Lesson-1A (Complementary Video-note) Introduction to Crop Physiology 5OCT2026
Updated: 12 hours ago
Complementary note:
[00:00] Opening and course housekeeping
Dr Amin: Have you started recording? Yes? OK. What's your name?
Student: Daim.
Dr Amin: Daim. Alright, cool, thank you, Daim. [laughter] I heard somebody say chocolate. How do I make this full screen? Ah, that is full screen. OK. Is everyone here? How many of you should there be?
Students: 25… no, 26. The last student on the list is Mohammed Naqiuddin.
Dr Amin: OK, cool, thank you. Alright, welcome to the first class. Well, not the first class — the first day of the semester. What class did you have today?
Students: Pathology.
Dr Amin: Pathology with whom? Dr Ganesan? Alright. How was it?
Students: Good.
Dr Amin: Learning is always good. How's the temperature? Do you want it cooler?
Students: No.
How the class will run
Dr Amin: I will spend about 10 minutes explaining how this class will run before we start the lesson. First, make sure you are in the right classroom. This is Crop Physiology, AGR3301, Group 2. Are you first-year, first-semester students?
Students: Second year.
Dr Amin: Everybody second year. Alright. So I don't have to be very kind to you, because you are not freshies, right? Or do you still need people to be kind to you? [laughter] How are you doing so far, getting into your second year? Great? Regret?
Student: It's a bit hard.
Dr Amin: It's normal to find it hard, because many things you are learning now are new to you. When it comes to learning anything, repetition is the key. Remember Standard One, or kindergarten, when you first learnt to read the alphabet? Did you learn it in one day, or did your teacher repeat it over many days and weeks? It was repetition, right?
It's pretty much the same here. Things get easier when you are consistent. Don't try to get it over with in one go, then vomit everything out at the end of the semester and be done with it. That way you will find it very difficult. Make it consistent. Learn bit by bit and spread your revision out, not in one go. Set yourself small targets. If you have 20 pages to read, have the discipline to read two pages a day. That is much more manageable.
The reason I'm saying this is that physiology can be difficult. It's not just regular biology. You are dealing with plants, which have something like 400,000 species on the planet. That's way more than us humans. If you go to medical school there is human physiology as well, but there you only deal with Homo sapiens — just one species. Plants are not one species, right? So there is a bit more to worry about. But it's manageable.
It took me how many years? When were you born?
Students: 2004… 2003.
Dr Amin: Not all of you are the same age, some a bit older, some younger. I first came to UPM in 2004, so it's been about 22 years now. Saying it that way makes me feel old. Imagine being in one place for that long. [laughter]
Groups and the class space
Dr Amin: Anyway, I want you to form your own groups. You don't have to decide now; we have the lab session on Wednesday. Since there are 25 or 26 of you — come here, please put your email in here so I can invite you into the class group space. Oh, you dropped my cap.
What's your name? Haziq? I met four Haziqs last semester and this is the fifth one. [laughter] If you can, use your student email, and make sure it's Gmail, because this is a Gmail-based platform. Your student email is Gmail.
In 2004 things were very different. There weren't many of these screens around. They used an OHP — an overhead projector. You don't even know what an OHP is? Cool. Is it Haziq Aiman? OK, I will invite you now. You need to accept the invitation so that you have access to all the announcements I make.
Divide yourselves into groups of five or six students, no fewer than that. Then do two things for your group. First, appoint a chief. Write your group members' names on a piece of paper, with the chief's name and matric number marked with a star so I know who the chief is. Second, give your group a name — whatever name you want, I don't care. Want to call yourselves Bubble Gum? Go ahead. This is the time to get creative.
Decide later; I'll give you time. Do you already have friends in mind for your group?
Students: Yes.
Dr Amin: That's fine. Having your neighbours as teammates is fine.
Lab sessions and the semester calendar
Dr Amin: Our lab will be on Wednesday. I think one or two of our lectures fall on public holidays this semester. If the government decides to throw in a general election, that will be a third. This happened about five years ago: during the general election the whole university had to shut for a week, because everybody had to go home to cast their votes. Let's hope that doesn't happen this semester.
The first topic: growth analysis
Dr Amin: The first topic is growth analysis. I have not changed the title, but I have changed how we will approach this lesson, because it involves a bit of mathematics. [laughter] Yes, yes. That part can be overwhelming, so I have prepared an additional document to help you with the mathematics. You will learn the formulas, but if you don't know how to use them you will be clueless in the lab practicals when you need to get your data.
Be aware that you are in university now. I'm not going to hover over you like teachers did in school. Pretty much everything is independent. You will be given a briefing and instructions, and then you conduct the experiment yourselves. You have done experiments before, right?
Students: Yes.
Dr Amin: Right. You are science students, so act like one. I'll be around, and it doesn't hurt to ask, but I'm not going to spoon-feed you everything. Conduct yourselves in a proper scientific manner, based on what you have learnt so far.
Next week I will not be around, because UPSI has called me to help them with something for the ministry. So we will do a practical this Wednesday, plus an activity you can come in and do by yourselves next week. It's not too difficult; I will explain more on Wednesday. That means there is no class next Monday and I will be unreachable — some people need my services. But that is not your licence to go off doing as you please.
