Mineral NutritionExperiment 4

INTRODUCTION

Introductory Concepts

• Plant nutrition –Organic nutrition - focuses on the

production of carbon compounds

–Inorganic nutrition - concerned with the acquisition of mineral elements from the soil

Introductory Concepts

• Nutrient–A substance needed to survive or

necessary for the synthesis of organic compounds

• Mineral – inorganic elements which come from the

soil and are dissolved in water and absorbed through the roots of the plants

Introductory Concepts

• Mineral Nutrient–may be toxic to plants–may play no role in metabolism–may be essential for plant growth

• A mineral nutrient is regarded as essential if, in its absence, a plant cannot complete its life cycle.

Introductory Concepts

• Essential Elements (essential mineral nutrients)1. one whose absence prevents a

plant from completing its life cycle

2. one that has a clear physiological role

Introductory Concepts

• Classification of Essential Elements–Based on their abundance in plants

1. Micronutrients

2. Macronutrients Nitrogen Phosphorus Potassium Calcium, Magesium, Sulfur, Silicon

Introductory Concepts

• Nutrient Deficiency–concentration of a nutrient decreases

below the typical range– lead to specific visual, often

characteristic, symptoms reflective of the role of that particular nutrient in plant metabolism

Objectives

1. To become familiar with the method of growing plants by hydroponics

2. To observe deficiency symptoms associated with inadequate supplies of selected essential element

METHODOLOGY

one -week old Zea mays

5 set-ups of amber bottle

with solutions

Observe for 3 weeks

Stock Solution

1Complete

2-N

3-P

4-K

5Distilled

H2O

1 M Ca(NO3)2 5 mL - 5 mL - -

1 M KNO3 5 mL - 5 mL - -

1 M MgSO4 2 mL 2 mL 2 mL 2 mL -

1 M KH2PO4 1 mL 1 mL - - -

FeEDTA 2 mL 2 mL 2 mL 2 mL -

Micronutrients 1 mL 1 mL 1 mL 1 mL -

1 M NaNO3 - - - 5 mL -

1 M NaH2PO4 - - - 1 mL -

1 M CaCl2 - 5 mL - - -

1 M KCl - 5 mL 1 mL - -

Other procedures

• Get initial and final length of root and shoot• Regularly aerate each set-ups• Regularly change the stock solutions in each

set-up

Sample set-up

Hydroponics5 set ups: 1 – complete; 2 – minus K; 3 – minus N; 4 – minus P; and 5 – distilled water

Zea mays seedlings

15 seedlings grouped into 5 according to height and age

RESULTS

Growth of Seedlings in Different Nutrient Solutions

Treatment

Average Initial length (cm)

Average Final length (cm)

Root Shoot Ratio Root Shoot Ratio

Complete 5.0 17.6 0.28 9.8 46.9 0.22

Minus N 9.0 19.0 0.47 9.1 36.5 0.25

Minus P 11.0 16.2 0.67 13.4 19.0 0.71

Minus K 6.5 17.5 0.37 7.2 19.2 0.38

Distilled H2O

11.5 18.0 0.63 43.1 29.6 1.45

Observations in each set-up

• Complete–Short roots but high amounts of lateral

roots–Good shoot growth–Lively green leaves–Minor chlorosis at leaf tips–Generally healthy

Observations in each set-up

• Minus Nitrogen–Very poor shoot growth–Interveinal Chlorosis–Violet leaf sheaths

Observations in each set-up

• Minus Phosphorus–Very minimal shoot growth–Very minimal root growth–Violet coloration of leaf sheaths–Root system is very fragile– Interveinal Chlorosis–Necrosis

Observations in each set-up

• Minus Potassium–Marginal Necrosis–Very poor root growth–Very poor shoot growth–Leaves were twisted, curled and fragile– Necrosis

Observations in each set-up

• Distilled Water–Chlorosis–Light green color–Very good root growth, but poor in

lateral roots–Violet leaf sheaths–Fragile shoot system

DISCUSSION

Hydroponics – the set-up

• Soil-less culture• Inorganic solution that contain nutrients• Roots of plants are immersed on the

solution• Continually aerated and exposed to

sunlight

Sample set upWith aerator, nutrients in the aqueous solution

Hydroponics – the set-up

• Better than the soil–chronic and acute deficiencies of several

elements may occur simultaneously–absence or excessive amounts of one

element may induce deficiencies or excess accumulations of another

–some virus-induced plant diseases may produce symptoms similar to those of nutrient deficiencies

Different hydroponic

set-ups

Hydroponics – the solution

• Sachs’ solution - contributed a total of nine mineral nutrients (K, N, P, Ca, S, Na, Cl,Fe, Mg)

• Hoagland solution–contain all of the known mineral elements

needed for rapid plant growth–Used in our experiment (slightly

modified)

Stock Solution

1Complete

2-N

3-P

4-K

5Distilled

H2O

1 M Ca(NO3)2 5 mL - 5 mL - -

1 M KNO3 5 mL - 5 mL - -

1 M MgSO4 2 mL 2 mL 2 mL 2 mL -

1 M KH2PO4 1 mL 1 mL - - -

FeEDTA 2 mL 2 mL 2 mL 2 mL -

Micronutrients 1 mL 1 mL 1 mL 1 mL -

1 M NaNO3 - - - 5 mL -

1 M NaH2PO4 - - - 1 mL -

1 M CaCl2 - 5 mL - - -

1 M KCl - 5 mL 1 mL - -

Hydroponics – the solution

• Modified Hoagland Solution–Concentrations of the elements were

set to their optimum levels in such a way that it will not produce any toxicity symptoms or salinity stress

–E.g. source of nitrogen which is ammonium (NH4

+) and nitrate (NO3-)

Hydroponics – the preparations

• Distilled water must be first placed in each bottle to prevent formation of precipitations

• one-week old germinating Zea mays –easily germinated –widely available–stored endosperm – food of the germinating

seed–suitable height for the transport of the

nutrients

Hydroponics – the preparations

• Proper aeration–provide the roots of the plants with sufficient

oxygen for their aerobic respiration• Maintenance of solution

– to replenish the consumed nutrients –and to remove by-products of metabolism

• Maintenance of pH –within 5.5 to 6.5 –element abundance is dependent to it

Essential Elements

• Nutrient deficiency symptoms - the expression of metabolic disorders resulting from the insufficient supply of an essential element.

