Effect of Plant Geometry on Growth and Yield of Corn in the Rice-Corn Cropping System
1930
plant−1 and the plants at 50 × 20 cm took 2.6 WAP (Ta-
ble 1). Although there was a difference of 0.6 weeks be-
tween the treatments, the difference was statistically si-
milar. The results of height and leaf numbers plant−1 sug-
gest that the tested plant geometry may not influence the
development of height and leaf production in corn.
In contrast to plant height and leaf numbers, the leaf
area and shoot biomass of corn were greatly influenced
by the plant geometry. At 4 and 8 WAP, highest leaf area
was produced by plants grown at 50 × 20 cm spacing
(Table 2). The plants grown at 75 × 30 cm spacing pro-
duced lowest leaf area m−2 and this was significantly
lower than the leaf area at other three spacing. Leaf area,
however, was not influenced between plants grown at 50
× 30 cm and 75 × 20 cm. A similar response was ob-
served for the aboveground biomass (Table 2). Plants
grown at 50 × 20 cm produced the highest shoot biomass
and plants grown at 75 × 30 cm produced the least shoot
biomass at 4 and 8 WAP. At 8 WAP, for example, corn
produced 1295 and 623 g·m−2 of biomass when grown at
50 × 20 cm and 75 × 30 cm, respectively. At both tim-
ings (i.e., 4 and 8 WAP), the plants produced similar
biomass at 50 × 30 cm and 75 × 20 cm spacing.
Plant geometry influenced the grain yield of corn.
Highest grain yield (8.2 t·ha−1) was produced by plants
grown at the narrowest spacing, that is, 50 × 20 cm (Fi-
gure 3). However, the yield at 50 cm row spacing was
not influenced (7.8 - 8.2 t·ha−1) by the plant to plant
spacing. Similarly, plant to plant spacing at 75 cm rows
did not influence grain yield and it ranged from 6.1 to 6.4
t·ha−1.
The results of our study suggest that narrowing row
may lead to increased leaf area and crop biomass per unit
area. Earlier studies hypothesized that narrow rows in-
creased light interception in the early growing season and
this led to increased crop growth rates and earlier can-
opy closure [3,9,12]. An earlier study reported that leaf
area increases and light transmittance to the soil surface
declines as corn plant population increases [13]. Al-
though we did not evaluate the effect of row spacing on
weed growth, various studies suggest that narrow row
spacing significantly suppresses weed growth due to ear-
lier canopy closure compared with wider rows [11,12,14,
Table 2. Effect of spacing (row and plant to plant) on leaf
area and corn biomass at 4 and 8 weeks after planting
(WAP).
Leaf area (cm2·m−2) Biomass (g·m−2)
Spacing (cm) 4 WAP 8 WAP 4 WAP 8 WAP
50 × 20 18947 (625) 53900 (1900) 115 (7) 1295 (104)
50 × 30 12645 (419) 38000 (1700) 72 (9) 900 (125)
75 × 20 11567 (524) 38600 (3200) 69 (6) 833 (81)
75 × 30 7249 (727) 25600 (900) 42 (6) 623 (27)
Row a nd plant to plant spacing (cm)
50 x 2050 x 3075 x 2075 x 30
Grain yield (t ha-1)
0
2
4
6
8
10
(t·ha
-1
)
Figure 3. Effect of plant geometry (row and plant to plant
spacing: 50 × 20, 50 × 30, 75 × 20, and 75 × 30 cm) on grain
yield of corn.
15]. Teasdale suggested the importance of the early can-
opy closure in a reduction of the critical period for weed
competition by one week [12]. Therefore, our study also
suggests that growing corn in narrow rows may have the
potential for improving weed management in reduced-
herbicide systems [12,16]. As crop cultivars differ in
their growth traits (e.g., height, leaf morphology, etc.),
more research is needed in tropical conditions to clearly
demonstrate the effect of narrow rows on growth and
yield of corn.
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