Vergara - 1976 - Physiological and morphological adaptability of ri

534 CLIMATE AND RICE
Grain yield (Who)
2 O
Mfly 2E Jun 4 Jill! IB
I5
IO
O5
O
1 i
O 6i) I20 O 6O I20 0 6O I20 0 6O I20
Nitrogen applied (kg/ho)
Seeding doles
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jWIE | a i4
Juri|4 S 4
— June l8
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E-Hurnsl dull 0| C22 4L Hon-u! 6am at 1R5
l l | I l |
50st moisture tension (cbl
e0 V
5Q r
4O '-
L
2O "
Q r i l l l l
Rainfall lITITl/Wll]
zao >
240 '
200
I
16C l‘
L
IZQ \-
EO *-
40 "
O
2 4 6 8 IO l2 l4 l6 IB 2022 24 25
Muy~+— June -—l--Ju|y —--+~— Aug —l-—- Sept —+——- 0c! ~4— Nov
Week and month
16. Nitrogen response of four varieties grovs-"n under
upland conditions at three dutcs of seeding. with solar
radiation total for reproductive and ripening period and
rainfall and soil moisltire tension in the experimental site
in relation to stage of crop growth. Bicol Rice and Corn
Experiment Station (lRRI-BP] cooperative project), 1973
wet season
paiture from the average except for dry periods in February and April. I969.
"Temperature and relative humidity were essentially normal.
The experiment consisted of five Varieties of contrasting plant type and six
nitrogen lcticls arranged in a randomized complete block design with three
replications. Halt‘ of the nitrogen. as urea. was applied 2| days after seeding
and the other hall‘ at panicle initiation.
There were no nitrogen responses in the lodging-susceptible varieties. IR4—2
produced the best yields and responded positively up to (at) kg N/hu. TRS produced
erratic responses caused by low panicle production at (i0 and 9O kg Nfha.
Blast infections were severe. more so in the local varieties Caroline and