NFREC Research Report 94-13
PEARL MILLET NUTRIENT UPTAKE AND AGRONOMIC CHARACTERISTIC Gy
IN RELATION TO PLANTING DATE AND GROWTH STAGE Jg 0 2~A
University of Florida
D.L. Wright, I.D. Teare', and J.A. Spitalniak
Traditionally pearl millet [Pennisetum qlaucum (L.) R. Br.]
has been managed as a low energy input crop, but it responds to
higher fertilizer rates (Gascho et al., 1995). Environmental
changes associated with planting date of HGMm100 pearl millet
(available water, day length and temperature) and the interactions
with insect and disease cycles must be better understood to
optimize crop yields. These interactions have been defined as
Systems Agriculture in recent years. Knowledge of plant, insect
and disease ontogeny in relation to growth stage, date of planting,
and nutrient uptake makes it possible to compare or to combine
limited bits of pearl millet management information from all over
the world to explain yield phenomena (Teare and Hodges, 1994).
Francis et al. (1984) conducted research that suggested
"planting time may affect genotype yield stability" in sorghum
(Sorqhum bicolor (L.) Moench]. They observed less interaction
North Florida Res. and Educ. Ctr. Quincy, FL 32351, Univ. of Florida, FL 32611); Fla. Agric. Expt. Stn. Res. Rep.
for yield between genotypes and environment when hybrids were
planted late than when planted early. This observation was
attributed to more rapid development and less exposure to stress
conditions in later plantings.
Plant tissues accumulate and store nutrients during ontogeny.
Gascho et al. (1995) have investigated above-ground pearl millet
whole plant nitrogen and found increased concentrations of N in
growth stage 4 and 7. Plants in stage 7 displayed lower N
concentration than those found in stage 4.
The objective of this study was to compare NPK concentrations
in relation to growth stages and agronomic characteristics for
pearl millet and to quantitatively describe the total accumulation
of NPK nutrient uptake during the pearl millet growing season.
MATERIALS AND METHODS
These studies were conducted in 1993 on a Dothan sandy loam
(fine, loamy siliceous, thermic Plinthic Kandiudult) located on the
North Florida Research and Education Center, Quincy, Florida. The
soil has a compacted layer located 8 to 14 inches below the
The pearl millet hybrid used in this series of experiments was
HGMT100. Pearl millet seed was no-till planted (in-row subsoiled
strip tillage) with a Brown Ro-Til implement with KMC unit
The pearl millet date of planting study was a split plot
design with planting dates (PD) as whole plots and growth stages
determined for six replications in relation to calendar date,
development period, and total water as subplots. Planting dates,
growth stages (GS), and nutrient uptake are shown in Table 1.
Plots were eight rows wide (rows were 36 inches apart) and 30 feet
long. Pearl millet seed were planted 3/4" deep at 4 lbs/A (302,667
seeds/A). This resulted in approximately 166,467 plants/A, or
approximately 55 % emergence.
Fertilizer (5-10-15 at 500 lbs/A) was applied three days prior
to planting. Nitrogen was sidedressed at a rate of 120 lbs/A at
boot stage (GS 5). Prowl @ 1 qt/A + Atrazine @ 2 qt/A were
applied between third visible leaf (GS 1) and 5th visible leaf (GS
2) (Table 1), 10 to 15 days after planting (DAP) when pearl millet
was 3 to 5 inches tall). I
Little rainfall occurred throughout the early growing season
for this experiment. One half inch applications of irrigation were
scheduled in response to paucity of rainfall.
Pearl millet plants were collected for nutrient uptake
analysis five times: first, from May PD, 38 DAP (2.5 feet tall);
second, from June PD, 37 DAP (3 feet tall); third, from April PD,
68 DAP (50 % stigma emerged); fourth, from May PD, 68 DAP (milk-
soft dough); and fifth, from April PD, 98 DAP (maturity).
RESULTS AND DISCUSSION
Table 1 presents growth stages, planting dates, cutting days,
and NPK concentration and accumulation for pearl millet.
Generally, nutrient concentration decreased and total uptake
increased during plant ontogeny.
Pearl millet showed very high N concentration at stage 4 (98
lb/A) which decreased with ontogeny (Fig. 1) and reached its
maximum uptake (accumulation) (136.7 lb/A) at maturity (GS 6).
Pearl millet maximum concentration was at GS 5 and accumulated
till GS 7.5 (0.16 lb/A) and then leveled off.
Potassium concentration was highest at GS 4 when the crop was
2.5 feet tall (6.2 %). Potassium accumulated from 203 lb/A at GS
4 through 444.5 lb/A at GS 9 at milk-soft dough stage and then
decreased toward maturity.
Based on this study, millet uses 2-3 times more K at the milk-
soft dough stage than N and 25-40 times more K than P followed by
a greater decline at maturity than N and P. Spitalniak (1995)
reported that pearl millet accumulated more potassium than tropical
or temperate corn.
Pearl millet head lengths and yield are shown for each planting
date in Table 2. The 15 July planting date (PD4) produced less seed
and sustained greater bird predation than the other planting dates.
Lower yield at the later planting date probably wasn't a lack of
available water (18.2 inches PD4 compared to 16.4 inches for PD,).
Seed size changes in relation to planting date indicates that
environment affected grain yield. Contrary to Mahalakshmi et al.