Remember, I told you this topic is difficult. A complementary note comes with it. Spend 30 minutes or so reading the mathematics again. If you think you have a problem with mathematics, do not take this lightly. It's easy once you understand the steps. It becomes difficult when you ignore it altogether.
Then the biological part comes in, and that's when it gets difficult. So far you have learnt mathematics on its own — calculus and so on. That was purely mathematics. Now it's mathematics plus biology, and the biological interpretation is what can be overwhelming. These are not just numbers; the numbers mean something. When the value is high, what does it mean? When it's low, what does it mean? When it doesn't change, that also means something. The good thing is that once you have grasped the concept, everything looks super easy. All good so far?
Students: All good.
The online notes
Dr Amin: Can you open the notes on your phone? I'm just checking, because I only activated the link earlier. Later on, if you want to search for something, there is a search box up here. Say you want to learn about photosystems: there are many lessons on photosystems here, and many of them come with videos. When you get old, you tend to have done a lot of things already, right?
I don't know what will happen to this website when I'm no longer working at UPM. Can you still access your old notes on PutraBLAST?
Students: No.
Dr Amin: That's the plus point of this site. Some of my students who finished five or six years ago can still come back here when they need something. There are labs here, botanical lessons, many things. OK, let's get on with the lesson.
[15:00] Plants or crops?
Dr Amin: This is Lecture 1A. 1B is the mathematics part, and that is what's different this time. Previously everything was taught in one go, and I don't think that was very healthy. Over the semesters more and more students failed the mathematics part — in 2019, 2020 and finally 2021. From then on everything went downhill. So this semester I have split it into two. 1A is purely the theory. 1B is for you to take home and read at your own pace. It's a self-guided lesson.
Let me make this bigger. The first concept: crops or plants? Have you taken your botany class?
Students: Yes.
Dr Amin: Good. That means you are familiar with the kingdom Plantae. When we talk about plants or crops, we are actually talking about the same organisms, but we perceive them differently. All crops are plants — you can see the Venn diagram up there. Where's my long ruler? [laughter] I usually bring my long rotan, but it split. This one isn't split, it's just bending — see?
In the Venn diagram, all crops sit within plants. A plant is any organism that falls in the kingdom Plantae, as you have learnt. The weeds you see, the moss you can feel on the surface of rocks, the pitcher plant — you know the pitcher plant, the one that eats insects?
Students: Yes.
Dr Amin: The pitcher plant, the big trees along the highway — our highways run through tropical rainforest, right — and the oil palm. They are all plants. However, when these plants are grown as a community for economic interest, they are called crops.
For example, if you go into the jungle, can you see banana plants there?
Students: Yes.
Dr Amin: But in the jungle you just call it a wild banana. You don't call it a banana plantation yet. If that same banana is grown in a big, managed plantation, with specific management to get an economic yield out of it — and people don't grow bananas only for the fruit; sometimes it's for the leaves, sometimes for the trunk, because people can extract fibre from the banana trunk — then that same banana is regarded as a crop.
So what's with the name? Are we learning plant physiology or crop physiology? Actually, we are learning both. When you are first introduced to the topic, it is plant physiology. We focus on the individual plant first: the different processes it contains, how it functions, and some relevant examples.
If we stop there, you are dealing with plant physiology. You just need to understand how the plant functions and what processes are involved. Then maybe how the plant responds when climatic factors come in — when it's too hot, in drought, or when it becomes too windy. That is just physiology.
But then you add another element: you want the plant to maximise the production of certain organs. For example, in a cabbage plantation, what's the organ of interest?
Students: Leaves.
Dr Amin: Right, it's a leafy vegetable. So you start asking: what can be manipulated so that this cabbage plant produces more leaves, in the shortest time and in the most productive way, in terms of biomass? When you manipulate the plant, based on what you have learnt from physiology, because you want the economic incentive — you want it efficient and productive — you are dealing with crop physiology.
Say you have a garden at home and you grow pitcher plants. What's pitcher plant in Malay?
Students: Periuk kera.
Dr Amin: In my head it's Nepenthes, the Latin name. So, the Nepenthes you grow at home — is that a crop or a plant?
Students: It's just a plant.
Dr Amin: Yes, it's just a plant. You grow it and think, "Oh, that's nice." But suddenly your neighbours become very intrigued by your pitcher plants, because you have so many of them and they are thriving. An auntie comes to your house and starts buying them. Now, is it a plant or a crop?
Students: Crop.
Dr Amin: It has become a crop. Same pitcher plant, same location, but the perspective has changed. To make it more profitable you advertise on social media that you are selling pitcher plants. Now you are an agronomist or horticulturist, doing crop physiology so that your crop production is the best it can be. That is the basic concept.
We learn plant physiology so that we can carry out agricultural activity. Once it involves agriculture, agronomy, horticulture or whatever, that is crop physiology. In books the two terms are used interchangeably, so don't worry too much about it. It's just a concept.
[22:40] What is physiology, anyway?
