Yoshida und Hara - 1977 - Effects of air temperature and light on grain fill

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<strong>Effects</strong> <strong>of</strong> <strong>air</strong> <strong>temperature</strong> <strong>and</strong> <strong>light</strong> 

on grain filling <strong>of</strong> an indica <strong>and</strong> 

a japonica rice (Oryza sativa L.) 

<strong>und</strong>er controlled environmental 

conditions 

Shouichi <strong>Yoshida</strong> a & Tetsuo <strong>Hara</strong> a b 

a The International Rice Research Institute , Manila , 

Philippines 

b College <strong>of</strong> Agriculture , Gifu University , Japan 

Published online: 29 Mar 2012. 

To cite this article: Shouichi <strong>Yoshida</strong> & Tetsuo <strong>Hara</strong> (<strong>1977</strong>) <strong>Effects</strong> <strong>of</strong> <strong>air</strong> <strong>temperature</strong> 

<strong>and</strong> <strong>light</strong> on grain filling <strong>of</strong> an indica <strong>and</strong> a japonica rice (Oryza sativa L.) <strong>und</strong>er 

controlled environmental conditions, Soil Science <strong>and</strong> Plant Nutrition, 23:1, 93-107, DOI: 

10.1080/00380768.<strong>1977</strong>.10433026 

To link to this article: http://dx.doi.org/10.1080/00380768.<strong>1977</strong>.10433026 

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Soil Sci. Plant Nut,., 23 (I), 93-107, <strong>1977</strong> 

EFFECTS OF AIR TEl\iPERATURE AND LIGHT ON 

GRAIN FILLING OF AN INDICA AND A jAPONICA 

RICE (Uryza sativa L.) 

UNDER CONTROLLED ENVIRONl\IENTAL 

CONDITIONS 


Shouichi YOSHIDA <strong>and</strong> Tetsuo HARAl 

The International Rice Research Institute, 

Manila, Philippines 

Received July 19, 1976 

. Th~. effects <strong>of</strong> <strong>air</strong> <strong>temperature</strong> <strong>and</strong> <strong>light</strong> on the grain filling <strong>of</strong> an indica (IR20) <strong>and</strong> ajaponica 

flce (FuJlsaka 5) was studied in artificially <strong>light</strong>ed cabinets. Within the daily mean <strong>temperature</strong> 

range <strong>of</strong> 16° to 28°C, the higher the <strong>temperature</strong>, the faster the grains filled <strong>and</strong> matured. At 

28°C, the upper grains <strong>of</strong> IR20 rice took 13 days to reach the maximum weight, whereas those 

<strong>of</strong> Fujisaka 5 took 18 days. The optimum daily mean <strong>temperature</strong> range to achieve maximum 

weight per grain was 19° to 25°C for IR20 <strong>and</strong> 16° to 22°C for Fujisaka 5. 

Apparently, IR20 rice is better adapted to higher <strong>temperature</strong>s during the ripening period 

than is Fujisaka 5 rice. More chalky grains occurred when the <strong>temperature</strong> was above or below 

the optimum range. Both day <strong>and</strong> night <strong>temperature</strong>s affected grain weight <strong>and</strong> grain quality. 

The daily mean <strong>temperature</strong> was fo<strong>und</strong> to be the most meaningful expression for describing 

the effect <strong>of</strong> <strong>temperature</strong> on grain filling. Low <strong>light</strong> intensity appeared to cause a s<strong>light</strong> delay 

in the grain filling <strong>of</strong> the whole panicle <strong>and</strong> a reduction in the percentage <strong>of</strong> filled grains on the 

lower branches. A combination <strong>of</strong> high <strong>light</strong> intensity <strong>and</strong> low <strong>temperature</strong> gave the best ripening 

grade (grain weight X percent filled grains). 

During the ripening <strong>of</strong> rice, the major effects <strong>of</strong> <strong>air</strong> <strong>temperature</strong> on grain yield is 

largely on the duration <strong>of</strong> the grain filling period <strong>and</strong> on the maximum weight per grain 

achieved; it also affects grain quality. 

