154
AGRONOMY JOURNAL, VOL. 93, JANUARY–FEBRUARY 2001
Table 4. Effect of Zn seed treatment source and rate on rice total Table 2. Effect of rice cultivar on grain yield, total dry matter
TDM, and harvest moisture averaged across Zn treatments dry matter TDM by 14 d after flooding compared with an
untreated and standard check at two locations in 1999.
during 1998 at the Rice Research and Extension Center RREC, near Stuttgart.
TDM† Cultivar
Grain yield TDM
Grain moisture Zn fertilizer treatment
PTBS‡ RREC§
kg ha
2
1
g kg
2
1
kg ha
2
1
Drew 4838
428 210
Control 659
377 Cypress
4435 358
230 11 kg Zn ha
2
1
PPI¶ 708
1007 Jefferson
3125 275
188 1.0 g Zn-ZnSO
4
kg seed
2
1
986 820
LSD0.05 353
95 21
2.2 g Zn-ZnSO
4
kg seed
2
1
1053 1056
4.7 g Zn-ZNSO
4
kg seed
2
1
1181 1111
Significant at the 0.05 level. 1.4 g Zn-EDTA kg seed
2
1
849 562
Significant at the 0.001 level. 2.8 g Zn-EDTA kg seed
2
1
1193 955
5.7 g Zn-EDTA kg seed
2
1
1147 1232
fertilizer treatment interaction but were significantly
LSD0.10 within location 136
LSD0.10 between locations 193
different among cultivars Table 2. The lack of differ- ences among the Zn fertilizer treatments suggested that
† P-value for Zn fertilizer treatment 3 location 5 0.092.
‡ PTBS, Pine Tree Branch Station, Colt, AR.
rice was not Zn deficient and would not show a signifi-
§ RREC, Rice Research and Extension Center, near Stuttgart, AR.
cant yield and growth response to Zn fertilization. Al-
¶ Standard check. PPI, preplant incorporated.
though not statistically significant at the 0.05 level of
Seeding rate for all treatments was 120 kg ha
2
1
seed.
probability P 5 0.16, the grain yield for both 11 kg Zn ha
2
1
PPI and 2.8 g Zn kg seed
2
1
was 214 and 360 plots while few or no symptoms were observed in the
kg ha
2
1
greater than the control, respectively, when 4.7 g Zn kg seed
2
1
as ZnSO
4
and 5.7 g Zn kg seed
2
1
averaged across the cultivars Table 3. as ZnEDTA plots. The deficiency symptoms were most
The tissue Zn concentration of whole-plant seedlings severe at the RREC. Thus, the response of the rice
14 d after flooding did show significant differences be- TDM among Zn treatments differed between locations
tween Zn fertilizer treatments Table 3. The tissue Zn for some treatments Table 4. The rice TDM response
concentration followed the highest-to-lowest order of at each location was indicative of the degree of Zn
11 kg Zn ha
2
1
PPI . 2.8 g Zn kg seed
2
1
. control. deficiency symptoms expressed among Zn treatments
Rasmussen and Boawn 1969 suggested that Zn seed at each location.
treatment of kidney bean was not an adequate alterna- At the PTBS, seeds that were treated with Zn pro-
tive to broadcast Zn fertilizer applications to the soil duced significantly greater TDM by 14 d after flooding
because Zn deficiency symptoms occurred, and Zn seed than both the control and 11 kg Zn ha
2
1
PPI, regardless treatment failed to produce yields equal to soil Zn appli-
of the Zn source or rate. It is unclear why Zn deficiency cation. Based on the 1998 tissue concentration data, 11
symptoms occurred in the 11 kg Zn ha
2
1
PPI treatment. kg Zn ha
2
1
PPI was superior to 2.8 g Zn kg seed
2
1
The random occurrence of deficiency symptoms within for supplying Zn to seedling rice plants. However, both
each 11 kg Zn ha
2
1
PPI plot suggests that uniform fertil- treatments increased tissue Zn in rice seedlings above
izer distribution at the applied rate could not supply the the level considered deficient 20 mg kg
2
1
while the plants that were physically located between fertilizer
control was near the critical threshold Sedberry et al., granules with adequate Zn nutrition. Both the control
1987. Although Zn tissue concentration data were a and 11 kg Zn ha
2
1
PPI treatments recovered from the useful means of evaluation, the effectiveness of Zn seed
treatments can best be made under Zn deficient con- early Zn deficiency symptoms within 14 d after plant
ditions. samples were taken. Within the Zn seed treatments, the
TDM tended to increase as the Zn application rate in-
1999 Experiments
creased. At the RREC, the TDM for 11 kg Zn ha
2
1
PPI was Zinc deficiency symptoms similar to those described
significantly greater than the control, 1.0 g Zn kg by Sedberry et al. 1978 were observed at both locations
seed
2
1
as ZnSO
4
, and 1.4 g Zn kg seed
2
1
as ZnEDTA in 1999. The symptoms were most severe in the control
treatments and equal to all other treatments. Stand loss
Table 3. Effect of Zn fertilizer treatment, averaged across culti-
occurred in two of four replications of the control plots
vars, on grain yield and tissue Zn concentration of seedling
at the RREC and resulted in a significantly lower TDM
rice 14 d after flooding during 1998 at the Rice Research and
than the control at the PTBS. The only other treatments
Extension Center RREC, near Stuttgart.
that showed significant differences between locations
Tissue Zn
were the 11 kg Zn ha
2
1
PPI and 1.4 g Zn kg seed
2
1
Zn fertilizer treatment Grain yield
concentration
as ZnEDTA treatments. It is unclear why the 11 kg Zn
kg ha
2
1
mg kg
2
1
ha
2
1
PPI treatment responded differently between the
Control 3929
19.7
two locations. The 1.4 g Zn kg seed
2
1
as ZnEDTA
11 kg Zn ha
2
1
PPI† 4143
31.6 2.8 g Zn kg seed
2
1
‡ 4289
24.4
and 1.0 g Zn kg seed
2
1
as ZnSO
4
treatments apparently
LSD0.05 NS§
2.6
contained insufficient Zn to maximize plant growth at
Significant at the 0.001 probability level.
the RREC. Based on the TDM data from both locations,
† PPI, preplant incorporated.
Zn seed treatments should be applied at rates between
‡ Seeding rate for all treatments was 120 kg ha
2
1
seed. § NS, not significant at the 0.05 level of probability. P
5 0.16.
2.2 and 5.8 g Zn kg seed
2
1
for optimum growth under
SLATON ET AL.: EVALUATION OF ZINC SEED TREATMENTS FOR RICE
155
Table 6. Effect of Zn seed treatment source and rate on rice grain Table 5. Effect of Zn seed treatment source and rate on rice
tissue Zn concentration by 14 d after flooding compared with yield and harvest grain moisture compared with an untreated
and standard check in 1999 data averaged across two lo-
an untreated and standard check at two locations in 1999. cations.
Tissue Zn concentration Zinc treatment
Grain yield Grain moisture
Treatment PTBS†
RREC‡ kg ha
2
1
g kg
2
1
mg kg
2
1
Control 6154
198 Control
17.5 17.5
11 kg Zn ha
2
1
PPI† 7590
187 11 kg Zn ha
2
1
PPI§ 19.4
31.0 1.0 g Zn-ZnSO
4
kg seed
2
1
‡ 7051
179 1.0 g Zn-ZnSO
4
kg seed
2
1
¶ 20.2
16.9 2.2 g Zn-ZnSO
