Group Title: Research report. (North Florida Research and Education Center (Quincy, Fla.)
Title: Dolomite and zinc interactions in two peanut cultivars
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Full Citation
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Permanent Link: http://ufdc.ufl.edu/UF00066093/00001
 Material Information
Title: Dolomite and zinc interactions in two peanut cultivars
Series Title: Research report. (North Florida Research and Education Center (Quincy, Fla.)
Physical Description: 9 pages : ill. ; 28 cm.
Language: English
Creator: Rhoads, Fred ( Frederick Milton )
Shokes, Frederick M ( Frederick Milton ), 1943-
Gorbet, Daniel W ( Daniel Wayne ), 1942-
North Florida Research and Education Center (Quincy, Fla.)
Publisher: North Florida Research and Education Center
Place of Publication: Quincy Fla
Publication Date: 1991
 Subjects
Subject: Peanuts -- Florida   ( lcsh )
Dolomite   ( lcsh )
Zinc   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical reference (p. 9).
Statement of Responsibility: F.M. Rhoads, F.M. Shokes, and D.W. Gorbet
General Note: Cover title.
 Record Information
Bibliographic ID: UF00066093
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 71171626

Full Text



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DOLOMITE AND ZINC INTERACTIONS'IN TWO

PEANUT CULTIVARS m t


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F. M. Rhoads, F. M. Shokes, and D. W. Gorbet







North Florida Research and Education Center

University of Florida











IFAS
SFlorida Agricultural Experiment Stations
Institute of Food and Agricultural Sciences
E -S-Bi-S 2 ,- University of Florida, Gainesville


Research Report 91-6









Dolomite and Zinc Interactions in Two

Peanut Cultivars

F.M. Rhoads, F.M. Shokes, and D.W. Gorbet



Previous research (Rhoads et al., 1989) indicated a difference

between Sunrunner and Southern Runner peanut cultivars in response

to zinc (Zn) fertilization. Southern Runner was more sensitive

than Sunrunner to Zn deficiency. Zinc toxicity occurred in both

cultivars with soil-test Zn above 8 lb/acre and soil-test calcium

(Ca) levels below 400 lb/acre. However, no toxicity symptoms were

observed with soil-test Ca above 800 lb/acre and soil-test Zn above

20 lb/acre.

Soil pH was shown to influence leaf Zn concentration of

peanuts in North Carolina (Cox, 1990). Leaf Zn decreased as soil

pH increased. The Ca/Zn ratio in young mature leaves of peanut was

found to be related to Zn toxicity symptoms in Georgia studies

(Parker et al., 1990). Zinc toxicity symptoms were observed in

plants with a Ca/Zn ratio below 50 and no symptoms were found in

plants with a ratio above 50. Lime and Zn interactions in peanuts

were not documented in the North Carolina and Georgia reports (Cox,

1990; and Parker et al., 1990).

The objective of this research was to examine interactions and

main effects of dolomite and Zn on dry-matter yield, tissue Zn,

tissue Ca, and tissue Mg of Sunrunner and Southern Runner peanut

cultivars. Also, the relationships between soil-test Zn and

applied Zn and between dry-matter yield and Ca/Zn ratio in peanut

tissue were determined.









METHODS AND MATERIALS

Soil was collected in plastic containers from the Ap horizon

of Norfolk loamy sand (fine-loamy, siliceous, thermic, Typic

Kandiudults) from an unfertilized area on the North Florida

Research and Education Center, Quincy. The soil was dried,

screened (with a non-metal screen) and weighed into plastic pots

(6.0 kg per pot). Each pot of soil was mixed with 2 g of 46%

triple superphosphate, 3.0 g of potassium sulfate, 4 g of ammonium

nitrate and the amounts of dolomite and Zn shown in Table 1.

Peanuts (Sunrunner and Southern Runner) in pots of the above mix,

were grown in a greenhouse for approximately nine weeks with three

levels of Zn (0,5 and 25 mg/kg) and three levels of dolomite (0,6,

and 12 g/pot) in four replications.

At the end of the growing period the above ground portions of

all plants were harvested, dried, and weighed. After weighing,

plant samples were ground, ashed in a muffle furnace at 500C and

taken up in dilute acid (HC1). Solution Zinc was determined with

atomic absorption (AA) spectroscopy and Ca and Mg were determined

with flame emission (FE) spectroscopy.

