Vergara - 1976 - Physiological and morphological adaptability of ri

522 CLIMXFE AND RICE
Géain yield tt/ha)
4
Marcos, Phitippines
Low N LEVEL
Rat Rat , Thailand
2
, Ra" i Rat, Thailand
‘Marcos, Philippines
o
I I I l I I l l I I l. l
O 20 40 60 0 2O 40 60
MEDIUM N LEVEL
6 .
Pedapulieru , India fiwpullfl“ - Md":
4 t- ,-
2 _ San NICOlOS , Philippines
’_
-\sm “molds” Philippines
0i:1
l l l l l l
q Ll l l l l l l
O 40 6O 80 IOO O 40 6O 80 I00
HIGH N LEVEL
IO
8»-
6- _
Kahumq-i, Indonesia
4p —
g.-
Kariyamonqatam, India
_
Kariyamanqalam, India
Wet season
Dr! season
0L‘? j_ | 4 | I |
| I i I 1 I
_H|
O 70 IIO I50 I90 0 7O llO I50 I90
Nitrogen applied (kg/ha)
Nilrflqfin Oppliefi lkq/hfll
9. Nitrogen response of modem varieties in selected villages in India. Indonesia. Thailand.
and the Philippines (adapted from Auden and Barker. 1973).
obtained l.l t/ha higher yield than farmers using no fertilizer. In the second
group. farmers using 100 kg Niha had an additional average yield increase of
0.7 t/ha. The farmers in the third group. using an average of 135 kg/ha. found
that nitrogen response was no better than in the second group (Fig. 9).
I11 the dry season of the same year. fanners using 60 kg Niha in Rai Rot.
lhailand. increased their yield by 50%; those in Kahuman. Indonesia. and
Kariyainangalarn in India increased their yield l1)’ 2.5 t/ha when they increased
N from 50 to 150 kg/ha (Fig. 9).
Although drjir- and wet-season differences in nitrogen response in the study
area in India. Indonesia. and Thailand were similar to differences reported in
various studies at experiment stations. the magnitude of nitrogen response was
considerably lower in the study-area villages. Therefore. Andcn and Barker
(I973) suggested that although N fertilizer appeared to be the main factor affecting
yield. other factors constrained yield in the study areas.
Weed control
Under farm conditions. weed infestation and its control affect the nitrogen response
of modern rice varieties. This contention is again substantiated with the