Group Title: Research report (North Florida Research and Education Center (Quincy, Fla.))
Title: Response of two peanut cultivars to soil zinc levels
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Permanent Link: http://ufdc.ufl.edu/UF00066092/00001
 Material Information
Title: Response of two peanut cultivars to soil zinc levels
Series Title: Research report (North Florida Research and Education Center (Quincy, Fla.))
Physical Description: 8 leaves : 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: Soil fertility   ( lcsh )
Soils -- Zinc content   ( lcsh )
Peanuts   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references.
Statement of Responsibility: F.M. Rhoads, F.M. Shokes, and D. W. Gorbet.
General Note: Cover title.
 Record Information
Bibliographic ID: UF00066092
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 71171521

Full Text
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Research Report: NF-91-5


RESPONSE OF TWO PEANUT CULTIVARS


TO SOIL ZINC


by


F. M. Roads, F. M. Shoes, and

F. M. Rhoads, F. M. Shokes, and


D. W. Gorbet






NORTH FLORIDA RESEARCH AND EDUCATION CENTER

Route 3 Box 4370, Quincy, FL 32351




INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES

UNIVERSITY OF FLORIDA











I, F J Florida Agricultural Experiment Station
Institute of Food and Agricultural Sciences
"I" E : 'University of Florida, Gainesville


LEVELS
f.'.


CD,


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Response of Two Peanut Cultivars to Soil Zinc Levels

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

Zinc (Zn) requirements of peanuts may differ among cultivars. In a 1985

cercospora leafspot field test, 'Southern Runner' showed Zn deficiency symptoms

while 'Sunrunner' in the same test looked normal. Extension specialists

recommend that peanuts (Arachis hypogaea L.) follow grass in rotation systems to

prevent buildup of pest (weeds, insects, disease, and nematodes) problems

(Beasley, 1987). Corn is grown in rotation with peanuts more often than any

other crop. Excess Zn may accumulate when peanuts are grown in rotation with

irrigated corn or in old pecan orchards that were fertilized with Zn over an

extended time period. Toxicity can occur in peanuts due to high Zn levels and
acidic soils (Johnson, 1987). Peanuts .are sensitive to Zn levels greater than

10 lb/A when pH is less than 5.4. A soil pH of 6.0 is recommended for peanuts

growing on high Zn soils. If Zn is greater than 10 lb/A peanut production is

not recommended until Zn level is reduced below 10 lb/A. Recent studies

indicated that Zn toxicity was related to peanut leaf Ca/Zn ratio and that

toxicity occurred when the ratio was below 50 (Parker et al., 1990).

Objectives of this research were to: (1) determine if Sunrunner and

Southern Runner respond differently to soil Zn levels, (2) which levels of

extractable soil Zn are toxic to these peanut cultivars, and (3) relationships

between extractable and applied Zn, and between Zn concentration in peanut tissue

and extractable soil Zn.

MATERIALS AND METHODS
Soil was collected in plastic containers from the Ap horizon of Tifton

loamy sand (fine-loamy, siliceous, thermic, Plinthic Kandiudults) near Marianna,

Florida, in the area where Zn deficiency symptoms were observed on Southern

Runner in 1985. Two batches of soil were collected for experiment-1, each batch

on a separate day. The first batch of soil provided enough for the three lowest

Zn level treatments and the second batch was used for the remaining Zn

treatments. A uniform single batch of soil was collected for experiment-2.

The soil was dried, screened (with a non-metal screen) and weighed into

plastic pots (7.5 kg per pot). Each pot of soil was mixed with 130 mg/kg of 46%

triple super phosphate, 270 mg/kg of K2SO4, 1.13 g/kg of dolomite, and the

appropriate amount of ZnSO4 to provide the applied Zn levels shown in tables 1










through 4. Peanuts (Sunrunner and Southern Runner) were grown in the greenhouse

for approximately 8 weeks with eight levels of Zn and five replications for each

cultivar.