Studies on japonica varieties <strong>of</strong> rice in Japan yielded evidence that the optimum 

<strong>air</strong> <strong>temperature</strong> for the ripening <strong>of</strong> rice is about 20° to 22°0 <strong>and</strong> <strong>temperature</strong>s higher or 

lower than this optimum may imp<strong>air</strong> the grain yield (1-3,7-9,21). Such findings 

may be relevant to the tropics where <strong>temperature</strong> is higher than 20° to 22°0 during the 

ripening period <strong>of</strong> rice. Even in a cool region <strong>of</strong> Japan, adoption <strong>of</strong> early planting 

practices has shifted the ripening period to the hottest month <strong>of</strong> the year, <strong>and</strong> thus, the 

rice crop is exposed to day <strong>temperature</strong>s as high as 33°C during ripening (13). Studies 

with IRS rice at Los Banos, Philippines showed no difference in the 1,000 grain weight 

1 Presently, College <strong>of</strong> Agriculture, Gifu University, Japan. 

93

94 S. YOSHIDA <strong>and</strong> T. HARA 


between the wet season <strong>and</strong> the dry season crop (28), although the <strong>temperature</strong> was 

higher during ripening in the dry season than in the wet season (29). 

The grain filling period <strong>of</strong> a field rice crop was estimated to range between about 

30 days at Los Banos, Philippines to 65 days at Sapporo, Japan <strong>and</strong> Yanco, Australia 

(20), based on visual observations <strong>of</strong> the maturity time. Presumably, these large differences 

in the length <strong>of</strong> the grain filling period are caused by differences in the <strong>air</strong> 

<strong>temperature</strong>. However, there is a dearth <strong>of</strong> reports on the effect <strong>of</strong> <strong>air</strong> <strong>temperature</strong> on 

the grain filling period <strong>of</strong> indica rice studied <strong>und</strong>er a well-defined environment. 

Solar radiation is the most influential climatic factor determining grain yield during 

ripening <strong>of</strong> rice in the tropics (29). Most data on the effect <strong>of</strong> <strong>light</strong> on grain yield 

deals mainly with photosynthesis, i.e., supply <strong>of</strong> assimilates to the rice grains, <strong>and</strong> not 

with the length <strong>of</strong> the grain filling period, for which there is no reported experimental 

evidence at present. 

The present study examines the effects <strong>of</strong> <strong>air</strong> <strong>temperature</strong> <strong>and</strong> <strong>light</strong> on the length 

<strong>of</strong> the grain filling period, the final grain weight, <strong>and</strong> grain quality <strong>of</strong> one indica (IR20) 

<strong>and</strong> one japonica (Fujisaka 5) rice. 

MATERIALS AND METHODS 

Both IR20 (indica) <strong>and</strong> Fujisaka 5 (japonica) rices were used in all experiments <strong>of</strong> 

this study. 

Controlled environmentalfacilities. All experiments were conducted in the bioclimatic 

laboratory <strong>of</strong> the International Rice Research Institute at Los Banos, Philippines. The 

plants were grown in a glasshouse room until 3 days after anthesis, after which they 

were transferred to artificially <strong>light</strong>ed cabinets, Koitotron KG-I06 SHL-D cabinets. 

The relative humidity <strong>of</strong> the glasshouse room was maintained above 70 percent while 

the <strong>temperature</strong> was kept at 29°C between 0900 <strong>and</strong> 1700 hr <strong>and</strong> 21°C during the night. 

Daylength was according to the natural conditions. 

In the artificially <strong>light</strong>ed cabinets, <strong>light</strong> was provided by 11 X 400 W Toshiba Yoko 

lamps DR 400/T <strong>and</strong> 12 x 40 W Mitsubishi white fluorescent lamps. The spectral 

composition <strong>of</strong> the radiation is similar in the visible region to that <strong>of</strong> sun<strong>light</strong>. However, 

the proportion <strong>of</strong> photosynthetically active radiation is only 25% <strong>of</strong> total short 

wave radiation for the artificially <strong>light</strong>ed cabinet compared to about 50 percent for 

sun<strong>light</strong>. Photosynthetically active radiation was 114 cal· cm- 2 • day-l at the flag leaf 

level unless specified otherwise. Daytime was from 0600 to 1800 hr. The relative 

humidity in the artificially <strong>light</strong>ed cabinets was maintained at 70 percent during daytime 

<strong>and</strong> 80 percent during the night. 