Dr Amin: So what is physiology anyway? Have you heard the word before? Have you been to a hospital?
Students: Yes.
Dr Amin: Never seen the word physiology in a hospital? Physiology — not physiotherapy. That's different; that's where you go after an accident.
I will do a bit of etymology. Do you know etymology? It's the study of word origins. I'm a bit biased, because I sometimes teach botany — not all the time, only when they ask me to. In botany everything is in Latin, so I tend to teach students what the words mean in Latin, because it helps your memory. So: etymology, the study of word origins.
Physiology comes from two words, physis and logos. Physis means nature — the natural phenomena you see around you. Logos means the study of something. Biology, for example: bios means living things, logos the study of, so biology is the study of living things. Put physis and logos together and physiology literally means the study of nature.
But you know physiology can be in the medical school, and it can be here in the Faculty of Agriculture as well. So what is it actually? You are studying how living things work.
Even if you never go to university, you are in nature. You walk about and see a very blue sky and ask, "Why is the sky blue?" The sky is nature, and you are asking how this part of nature works. You walk on — maybe you are in Japan, enjoying hanami. You know hanami?
Student: Viewing the sakura blooming.
Dr Amin: Yes, viewing the sakura in bloom — that's hanami. Hana is flower in Japanese. Hanami is a natural phenomenon, and it triggers a question in you: why does it happen in spring? You know spring?
Students: Yes.
Dr Amin: Right, the flowering season. Scientists use this concept and use the word physiology. Whenever you are trying to explain something, especially something involving nature, you use the word physiology. So there is animal physiology, human physiology, insect physiology. Have you taken entomology?
Students: Yes.
Dr Amin: So insect physiology is a branch of that study, and this course is crop physiology. You want to understand how your crop functions. Why? Not only because you want it healthy — if you only want it healthy, you stop at plant physiology. Now you have the economic incentive. You want it healthy and productive, so you can sell it and make money, or for whatever reason. Sometimes people don't sell it at all; the plant is simply providing a service to you.
What plants give us
Dr Amin: Plants can provide services. What do plants give you?
Students: Food.
Dr Amin: Food. What else?
Students: Fibre.
Dr Amin: Fibre. I have a small formula to remember this, in case it comes out in your exam: 4FMO — not FOMO.
Food
Fuel
Feed
Fibre
Medicine
Ornament — not oxygen, ornament.
The Nepenthes you grow at home falls in which category?
Students: Ornament.
Dr Amin: Ornament. Your Nepenthes isn't feeding you, and it isn't giving you enough fibre to make clothes. But it is giving you a service. When you look at it you feel happier. It soothes you, calms you, de-stresses you. So the plant is providing a service to you.
[28:15] The three questions of physiology; plant vs human physiology
Dr Amin: When you deal with physiology, these are the three questions a physiologist tries to address.
Mechanism: how does the process work? There are many processes in a plant: the process of making food, absorbing nutrients, warding off pathogens, and so on.
Role: what does it do — how does it function?
Regulation: a plant is a living thing just like you, which means it is dynamic. Dynamic means actively changing, responding to environmental factors.
Have you learnt about abiotic and biotic factors? Biotic means the living factors: plants, animals, tigers, snakes, you, your cousin and so on. Abiotic, for example?
Students: Rain, rock, wind, snow, earthquake, air, tornado.
Dr Amin: Yes, tornado. Anything non-living. All of these affect your plant. So you want to understand what regulation is involved when your plant experiences too much heat, or too much water, like in a flood. We had floods recently, right?
Students: Yes.
Dr Amin: These are the questions you ask. Go a step further and apply them to plants grown as a community, because you are dealing with crops, and you study at the plantation level. If you only ask and answer these questions for one plant, that's plant physiology. When you deal with a whole plantation — hectares and hectares of oil palm, for example — that is crop physiology, because the unit shifts from one plant to the canopy per square metre. Now it's big.
The reason I bring all this up is to enrich your scientific vocabulary. My advice: if you think your scientific vocabulary is still weak, keep a small book. Whenever you learn a new word, write the word, its part of speech — noun, adjective — and its meaning. Writing, reading and repeating strengthens your psychomotor memory and helps your long-term memory.
Same problems, different solutions
Dr Amin: Let's go through this quickly. It compares the human physiology that medical students learn with what you will learn here for the rest of the semester.
Energy. We humans can't make our own food; we are heterotrophs. Plants are autotrophs; they make their own food.
Lifestyle. We are very mobile. Plants are sessile. If you don't know the word, write it in your little vocabulary book — if you don't have one, write it on paper and staple it together later. Sessile: immobile, unable to move, unable to get away.
Growth and repair. Both humans and plants grow and repair. But if a human loses a hand, can it grow back?
Students: No.
Dr Amin: If a tree loses a branch, can it grow back?
Students: Yes.
Dr Amin: So the regenerative capacity of plants is much stronger than ours. Our lifespan is also short compared with plants, because plants have special genetics. I'm not talking about annual plants. You learnt the three growth habits in botany: annual, and what are the other two?
Students: Biennial and perennial.