Soil samples were also collected from pots at the end of the

growth period and extracted with Mehlich-I soil extractant. Soil

pH was measured in a 1:1 v/v soil-water suspension.

The experimental design was a randomized complete block with

treatments arranged factorily (2x3x3), containing two cultivars,

three levels of Zn, and three levels of dolomite. Analysis of

variance procedures were used to evaluate main effects and

interactions of treatment factors. Regression analyses were used









to evaluate soil-test Zn and Ca/Zn ratio in peanut tissue (Steel

and Torrie, 1960).

RESULTS AND DISCUSSION

Main effects of cultivar and lime rate on dry-weight of

Sunrunner and Southern Runner peanuts were not significant (P>0.05)

(Tables 1 and 2). Dry-weight was significantly (P<0.01) reduced

with 50 lb Zn/acre (25 mg/kg) in both cultivars at all lime rates.

Interaction between cultivar and lime rate was significant (P<0.05)

for dry-weight as shown by maximum yield of Sunrunner at 6 g/kg

lime and maximum yield of Southern Runner at 12 g/kg lime.

Cultivar and Zn rate interaction on dry-weight was shown by a

higher yield of Southern Runner at the 25 mg/kg Zn rate than that

of Sunrunner. Lime significantly (P<0.01) increased dry-weight at

25 mg/kg Zn.

Sunrunner contained the highest average tissue Zn

concentration, 53 ppm versus 44 for Southern Runner (Tables 1 and

2). Zinc concentration in tissue decreased with added lime and

increased with added Zn. Cultivar by Zn interaction and lime by Zn

interaction were shown by variation in slope of tissue Zn versus

added Zn.






Table 1.


Dry-weight, tissue Zn, Ca, and Mg concentration, and
Ca/Zn ratio of Sunrunner and Southern Runner peanuts with
three levels of dolomite and Zn; and soil pH at harvest.


Applied to Soil
Dolomite Zinc Dry-weight Zn Ca Mg
g/pot mg/kg g/pot ppm % % Ca/Zn Soil-pH


Sunrunner Cultivar

0 0 51 10 0.83 0.49 885 5.6
0 5 49 32 0.67 0.44 235 5.5
0 25 4 177 0.54 0.43 31 4.8
6 0 50 7 0.79 0.77 1282 5.7
6 5 51 21 0.70 0.66 335 5.9
6 25 23 103 0.51 0.53 50 5.6
12 0 44 5 0.76 0.87 1738 5.9
12 5 46 26 0.71 0.89 348 5.9
12 25 8 94 0.60 0.63 64 5.7

Southern Runner

0 0 45 10 0.64 0.46 690 5.6
0 5 48 31 0.64 0.44 205 5.4
0 25 8 141 0.42 0.39 30 5.2
6 0 37 8 0.68 0.64 1108 5.6
6 5 41 21 0.70 0.58 349 5.8
6 25 26 103 0.57 0.57 57 5.6
12 0 43 6 0.72 0.71 2369 5.8
12 5 43 17 0.73 0.67 487 6.0
12 25 31 62 0.57 0.63 93 6.0




Table 2. Analysis of variance for peanut dry-matter yield, and
tissue concentration of Zn, Ca, and Mg.


Source df Yield Tissue Zn Tissue Cat Tissue Mgt


Cultivar 1 N.S. ** N.S. **
Lime Rate 2 N.S. ** N.S. **
Zinc Rate 2 ** ** ** **
CvxLR 2 N.S. N.S. N.S.
CvxZnR 2 ** ** N.S. N.S.
LRxZnR 4 ** ** N.S. N.S.
CvxLRxZnR 4 N.S. N.S. N.S. N.S.


tLime source was dolomite; N.S. = not significant
*'indicate significance at P = 0.01 and 0.05, respectively.









Zinc rate was the only treatment factor that influenced peanut

tissue Ca (P<0.01). Tissue Ca decreased with increased Zn.

Sunrunner contained a higher average tissue Mg content that

Southern Runner (Tables 1 and 2). Addition of dolomite increased

tissue Mg whereas Zn addition decreased it.

