ACHARYA N.G RANGA AGRICULTURAL UNIVERSITY

DRY MATTER PARTITIONING AND GRAIN YIELD POTENTIAL OF MAIZE
fertilized with a uniform dose of 60 kg ha -1 P 2
O 5
as
single super phosphate, potassium @ 60 kg ha -1 as
muriate of potash and ZnSO 4
@ 50 kg ha -1 . The entire
P 2
O 5,
ZnSO 4
and half of K 2
O were applied at sowing.
Nitrogen was applied as per the treatments in the
form of urea (46% N) in three equal splits (1/3 each
at basal, at knee-high and tasseling). Similarly the
remaining potassium was applied along with urea
during second top dressing at tasseling. Other cultural
operations and plant protection measures were
followed as per the recommendations. During the crop
period rainfall of 538.7 mm was received in 31 rainy
days in 2009 and 943.8 mm in 56 rainy days in 2010,
respectively as against the decennial average of
588.1 mm received in 37 rainy days, for the
corresponding period indicating 2010 as wet year.
Plant samples of maize were collected for dry matter
estimation at six leaf, tasseling, silking and
physiological maturity stages from different
treatments. Data were collected on seed yield. Dry
weight per plant was calculated as sum of the dry
weights of the plant components. Cobs were
threshed, grains were counted, weighed and the grain
yield per plant was worked out.
RESULTS AND DISCUSSIONS
Dry matter production increased steadily
after crop establishment until maturity in all the
treatments. The crop accumulated more DM during
2009 as compared to 2010 wet season. In 2009, 21
July (D 2
) sown crop and 7 July (D 1
) sown crop
produced onpar dry matter at six leaf, tasseling,
silking and physiological maturity stages (Table 1 ).
Lowest DM accumulation at all these stages was
observed in 22 August (D 4
) sown crop. In 2010, 18
June (D 1
) sown crop showed maximum DM
accumulation at six leaf (9.8 g plant -1 ), tasseling (83.3
g plant -1 ), silking (89.9 g plant -1 ), and maturity stages
(203.2 g plant -1 ), and was on par with 2 July (D 2
)
sown crop and significantly superior to 17 July (D 3
)
and 2 August (D 4
) sown crop. Sowing beyond 21 July
and 17 July reduced the DM production in 2009 and
2010 by 11% and 11%, respectively over early sown
crop. The observed difference in DM accumulation
during development may result from differences in
climate, differential absorption of PAR due to variation
in plant population and LAI, or differences in the
efficiency of converting absorbed photosynthetic
active radiation (APAR) into DM (Tollenaar and Aguilera,
1992).
Relatively higher DM accumulation was recorded with
400 kg N ha -1 at six leaf, tasseling, silking, and
physiological maturity stages (Table 1), but significant
increase was observed only upto 200 kg N ha -1 over
100 kg N ha -1 and control (N 0
). The increase in DM
accumulation with higher level of nitrogen was due
to better crop growth, which also gave maximum plant
height, LAI and ultimately produced more biological
yield. Enhanced DM production with adequate supply
of nitrogen, as evidenced in this investigation
corroborates the findings of Raja (2001) and Ramu
(2005).
Observations were also made on dry matter
partitioning. Dates of sowing and graded levels of N
had significant effects on leaf weight per plant. In
2009, delay in sowing significantly reduced the leaf
weight per plant from 34 to 25 g plant -1 , but 21 July
(D 2
) sown crop and 7 July (D 1
) sown crop produced
onpar leaf weight per plant. In 2010 also crop showed
similar trend and 18 June (D 1
) sown crop produced
significantly higher leaf weight per plant (34 g plant -1 )
followed by 2 July (D 2
) sown crop (33 g plant -1 ) while
lowest leaf weight per plant was observed in 2 August
sown crop.
Increase in the rate of N significantly
increased leaf per weight plant from a minimum of
16.0 g at the lowest rate of N to a maximum of 39.0
g at higher rates (400 kg ha - 1) of N application.
Increase in leaf weight per plant with increase in N
rate application was due to the increase in leaf size
and chlorophyll content, which resulted in higher leaf
weight per plant. These results are in confirmation
with those of Rajcan and Tollenaar (1999) that
increase in N rates increased leaf longevity and
photosynthesis in maize which results in higher dry
matter production. Similar results were reported by
Pandey et al. (2000) and Turgut (2000) that dry matter
production of maize increased with increase in the
rate of N application.
Dates of sowing and graded levels of nitrogen
significantly affected stem weight per plant (Table
1). Higher stem weight of 41.0 g plant -1 was recorded
in the crop sown on 21 July and 18 June in 2009 and
2010. Lowest stem weight was recorded in 22 August
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