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 5500C and taken up in dilute acid (HC1). Zinc was

determined in the solution with atomic absorbtion (AA) spectroscopy and Ca was

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-test Zn was determined with

AA, and K, Ca, and Mg were determined with FE, and P was determined

colorimetrically. Soil pH was measured with a pH-meter in a 1:1 v/v soil-water

suspension.

Analysis of variance procedures were used to statistically analyze the

data. Single degree of freedom F-tests were used in making orthogonal

comparisons between groups of treatments. Regression analyses on soil-test Zn

versus applied Zn and concentration of Zn in peanut tissue versus soil-test Zn

were performed on the data (Steel and Torrie, 1960).

RESULTS AND DISCUSSION

Dry weight of both cultivars in experiment-1 decreased substantially at

applied Zn levels above 11.2 lb/acre (Table-1). Apparently Zn rates above 11.2

lb/acre were toxic to peanuts, however, tissue and soil-test Ca levels also

decreased significantly (P<0.01) above this level of Zn. The effects of Zn and

Ca were, therefore, confounded in experiment-1. However, response to Zn can be

statistically evaluated between 0 and 11.2 lb of Zn/acre and between 22.4 and 84

lb of Zn/acre. The use of orthogonal single-degree-of-freedom comparisons shows

a difference between the two cultivars in response to Zn rates (Steel and Torrie,

1960). A comparison between 0 lb Zn/acre and 5.6 + 11.2 lb Zn/acre reveals no

significant (P>0.10) difference in dry-matter yields for Sunrunner but Zn

significantly (P<0.05) increased the yield of Southern Runner with high levels

of tissue and soil-test Ca. Dry-matter yield of Sunrunner did not respond to Zn

in the range of 22.4 to 84.0 lb/acre, while the yield of Southern Runner at 22.4

lb Zn/acre was about double the yields at higher Zn rates and slightly higher

than that of zero applied Zn.










Table 1. Dry weight and Zn and Ca concentration of two peanut cultivars grown
in greenhouse experiment-1 with different rates of Zn.


Sunrunner Southern Runner
Zinc rate Dry wtt Tissue Zn" Tissue Cat Dry wt* Tissue Zn" Tissue Cat

lb/Acre g/pot ppm % g/pot ppm %

0 52 a 16 1.02 a 20 a 12 0.98 a
5.6 61 a 16 0.94 a 33 b 17 0.89 a
11.2 68 a 18 1.14 a 36 b 19 0.84 a
22.4 24 b 34 0.69 b 27 d 32 0.67 b
33.6 10 b 53 0.61 b 10 c 41 0.56 b
44.8 27 b 58 0.64 b 6 c 54 0.54 b
56.0 17 b 85 0.61 b 14 c 58 0.56 b
84.0 20 b 96 0.65 b 17 c 80 0.67 b

ta is different from b (P<0.01) as shown by orthogonal comparison.
*a is different from b (P<0.05), a and b are different from c (P<0.01), d is
different from c (P<0.01) as shown by orthogonal comparisons. A comparison
between a and d is not orthogonal because each of these treatments were
contained in separate groups in another orthogonal comparison.
fRegression analyses were performed on tissue Zn data, see Fig. 2.


There was no indication in experiment-2 of Zn toxicity in peanuts at
extremely high Zn rates, however, tissue Ca levels were above 0.70% (Table 2).
This suggests that Zn toxicity symptoms in experiment-i resulted from a


combination of high Zn rates and low tissue Ca.


Tissue Ca levels in


experiment-1 were below 0.70% for Zn rates above 11.2 lb/acre.


Table 2. Dry weight and Zn and Ca concentration of two peanut cultivars grown
in greenhouse experiment-2 with different rates of Zn.


