- Basic Information of Lecture
– Lecture Title: A Beginners Guide of Nutrient Deficiency
– Online address: https://www.youtube.com/watch?v=9SotrCwqfHo
– Time: 23:58
– Name and title of lecturer: Ethan Walter
– Accent of lecturer: American
- Brief description of lecture
It’s a brief beginners guide of hydroponic plant nutrient deficiencies about the explanation of it, how to diagnose it, how to treat it and some scientific theory behind it.
- Terms and definitions
Macronutrient: N any substance, such as carbon, hydrogen, or oxygen, that is required in large amounts for healthy growth and development 大量营养素; 碳、氢或氧等为健康成长和发展所大量需求的物质
Micronutrient: N any substance, such as a vitamin or trace element, essential for healthy growth and development but required only in minute amounts 微量营养元素
Nitrogen: Nitrogen is a colorless element that has no smell and is usually found as a gas. It forms about 78 percent of the Earth’s atmosphere, and is found in all living things. 氮
Phosphorus: Phosphorus is a poisonous yellowish-white chemical element. It glows slightly, and burns when air touches it. 磷
Potassium: Potassium is a soft silvery-white chemical element that occurs mainly in compounds. These compounds are used in making such things as glass, soap, and fertilizers. 钾
Calcium: Calcium is a soft white chemical element which is found in bones and teeth, and in limestone, chalk, and marble. 钙
Magnesium: Magnesium is a light, silvery white metal which burns with a bright white flame. 镁
Chlorosis: N a disorder, formerly common in adolescent girls, characterized by pale greenish-yellow skin, weakness, and palpitation and caused by insufficient iron in the body 黄化，失绿，萎黄病 (Also called greensickness)
Necrosis: Necrosis is the death of part of someone’s body, for example because it is not getting enough blood. 文中指植物组织坏死
Lettuce: A lettuce is a plant with large green leaves that is the basic ingredient of many salads. 莴苣
Vein: The veins on a leaf are the thin lines on it. 文中指叶脉
Magnesium sulfate: 硫酸镁
Growing tip/point: 生长点(比如叶的边缘，芽，茎尖)
Inter-venial chlorosis: 脉间失绿，叶脉之间的组织黄化，变白
Basil: Basil is a strong-smelling and strong-tasting herb that is used in cooking, especially with tomatoes. 罗勒
UV filtration system: 紫外线水过滤消毒装置
Chelated iron: soluble complex of iron, sodium and a chelating agent such as ethylenediaminetetraacetate (EDTA), EDDHA, or others, used to make the iron soluble in water and, for the purposes of agriculture, accessible to plants. 螯合铁
HVAC: Heating Ventilation Air Condition. 空气调节系统，调节温度、湿度
Epsom salt: 泻利盐，七水合硫酸镁
- Summary of content
The lecture discussed hydroponic nutrient deficiencies: what they are, how to identify them, and how to treat them.
A nutrient deficiency occurs when a plant is not getting enough of a nutrient for the normal plant functions. Common deficiencies are N, P, K, (three of the macronutrients), and Ca, Mg, and Fe.
Nutrients are measured in water with a number called EC. EC is a very useful number, but it doesn’t tell you what the ratio of one nutrient to another is. If you have the wrong ratio of one nutrient to another, you could encounter the situation that the EC was sufficient, but a certain nutrient is actually too low and the plant leaves had some typical symptom.
Deficiencies are identified by their symptoms. Some common deficiencies are chlorosis, necrosis, and stunted growth. The pattern that those symptoms occur in are important. Pay attention to where symptoms occur, whether it’s on new or old growth, and what combinations symptoms occur in.
Plant nutrients are categorized as either mobile or immobile in the plant. Mobile nutrient deficiencies occur first in older growth, and immobile nutrients occur in younger growth.
A plant deficiency key is a useful tool for farmers to identify deficiencies. If you’re still having trouble, consult with your local extension agents. Google is not a great way to identify deficiencies unless it’s from a reputable source
Treat deficiencies by supplementing the nutrient that is lacking. You can supplement through your nutrient reservoir or foliar feeding (but be careful; high concentrations can burn the foliage and ruin a crop). Consider making regular supplements or switching suppliers if the deficiency occurs commonly.
Here are some common deficiencies and diagnosis tips:
Nitrogen is the “green up” nutrient. Nitrogen is mobile, so it will affect older growth first, and will cause total chlorosis starting at the tip of the leaf. You will also see stunted growth.
Phosphorus deficiency rarely displays outward symptoms noticeably or quickly. You may see stunted growth and the leaves will begin to get darker and purplish/bronze. Like nitrogen, these symptoms will begin on the old growth.
Potassium deficiencies is slow to show symptoms similar to phosphorus. Over time, you’ll see chlorosis around the edge of the leaf (the margin). Chlorosis will move from the tip to the back, but will leave the center of the leaf untouched. Like nitrogen, these symptoms will begin on the old growth.
Magnesium is a very common deficiency in hydroponics. It’s mobile, so it starts on old growth first. It looks similar to nitrogen deficiency, but will have inter venial chlorosis instead of complete chlorosis. It also turns almost completely white (in comparison to the light green of a nitrogen deficiency). When you correct it, the old foliage will stay chlorotic, but new leaves will look healthy.
Calcium is an immobile nutrient, so it affects the top of the plant (new growth) first. Calcium deficiencies show up as necrosis on the margin on the leaf. It will usually start at the tip of the leaf – which gets confused with tip burn – but be splotchy along the margin unlike tip burn.
Calcium deficiency happens a lot in indoor systems with poor HVAC systems. The more airflow, the more respiration the plant does, allowing the immobile calcium to be sent to the leaf tip. Another cause is high humidity. Try to keep humidity between 40-60%.
Iron is an immobile nutrient, so it affects he top of the plant (new growth) first. The example used here is basil, and it’s worth mentioning that basil deal with this a lot. The symptom is inter-venial chlorosis in new growth, similar to calcium.
Iron deficiencies are especially common in symptoms that use UV filtration. The UV light creates a chemical reaction in the plant-ready iron (chelated iron) and makes it precipitate out of the solution. It sinks to the bottom, and the plants can’t use it. When we add iron, we unplug the UV filter for 24-36 hours. Iron can also be added through foliar applications.
- Suggested reading
The lecturer recommends reading the materials about nutrient deficiencies on Montana State University’s website.
- Comment on the lecture
The lecturer is a plant nutrient professor in Bright Agrotech, a company which produces hydroponic equipment. They recorded this video in their greenhouse and describe the diagnosis and treatment method with their vegetable pot cultures. And next, they uploaded the video to YouTube and posted on the company’s official account. I think this kind of professional video about hydroponic planting can not only attract many horticultural amateurs, but also be a good advertisement of the company. About 40 thousand people have seen this video. It’s a good example for Chinese companies to learn.
钙是一种固定的营养素，所以它首先影响植物的顶部（新的生长）。叶片边缘的钙缺乏表现为坏死。它通常会从叶尖开始 – 与尖端燃烧相混淆 – 但是与边缘燃烧不同，沿边缘会有污点。