Plant culture. To obtain a large number <strong>of</strong> panicles that would flower simultaneously, 

20 pregerminated seeds were sown in a circular pattern in 4-liter plastic pots 

(19). Each pot contained 3 kg Maahas clay soil fertilized with 1 g N, 0.5 g P 2 

0 6 , <strong>and</strong> 

0.5 g KIO. 

Sampling <strong>and</strong> measuring procedures. Grain samples were collected from the panicles

Temperature <strong>and</strong> Light on Rice Grain Filling 95 


<strong>of</strong> the main culm at anthesis, 3 days later, <strong>and</strong> then every five days. To measure the 

length <strong>of</strong> the grain filling period, nine grains were sampled from the 3rd, 4th, <strong>and</strong> 5th 

positions from the top on three upper primary branches with the same flowering date. 

It was replicated three times. The panicles from which the nine grains were sampled 

were allowed to ripen to maturity <strong>and</strong> were used for measurement <strong>of</strong> yield components. 

The sampled grains were weighed immediately after harvest to record the fresh 

weight, then oven dried for 3 days at 70°0, <strong>and</strong> finally weighed for dry weight. Total 

nitrogen was measured with the Kjeldahl method. 

At maturity, 15 selected panicles were harvested for yield components <strong>and</strong> grain 

quality. The grains were separated by h<strong>and</strong> into filled <strong>and</strong> unfilled grains, unfilled 

grains were further divided by the iodine test into unfertilized <strong>and</strong> partially filled grains 

( 5). Each <strong>of</strong> the 200 r<strong>and</strong>omly sampled grains were de hulled <strong>and</strong> examined visually 

for chalky grains. 

Experiment 1. Effect oj the daily mean <strong>temperature</strong> on grain filling. The daily mean 

<strong>temperature</strong> was varied from 16° to 28°0 with a constant day-night <strong>temperature</strong> difference 

<strong>of</strong> 8°0. Thus, at a daily mean <strong>temperature</strong> <strong>of</strong> 16°0, the day <strong>temperature</strong> was 

20°0 <strong>and</strong> the night <strong>temperature</strong> was 12°0; this is expressed as 20°/12°0. 

Experiment 2. Effect <strong>of</strong> night <strong>temperature</strong> on grain weight <strong>and</strong> grain quality. The night 

<strong>temperature</strong>. was varied from 14° to 32°0 with a constant day <strong>temperature</strong> <strong>of</strong> 32°0; 

thus, the dally mean <strong>temperature</strong> ranged from 23° to 32°0. 

Experiment 3. Effect oj day <strong>temperature</strong> on grain weight <strong>and</strong> grain quality. The day 

Table 1. 

Effect <strong>of</strong> daily mean <strong>temperature</strong> on grain weight <strong>and</strong> grain quality <strong>of</strong> 

IR20 <strong>and</strong> Fujisaka 5 rices. 

Day Night Daily mean 

Grain Filled 

Partially 

Grain quality 

tempera- tempera- tempera- 

Unfertilized 

wtl) grains 

filled 

grains Chalky'· Green 

ture ture ture 

(mg/grain) 

grains 

(%) 

(%) grains grains 

(0C) (OC) (OC) (%) (%) (%) 

IR20 

20 12 16 14.3 ( 86)'· 73 19 8 83 II 

23 15 19 16.3 ( 98) 77 15 8 16 9 

26 18 22 16.6 (100) 79 15 6 11 8 

29 21 25 16.3 ( 98) 79 14 7 12 8 

32 24 28 15.5 ( 93) 77 16 7 31 9 

Fujisaka 5 

20 12 16 23.7 (100) 88 3 9 14 8 

23 15 19 23.6 (100) 90 1 9 9 0 

26 18 22 23.7 (100) 89 1 10 11 0 

29 21 25 22.5 ( 95) 90 9 14 0 

32 24 28 21.2 ( 89) 89 10 58 0 

11 LSD value at 5% level is 0.2 for both varieties. II Including chalky, white center, white belly <strong>and</strong> white 

back grains. I. Figures in parenthesis indicate relative values taking the maximum as 100.

