Dr. Luke Talks about Types of Plants

Today  Dr. Luke will talk about types of plants and what importance this has to agriculture.  There are hundreds, no thousands, of different types of plants in the world.  These plant types have been classified in a number of ways.  Plants are sometimes classified as annuals or perennials, tropical, or even aquatic.  However, in the field of agriculture many crops are classified as a grass or a broadleaf.

Some examples of grass include rice, wheat, corn, and oats.  There are also many undesirable grass weeds.  One characteristic of grass is a fibrous root system.  This is where the roots are all very fine and grow down in a mass under the plant.  These root systems are able to collect soil nutrients and water efficiently because there are so many roots in a small area.  However, these roots do not generally go very deep.  Therefore, under very dry conditions where there is not any surface water grass will generally suffer sooner than other plants.

Another characteristic of grasses are the veins in their leaves.  These veins will always run parallel to one another.  If you find a plant that has a fibrous root system and parallel veins you can be sure it is some kind of grass.

In contrast, broadleaves including soybeans, cotton, and canola generally have a taproot system.  This is when there is one main root extending down with smaller roots extending out from the taproot.  The taproot of some plants is very large and in some cases it is actually the crop.  The best example is a carrot.  The carrot itself is a taproot.  These roots are not as efficient at collecting surface water and nutrients.  However, taproots can reach much deeper depths than fibrous roots.  Therefore, broadleaf plants can endure dry conditions longer than many grasses.

There are also differences in the veins pattern in the leaves of broadleaves and grasses.  The veins in broadleaves have a web like pattern.  There is generally a large middle vein with many smaller veins stretching out across the leaf.

This has been a very simplistic comparison between grasses and broadleaves.  I remember when I was at college and I was studying agriculture we studied the differences between grasses and broadleaves.  I learned a great deal, but I really found a group of broadleaves the most interesting.  They were called legumes.  The legume family is the third largest in the world and there are over 13,000 species.  Important agricultural species include beans of all types, lentils, and peanuts.  But I found legumes interesting for another reason.  They do not need any nitrogen fertilizer, they make their own!  Nitrogen is important because all organisms use nitrogen to manufacture proteins and other nitrogen-containing components necessary for life.    Let me tell you how they do it. 

Nitrogen is one of the most important nutrient needed for plant growth, but it is found is relatively low concentrations in the soil.  In the air however it is a different story.  Approximately 80% of the air we breathe is nitrogen gas. Unfortunately this form of nitrogen is unusable by most living organisms. Ironically plants can die of nitrogen deficiency when they are surrounded by nitrogen gas. 

Legumes are able to transform the unusable nitrogen gas into ammonia nitrogen, which is useful for plants.  This process is called biological nitrogen fixation.  Legumes do not actually transform the nitrogen they have some help from a group of bacteria called Rhizobium.  There is a specific kind of Rhizobium bacteria for each type of legume.  I find it so amazing how well this world was created and how well everything works.  This creation though was not by accident.  God created all of these things to work like this.

Have you ever pulled up a bean plant and seen the little nodules attached to the roots of the bean.  Inside these nodules is where the nitrogen-fixing bacteria lives and transforms the unusable nitrogen gas in the air to a useful form of nitrogen.  Nitrogen fixation by legumes is a partnership between a bacterium and a plant. This is a beneficial relationship for both the plant and the bacteria.  The plant receives nutrition and the bacterium receives a safe place to live.  These two organisms have a beneficial relationship with one another.  Again, this was not an accident but  God designed the world to operate so amazingly.

When I think of relationships I think of many kinds.  We have relationships with friends, family, and co-workers.  In a relationship we are able to share ideas and feelings, talk and laugh, and support one another.  We all have relationships, which allows us to do this.  However, did you know that you could have the same types of relationship with God?  And that He wants to have this type of relationship with you!

I, that is Dr. Luke,  would like to tell you about my relationship with God.  When I am feeling down from a bad day at work, or when things just are not going my way I am able to talk to God about it through prayer and ask for His help.  And on the other hand when things are going great I am able to share my joy with God and to thank Him for all He has given me. 

Did you know that the God who created the entire world and everything in it wants to have a relationship with you?  The Bible tells us that in the beginning God created the world.  God created the sky, the sun, the moon and the stars.  But He did not stop there He also created the seas, the land, all of the animals and plants of the world, and the fish of the sea.  The last day of creation God created Man –named Adam - and when He was done He said it was good.  God and Adam had a great relationship at this time.  God and Adam walked and talked together.  All of God’s creation was then given to Adam/mankind to use and to take care of.  This is an incredible gift.  But there is a greater gift I want to tell you about later.  God did give Adam one command, and it was not to eat the fruit from the tree of the knowledge of good and evil.

I can remember as a child my parents telling me not to eat any cookies because they were for latter.  That always made me want the cookies just that much more.  I would sometimes take a cookie and then I was in trouble.  Adam too ate some of the fruit from the tree knowledge of good and evil.  Likewise, Adam was in trouble with God.  Their perfect relationship had been broken.  When we break a commandment from God it is called sin, and it is sin in our lives that separate us from God.  The Bible tells us that all have sinned and fallen short of the glory of God.