(1988), we found differences in seed size (lb/1000 seed) due to
planting date (Table 2). One would expect that the 15 July
planting date (PD4), with fewer seeds per head, should have large
seeds like PD2 or at least seeds the same size as PD, and PD3, but
the seed size and number of seeds was less than the earlier
plantings. Seed size (lb/1000 seed) and grain yield (Table 2) were
increased by increased available water (19.1 inches for PD2) and
extended the no. days from planting date to maturity to 89
(compared to PD4) of 75 days)(Teare et al., 1995). Thus, PD2 (17
May) may be the optimum planting time for pearl millet in North
Maximum leaf area per plant, main stem, and tillers are shown
in Table 2, in relation to planting date. Two peaks in LA occurred
in PDi, PD2, and PD3 (data not shown). The first peaks were at GS
6, 5.5, and 5.7, respectively. The second peaks were at GS 8,8,
and 7; respectively. The leaf area for PD4 only peaked at GS 6.5.
Leaf area duration (LAD) is defined as the days where LAI was
greater than 3.5. Leaf area duration occurred from the boot stage
(GS 5) to black layer formation (GS 9) for all PD's but PD3 which
attained a LAI of 3.5 when the flag was visible (GS 4) and remained
at 3.5 until black layer formation (GS 9).
Our thanks to E. Brown Agricultural Technician IV; North Fla.
Res. and Educ. Ctr. Univ. of Fla., Quincy, FL; for plot
preparation and management, data collection, computer processing,
and data illustration.
Francis, C. A., S. Mohammed. L.A. Nelson, and R. Moomaw. 1984.
Yield stability of sorghum hybrids and random mating
populations in early and late planting dates. Crop Sci.
Gascho G.J., R.S.C. Menezes, W.W. Hanna, R.K. Hubbard, and J.P.
Wilson. 1995. Nutrient requirements of pearl millet. pp. 92-97.
In: I.D. Teare (Ed.) Proc. of First Nat. Grain Pearl Millet
Symp. Tifton, GA. Jan 17-18.
Mahalakshmi, V., F.R. Bidinger, and G.D.P. Rao. 1988. Timing ad
intensity of water deficits during flowering and grain-
filling in pearl millet. Agron. J. 80:130-135.
Spitalniak, J.A, D.L. Wright, I.D. Teare, and N.R. Usherwood.
1995. Nutrient uptake (NPK) in relation to growth stage for
pearl millet, tropical corn and temperate corn. pp. 92-97. i
I.D. Teare (Ed.) Proc. of First Nat. Grain Pearl Millet STp
Tifton, GA. Jan 17-18.
Teare, I.D., D.L. Wright, and N.R. Usherwood. 1995. Planting de
effects on HGMTM100 pearl millet physiological development and
agronomic characteristics. pp. 42-46. In: I.D. Teare (Ed.)
Proc. of First Nat. Grain Pearl Millet Symp. Tifton, GA. Jan
Teare, I.D., and Hodges. 1994. Soybean ecology and physiology.
pp. 4-7. In Leon Higley and David Boethle (ed.). ESA Handbook
of Soybean Insect Pests. Lanham, MD 20706.
Wright D.L., I.D. Teare, F.M. Rhoads, and R.K. Sprenkel. 1993.
Pearl millet as an alternate crop in a double-crop system. Fla.
Agric. Exp. Stn. Res. Rep No. NF-93-5: 1-9.
Table 1. N P K concentration and nutrient uptake of pearl millet in relation to planting date, stage of growth, days from planting to cutting, and agronomic
characteristics, Quincy, FL 1993.
Growth Planting Planting Concentration Total N Total P Total K
Crop stage Description date to cutting % N % P % K uptake uptake uptake
(days) (lb/A) (lb/A) (lb/A)
Pearl 4 2.5 feet tall 15 May 38 2.96 0.19 6.20 98.1 6.1 203.2
millet 5 3.0 feet tall 15 June 37 2.91 0.21 6.50 108.4 7.8 243.6
(HGMTo100) 6 50% stigma emerged 15 April 68 2.34 0.16 5.20 143.6 9.9 315.5
7.5 milk-soft dough 15 May 68 1.35 0.16 4.30 139.7 16.0 444.5
9 maturity 15 April 98 1.33 0.14 3.40 136.7 14.1 341.7
Table 2. Mean agronomic characteristics of pearl millet at maturity unless otherwise specified in relation to planting date, Quincy, FL 1993.
Grain Yield Stalk
Planting Plant'J Head Stem Leaf Stalk3' Seed size Cage Max LAI
date Ht. length2J DW DW DW (lb/1000 Harested Main LADJ
(inches) (inches) (Ton/A) (Ton/A) (Ton/A) seeds) (lb/A) (T/A) (Bu/A) (% grain)' stem Tillers Plant days
5 May 82 13.5 7.1 3.3 10.4 0.015 3266 1.63 57 15.6 1.4 3.0 4.4 50
17 May 76 15.0 8.8 4.5 13.3 0.022 3705 1.85 65 13.9 5.6 2.9 8.5 53
15 June 78 12.5 7.1 4.9 12.1 0.014 2998 1.50 53 12.4 2.6 2.4 5.0 50
15 July 65 11.8 5.1 3.3 8.4 0.008 2029 1.01 36 12.0 2.1 3.4 5.6 40
'J Approximately 166,467 pl/A.
2J Approximately 144,600 hd/A.
3J Grain (T/A) = % grain; stalk DW = leaf DW + stem DW
4J LAD = leaf area duration, the days from LAI of 3.5 to black layer formation(LAI = 3.5).
140 P-earl millet
1 2 3 4 5 6 7 8 9 10
Stage of growth
Stage of growth
S\ Pearl millet
2 3 4 5 6 7 8 9 10
Stage of growth