96 s. YOSHIDA <strong>and</strong> T. HARA 

<strong>temperature</strong> was varied from 16° to 34°0 with a constant night <strong>temperature</strong> <strong>of</strong> 16°0; 

thus, the daily mean <strong>temperature</strong> ranged between 16° <strong>and</strong> 25°0. 

Experiment 4. Effict oj <strong>temperature</strong> <strong>and</strong> <strong>light</strong> on grain filling. Two levels <strong>of</strong> <strong>light</strong> intensity 

(low <strong>light</strong>=36 cal· cm- 2 • day-I; high <strong>light</strong>=1l4 cal· cm- I • day-I) were 

combined with two levels <strong>of</strong> <strong>temperature</strong> (23°/15°0 <strong>and</strong> 32°/24°0). The low <strong>light</strong> 

intensity was achieved by placing a mesh screen beneath the bank <strong>of</strong> <strong>light</strong>s. 

RESULTS 


Effect oj the daily mean <strong>temperature</strong> on grain filling 

Grain growth curve. Five daily mean <strong>temperature</strong>s (Table 1) were used, but in this 

coverage data will be presented for only three daily mean <strong>temperature</strong>s (16°, 22°, <strong>and</strong> 

28°0). The slope in the grain growth curve suggested that the rate <strong>of</strong> grain filling was 

faster at the higher <strong>temperature</strong> in both varieties (Fig. 1). Additionally, the grain 

filling period was shorter at the higher <strong>temperature</strong>s for both varieties <strong>of</strong> rice. The 

leaves <strong>of</strong> IR20 rice turned yellow within 24 hours only after the plants were subjected 

to daily mean <strong>temperature</strong> <strong>of</strong> 16°0, indicating that day <strong>temperature</strong> <strong>of</strong> 20°0 is subnormal 

for leaf activity, i.e., photosynthesis (14) <strong>and</strong> others. Grain filling at this 

<strong>temperature</strong> was very slow, but the final grain weight was similar to that achieved <strong>und</strong>er 

the 22°0 <strong>and</strong> the 28°0 regimes. The duration <strong>of</strong> grain filling period, defined as number 

<strong>of</strong> days required to reach the maximum weight, was 13 days at 28°0 <strong>and</strong> 33 days at 

16°0 for IR20 rice. 

..... 20 

c:: 

.OJ 

...... 

&. 

tlO 15 

E 

'-' 

.... 

.s::: 

tlO 

'iii 

~ 

c:: 

.iij fUJISAKA 5 

... 

0 

0 10 20 30 40 o 10 20 30 40 

Days after flowering 

Days Ifter flowerini 

Fig. 1. 

25 

10 

Effect <strong>of</strong> <strong>temperature</strong> on grain growth <strong>of</strong> IR20 <strong>and</strong> Fujisaka riel'S. 

Leaves <strong>of</strong> Fujisaka 5 rice remained green even at a daily mean <strong>temperature</strong> <strong>of</strong> 16°C. 

The grain growth curve <strong>of</strong> Fujisaka 5 at 16°0 was characterized by a long lag-phase 

following a linear phase. At a daily mean <strong>temperature</strong> <strong>of</strong> 28°C, the grain weight 

declined after the peak weight was reached, <strong>and</strong> the final grain weight was about 15



percent less than that at 16°C. The grain filling period was 18 days at a daily mean 

<strong>temperature</strong> <strong>of</strong> 28°C <strong>and</strong> 43 days at 16°C. Thus, <strong>temperature</strong> appears to affect markedly 

the grain filling period. The length <strong>of</strong> the grain filling period differed between 

the varieties; at a daily mean <strong>temperature</strong> <strong>of</strong> 28°C, Fujisaka 5 required five additional 

days to reach the maximum grain weight over the time required by IR20 rice. 