Sunrunner Southern Runner
Zinc rate Dry wtt Tissue Zn" Tissue Ca* Dry wtt Tissue Znt Tissue Ca*

lb/Acre g/pot ppm % g/pot ppm %

0 39 3 0.84 32 6 0.86
2.8 42 4 0.81 29 7 0.90
5.6 37 8 0.75 35 12 0.86
11.2 43 15 0.80 32 16 0.81
22.4 37 30 0.85 32 27 0.84
33.6 42 42 0.83 31 36 0.82
44.8 39 49 0.88 24 40 0.78
56.0 38 63 0.83 29 67 0.73

tEffect of Zn rate on dry wt was not significant (P>0.10).
*Concentrations of Ca in peanut tissue are not significantly (P>0.10)
different among treatments.
tRegression analyses were performed on tissue Zn data, see Fig. 2.











Lower peanut tissue Ca levels (<0.70%) in experiment-1 correspond with
lower soil-test Ca in the second batch of soil which was used in the highest
five levels of Zn treatments (Table 3). Soil pH was also lower with the lower
soil-test Ca levels.
Table 3. Soil pH, Zn, and Ca in samples from pots in which two peanut
cultivars were growing in greenhouse experiment-1 with different
rates of Zn.


Sunrunner Southern Runner
Zinc rate Soil pH Soil Zn* Soil Ca Soil pH Soil Zn* Soil Ca

lb/Acre ------lb/Acre---- ------lb/Acre-------

0 7.2 2.4 1096 bt 7.2 2.9 1112 ct
5.6 7.2 3.4 1074 b 7.3 4.4 1134 c
11.2 7.3 5.6 962 b 7.1 6.1 882 b
22.4 6.7 7.2 350 a 6.8 7.8 296 a
33.6 6.8 11.3 420 a 6.8 11.6 344 a
44.8 6.8 13.1 394 a 6.8 13.6 356 a
56.0 6.7 15.5 312 a 6.7 17.3 334 a
84.0 6.6 25.0 318 a 6.7 24.5 328 a


tNumbers within columns followed by different letters are significantly
different (P<0.01), numbers followed by the same letter are not significantly
different (P>0.05).
*Regression analyses were performed on soil Zn data, see Fig. 1.

Soil Ca levels in experiment-2 were all above 800 lb/acre (Table 4) and

soil pH ranged from 6.5 to 6.8. The yield increase of Southern Runner due to

added Zn in experiment-i occurred in the soil pH range of 7.1 to 7.3 (Table

2.). Extractable soil Zn in experiment-2 ranged from 0.4 to 20.6 lb acre

(Table 4.).


Table 4. Soil pH, Zn, and Ca in samples
cultivars were grown in greenhouse
of Zn.


from pots in which two peanut
experiment-2 with different rates


Sunrunner Southern Runner
Zinc rate Soil pH Soil Zn* Soil Ca Soil pH Soil Zn* Soil Ca

lb/Acre lb/Acre lb/Acre

0 6.6 0.4 808t 6.7 1.3 902t
2.8 6.7 0.7 808 6.7 1.8 904
5.6 6.7 1.3 822 6.6 2.8 872
11.2 6.5 3.1 846 6.6 5.5 932
22.4 6.5 7.3 962 6.8 8.4 886
33.6 6.5 12.0 860 6.7 13.0 964
44.8 6.7 15.6 922 6.8 17.2 922
56.0 6.5 20.6 954 6.7 20.1 890


tSoil calcium levels not significantly different (P>0.10).
*Regression analyses were performed on soil Zn data, see Fig. 1.











Extractable soil Zn was a linear function of applied Zn in both

experiments (Figure 1). Soil Ca and pH apparently did not have much influence

on extractable Zn, since applied Zn accounted for more than 90% of the

variation in extractable Zn. Average recovery of applied Zn in soil extract

ranged from about 26% in experiment-i to about 36% in experiment-2.

Zinc concentration in the tissue of Sunrunner peanuts was a quadratic

function of soil-test Zn in both experiment-1 and experiment-2 with maximum

predicted concentration above the range of values found in these experiments

(Figure 2). Whereas, a linear function was observed in Southern Runner in

both experiments (3.1 ppm per lb of soil-test Zn in experiment-1 and 2.7 in

experiment-2). The larger slope of the quadratic functions compared with the

linear functions in the soil-test Zn range of 0 to 5 lb/acre suggests that

Sunrunner takes up Zn more efficiently than Southern Runner.