Dr Amin: I'm talking about perennials. Any idea how old the oldest tree on the planet is? It's a perennial, of course. 20,000 what — minutes? [laughter]
Students: 20,000 years.
Dr Amin: There are some around 20,000 years, but the oldest is about four times that: roughly 80,000 to 100,000 years. Pando. It's an aspen. We don't have it here; it's in Canada [editor's note: Pando is in Utah, USA]. The whole forest of Pando aspen is actually one plant. It never dies; it just keeps growing and growing. The whole forest is genetically identical, because it all came from one tree that kept sending up new shoots — offsets, new pups. So, 80,000.
If you're talking about a single tree, I think the name is — let me spell it right — the bristlecone pine. That one is about 4,500 to 5,000 years old and still living. Imagine: this tree was around when Pharaoh was building the pyramids. And where's Pharaoh now?
Students: Underground.
Dr Amin: Actually not really underground. He's in the museum now, in a glass case. If you go to Egypt you can see the pharaoh. They were royalty, so they weren't buried in the ground like commoners. They had their own tombs and highly elaborate sarcophagi. Sorry, I don't want to bore you with all these weird English words.
My point is that plants and humans have all of these, but to different capacities.
Transport. You have a heart. Do plants have hearts? Some plants, like the redwood, are about 120 metres tall. Do you have any idea how tall 120 metres is? It's about a quarter of KLCC. I think the name of that tall tree is Hyperion; you can look it up later. Scientists keep the location of this tree secret because they don't want people to find it. Humans are ugly that way: when they find something interesting, they destroy it or take advantage of it. Hyperion is also very old, but not as old as the bristlecone pine; it's just very tall. Last time I checked, it was almost 120 metres and still growing.
Control. We have the brain, nerves, the central nervous system. Plants have hormones.
Temperature regulation. You sweat; plants transpire.
Gas exchange. You have lungs to exchange oxygen and CO₂. Plants do that with their leaves, through stomata.
Defence. You have your immune system. Plants have immunity as well, local and systemic. So it's pretty much the same.
Applied unit. Medicine deals with the health of one individual. This is the difference. In a hospital, the doctor treats you one by one before moving to the next patient. In a plantation, when an agronomist treats the crop, he isn't treating one plant; he's treating the whole plantation.
Remember your COVID vaccine? How did the nurse give you the jab — one at a time, or did the whole hall come in and the nurse shoot everyone at once? [laughter] The nurse is not an agronomist. She has to give the jab to you one by one; she can't do 100 shots in one go. Nurses aren't trained to use an M16.
The three tasks: think like a doctor
Dr Amin: This is the concept I mentioned earlier, the three tasks of physiology: how does it work, what does it do, and what if it changes. This trains you to become a crop doctor later on. You can't be a doctor yet; your diagnosis might be wrong. But this is the idea.
A doctor has already learnt in medical school how the heart pumps, and understands that the pumping does something: it circulates blood through the body. When a patient comes in, the doctor can work out what's wrong. Is the heart doing the job it should be doing, or not?
These days some very young people have heart attacks, not even 30 years old. Thanks to modern food. Are you enjoying your viral food? Your viral food will bring your visit to the doctor sooner and sooner with every generation.
[40:45] Task 1: fundamental physiological processes
Dr Amin: Let's see what each task is about, one by one. Number one: define the fundamental physiological processes. You must first learn what the processes in a plant are. Throughout the semester you will learn about energy flux: photosynthesis and respiration.
I don't think respiration is in your syllabus. Actually, I want to add it, because it's incomplete to learn how plants make sugar without learning how plants use the sugar they have made. So we are going to change the syllabus a bit.
Then water relations and transport: how water and nutrients move. Take Hyperion. Without a heart, how on earth does water get from 0 metres all the way to 120 metres, every second, without fail? No heart needed. If you stand near Hyperion, can you hear a pump, like an aquarium pump? It's completely silent. If you have an aquarium at home, it's very noisy with all the pumps, and that's not even 100 metres. Plants are very elegant in that sense. They do everything super clean and super elegant.
We will also learn about ion absorption, and what happens to these processes at different organ levels and growth stages: seed germination, seed formation, flowering, vegetative growth and so on.
Even at medical school, you must learn these fundamental processes of the living organism first. If you are an entomologist, you learn about insects. If you are an ornithologist — you know ornithologist? Entomology is insects, and ornithology is…?
Students: Birds.
Dr Amin: Birds. I just want you to learn more vocabulary. Do you have a favourite bird? What's your favourite bird?
Student: Parrot.
Dr Amin: Parrot is good. I saw a video two days ago of a very annoying parrot. Not only can it talk and mimic you, it can actually ask its owner questions — like a very annoying six-year-old. Parrots are getting smarter too.
[43:55] Task 2: function at each level
Dr Amin: Moving on to Task 2 of crop physiology. Once you understand these fundamental processes, next comes understanding the organs of the plant: what they do and how they function, because one organ can carry out more than one process. Actually, I wanted to put this first, but it's alright.
