Nutrient Deficiencies in Horticultural Crops Flashcards
What are the macronutrients plants require for their adequate growth?
nitrogen (N)
phosphorus (P)
potassium (K)
magnesium (Mg)
calcium (Ca)
sulfur (S)
What are the micronutrients plants require for their adequate growth?
copper (Cu)
iron (Fe)
manganese (Mn)
zinc (Zn)
boron (B)
chlorine (Cl)
nickel (Ni)
molybdenum (Mo)
What are the mobile plant nutrients? In what forms are they mobile within plants and soils?
nitrogen (NO3-, NH4+)
phosphorus (H2PO4-)
potassium (K+)
magnesium (Mg2+)
molybdenum (MoO42-)
What are the immobile plant nutrients? In what forms are they mobile within plants and soils?
calcium (Ca2+)
sulfur (SO42-)
copper (Cu2+)
iron (Fe2+)
manganese (Mn2+)
zinc (Zn2+)
boron (H3BO4)
chlorine (Cl-)
nickel (Ni2+)
What are the two classic symptoms of nitrogen deficiency in plants?
(1) stunted growth
(2) general pale yellowing of leaves
In addition to readily visible signs of deficiency in the aerial tissues, how else can a nitrogen deficiency be observed using a rhizo-box?
nitrogen-deficient roots are often longer than the better-fed plants
The yellowing associated with a nitrogen deficiency is first detectable in what group of leaves?
older leaves first
What are three symptoms associated with a deficiency in phosphorus? HINT: two of these are readily visible without soil excavation, the third is not.
(1) stunting in the above-soil portions of the plant
(2) purplish coloration in younger leaves due to anthocyanins
(3) root systems will grow more at the lateral to better scavenge nutrients from the soil, while growth at the apical bud is suppressed
What are the roots associated with a phosphorus deficiency referred to as?
cluster roots
Potassium deficiency symptoms in plants appear similar to those under drought – what are the two characteristics of potassium deficiency?
(1) wilting appearance (and downward-oriented petioles)
(2) yellowing at the edges when minor, marginal necrosis at leaf edges when severe
Why are potassium deficiency symptoms similar to drought symptoms?
potassium helps to maintain turgor pressure in the guard cells – when it leaves those cells, water leaves with it, causing guard cells to become flaccid and close
What part of the cell is calcium said to assist in the construction and maintenance of, which causes those cells to be flabby and deteriorate in its absence?
calcium helps to maintain cell walls
Soon after calcium enters the plant cell, where is it placed? Why is this done?
calcium is placed in the vacuole of the plant cell to maintain turgidity
calcium ions have an antagonist relationship with ions of what other nutrient?
magnesium
What is the first sign of a calcium deficiency in a plant?
curling of new leaves if deficiency is moderate, necrotic tips of new leaves if deficiency is severe
What is the symptom of calcium deficiency relevant to the apple industry?
bitter pit
What is the symptom of calcium deficiency relevant to the tomato industry?
blossom end rot
What are the two notable roles played by magnesium in plant metabolism?
(1) magnesium activates RuBisCO to begin fixing carbon dioxide in photosynthesis
(2) magnesium has a central role in the porphyrin ring of the chlorophyll pigment
What are the two classic symptoms of magnesium deficiency?
(1) interveinal chlorosis and veins which are lighter tinted than those of well-fed plants (bronzing and death of yellow areas when interveinal chlorosis goes too long without correction)
(2) stunting due to reduced rates of photosynthesis
Why can some plant leaves appear purple under a magnesium deficiency?
magnesium is a phosphorus carrier, so low magnesium levels can cause a phosphorus deficiency as well
What are the two classic symptoms of sulfur deficiency in crops?
(1) generalized yellowing
(2) stunted growth
How do sulfur deficiencies differ visually from nitrogen deficiencies?
Because sulfur is an immobile nutrient, it causes the plant to acquire a yellow appearance in both young and old leaves, while the older leaves of plants typically show signs of nitrogen deficiency first
What does it mean that sulfur acts as a soil conditioner?
sulfur helps to reduce the sodium content of soils
Typically, because soil is required in low volumes, most plants only need about how much sulfur to grow adequately?
10 to 30 pounds of sulfur per acre
Sulfur plays an important role in providing flavor to what five crops?
(1) black currants (Ribes nigrum)
(2/3) horseradish/mustard (Brassicaceae)
(4/5) onions/garlic (Alliums)
What is the major risk associated with adequate boron nutrition?
boron is required in very small amounts, and toxicities can arise if too much is applied
In what form can boron enter the cell via simple diffusion?
boric acid (H3BO3)
In what form is boron taken into the cell with an energy-consuming symport mechanism?
borate (H2BO42-)
What role does boron play BETWEEN plant cells?
boron can crosslink cells by attaching to cellulose microfibrils in two different cell walls
What are the two classic symptoms of boron deficiency in plant cells?
(1) reduced fruit set
(2) malformation in young plant leaves and stems
Boron deficiency symptoms can easily be mistaken for a deficiency in what other nutrient?
calcium
What is the underlying reason for which boron and calcium deficiencies are similar?
both link components of the membranes between plant cells – boron links cellulose microfibrils, calcium links pectins
New additions of boron to the soil can be beneficial in what kinds of soil? Why?
boron reapplications may be useful for sandy soils, due to the propensity for boron to leach
What are some of the symptoms associated with a moderate chlorine deficiency?
wilting or curling of the leaves at the margins
What are some of the symptoms associated with a severe chlorine deficiency?
chlorosis, bronzing and necrosis of the leaves
What are three symptoms associated with a copper deficiency in plants?
(1) new leaves begin to cup
(2) chlorosis and necrosis in localized spots
(3) leaf nodes grow closer together, causing a more squat plant to arise
What are the characteristics of interveinal chlorosis in iron-limited plants?
typically in young tissues (blooms and leaves) first, with the chlorosis being very symmetrical
How does a manganese deficiency differ from a deficiency in iron?
manganese deficiencies are less symmetrical and more abrupt between the green and yellow areas than seen in iron
What is the underlying reason for which plants suffer low-nitrogen symptoms when they are deficient in molybdenum?
molydenum enables plants to metabolize nitrate, so when molydenum is not adequately present, nitrates build up overtime in the leaves and other tissues
What can occur if too many nitrates build up in plant leaves due to molybdenum deficiencies?
burning of the leaves at the margins (plants may also experience stunted growth)
What special use do legumes have for molybdenum relative to non-legumes?
fixation of atmospheric nitrogen in the root nodules
What are the two symptoms of zinc deficiency in crop plants?
(1) whitening of the leaf margins in a mottled manner
(2) stunted overall growth
