Ramasamy et al. - 1997 - Yield formation in rice in response to drainage an

S. Ramasamy et al. /Field Crops Research 51 (19971 65-82 71
Table
Treatment
D;N100
D,-Nl50
D, -N200
1 (continued)
Root wt at Productive tillers Spikelets per panicle (No.)
harvest (kg/ha) (No. pa hill)
total filled unfilled
1240 10.8 75.2 65.1
1300 11.1 78.6 66.3
1310 11.5 82.6 67.5
10.2
12.3
15.3
Grain weight Harvest Index Grain yield
hg) (ratio) (kg/ha)
18.5 0.53 8380
18.6 0.52 8460
18.5 0.52 8870
Drainage
SEd
CD
Nitrogen
SEd
CD
D at IX
SEd
Cd
N at D
SEd
CD
31 0.3 0.93 0.71 0.62 0.24 0.01 51
71 NS NS 1.60 1.40 N’s 0.03 162
29 0.3 1.11 0.58 0.73 0.14 0.0 1 79
NS 0.54 2.3 NS 1.5 0.28 0.02 172
4s 0.32 1.59 0.69 1.04 0.29 0.02 160
NS NS NS NS 1.2 NS 0.04 350
39 0.37 1.58 0.82 1.03 0.19 0.03 152
NS NS NS 1.69 2.1 NS NS 331
Expt. 4 *
4
D, + N
DW
D, + N
2. I
2.1
4.3
3.2
9.1
9.1
8.3
8.3
120 71.1
121 70.2
116 89.3
116 95.0
43.2
50.6
26.7
21.2
18.9 n.d. 6500
18.7 n.d. 5850
20.3 n.d. 7390
20.3 n.d. 7740
SEd
CD
0.05
0.11
0.3
0.6
1.3 3.1
2.8 6.7
2.3
4.9
0.35 n.d. 209
0.75 n.d. 455
NS: not significant at P = 0.05; CD: critical difference at P = 0.05; n.d.: not determined: 0,: undrained; D,: drained; NlOO, N150, N200:
100, 150 and 200 kg fertilizer N ha-’ : + N (Expt. 4): 30 kg N ha ’ at heading.
’ Root oxidizing power in mg h- ’ per g of fresh root.
of the drained plots. Larger applications of N resulted
in greater leaf N concentrations and total
amounts of N in leaves. The maximum amount of N
in green leaves recorded in all three experiments was
68 kg/ha (Expt. 2, at 61 DAT with 200 kg N). The
amount of N in green leaves just before harvest was
significantly larger in plants from drained than in
those from undrained plots (Table 3; Fig. 2).
Drainage increased the translocation of N accumulated
in stems, from 24 to 34 kg N haa’ (i.e.
57-64% of accumulated stem N) to 46 to 56 kg
ha- ’ (SO-82%). More N was translocated from stems
than from leaves, under drained conditions (Table 3).
3.5. Root growth. color und actidty; culms
The amount of N in dead and senescent leaves Total root dry weight increased up to heading and
and also the corresponding N concentrations, in- was greater under drained conditions. It decreased 14
creased as crop age advanced. A largest quantity of to 23% in drained field conditions after reaching its
25 kg N in dead and senescent leaves was recorded peak value, compared to 26 to 29% in undrained
for IR20 at harvest (Expt. 2). The N concentration in plots, leading to final values (at harvest) that were 20
these tissues increased from 0.3% of dry matter soon to 36% greater in drained than in undrained treatafter
heading to 0.7% at maturity. Values were ments. Root biomass increased with N application
slightly lower in drained than undrained plots. level. The largest amounts were observed in Expt. 2