Houseplants

Have you ever wanted to grow some fresh food but simply don’t have the yard space for a garden? Or how about searching for home decorations, and can’t seem to find the right wall hanging? Personally, I’ve fought with both of these scenarios before and have found a simple solution – house plants! Growing greenery inside can be beneficial to your health, mentality, and add to the overall aesthetic wherever you call home.

With growing up in the rural Midwest, I have been surrounded by plants my entire life. Whether from nearby corn fields, wildflowers in pastures, or hanging air plants in my living room, photosynthesizing organisms have always been present in my day-to-day activities. However, this all changed when I moved to a college city to pursue higher education. I had never lived in such a restricted area before and was searching for ways to make it feel less bleak. After consulting some lists recommending the best house plants, I decided to start my plant collection off with one that required minimal watering and management.

Resized_20190327_085802

Undoubtedly the best roommate I’ve ever had is this little cactus. If I stay up late working on coursework, it never complains about the light always being on. If I am gone for a week or two, it won’t fuss about being lonely or stuck in a small room. And to top it all off, if I forget to water it for a few weeks it has yet to show signs of neglect! Its tiny size means it can easily fit into a windowsill and not take up any more valuable space. Additionally, succulents have an unspoken beauty that many have come to respect and admire.

Why is there such a hype around growing plants in your living space?  

Plants Can Purify the Air.

Have you heard of the term ‘phytoremediation’ before? This process is how certain plant species are able to clean the surrounding environment by filtering out harmful contaminants. Simply put, this means some plants can purify the air surrounding it. On large scale remediation operations, plants can be chosen by which contaminant they excel at removing. An interesting example of this is cabbage grown near a zinc smelter, with the sole purpose of reducing the lead concentration in the local environment. House plants can work in similar ways but on a much smaller scale. It’s also important to remember that even though some plants have these cleansing properties, you would need an excessive amount to completely clean the air. Some effective species are the Peace Lily, Spider Plant, English Ivy, Golden Pothos, and Gerbera Daisy. These are all beautiful plants that can thrive inside a house as long as they’re near a window and receive adequate watering!

Another interesting benefit is that houseplants can increase the humidity in your house or apartment! This means that plants can act as a humidifier (of sorts), as they release more than 90% of the water they take up through their roots into the air. This increase in moisture can be extremely helpful during the winter months, which could help combat your dry skin, common colds, or respiratory diseases.

Plants Can Improve Concentration & Memory.

Believe it or not, there are studies showing that being near plants can improve one’s concentration both at home and while in the workplace. In fact, it’s been proven that interacting with nature, whether it be in the form of a picture or actually walking through a park, can boost memory retention up to 20%. When considering which plants to choose, ornamentals are always a great option. They’re known for having eye-catching colors and designs, without the negative impacts of becoming distracted. When plants have a calming influence on your brain, it could improve your life in many cognitive aspects. With possible benefits like this, who wouldn’t want to keep a houseplant by them at all times?

Plants Can Provide Healthy Food.

A lot of herbs and leafy greens can be grown in the convenience of your own home and can be placed anywhere from a narrow windowsill to a table near a window. I’ve seen a lot of cilantro, basil, rosemary, and lettuce grown inside. Some people even have small citrus trees (mandarins, lemons, kumquats) or pepper plants in their kitchen or spare room. These types of plants require more maintenance than some of the other plants I’ve mentioned. Herbs, fruits, or anything you plan to eat will generally require much more water and some additional fertilization as well.

8920-herbs-on-windowsill

Here’s a great example of some herbs being grown indoors on a window sill! Photo from gardeners.com

And here’s a few general reminders of what to do or not do with indoor plants!

  1. Always use a pot with drainage holes in the bottom! And to avoid any water harm to your home’s surfaces, just add a tray underneath the pot to catch any excess water.
  2. Do your research on the individual plant. This can include how often it should be watered, what soil mix to plant it in, and which direction the window should be facing to receive the most beneficial type of sunlight.
  3. The quality of water you use is also important. A good rule of thumb is to avoid repetitive use of softened water, with the hopes of avoiding a sodium buildup in the soil.
  4. Take into account your temperature! Most plants will do fine in room temperature areas, but be sure to note temperature fluxes near windows, doors, and during varying seasons.

I hope this helped open your eyes to not only some of the benefits of growing plants in your home but also the feasibility and ease of doing so!

-Rosie