- -   AGRICULTURE CORE CURRICULUM  - -


(CLF7000)  Advanced Core Cluster:  PLANT AND SOIL SCIENCE

  (CLF7450)   Unit Title:  ELEMENTS NECESSARY FOR PLANT GROWTH

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  (CLF7457)   Topic:  SYMPTOMS OF               Time      Taught in Year(s) 
                      DEFICIENCIES             1 hour          3 and 4         
                      (N,P,K,FE,S,MG,B,ZN)
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         Topic Objectives:  Upon completion of this lesson the student will 
         be able to:

         Learning Outcome #:

           (H-9)  -  List symptoms of plant nutrient deficiencies when the 
                     following minerals are inadequate:  N,P,K,Fe,S,Mg,B 
                     and Zn.

         Special Materials and Equipment: Colored pictures of plants with 
                     various deficiencies and/or fresh or dried samples of 
                     plants with deficiencies.  Copies of commercial soil
                     test reports.

         References: Interstate Printers, Inc.
                     WESTERN FERTILIZER HANDBOOK.
                     Pages 55-81.

                     Arios.  (1978).  PLANT PATHOLOGY.
                     Pages 164, 165.

         Evaluation: Quiz by instructor


TOPIC PRESENTATION:  SYMPTOMS OF DEFICIENCIES

A.  When essential elements are present in the plant in amounts smaller than 
    minimum levels required for plant growth, the plant exhibits various 
    external and internal symptoms.

    1.  These symptoms may appear on any or all organs of the plant 
        including leaves, stems, roots, flowers fruit and seeds. 

    2.  A knowledge of these symptoms will help the student determine their 
        cause and aid in finding the cure.

B.  Symptoms of nitrogen deficiency in plants include: 

    1.  slow growth, stunted plants, 

    2.  plants are light green to yellow in color (chlorotic), and

    3.  "firing" of tips and center position of leaves beginning with the
        older leaves. 

C.  Phosphorus deficiency symptoms include:

    1.  slow and stunted growth,

    2.  purplish coloration on foliage of some plants (this may be 
        associated or confused with cool or cold temperatures),

    3.  dark green coloration with tips of leaves dying, 

    4.  delayed maturity, and

    5.  poor grain, fruit or seed development.

D.  Symptoms of potassium deficiency in plants include:

    1.  tip and marginal leaf chlorosis and then death starting on more
        mature (most recently developed fully mature) leaves, 

    2.  weak stalks, plants "lodge" easily, 

    3.  small fruit or shriveled seeds, and

    4.  plants have thin shoots and in severe cases show dieback.

E.  Symptoms of iron deficiency in plants include:

    1.  interveinal chlorosis of young leaves.  Veins remain green except in 
        severe cases, 

    2.  twig dieback, 

    3.  part of or entire leaf may dry, 

    4.  leaves may be shed, and 

    5.  in severe cases, death of entire limbs or plants.

F.  Sulfur deficiency symptoms include: 

    1.  young leaves light green to yellowish in color, 

    2.  symptoms resemble those of nitrogen deficiency, 

    3.  small and spindly plants, and

    4.  retarded growth rate and delayed maturity. 

G.  Magnesium deficiency symptoms include: 

    1.  interveinal chlorosis (yellowing) in older leaves, 

    2.  sometimes necrotic spots appear, 

    3.  curling of leaves upward along margins, 

    4.  leaves may drop off, and 

    5.  "Christmas tree" area along midrib of leaf in the case of citrus.

H.  Symptoms of boron deficiency in plants include: 

    1.  death of terminal growth, causing lateral buds to develop and 
        produce a "witches broom" effect,

    2.  thickened, curled, wilted and chloritic leaves, 

    3.  fruit or tubers may crack on surface and rot in the center, and 

    4.  reduced flowering or improper pollination.

I.  Symptoms of zinc deficiency in plants include: 

    1.  decrease in stem length and rosetting of terminal leaves, 

    2.  leaves may be mottled or show interveinal chlorosis, 

    3.  reduced fruit bud formation, 

    4.  leaves are shed progressively from base to tip, and

    5.  causes "little leaf" of apples, stone fruits, grapes and walnuts.

J.  Note that although not considered an "essential element" in the past
    there have also been molybdenum (Mo) deficiencies observed in California 
    fields of alfalfa and melons.

          __________________________________________________________
          ACTIVITY:  
                      
          1.  Have students study colored pictures and preserved or
              fresh samples of deficient plants and determine the 
              deficient element.
          __________________________________________________________


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Note:  It is difficult for a beginning student to make determinations
       of deficient elements by symptoms, since they will often vary 
       with the specie affected and by the degree of deficiency.  
       The student, though, can develop an appreciation of this important
       specialty through experiences.

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7/25/90 sg

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