Lesson 2.4. Crop Production (New Mineral Nutrition) (Lec)

New Mineral Nutrition

Mineral

An inorganic element acquired mostly in the form of inorganic ions from the soil

Nutrients

A substance needed to survive or necessary for the synthesis of organic compounds

Mineral nutrition

the process by which plants absorb and utilize essential inorganic elements from the soil for growth and metabolism

Essential nutrients

elements a plant requires; there are 17 of them, derived from water, air and soil

Beneficial nutrients

promote plant growth but are not necessary to complete the life cycle

Arnon and Stout

proposed the three criteria for essentiality

Essential for life cycle, Specific, irreplaceable function, Direct metabolic role

Three Criteria for Essentiality

Essential for life cycle

a deficiency makes it impossible for the plant to complete its vegetative or reproductive stage

Specific, irreplaceable function

the deficiency is specific to that element and can be prevented or corrected only by supplying it

Direct metabolic role

the element is directly involved in the nutrition of the plant

Macronutrients (9)

needed in large quantities (more than 10 mmole/kg dry matter)

Micronutrients (8)

needed in small quantities (less than 10 mmole/kg, or less than 50 ppm)

Non-mineral nutrients

C, H, O; generally available through air and water

Primary macronutrients

N, P, K; deficiencies are more common but can be corrected with fertilizers

Secondary macronutrients

Ca, Mg, S

Trace elements

another name for micronutrients

Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Pota, Calcium, Magnesium, Sulfur

The 9 Macronutrients Elements

Iron, Boron, Zinc, Copper, Manganese, Molybdenum, Chlorine, and Nickel

The 8 Micronutrients Elements

Carbon

taken in as CO₂ from the atmosphere

Oxygen

absorbed in molecular form from air or water; also generated within the plant during photosynthesis

Hydrogen

released from water during photosynthesis

Nitrogen

absorbed from the soil as nitrate or ammonium; some bacteria and cyanobacteria can fix N from the air directly

mineral elements

absorbed from the soil as ions; derived from weathering of rocks

Carbon

forms the backbone of most plant biomolecules (proteins, starches, cellulose)

Oxygen

required for aerobic cellular respiration to break down glucose and produce ATP

Hydrogen

builds sugars; H⁺ is needed for the proton gradient that drives the ETC in respiration and photosynthesis

Nitrogen

synthesis of amino acids, proteins, nucleic acids, vitamins, hormones, coenzymes, ATP and chlorophyll; needed especially in meristematic tissues

Potassium

activates enzymes; K⁺/Na⁺ pump and active transport; anion-cation balance; opens and closes stomata; helps turgidity of cells (common in cell sap of vacuole)

Phosphorus

synthesis of nucleic acids, phospholipids, ATP, NAD and NADP; part of the cell membrane and some proteins

Magnesium

part of the chlorophyll molecule (its central atom); activates enzymes of phosphate metabolism; DNA and RNA synthesis; binding of ribosome subunits

Sulfur

constituent of cysteine and methionine and some proteins; present in coenzyme A, thiamine, biotin and ferredoxin

Iron

synthesis of chlorophyll; constituent of ferredoxin and cytochromes; activates catalase

Manganese

activates enzymes of photosynthesis, respiration and N₂ metabolism; electron donor for chlorophyll b; decarboxylation in respiration

Molybdenum

required for nitrogen fixation; activates nitrate reductase

Boron

increases uptake of water and calcium; meristem activity and pollen tube growth; translocation of carbohydrates

Copper

component of oxidase enzymes and plastocyanin; electron transport in photosynthesis

Zinc

component of indoleacetic acid (a plant hormone); activates dehydrogenases and carboxylases; present in carbonic anhydrase

Chlorine

water-splitting reaction leading to O₂ evolution in photosynthesis; anion-cation balance

Calcium

forms calcium pectate in the middle lamella of cell walls; activates enzymes for root and shoot tip growth; needed for cell division and enlargement

K⁺ pumped into guard cells

water potential decreases inside, water moves in, cells become turgid and the stomata open

K⁺ pumped out of guard cells

water potential increases inside, water moves out, cells become flaccid and the stomata close