Accumulation <strong>of</strong>nitrogen in the rice grains. The accumulation <strong>of</strong> nitrogen in rice graim 

can be assessed in two ways, i.e., changes in the percent nitrogen <strong>and</strong> in the total nitrogen 

per grain. During the initial stages <strong>of</strong> grain filling, the percent nitrogen was relatively 

high, indicating that the accumulation <strong>of</strong> nitrogen relative to the starch accumulation 

in the grains was faster at this stage than at later stages (Fig. 2). At maturity, within a 

o~--~--~~--~--~~~--~--~~~~--~~ 

010 20 30 40010 20 

Doy.afftr~ 

Fig. 2. Nitrogen uptake by IR20 <strong>and</strong> Fujisaka 5 rices at successive stages <strong>of</strong> 

grain growth <strong>und</strong>er three <strong>temperature</strong> regimes. 

, 

FUJISAKA5 

~ 

..... '" 

-c: 

'" 

'E 

0 

u 

~ 

~ 

~ 

10 

0 

40 

30 

..... 

20 

_ 

9' ...... 

10 

10 20 30 40 50 0 10 20 30 40 



Fig. 3. Changes in the water content at successive stages <strong>of</strong> grain growth <strong>of</strong> two varieties <strong>of</strong> rice <strong>und</strong>er 

three <strong>temperature</strong> regimes. 

50



daily mean <strong>temperature</strong> range <strong>of</strong> 16° to 28°C, the higher was the <strong>temperature</strong>, the higher 

was the percent <strong>of</strong> nitrogen. Curves for the accumulation <strong>of</strong> nitrogen per grain are 

basically similar to those for dry weight; the higher was the <strong>temperature</strong>, the faster the 

nitrogen accumulated in the rice grains. The variation in the percent nitrogen among 

the three <strong>temperature</strong> regimes was greater than that <strong>of</strong> the nitrogen accumulated per 

grain. However, because the weight per grain <strong>of</strong>IR20 was lower than that <strong>of</strong> Fujisaka 

5, IR20 rice contained less nitrogen per grain, but contained a higher percent nitrogen 

than did Fujisaka 5. 

Changes in water content in the grains. During the initial phases <strong>of</strong> the grain filling 

period the water content <strong>of</strong> the grains was about 58 percent <strong>and</strong> then declined to less 

than 17 percent during the later stages <strong>of</strong> development (Fig. 3). The rate <strong>of</strong> this decrease 

in water content with maturity increased with the increase in the <strong>temperature</strong> 

regime. The water content <strong>of</strong> grains at the time <strong>of</strong> maximum grain weight, in general, 

ranged from 19 to 24 percent, but it was 29 percent for IR20 rice grains when the daily 

mean <strong>temperature</strong> was 16°C. 

Grain weight <strong>and</strong> grain quality. Based on data collected from whole panicle grains, 

the optimum daily mean <strong>temperature</strong> for maximum weight per grain appeared to range 

between 19° <strong>and</strong> 25°C for IR20 rice <strong>and</strong> 16° to 22°C for Fujisaka 5 (Table 1). In IR20 

rice the grain weight <strong>of</strong> upper branches at a daily mean <strong>temperature</strong> <strong>of</strong> 16°C did not 

differ appreciably from that obtained at a daily mean <strong>temperature</strong> <strong>of</strong> 22°C (Fig. 1), but 

the average grain weight <strong>of</strong> the whole panicle at 16°C was significantly lower than that 

at 22°C. This was because at 16°C the grains <strong>of</strong> the upper branches matured normally 

but those <strong>of</strong> the lower branches were not mature at harvest. The lowest weight per grain 

for IR20 rice occurred with a daily mean <strong>temperature</strong> <strong>of</strong> 16°C, while that for Fujisaka 

5 occurred with a daily mean <strong>temperature</strong> <strong>of</strong> 28°C. IR20 rice appeared to be sensitive 

to a low daily mean <strong>temperature</strong> while Fujisaka 5 appeared to be sensitive to a high 

daily mean <strong>temperature</strong>. Similarly, the maximum amount <strong>of</strong> chalky grains in IR20 

rice occurred at 16°C, while this was true for Fujisaka 5 rice at 28°C. A lower weight 

per grain seemed to be associated with a higher percentage <strong>of</strong> chalky grains. Green 

grains were fo<strong>und</strong> with all three <strong>temperature</strong> regimes with IR20 rice, but they were 

fo<strong>und</strong> only at 16°C with Fujisaka 5 rice. Additionally, the brown rice <strong>of</strong> IR20 became 

red brown in color when the daily mean <strong>temperature</strong> ranged between 16° <strong>and</strong> 22°C. 