God however provided a new way of rebuilding a relationship between Him and us.  ‘For God so loved the world he gave his one and only son and whoever believes in him shall not perish but have everlasting life (John 3.16).’  God giving his son (Jesus) to rebuild the lost relationship is truly the greatest gift ever.  The question, which is often asked, is why should I believe in Jesus?  My response comes from the Bible; it says that Jesus died for our sins according to the Scriptures; and that He was buried, and that He rose again the third day according to the Scriptures.  Jesus died for my sins; he also died for your sins.  But because he did we can all have a relationship with God the father.  The Bible says that if you confess with your mouth the Lord Jesus and believe in your heart that God raised him from the dead, you will be saved.

Would you like to receive Jesus so that you can have a relationship with God?  If you would there is a simple prayer you can pray to receive Jesus as your personal Lord and Savior.  Here is an example prayer: “Dear Jesus, I believe that You died for my sins and that You arose from the grave.  I now ask You to forgive me of my sins and to save me from my sins. Amen.”  If you pray this prayer from your heart you can have a relationship with God.

Let me return to the legumes.  Legume nitrogen fixation starts with the formation of a nodule. A common soil bacterium Rhizobium, invades the root and multiplies. The plant supplies all the necessary nutrients and energy for the bacteria. Within a week after infection, small nodules are visible with the naked eye. In the field, small nodules can be seen 2-3 weeks after planting, depending on legume species and germination conditions. When nodules are young and not yet fixing nitrogen.  The way to determine if nodules are producing nitrogen is by cutting them in half.  Young nodules that are white or gray inside are not yet producing any nitrogen. As nodules grow in size they gradually turn pink or reddish in color inside, indicating nitrogen fixation has started. The pink or red color is caused by leghemoglobin (similar to hemoglobin in blood) that controls oxygen flow to the bacteria.

Nodules on annual legumes such as beans, peanuts, and soybeans are round and can reach the size of a large pea. Nodules on annuals are short-lived and will be replaced constantly during the growing season. At the time of pod fill; nodules on annual legumes generally lose their ability to fix nitrogen because the plant feeds the developing seed rather than the nodule. Beans will generally have less than 100 nodules per plant, soybeans will have several hundred per plant, and peanuts may have 1,000 or more nodules on a well-developed plant.

Legume nodules that are no longer fixing nitrogen usually turn green, and may actually be discarded by the plant. Pink or red nodules should predominate on a legume in the middle of the growing season. If white, gray, or green nodules predominate, little nitrogen fixation is occurring as a result of an inefficient Rhizobium strain, poor plant nutrition, pod filling, or other plant stress.

The legume’s ability to fix atmospheric nitrogen is often discussed in terms of the plant's ability to fix nitrogen. The amount of fixation that takes place is strongly influenced by soil conditions. Factors such as moisture, temperature, and fertility in the soil can influence fixation. Diseases and insects can also affect the degree of nitrogen fixation.  When all growing factors are favorable for plant growth, legumes can fix a large amount of atmospheric nitrogen into the soil.

Different legumes also vary in the amount of total nitrogen they can fix. Listed below are common legumes used in agriculture and the total amounts of nitrogen they fix during a growing season.  The common legume crops alfalfa, field peas, red clover, and soybeans can produce 150, 185, 85, and 160 kilograms of useable nitrogen per hectare per year, respectively.

Legumes also help other plant around them.  As the legume dies at the end of the year they release nitrogen for non-leguminous crops.  By understating how legumes work one can use them to your benefit.  A soybean and wheat crop is very common in my area.  The farmers have learned that if they can grow soybeans in the summer then the wheat planted in the fall will receive a free application of nitrogen.

There can be a lot of examples drawn between legumes and what Jesus did for us.  The first is the relationship between the plant and the bacteria.  The bacteria come to live within the plant to benefit the plant.  This is similar to the relationship between God and man.  God wants a relationship with you this can be done through accepting His son Jesus into your heart. 

The other example that jumps out at me are how the nodules change as they mature.  Early in the life of the legume they have no nodules.  This is similar to people before they know God.  As the plant grows the bacteria comes to live within the plant.  This is exactly what God wants to do in us.  As the nodules grows it starts with a gray color and eventually has a pink color within it as it matures.  As a Christian I think that I need to sometimes look into my heart and see what color it is.  Is it a non-producing gray color or is it a pink color?

Do you know what is even worse than having a gray colored nodule on a legume plant?  It is not even having any nodules. This is the same as not having real life. I would like to repeat the prayer I told you earlier in case you have not received Jesus.  “Dear Jesus, I believe that You died for my sins and that You arose from the grave.  I now ask You to forgive me of my sins and to save me from my sins. Amen.”  Without having Jesus in your life is the same as not having real life.  If you have prayed this prayer you are now a child of God and will live forever.