You have learnt about nucleic acids, DNA and everything in the cell. You learnt about the chemical constituents: ions, sugars, proteins. These substances are present in the organelles. Organelles are the membrane-bound components in cells. You have the animal cell structure and the plant cell structure. What's the difference between an animal cell and a plant cell?
Students: The cell wall.
Dr Amin: Yes, most prominently the cell wall. Go one step up and you have specialised cells: stomata, root cells, xylem, phloem. These cells come together to form specialised tissues. For example, xylem and phloem together are called vascular tissue. We have vascular tissue too: your arteries and veins together form the vascular system — the plumbing, the piping that runs through your body. Plants have that too. You also have palisade tissue, mesophyll, parenchyma and so on, which you learnt in botany.
Then come the organs: leaf, root, stem. Do you have organs? How many organs do you have?
Student: Two.
Dr Amin: Two? If you have two, you're a sotong. [laughter] How many have you got? Don't you find it interesting? You are a human, and you don't know facts about your own body.
Student: 78.
Student: Over 300.
Dr Amin: It can be, because sometimes it depends on perspective — how you count. Don't worry about it.
Then you have the whole plant. All these functions come together as plant-level functions: reproduction, energy assimilation, resource distribution, growth, and environmental sensing and signalling. Number four, sensing and signalling, is very important for agriculture. If you don't understand how crops sense and respond to the environment, you will cause the whole plantation to die very soon. That involves a lot of money, and the agronomist will not be very happy with you.
[47:25] Task 3: responses to the environment; hormones
Dr Amin: Finally, the third task in crop physiology: explain how crops respond to environmental change. This is the special part of crop physiology. If you just grow Nepenthes, you don't need to worry much about how it responds to environmental change, because no money is involved.
There are four key factors. Are they biotic or abiotic?
Students: Abiotic.
Dr Amin: Yes: light, temperature, water and nutrient availability. When these are too much or too little, they affect the plant. So we will learn what happens with too much light, too little water and so on. Of course there is no single fixed lesson, because for some plants too much water is fine: "I am a lotus, I don't care." For others, too much water is a problem. Say your soya bean plant: what will happen to it?
Student: It'll grow more soya?
Dr Amin: No. What will happen to your soya bean plant if you grow it in a lotus pond? I'm about to give you a new word, so that you are bombarded with new vocabulary: hypoxia.
Student: Hypoxia — what's that?
Dr Amin: Look it up. I need to learn your names anyway. Let's go with number 14 today. Who's number 14? Eleanor Nicole. What does hypoxia mean? Stand up and speak clearly so your friends can hear.
Eleanor: [Reads a definition: oxygen deficiency, with low oxygen saturation — partly inaudible.]
Dr Amin: So in one word, your plant is…?
Students: Drowning.
Dr Amin: Yes, drowning. No oxygen. Can you experience hypoxia?
Students: Yes.
Dr Amin: Yes, because you are not equipped with gills. You're not a fish. Thank you. Add this to your vocabulary.
Internal control: hormones
Dr Amin: There is also internal control. We are not going to learn everything today; this is a quick introduction to what you will look at throughout the semester. Hormones come towards the end. These are not names of individual hormones but classes of hormones.
Do you have hormones? What hormones do you have?
Student: Hormone X and hormone Y. [laughter]
Dr Amin: That's chromosomes. Chromosomes determine your sex; they have nothing to do with your hormone levels. Although when you are very worked up, you can say you are very hormonal. Let me ask number 22. Who's this? Aqil Zikry. Do you have hormones? What hormones do you have?
Student (another): Insulin.
Dr Amin: Let him answer, please. [laughter] Come on, Aqil. What hormones do you have? Or are you hormoneless? Didn't you learn this in school?
Aqil: Endocrine…
Dr Amin: Endocrine is the system, not a hormone. Does anybody want to help him? Let's go with number 18. Beatrice. What hormone do you think he has?
Beatrice: Oestrogen.
Dr Amin: [laughter] I asked you to help him! It's true, he has oestrogen too. But isn't that from the ovary? Aqil, do you have ovaries? That's what Beatrice is saying. [laughter] No. Alright — yes, men have oestrogen too.
This is part of the endocrine system he mentioned: the hormone balance in your body. Too much of one hormone can cause havoc in your body. Hormonal control is even more critical for females, especially before menopause, when it gets very busy. So if your female friends get irritated or seem unreasonable, their hormones may be doing something — just let it slide. Don't get too touchy with your female friends. Plants, though, don't get emotional because of their hormones. That's not happening.
So that's the summary of all this. Don't worry; take your time to read it again later. It's not for one sitting. You have learnt many words and much information today. Understand this: it is part of being involved with nature. Even if you decide not to do agriculture after this, this knowledge stays with you for the rest of your life.
Short break
Dr Amin: What time is it now? Do you have another class today?
Students: Yes.
Dr Amin: What time? OK. We will finish 30 to 40 minutes early so you can rest. There are just a few more slides. Do you want to take five? Alright, take five. Go to the toilet if you want. Pause the recording, please. Thank you.
