Nutrient deficiency

追加: 2026-05-13

[00:00:00]hi everyone we're back at it today's lessons on nutrient deficiencies this is we finally get to this topic I know you guys want this for your projects so let's get on with it before we get too far I want to go over some real basic stuff you're gonna be laughing at first but trust me this is something a lot of times you forget keep in mind that plants grow at the tip okay that means that new cells new growth happens at the tip okay so new growth versus old growth that means that as leaves are grown the plant moves up leaving them behind so where they've been put in place they are now considered old and where new leaves are growing they're considered new okay keep this in mind so when we're talking about nutrients for example they come in the roots right they move up into the plant they go to where there's the most activity which is the apical meristem that's where the plant is actively growing that's where new materials being constructed proteins cell walls DNA all that stuff that the plant needs to grow those nutrients are then incorporated into the leaves and it continues to move forward leaving those nutrients behind so as far as mobile nutrients and immobile nutrients nutrients that are left behind that are not mobile stay left behind right where mobile nutrients can actually be removed from the leaf and reallocated to the growing tip that's advanced further ahead so mobile nutrients are nutrients that can be extracted and recycled okay so we've got a mobile and we've got mobile all right so immobile nutrients they're in the old leaves and mobile nutrients all in the new leaves as far as deficiencies right so that means that immobile nutrients we were looking for symptoms in the plant so let's say there's not enough of a nutrient and we're looking at where the deficient she is presenting if the deficiencies at the top of the plant that means that the roots are not supplying the nutrient there's not enough of that nutrient in the root zone and because it's immobile the plant can't take it from old leaves and move it up so the deficiency presents at the top of the plant all right so mo ball nutrients present at the top and mobile nutrients that means that if the roots are not presenting enough of the nutrient the plant can actually extract the nutrient from the leaf and move it to the tip which means that the old leaf will now show the deficiency okay so this is an important concept here's a list of mobile nutrients so in plants nitrogen phosphorus potassium magnesium sulfur molybdenum those are mobile that means they can be removed from old leaves and reallocated repurposed to new leaves immobile or non mobile nutrients are iron manganese calcium boron copper and zinc I also you to go over some terminology here when you're doing your nutrient deficiency projects it's really important you use proper terminology right you're trying to become professional horticulturalist so you've got to use the proper terminology so instead of saying the leaf is yellowing we're gonna say the leaf is becoming chlorotic or it's demonstrating chlorosis okay that basically means that chlorophyll here's a healthy leaf chlorophyll is being degraded and you're left with the non green pigments in the leaf so it looks yellow intervening chlorosis so it's chlorosis but it's between the veins you're all familiar with the vein structure of a leaf right there's the rib and the side branching so some nutrients present as intervenor chlorosis that means the yellowing is between the veins all right that's between the veins so that's interval rose's necrosis or necrotic growth this is dying brown crispy edges of the leaves necrosis okay that's the term we want to use so let's get into it let's look at nitrogen deficiency so nitrogen is a mobile element it is important for the production of chlorophyll there's actually four nitrogen atoms for every chlorophyll molecule if you don't have enough nitrogen you can't make chlorophyll so that means your leaves are yellow chlorosis typically you get weak growth because you can't make any Pro chlorophyll it can't make sugars it's very difficult to make proteins basically everything grinds to a halt it is in the lower leaves why because it is mobile which means it can relocate so typically plants will remove the nitrogen from the lower leaves and move it to the top of the plant where the growth is by the way nitrogen is probably the most common nutrient deficiency in house plants that's why the lower leaves get yellow and fall off because you're not feeding your house plant you just give it city water every time no food and eventually it starts removing nutrients from the old leaves and moving them up to the new ones and so they drop their old leaves possible causes don't forget the obvious one you may be deficient for nitrogen because you just don't have enough fertilizer but another interesting one is that the soil might actually be too wet so if you have really wet soil you get bacteria that grow and they actually will take the nitrogen and convert it into nitrogen gas and so typically plants that are in really wet soil get yellow quickly because all the nitrogen in the soil is converted to nitrogen gas which evaporates out of the soil into the atmosphere and it's lost some more pictures of nutrient nitrogen deficiency these are older leaves so it's mobile older leaves and it's chlorosis this is a ficus so a common house plant or these those trees you see in shopping malls and dropping leaves corn nitrogen deficiency let's look at phosphorus phosphorus is a mobile nutrient and it causes purpling of leaves they didn't have a terminology fancy term for that you can call it purpling if you want typically it's what we call the production of a pigment called anthocyanin so on this strawberry plant here you'll see this purple pigment at the edges of the leaves and in this tomato you can see underneath the leaves there