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the potassium fertilization, but not enough for dilution to account for the
differences in Cs-137 contents. The absence of radiocesium in the P-K treatment
was associated with an unusually high K level in the plant tissue.
Following this preliminary experiment with tomato, a further greenhouse trial
was made with squash, varicty Hubbard. Squash was used because it is one of
the fewherbaccous plants successfully cultivated in the northern Marshall Islands.
The treatments were set up in triplicate. replication was good, and the plants
grew well except for some chlorosis which was not entirely corrected bv the
application of 1.5 mg Fe per pot as NaFeEDTA(Fe chelated by ethyvlenediaminetetraacetic acid), The plants were divided into upperleaf, lower leaf, and stem
fractions at harvest. Since the results were qualitatively the same for the different
fractions andspaceis limited, Table 1 presents the vields and K and Cs analyses
on the basis of the entire shoot. The results of this experiment were in general
TABLE 1
Cesium aND Potrassiust CONTENTS OF SQUASH AND OF NATIVE SPECIES
Description
Average
drv vield
igm)
meq
KR
per 100 gm
Csi
d/m/g
Squash in greenhouse pot cultures (total shoot}
No fertilizer
45
29.6
410434
Ni Py Re
80
77
WOs11
NaP. Rk:
N3 Pa Ke
5.4
8 4
47 5
26 8
15U = 14
120=16
Ww 2
205.3
Plu 15
NiP, RK:
N, P,; Kk. Fe
v4
36.5
1304 14
Foliage collected from woody plants on Rongeiap Isiand
Messerschmidta argentea
upper ieaves
33
upper leaves
35
upper leaves
18 3
(soil pit 25,
lower leaves
(soil pit 25)
lower ieaves
(village-2)
lower leaves
Scaevoa sericea
Pandanus tectortns
6.6
12
84
2408
1307
Hoa
1aG47
26345
13544
lError given is 95% counting error.
"Subscripts refer to rate of application per acre of N, P:O-. or KO,
in hundreds of pounds.
similar to those with the tomato, although there was no response in vield to
potassium additions, and the tissue from the N.P,K» treatment contained Cs-137.
In all cases the fertilizer amendments caused a sharp reduction in the Cs-157
content expressed on a d/m/gm drv basis, although this effect could not be
associated with a particular fertilizer element. The depressive effect of fertilization on cesium uptake is also evident when the total Cs-137 in the shootis caleu-
lated, indicating that dilution by a greater amount of drv vield cannot explain
the reduced cesium content. In the difterent portions of the squash shoots, Cs-137
was in all treatments highest in the upper leaves, lowest in the lower leaves,
and intermediate in the stem. Squash plants grown on the same benchat the
same time but in a greenhouse loam soil contained no Cs-137. Results of analyses
for Ca, Mg Na. and PO,in thetissue do notoffer anv obvious explanation for the
differences in cesium uptake, although it should be noted that calcium levels
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