[55:20] Major parts of a crop plant
Dr Amin: Not too many slides left. Let's continue. You have organs, and plants have organs as well. We usually divide plant organs into two: the root system, whatever is underground, and the shoot system. These are the organs and their main functions: leaves, stem, root, flower, fruit and seed.
This is why you learnt them one by one in botany. Botany is very important. Otherwise you won't understand the diversity of plant organs. Even for leaves alone there is so much morphology: leaf apex, leaf margin, leaf base, leaf colour. So much variety. You learnt that, right?
Students: Right.
Dr Amin: If a leaf is heart-shaped, what do you call it? It's from your botany; you should know this. Almost like this — what is it? Starts with C.
Students: Cordate.
Dr Amin: Yes, cordate. An example of a plant with cordate leaves?
Student: [inaudible]
Dr Amin: No, that's Bauhinia blakeana, the camel's foot plant. [laughter] If you go to Borneo, I think they use ketapang (Terminalia catappa) leaves to wrap rice, like ketupat.
Please be familiar with all of this. As an agriculture student, I expect you to be able to draw a whole plant and label each organ correctly. That is your level now. You must be able to draw and label one complete plant body and its important parts. It can be a plant of your choice. This is a tomato; if you don't want a tomato, use an eggplant. Go for it, it doesn't matter.
[58:00] Growth, development, differentiation
Dr Amin: Growth, development and differentiation. This concept is very important because you will need it in your practical, so get the terminology correct. Earlier you learnt the three tasks, or three missions, of physiology. Now the three growth-related terms.
Growth
Dr Amin: Number one is growth. What is it? Growth is quantitative, meaning you can get numbers from it. It is irreversible: once a plant has reached a certain size, you cannot reverse it. You can cut it off, but that's not natural. You can measure growth using dry biomass, plant height, leaf area and organ number.
Everything starts from cell division. What process is this?
Students: Mitosis.
Dr Amin: Right. Cells divide, then expand, and biomass accumulates. So growth is basically an increase in size, so to speak.
Development
Dr Amin: Be careful with development. Development involves a change in form: the organism changes from one form to another. It does not necessarily get bigger; it could even get smaller. The key is that it changes form, and you call it by a different name.
For example, the meristematic cells in plants. You have meristematic cells too. Where are they?
Student: Skin?
Student: Bone…
Dr Amin: Bone what? Bone marrow. Your bone marrow is your meristem. You don't have meristem in your finger. Try cutting your finger and see whether it grows back next week. Your fingers are not meristematic; your bone marrow is.
The proof: if you go to the blood centre and donate a pint of blood, does it stay that way, or is it replenished?
Students: Replenished.
Dr Amin: Yes, because your bone marrow can produce more erythrocytes — red blood cells — and the rest of the components.
So a meristematic cell can become a leaf cell, a root cell or a vascular cell. One meristematic cell can have three destinies. We say the meristematic cell has developed into a leaf cell, root cell or vascular cell. Why? Meristematic cells have a special ability called pluripotency. It's not in your notes, but it's good to know. Actually there are two terms: pluripotency and totipotency. [laughter] Totipotency means one cell can give rise to the whole organism — total. Pluripotency, as in plural, means one cell can give rise to various cell types, like the meristematic cell here.
What was the other example? The crop. You sow a seed, the seed grows into a seedling, then it grows all its vegetative leaves and stems, then flowering, grain filling, and maturity or senescence. This is one complete development of a cereal such as rice or wheat. At the end, does it look like it did at the beginning? It has changed, right?
Same concept with the foetus — the zygote and embryo developing in the womb. When it's born it looks like a baby. But did the baby look like that from the beginning?
Students: No.
Dr Amin: It changed. In previous semesters I liked to use Pokémon as an example. Your Pokémon can evolve, right?
Students: Yes.
Dr Amin: Say the fire-breathing one, at entry level. What do you call it? (A student answers: Charmander.) Is it? I've forgotten already. [laughter] Anyway, it evolves from one form to another, and another. Does its shape change as well?
Students: Yes.
Dr Amin: Same concept here. Whenever it involves a change of shape and function, that's development. Whenever it involves a change of size, usually irreversible, that's growth.
Determinate and indeterminate growth
Dr Amin: If you go to some vegetable gardens, you'll see that some tomatoes have indeterminate growth and some determinate. Indeterminate means it keeps on growing. Well, not forever — it will die eventually — but it means you can harvest for longer.
In horticulture this is the basis for deciding which variety a farmer uses. Maybe the farmer wants the business to be steady rather than big, perhaps because of a limited labour supply. Then they will go for indeterminate varieties: not so much at once, but harvests that go on for maybe a year and a half. But if they want it super fast and very dense, they will go for a determinate variety — dwarf, with a shorter period — so it yields a harvest much sooner than the other one. That's a horticultural decision.
Development from formation to ripening
Dr Amin: Back to the tomato. Growth makes the tomato bigger. Development enables the tomato plant to have various organs: flowers, leaves, branches. Development also gives the plant various specialised cells. You know how tomato plants sometimes have fuzzy hairs? Those are specialised cells — trichomes. Not every plant has them; only some.