Effect oj night <strong>temperature</strong> on grain weight <strong>and</strong> grain quality 

Within a range <strong>of</strong> night <strong>temperature</strong>s <strong>of</strong> 14° to 32°C with a constant day <strong>temperature</strong> 

<strong>of</strong> 32°C, the grain weight among the different <strong>temperature</strong> regimes was similar, 

except when the night <strong>temperature</strong> for Fujisaka 5 rice was HOC (Table 2). The daily 

mean <strong>temperature</strong> <strong>of</strong> the 32°/14°C <strong>temperature</strong> regime was 23°C which should have 

been optimum for maximum grain weight <strong>of</strong> Fujisaka 5 rice (Table 1). Apparently, 

the large difference (l8°C) between the day <strong>and</strong> night <strong>temperature</strong>s had an adverse 

effect on the ripening <strong>of</strong> Fujisaka 5 rice plants. The large difference in the day <strong>and</strong> 

night <strong>temperature</strong>s had little effect on the grain weight <strong>of</strong> IR20 rice.

Temperature <strong>and</strong> Light on Rice Grain Filling 

99 


Table 2. Effect <strong>of</strong> night <strong>temperature</strong> on grain weight <strong>and</strong> grain 

quality <strong>of</strong> 1R20 <strong>and</strong> Fujisaka 5 rices. 

Grain quality 

Night Daily mean Grain 

<strong>temperature</strong> ll <strong>temperature</strong> wtt) Chalky Green 

(0C) 

(0C) 

(mg/grain) grains grains 

(%) (%) 

IR20 

14 23 15.8 ( 98)11 42 5 

20 26 16.2 (100) 24 5 

26 29 15.9 ( 98) 33 5 

32 32 15.4 ( 95) 81 5 

Fujisaka 5 

14 23 19.9 ( 90) 89 0 

20 26 22.0 (100) 25 0 

26 29 21.6 ( 98) 51 0 

32 32 20.6 ( 94) 93 0 

1) Day <strong>temperature</strong> was kept at 32°C. I) LSD value at 5% level is 0.2 for both varieties. I) Figures 

in parenthesis indicate relative values taking the maximum as 100. 

Most chalky grains were fo<strong>und</strong> at the low (14°0) <strong>and</strong> high night (32°0) <strong>temperature</strong>s. 

In general, more chalky grains occurred than was expected when compared 

with the previously described experiment with similar daily mean <strong>temperature</strong>s. Since 

night <strong>temperature</strong>s as low as 15°C or 18°C did not seem to cause a high incidence <strong>of</strong> 

chalky grains (see Table 1), it was probably the high day <strong>temperature</strong> that affected the 

increased percentage <strong>of</strong> chalky grains at 32°/20 o e. For instance, 12 percent <strong>of</strong>th~IR20" 

grains was chalky when the daily mean <strong>temperature</strong> was 25°C with a temperat~~ t 

regime <strong>of</strong> 29°/21°e. However, in this experiment, when the daily mean <strong>temperature</strong> 

was 26°C with a <strong>temperature</strong> regime <strong>of</strong> 32° j200e, 24 percent <strong>of</strong> the IR20 grains was 

chalky. 

In Fujisaka 5 rice, a high incidence <strong>of</strong> chalky grains was fo<strong>und</strong> not only at 32° /32°C 

but also at 32°/14°e. At 32°/14°C, either night <strong>temperature</strong> or day <strong>temperature</strong> or 

daily mean <strong>temperature</strong> should not cause the high incidence <strong>of</strong> chalky grains. Consequently, 

it must be the large difference in <strong>temperature</strong> between day <strong>and</strong> night which 

is responsible for the high incidence <strong>of</strong> chalky grains. 