The Ca/Zn ratio in peanut tissue was below 100 in all

treatments receiving 25 mg/kg added Zn (Table 1). The critical

level of Ca/Zn ratio was 140 for this experiment (Fig. 1) compared

to a value of 50 in Georgia tests (Parker et al. 1990). However,

there is not necessarily a conflict between our data and Georgia's

because our critical level was based on dry-weight while theirs was

based on presence or absence of symptoms of Zn toxicity. We used

whole plants for chemical analysis and they used youngest mature

leaves. Furthermore, five out of six treatments showing Zn

toxicity in our tests had Ca/Zn ratios below 65.

Zinc concentration in peanut tissue did not change much with

soil pH at zero and 5 mg/kg Zn rates (Table 1). However, soil-pH

accounted for 66% of the variation in Zn concentration at the 25

mg/kg Zn rate. Peanut tissue Zn concentration changed an average of

78 ppm per unit of change in soil-pH with the 25 mg/kg Zn rate.

The following equation, ppm Zn = 540-78(soil-pH), predicts that

soil-pH above 6.3 would result in Zn concentrations below 50 ppm

for the 25 mg/kg Zn rate. A liming test in North Carolina showed

very little change in peanut tissue Zn in the soil-pH range of 5.0

to 6.2 with non-toxic levels of Zn (Cox, 1990).









Rate of applied Zn accounted for 92% of the variation in soil-

test Zn level in this experiment (Fig. 2). The Mehlich-I

extractant removed an average of 22% of the Zn added as ZnSO4. Dry-

weight of peanuts was related to Zn rate by the following equation:

Y = 44.9+0.622X-0.0703X2; where Y = dry-weight of peanut plants in

g/pot and X = Zn rate in ppm (mg/kg). Maximum dry-weight was

predicted from the above equation to occur at 4.42 ppm Zn applied

to the soil which is equivalent to 2.02 ppm soil-test Zn from the

equation in Fig. 2. Five pounds of extractable Zn per acre was

adequate for maximum growth of peanuts in this test.

CONCLUSIONS

Yield of peanuts and peanut tissue calcium concentration were

not affected by cultivar and dolomite. Sunrunner contained the

highest Zn and Mg concentrations in the tissue. Dolomite decreased

peanut tissue Zn and increased tissue Mg. A Zn rate of 50 lb/acre

(25 mg/kg) reduced yield and tissue concentration of Mg and Ca.

Tissue Zn concentration in peanuts was directly related to rate of

Zn application and inversely related to soil pH. Interactions

between cultivar and Zn rate and between dolomite and Zn on yield

and tissue Zn were highly significant.












Dry-weight vs Ca/Zn in Peanuts
Regression

Yield (g/pot)
60

50 xx x
xx
40- x
x Trt Means
30-
0 x L-P Model
20
Y -1.67 + 0.338X X < 140
10-
Y 45.65 X = or > 140
0 I I I


0 200


400 600 800
Calcium/Zinc Ratio in Tissue


1000 1200


Figure 1. Relationship between peanut plant dry-weight and Ca/Zn ratio in plant
tissue. Data points are treatment means. A linear-plateau (L-P) model
is shown as determined from regression analysis.

Soil-Test Zinc
Regression Zinc Rate


Soil-Test Zinc (ppm)


0 5 10 15 20 25 30
Zinc Rate (ppm)


Figure 2. Regression analysis of soil-test zinc on rate of Zn applied to the soil.









REFERENCES

1. Cox, F.R. 1990. A note on the effect of soil reaction and

zinc concentration on peanut tissue zinc. Peanut Science

17:15-17.

2. Parker, M. B., T. P. Gaines, M. E. Walker, C. O. Plank, and J.

G. Davis-Carter. 1990. Soil zinc and pH effects on leaf zinc

and the interaction of leaf calcium and zinc on zinc toxicity

of peanuts. Commun. In Soil Sci. Plant Anal. 21(19 &

20):2319-2332.

3. Rhoads, F. M., F. M. Shokes, and D. W. Gorbet. 1989.

Response of two peanut cultivars to soil zinc levels. Univ of

Fla (IFAS), NFREC, Quincy Res. Rpt. 89-2.

4. Steel, R. G. D., and J. H. Torrie. 1960. Principles and

procedures of statistics. McGraw-Hill, New York.




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