Aluminum, Cobalt, Lithium, Silicon, Sodium

Beneficial Elements

Aluminum

increased antioxidant properties and growth

Cobalt

involved in N-fixation by legumes; increases growth, nodule number and weight, and pod yield and quality (peanut example: best result with seed treatment plus foliar sprays)

Lithium

enhances transport of sugars from leaves to roots in certain plants; increases chlorophyll content

Silicon

taken up as silicate; strengthens cereal stems to resist lodging; thickens and strengthens cell walls

Sodium

taken up as Na⁺; can partly replace K for some crops

Nutritional disorder

caused by a nutrient deficiency or toxicity

Deficiency symptoms

appear when minerals are not available to plants

Toxicity symptoms

appear when minerals are in excess

Mobile elements

move to new growth areas, so deficiency symptoms show first in older leaves (N, P, K, Mg, Cl, Na, Zn, Mo)

Immobile elements

do not move to new growth, so deficiency symptoms show first in new growth (Ca, S, Fe, B, Cu)

Corrective measures

agronomic methods (fertilizer, crop rotation, Integrated Nutrient Management, cover cropping), soil improvement (soil testing, organic amendments, biofertilizers), varietal improvement (breeding for root architecture, GMO)

Nitrogen

yellowing starting at the tip and spreading along the midrib; old leaves light green and chlorotic at the tip; stunted plants; corn shows yellow or brown midribs

Phosphorus

reddish-purple leaves (especially young plants); stunted growth; brown necrotic tips; older rice leaves orange or purplish

Potassium

“firing” (drying) along the tips and edges of lowest leaves; stunted, easily lodged plants; brown spots on rice often mistaken for disease; green “arrow” shape in barley

Magnesium

whitish stripes along veins and purplish undersides of lower leaves; reddening or browning of leaf tips and margins in corn; chlorosis on the flag leaf of rice

Calcium

chlorotic-white leaf tips and drying of growing points; new leaves curl and edges turn necrotic and scorched

Sulfur

chlorotic-white leaf tips and drying of growing points; new leaves curl and edges turn necrotic and scorched

Iron

yellowing on young leaves while older leaves stay normal; green veins fade to pale yellow if it persists

Manganese

pale grayish-green or pale yellow interveinal chlorosis on young leaves

Zinc

white band on corn leaves with green midrib and margins; dusty brown spots on rice; small necrotic spots on wheat

Boron

young leaves become brittle, twisted, with wrinkled tips

Copper

rice leaves do not unroll and tips look needle-like; corn leaves spiral with a bluish-green tint

Molybdenum

pale leaves that may be scorched, cupped or rolled; thick, brittle leaves that wither leaving only the midrib

Chlorine

chlorotic and necrotic spotting with abrupt boundaries between dead and live tissue; often misdiagnosed as physiological leaf spot

Herbicide damage

burned tips and edges, whitecap leaves

Drought stress

grayish-green color and leaves rolling up to the size of a pencil

Helminthosporium blight

small spots that gradually spread across the leaf (a fungus; saprophyte on dead tissue)

Healthy leaf

dark green due to high chlorophyll

Nitrogen

dark green plants, succulent new growth, susceptible to disease and insects, easy lodging under drought, blossom abortion and lack of fruit set

Phosphorus

no direct effect, but shows deficiencies of Zn, Fe and Mn; may interfere with Ca nutrition

Potassium

shows Mg and possibly Ca deficiency due to cation imbalance

Calcium

may show Mg deficiency and, in high excess, K deficiency

Magnesium

cation imbalance showing signs of Ca or K deficiency

Sulfur

premature senescence of leaves

Boron

leaf tips and margins turn brown and die

Copper

Fe deficiency may be induced, very slow growth, stunted roots

Iron

bronzing and tiny brown spots on leaves

Manganese

brown spots surrounded by a chlorotic zone and circle on older leaves

Molybdenum

not of common occurrence

Zinc

Fe deficiency develops

4Rs framework

Right Source, Right Place, Right Time, Right Rate (for greatest fertilizer nutrient use efficiency)

Right source

matches fertilizer type to crop needs

Right place

keeps nutrients where crops can use them

Right time

makes nutrients available when crops need them

Right rate

matches the amount of fertilizer to crop needs