Effect oj day <strong>temperature</strong> on grain weight <strong>and</strong> grain qualiry 

The weight <strong>of</strong>IR20 rice grains was the lowest when the day <strong>temperature</strong> was 16°C 

(Table 3) , which is below the optimum for leaf photosynthesis <strong>of</strong> IR20 rice. The grain 

weight <strong>of</strong> Fujisaka 5 rice was the lowest when the day <strong>temperature</strong> was 34°C. IR20 

rice appeared to be sensitive to a low day <strong>temperature</strong> <strong>and</strong> Fujisaka 5 rice was sensitive 

to a high day <strong>temperature</strong>. 

The largest percentage (99%) <strong>of</strong> Fujisaka 5 grains Were chalky at the highest day 

<strong>temperature</strong> (34°0), while the incidence <strong>of</strong> chalky grains <strong>of</strong> IR20 rice occurred at both



Table 3. Effect <strong>of</strong> day <strong>temperature</strong> on grain weight <strong>and</strong> grain 

quality <strong>of</strong> IR20 <strong>and</strong> Fujisaka 5 rices. 

Grain quality 

Day Daily mean Grain 

tempera turell <strong>temperature</strong> wt" Chalky Green 

(0C) (OC) (mg/grain) grains grains 

(%) (%) 

IR20 

16 16 13.3 ( 82)11 87 

22 19 15.9 ( 98) 7 

28 22 16.2 (100) 12 

34 25 15.0 ( 93) 82 

Fujisaka 5 

16 16 22.4 ( 97) 10 

22 19 23.2 (100) 2 

28 22 22.8 ( 98) 14 

34 25 18.7 ( 81) 99 

1) Night <strong>temperature</strong> was kept at 16°C. I) LSD value at 5% level is 0.2 for both varieties. 

I) Figures in parenthesis indicate relative values taking the maximum as 100. 

Grain wI (1IlQ/~ain I 

20 

3 

21 

11 

2 

0 

0 

0 

0 

o o~--':K)---:':2O:---...I30i.--....I40 0 

K) 20 

Days oller flower"" 

Fig. 4. Grain growth <strong>of</strong> upper grains <strong>and</strong> whole panicle in IR20 rice 

<strong>und</strong>er two levels <strong>of</strong> <strong>light</strong> intensity <strong>and</strong> <strong>temperature</strong>.


the lowest (16°0) <strong>and</strong> the highest (34°0) day <strong>temperature</strong>, 87 <strong>and</strong> 82 percent, respectively. 


Effect <strong>of</strong> <strong>temperature</strong> <strong>and</strong> <strong>light</strong> on grain filling 

Grain growth curve. While <strong>light</strong> intensity did not affect the length <strong>of</strong> the grain filling 

period in the upper grains, it affected the grain weight <strong>of</strong> IR20 rice (Fig. 4) <strong>and</strong> <strong>of</strong> 

Fujisaka 5 rice (Fig. 5). The length <strong>of</strong> the grain filling period in the whole panicle 

grains was increased by 5 days at a high <strong>light</strong> intensity for IR20 rice only, but it was 

extended by 10 <strong>and</strong> 5 days at a low <strong>light</strong> intensity for IR20 <strong>and</strong> Fujisaka 5, respectively. 

This suggests that low <strong>light</strong> intensity may delay the ripening <strong>of</strong> the whole panicle grains, 

probably because <strong>of</strong> a limited supply <strong>of</strong> assimilates to grains on lower branches. 

The effect <strong>of</strong> <strong>light</strong> intensity on grain weight was more pronounced on the grains <strong>of</strong> 

the whole panicle than on the upper grains, because all <strong>of</strong> the grains (filled <strong>and</strong> unfilled) 

were used to measure the average weight <strong>of</strong> the whole grains <strong>and</strong> the low <strong>light</strong> intensity 

increased the percentage <strong>of</strong> unfilled grains at the lower branches (Fig. 6). 