So what controls development? Of course, genes plus a combination of hormones. You learnt DNA, RNA and gene expression in earlier biology classes, but in crop physiology you worry a bit more. Here come the hormones to make the story even more complicated. Well, not too complicated; it's just not linear. It can go many ways.
Then, to make it even more challenging, there are environmental factors. The plant has its genes and hormones from inside, and then the environmental factors from outside: wind, heat, snow and everything. How the crop will respond and manage — that's what you will learn. And eventually, will you get your harvest or not?
I've put fruit development here. Did you learn this in botany — the morphological changes from flower to fruit? No? It's alright. What you are expected to know here is the sequence. As a science student, you must know the sequence. The exam question might give you this and ask you to fill in the blanks:
Flowering
Pollination
Fruit set
Early fruit growth
Fruit enlargement
Maturation and ripening
Get your terminology correct.
[1:07:15] Root growth, cell division and auxin
Zones of the root tip
Dr Amin: Next, the cellular processes behind how an organ — the root — gets bigger. For it to get bigger, it's not happening in only one region. It's usually divided into three regions. This is the tip of a root: the regions of division, elongation and differentiation.
Division is growth. Elongation is still growth. Differentiation is development. That's why you learnt the concepts earlier.
You might think the very tip is the youngest part. That's the trick question. The tip of the root is not the youngest; it's actually right behind it — the stem cells, a bit like your bone marrow. Learn a new word here and add it to your vocabulary: quiescent. It means sleeping, dormant — ready to act when needed. So that is the meristematic region. Then you have the elongation zone.
You can see that the region down here is all about growth: division and elongation. The region up here is differentiation — the change of shape, the development I told you about earlier. This is where you get different cell types, like the root hairs coming out to the side.
The root cap
Dr Amin: Now the root cap. Did you learn this in botany? What's its function?
Students: To protect.
Dr Amin: Protect what?
Students: The tip of the root.
Dr Amin: Is that all? There's another function. At the tip it also produces mucilage, like a lubricant. The soil is very hard, with rocks and everything, so the root needs lubrication and a softening agent to move and manoeuvre through soil that is dry and dark. Mucilage — or is it mucin gel? I think mucin is a different thing; you need to check this. I think mucin is the one that comes from snails, which some ladies I know put on their faces to make themselves more cosmetically appealing.
Plant cell division
Dr Amin: This is just so you recall mitosis. Remember one key difference in plant cell mitosis. Do you remember the stages of mitosis? It starts with what?
Students: Prophase, metaphase, anaphase, telophase.
Dr Amin: Finally, what happens in the plant cell that doesn't happen in the animal cell? Cell plate formation during cytokinesis. When the cell splits, plants form this cell plate. It doesn't happen in your cells; you don't have a cell plate because you don't have a cell wall. I've put the cleavage furrow here to show the difference for animal cells. You have learnt this; it's just revision.
Don't worry about this part yet. Later, when you learn about hormones, we will emphasise auxin: how auxin enables the cell to become looser and bigger before it splits into two. That is thanks to auxin, the plant hormone.
Do you have auxin? Are you sure? I think there's a part of your body that has auxin. That's why if you do this to your vegetables, they grow very big. Where is it, potentially? In your pee. In villages, especially in the past, people used human waste to fertilise crops, right? That actually contains auxin. So next time you go to the toilet: "Oh, I've got auxin." Auxin-induced pee. [laughter]
It won't make you larger, though. That's for plants; for you, it's waste. It's like oxygen for plants: oxygen is a by-product of photosynthesis. For you, is oxygen a by-product? It's essential for your life, right? So one man's poison is another man's happiness, or something like that.
[1:13:35] Cell differentiation and closing discussion
Forming a stoma
Dr Amin: To conclude today's lesson: cell differentiation. It's also part of development, meaning something changes. The example I usually use for plants is the stoma. Please know how to draw this, because it can come out as an exam question — how it starts.
When you learnt mitosis, the cell divided into two equal parts, right? That is called symmetric division. Stomatal formation, however, involves two kinds of mitosis: symmetric division and asymmetric division.
You can see here the meristemoid mother cell. Then it divides — this is mitosis — but do the two cells look equal?
Students: No.
Dr Amin: So the first division is asymmetric. It is still mitosis, but asymmetric division. It may divide again and again, and eventually it becomes this GMC, the guard mother cell. Here comes the regular symmetric division you learnt. That's why you get two guard cells for one stoma. So this is special: it involves both symmetric and asymmetric division.
Does this kind of symmetric and asymmetric division happen anywhere in your body? I think when you were a zygote, an embryo, this is what happened as well.
How plants grow: summary
Dr Amin: I think that's all. This is just a summary of what you have learnt. Cells need to increase in number; the term is cell proliferation. That's how the tissue can get bigger. Cells can also expand by letting more water in. The wall becomes softer thanks to auxin; auxin basically makes the cell wall softer. When it's softer, it becomes flexible and somewhat springy. And then cells accumulate biomass. You have learnt all this before: sugar, protein, starch and lipid. Plants can make them all. They have the complete genetic instructions to make everything from scratch.
What can't the human body make?