is purple coloration that is classic phosphorus deficiency another thing that's really interesting about phosphorus is when you don't have enough the plant is stunted often growers like to actually purposely hold back phosphorus from their producing young plants because that keeps them compact another interesting fact about phosphorus is that when the soil is cold plants have a difficult time accessing phosphorus which is why plants often look purple when it's cold in the spring potassium is a mobile nutrient it starts with yellowing on the margins of the leaves like in this picture and as it gets worse the edges become necrotic so there's that term necrosis okay so this is late this is early stage deficiency with tomato plants you get curling at the tip as well of the leaf potassium is an interesting nutrient is used mostly for osmotic regulation right so the biggest job that potassium does is open and close stomata so that's in order for the leaves to breathe so if you start running out of potassium you have a hard time getting your leaves to open and let gases in and so the plants start to run out of sugar magnesium magnesium is a critical atom for chlorophyll I already mentioned that there's four nitrogens so typically the nitrogen's form like a grid and in the middle of those four nitrogen's there is a magnet and that's what does all the catalytic work that magnesium is critical for splitting water to produce hydrogen and electrons so if you start running out of magnesium you're gonna start getting reduction in chlorophyll so you see the intervener chlorosis that's happening on this leaf that's classic magnesium deficiency and it's mobile so it is on the older leaves okay here's another picture of magnesium you can see classic intervener chlorosis you can't see that this is older leaves because the pictures just showing one leaf but it would be at the bottom of the plant one of the quickest ways to solve magnesium deficiencies is to add epsom salts to the plants because that's basically magnesium sulfate which will solve that problem fairly quickly here's magnesium deficiency in a tomato plant again this would be old leaves that are having intervenor chlorosis there is the picture I've been looking for it's got the nitrogens there's three and four with the magnesium suspended in the center and that's where all the busy work happens in chlorophyll the magic and there's magnesium deficiency and peppers lots of examples of magnesium deficiency possibly because a lot of ready-made bagged fertilizers don't actually have a lot of calcium magnesium in them if you want a complete fertilizer you need to buy something that will say you know have five numbers on it so NPK so nitrogen phosphorus potassium and then the next two numbers would be calcium magnesium so sulfur deficiency is an interesting one technically this is what we call partially mobile and this is an this is a nutrient that presents differently across different plant species up at the top is eggplant down below as Tomatoes the next slide is petunias all very different well I guess the eggplants and petunias are similar but partially mobile means that it kind of can reallocate old leaves to the new growth but not always but generally the entire plant has a lighter green color primarily because sulfur is used to make one particular amino acid which is needed to make all the proteins in the plant so if you don't have enough sulfur you're missing out on that one building block and that means the plant can't make all the proteins that it actually needs petunias are a real classic example of a crop that's sulphur sensitive if you see a stunted yellow petunia you almost always have a sulphur deficiency so on the left is healthy on the right is sulphur deficient petunia molybdenum this is a unique nutrient it is partially mobile like sulfur really the only crop that I know of that we have troubles with molybdenum is poinsettias and what you see is this sort of yellowing on the margins of the leaves and it's usually older leaves but if you look carefully the new leaves have a bit of a yellower tinge as well so it's partially mobile but it is not a very common deficiency here's an interesting tip to help you remember which nutrients are mobile which ones are not all the micronutrients are generally speaking in mobile so iron manganese calcium boron copper zinc those are all in mobile they cannot be reallocated so iron which is a classic nutrient deficiency that often you come across presents at the top of the plant because it's not mobile right the plant can't go down to the old leaves and pull out some nitrogen and move it up to the new growth because it's immobile so it presents at the top new growth so we get chlorosis right so yellowing or even bleaching basically loss of chlorophyll in the top parts of the plant sometimes it's intervenor chlorosis sometimes it's all the way across generally you can still see the veins but the veins are not as green as they would be for say like what magnesium looks like but this is again this is new growth with not old growth pH is almost always the reason why you end up with AI efficiencies if you look at this chart if your pH gets too high this actually I don't have the I think this is pH 7 here and this is pH 5 something like that so you're looking at if your pH is too high iron becomes less available and you get iron deficiency so first thing you want to check is the pH in your soil manganese so manganese looks similar to iron it's non mobile which means new growth but the veins are much more pronounced so the intervener chlorosis is not as as broad as it is with iron deficiency so it's this is a tricky one to diagnose between different crops but it is not as common as iron so your first guess is gonna be iron every time and then you're gonna if you add iron or change the pH and doesn't fix then you know you've got a manganese problem calcium this is another one that you will