A critical value of 50 for the Ca/Zn ratio in peanut leaves was

suggested by Parker et al. (1990). They found no Zn toxicity in peanuts with

Ca/Zn above 50 and all plants showing toxicity symptoms had a leaf Ca/Zn ratio

below 50. Our data cannot be compared directly with theirs because we

analyzed whole plants (stems and leaves) rather than youngest mature leaves.

Plant size may influence the critical Ca/Zn ratio in peanuts since Sunrunner

plants showed toxicity symptoms at values below 205 and Southern Runner plants

showed symptoms below values of 140 in experiment-1. Furthermore, the smaller

plants in experiment-2 had Ca/Zn ratios as low as 132 and 109 for Sunrunner

and Southern Runner, respectively, with no toxicity symptoms. Also, there is

not enough information available to determine the effect of soil-test Ca level

on the critical Ca/Zn ratio in peanuts.

CONCLUSIONS

Southern Runner produced a positive response to Zn rate with soil pH

above 7.0 and soil Ca above 1000 Ib/acre. However, Sunrunner did not respond

to Zn rates without a concurrent change in soil Ca. The data support the

hypothesis that Southern Runner is more sensitive to Zn deficiency than

Sunrunner. An extractable Zn level of 5 lb/acre appeared adequate for peanut

production at soil Ca levels above 800 lb/acre.

Peanut response to Zn when soil-test Zn was low appeared to be dependent

on soil pH. High Zn (up to 20.6 lb/acre of extractable Zn) did not influence











EXTRACTABLE VS APPLIED ZINC


Soil-Test Zn (Ib/acre)
30
CD 0.964
!5

CD 0.947
!0-

15 C 04

10

5-

0
0 20 40 60 80 10
Zinc Rate (Ib/acre)


Figure 1. Extractable soil Zn
experiments for two


Data Source
V Means Expt. 1
-- Y 2.41 + 0.259X
x Means Expt. 2
- Y 0.329 + 0.357X


as a function of fertilizer Zn rate in two peanut
cultivars. CD = coefficient of determination.


TISSUE ZN IN PEANUTS VS SOIL-TEST ZN


Tissue Zn (ppm)
120

100


0 5 10
Soil-Test


Data Source
V Exp-1 SunR
- Y*-4.7+6.2X-.084X^2
x Exp-1 Southern R.
Y 5.12 + 3.08X
SExp-2 SunR
Y3.2+4.0X-.058X'2
x Exp-2 Southern R.
- Y 2.20 + 2.74X


15 20 25
Zn (Ib/acre)


Figure 2. Zinc concentration of peanut plants as a
in two experiments for two cultivars. CD
determination.


function of extractable soil Zn
= coefficient of




- w


plant growth with soil Ca levels above 800 lb/acre and a soil pH range of 6.5

to 6.8. Extractable soil Zn at 7.2 lb/acre and above reduced plant growth of

both cultivars at soil Ca levels in the 300 to 400 lb/acre range with soil pH

values of 6.6 and above. Therefore, Zn toxicity was related to soil Ca as

well as soil Zn.

Average recovery of applied Zn in the soil extract ranged from 21 to

37%. Extractable Zn was highly correlated with applied Zn rates and peanut

tissue Zn was highly correlated with soil-test Zn levels.

REFERENCES

Beasley, J. P.. 1987. Crop rotation. Chap. 2. In W. C. Johnson (ed.) Georgia

peanut production guide. Cooperative Extension Service, Univ. of

Georgia, and U.S.D.A. Athens, Georgia.

Johnson, W. C. 1987. Soil fertility. Chap. 3. In W. C. Johnson (ed.)

Georgia peanut production guide. Cooperative Extension Service, Univ.

of Georgia, and U.S.D.A. Athens, Georgia.

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.

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

statistics. McGraw-Hill, New York.




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