Dr Amin: Can your body make everything? What is one thing your body cannot make, so you have to eat it? What nutrient can't your body make?
Student: Nitrogen.
Dr Amin: Nobody can make nitrogen. We all get nitrogen from the air. Carbon — nobody makes that either. I'm not talking about elements; I'm talking about a substance, a compound, a nutrient your body cannot make. If you don't get it, this is what you learnt in school: you get scurvy.
Students: Calcium… vitamin C.
Dr Amin: Vitamin what?
Students: C.
Dr Amin: Vitamin C. And the scientific name for vitamin C is…? I know, acid — what acid? Ascorbic acid. Are you science students or not? [laughter]
Vitamin A — retinol
Vitamin B — tricky, because there are so many: thiamine, riboflavin, nicotinamide, biotin and so on
Vitamin C — ascorbic acid
Vitamin D — cholecalciferol
Vitamin E — tocopherol
Those are the scientific names. Now vitamin K. What is it? You don't know vitamin K? What's the function of vitamin K?
Students: Cholesterol?
Dr Amin: Menaquinone.
Dr Amin: Just because you are studying agriculture doesn't mean you can ignore this. It actually makes perfect sense for you to know more about your body, because you are producing food for your body. When you know what you produce to nourish your body, you will be very healthy, because you know what you're dealing with.
Which plants do you think are very rich in vitamin K?
Students: Spinach.
Dr Amin: Yes, spinach — green leafy vegetables.
Student: Soya bean.
Dr Amin: True, yes.
[1:19:15] Wrap-up and attendance
Dr Amin: Alright, that's all for today. Any questions? Any regrets? [laughter] You can still drop the course until week two, right? From what I understood last semester, you can drop later, in week three or after, but you have to pay RM50.
Student: They want your money so bad.
Roll call
Dr Amin: I just want to check you're all here. There are 26; let's go from number one.
Names called, in order (names as on the class list):
Lee Wei Yuan (no. 1)
Hillary Lee (no. 2): "Are you two related? You're both Lee." "No, I'm not related to her. Don't ever associate me." [laughter]
Tan Jian Yang (no. 3)
Nurul Nadiah Ahmad Nazeli (no. 4)
Danish Hamizan (no. 5)
Syam Johan (no. 6)
Olivia Lubin (no. 7)
Rabiah Roslan (no. 8)
Dayang Nazzatul Aisya (no. 9)
Siti Aishah (no. 10)
Mohamad Hamidi (no. 11)
Muhammad Haziq Aiman (no. 12): "That must be you, right? No — the one who came later. Sorry."
Hadea Syamimi (no. 13)
Eleanor Nicole (no. 14, called earlier)
Muhammad Harith (no. 15)
Nur Aina Najwa (no. 16)
Putri Nisrina Nabihah (no. 17): classmates said toilet, then MC, but she had only stepped out. "Don't slander your friends, Beatrice."
Beatrice Evedin (no. 18)
Shaidatul Ain Shafida (no. 19)
Low Chi He (no. 20): [laughter] "Give me a chance to pronounce your name. I give you chances, you need to give me chances as well."
Wan Muhammad Daim (no. 21)
Aqil Zikry (no. 22): "It's so bad, I'm picturing ovaries now when I see your name. Thank you to Beatrice for pointing that out." [laughter]
Wan Muhammad 'Afif Isqandar (no. 24)
Mohammad Muqkhriz (no. 25): "Why so many letters? M-U-Q-K-H-R-I-Z."
Mohammed Naqiuddin (no. 26)
Siti Nuradibalisya (no. 23): missed at first and called after classmates pointed it out
Dr Amin (during the roll call): By the way, whoever helps with the photography will get extra marks for benevolence. During finals, lecturers can give marks based on your effort and other things, so they look at the record. Sometimes you are two marks away from a better grade. If you are good in class and just need a little push, they can give it to you. But they can't give it freely if you're not working.
Being a plant scientist is very bad: once I get a picture in my head, it's so hard to get it out.
Student backgrounds
Dr Amin: I just need to know your backgrounds very quickly. Are you all from matriculation?
Students: No.
Dr Amin: Who's from matriculation? Oh, just two or three. From Form Six or A-Level? Three. Anybody from diploma? OK — so these are the older ones. [laughter] Asasi (foundation)? One, two. Anybody else I didn't mention? Everybody went through Form Five, right? Anybody whose background I didn't mention?
Students: No.
Closing
Dr Amin: OK, that's all for today. I'll let you know if I update anything. Anybody whose name I didn't call? Good.
I'll see you on Wednesday. Please don't be late, because we need to start the lab together. If you come early, we can finish early. I usually try to finish the lab an hour early. And you can't be very noisy, because the other groups will be unhappy about it. My lab classes usually finish very early in the semester, maybe week seven or eight, so that you have free time for your other subjects. I do sympathise; you have to take many subjects, right?
Students: Yes.
Dr Amin: So I have designed it for you to participate and do things. If you don't get an A, that's because you are acting up. It's quite easy to get an A with me — that's what you're all after, right? Alright, if there are no questions, I'll see you on Wednesday. See you later.
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