often come across calcium is immobile calcium is used to strengthen cell walls so if you don't have enough calcium your cell walls become weak so on this picture here of the strawberry that's deficient for calcium the tip of the leaf cannot handle the expansion and so it cracks and splits and starts to die back that's typical for calcium and with tomatoes if you don't have enough calcium the ovaries don't form properly and then as the tomato matures the the tip of the older e which is furthest from the vasculature starts to die from weak cell walls and you get this black spot at the bottom of your tomatoes that's telling you that you do not have enough calcium in your root zone we call that blossom end rot remember that one because I always like to ask that question on the final exam so leaf tip burn and blossom end rot it is a critical nutrient for cell walls one of the reasons why it says here that you need good airflow is because calcium in and of itself is actually a very large atom and to try to get it from the roots up into the plant means you need to have water moving through the plant rapidly to pull it all the way to the edge it comes up the vasculature and works its way through the veins of the leaf and has to get to the edge of the leaf that's growing right that takes a lot of water movement to pull it through so typically we see calcium deficiency problems when our growing environment is too humid because we're not getting enough water flowing up to the plant so it's important to have good airflow and not have high humidity if you're trying to avoid calcium deficiencies the classic example is lettuce this kind of edge burn you see here is from too much humidity and not enough airflow and lettuce is particularly susceptible because if you think about it a head of lettuce is a dense ball of leaves or not open like a bush which means it's very difficult to get air to flow between the leaves which means you're not gonna have that moisture being pulled up through those leaves so it's usually important to over supply calcium for lettuce just to make sure you don't get that tip burn or grow varieties that are more open to let air into the head boron this is an interesting one boron you often run into with a lot of bedding plant crops I see it often in peppers it is a fairly abundant mineral in soil so it's often presented in soilless media low so that would be like peat moss square or hydroponics it's an important nutrient it's especially important for apical growth your meristem if you don't have enough boron your meristem doesn't grow properly it wasn't grow property get deformed growth right so your early cell wall and cell division is is affected and you have really weird-looking plants I'll say this boron deficiencies are often confused with insect damage so if you see plants where the new growth looks all distorted you're going to get out your magnifying glass you're going to look for pests you may even need microscope because broad mites which are very small have very similar symptoms to boron deficiency so this is one you need to get a microscope out for to make sure copper rare it's a very rare nutrient deficiency I'm going to be honest I haven't seen in my life other than trying to recreate it in labs but the plants become blue green and the color it's a weird blueish hue as you run out of copper but you know it's non mobile so it's gonna present where in the apical meristem not at the bottom of the plant zinc another one that I don't think you're gonna run into especially in greenhouses because greenhouses have a lot of galvanized steel and so rainwater runs over it gets into the tanks and it takes zinc from the rain from the galvanizing in the structure so there's almost always plenty of zinc but you know it's a non-mobile so it's gonna present as chlorosis and stunting in new growth as far as roots we should pay attention to roots phosphorus causes stunted roots nitrogen typically we don't have nitrogen think about it from a plant perspective the plants not very big because it needs more and it's gonna put its energy into roots to find new sources of nitrogen so look how long the roots are relative to the control potassium you need potassium to four cells to expand so the cells are a little smaller the roots are a little smaller iron doesn't look too much different another one that's worth putting here I don't have it is calcium calcium looks a lot like phosphorus the roots are small and stunted and thick because they have trouble putting out new root tips this is a picture of some tomato plants growing at the college last spring this was towards the end of our season and they had been in the pots for a long time and they had not been fed much so let's look at them and see what kind of deficiencies we've got we're looking at the bottom of the plant and we see a general chlorosis I can also see some kind of purpling in the center of the leaves and maybe even on the tips of the leave there's a little bit of necrosis happening what does this tell us well it tells us a couple of things first of all I gave you a big hint when I started by saying they haven't been fed in a while so they haven't been fed that means they're missing everything so we're looking at nitrogen deficiencies right so old leaves are going yellow we're looking at phosphorus deficiencies because the veins are going purple right and we're looking at potassium because there's necrosis at the tips of the leaves not that I've colored the home and all you can't see that but and it's really early stages these are a couple of slides I've posted them on this week's folder as well as a key for you helping you to determine nutrient deficiencies these are really helpful for you you might want to be able to use them for your assignment although I do want you to use proper terminology like chlorosis in necrosis and your nutrient deficient efficiency report and this is the one for immobile elements