• Two types of elements based on their mobility1. Mobile

2. immobile

Mobile – deficiency seen in old leafImmobile – deficiency seen in young leaf

Essential Elements – Categories

1. Based on Abundancea. Micronutrients – Cl, Fe, I, B, Mn, Na, Zn,

Cu, Ni, Mo

b. Macronutrients – N, K, Ca, Mg, P, S, Si

Essential Elements – Categories

2. Based on biochemical roles and physiological function

a. G1: forms the organic components of the plant

b. G2: important in energy storage or maintaining structural integrity

c. G3: of the free ions or ions bound to pectic acids present in the plant cell wall

d. G4: important roles in electron transfer

Nitrogen (NH4+, NO3

-)

• Functions– constituent

of many important cell components • Amino acids• Nucleic acids• Chlorophyll• hormones

• Deficiencies – inhibited plant

growth–Chlorosis–woody stems – formation of purple

pigmentation

Observations in each set-up

• Minus Nitrogen–Very poor shoot growth–Interveinal Chlorosis–Violet leaf sheaths

Phosphorus (HPO4−, HPO2−)

• Functions–DNA and RNA–Sugar-phosphate

int. :RuBP –plant

metabolism: ATP–phospholipids

• Deficiencies–Stunted growth–Necrosis–Purple

coloration–Slender stems–Delayed

maturation

Observations in each set-up

• Minus Phosphorus–Very minimal shoot growth–Very minimal root growth–Violet coloration of leaf sheaths–Root system is very fragile– Interveinal Chlorosis–Necrosis

Potassium (K+)

• Functions–regulation of

osmotic potential in plant cells

–Activation of enzymes in respiration and photosynthesis

• Deficiencies–chlorosis necrosis–Leaf curl and crinkle–slender and weak–abnormal short

intermodal region– roots susceptible to

rotting due to fungi– tendency to lodge off

Observations in each set-up

• Minus Potassium–Marginal Necrosis–Very poor root growth–Very poor shoot growth–Leaves were twisted, curled and fragile– Necrosis

Observations in each set-up

• Complete–Short roots but high amounts of lateral

roots–Good shoot growth–Lively green leaves–Minor chlorosis at leaf tips–Generally healthy

Observations in each set-up

• Distilled Water–Chlorosis–Light green color–Very good root growth, but poor in

lateral roots–Violet leaf sheaths–Fragile shoot system

CONCLUSION

1. To become familiar with the method of growing plants by hydroponics

Hydroponics – uses a soil-less culture that uses only inorganic solutions as source of nutrients where the roots of the plant are immersed and are continually aerated, and exposed to ample sunlight

2. To observe deficiency symptoms associated with inadequate supplies

of selected essential element

• Minus Nitrogen - inhibition of growth and yellowing of leaves

• Minus Phosphorus - dark green coloration of leaves or necrosis and stunted growth

• Minus Potassium - plant lodged off and exhibited curling and necrosis in leaf tips

The Conclusion

• Essential elements – needed by plants to grow and develop (N, P, K)

• Specific functions can be observed using methods such as hydroponics

• Deficiency symptoms are reflective of the nutrients’ functions

• Nitrogen influences plant growth, phosphorus stores energy, and potassium regulates osmotic potential

GUIDE QUESTIONS

Study Questions

• What can be deduced from the relative age of organ showing the first sign of deficiency for a given nutrient?

Helps determine mobility of nutrients

Study questions

• Why are dark colored containers preferably used in culture solution studies?

In order to keep out lightreduce the growth of algae that would

compete with the plants for nutrientsPrevent reactions of chemical that can

be induced by light

Study questions

• Why is it necessary to observe aseptic protocols in the experiment?

to avoid contaminationeven a little increase or decrease in the

nutrient content can have a considerable effect on the results, making them unreliable

Study questions

• Give examples of plants that have been grown using hydroponics (not necessarily in the Philippines).

WatercressTomatoesPepperLettuceSeedless cucumber

Study questions

• Soil-less agriculture is practiced extensively in Israel. Why do you think so?

country lacking in fertile agricultural landdeserts (not efficient in water retention)less organic materials – less retention

for nutrients (low CEC)

REFERENCES

• F. Evangelista. 2012. Lecture in Plant Nutrition in a plant physiology course. Gat Andres Bonifacio bldg., University of the Philippines, Manila

• Hopkins. 2009. Introduction to Plant Physiology 4th Edition. John Wiley & Sons, Inc. United States of America

• Taiz & Zeiger. 2002. Plant Physiology 3rd Edition. Sinauer Asssociates Inc., Publishers, Sutherland, Massachusetts

• Plant Mineral Nutrition PowerPoint. 2010

Prepared byUy, Masa, Josue, De layola,

CortezPlant Physiology Laboratory, WAB2

August 8, 2012