To <strong>und</strong>erst<strong>and</strong> better how <strong>light</strong> intensity affected grain filling <strong>of</strong> the whole panicle, 

sample grains were collected from primary branches at different positions. Similar 

UPPER GRAtlS 

2~~======::! ~=====:: 

20 

I~ 

10 

°O~--~~--~20~--~~--~~~ O~--~O~--20~---~~ 

Days orlef rlcooorinQ 

Fig. 5. Grain growth <strong>of</strong> upper grains <strong>and</strong> whole panicle in Fujisaka 5 

rice <strong>und</strong>er two levels <strong>of</strong> <strong>light</strong> intensity <strong>and</strong> <strong>temperature</strong>.



results were obtained for both IR20 <strong>and</strong> Fujisaka 5 at two <strong>temperature</strong>s, hence the data 

are presented for only IR20 at a daily mean <strong>temperature</strong> <strong>of</strong> 28°C (Fig. 6). Low <strong>light</strong> 

intensity consistently decreased grain weight to a small extent on all the branches. On 

the other h<strong>and</strong>, low <strong>light</strong> intensity decreased the percentage <strong>of</strong> filled grains markedly on 

the lower branches <strong>of</strong> the panicle. These effects <strong>of</strong><strong>light</strong> intensity on grain fIlling are in 

good agreement with our previous findings that low <strong>light</strong> intensity during ripening 

period affects grain yield through decreasing the percentage <strong>of</strong> fIlled grains but it has 

little effect on grain weight (29). 

Grain weight <strong>and</strong> percentage oj filled grains. Since <strong>light</strong> affects both grain weight (W) 

<strong>and</strong> percent fllled grains (F), the overall effect <strong>of</strong> the <strong>light</strong>-<strong>temperature</strong> interaction on 

grain yield can be best assessed by computing W X F, i.e., ripening grade. The combi. 

Xl 1 

.s:: 

g 2 

as 

li 3 

~4 

E 

'~ 5 

'0 6 

Grain weight (mg) Filled grains (%) Grain number 

o 13 14 15 16 17 0 50 60 7080 90100 O'{-_-i5~_.!.Ir-0_--=-15;; 

.... 5 7 

'in 8 

~ 

9'---0----' 

1 

2 

3 

1 . 

2· 

3 

4 

5 

6 

7 

8 

9~~--.......... --.......... ~ 

Fig, 6. Effect <strong>of</strong> <strong>light</strong> on grain filling <strong>of</strong>IR20 riee at 32/24·0. (Low <strong>light</strong>-36 

cal. em-" day-I; high <strong>light</strong>=1l4cal. cm-·. day-I PAR.) (PAR: Photosynthetically 

active radiation). 

Table 4. 

Effect <strong>of</strong> <strong>light</strong> <strong>and</strong> <strong>temperature</strong> on grain growth <strong>of</strong> IR20 <strong>and</strong> Fujisaka 5 rices. 

Grain Filled Ripening 

Lightll Temperatures, weight (W)I' grains (F) grade 

(mg) (%) (WxF) 

IR20 

Low Low 15.5 65 1014 ( 71)11 

Low High 14.8 62 9)0 ( 64) 

High Low 16.3 87 1423 (100) 

High High 16.0 85 1370 ( 96) 

Fujisaka 5 

Low Low 22.0 86 1890 ( 90) 

Low High 2M 84 1718 ( 82) 

High Low 23.0 91 2102 (100) 

High High 21.9 92 2013 ( 96) 

1) Low: 36cal. em-I. day-l PAR (photosynthetically active radiation), High: 114cal. cm-•• day-' PAR. 

II Low: 23/15°0, High: 32/24°0. I' LSD value at 5% level is 0.2 for both varieties. "Figures in parenthesis 

indicate relative values with 100 serving as the maximum.


nation <strong>of</strong> high <strong>light</strong> intensity <strong>and</strong> a low <strong>temperature</strong> gave the maximum ripening grade 

for both rice varieties (Table 4). Taking the maximum value as 100 for each variety, 

the ripening grade was reduced by 36 percent in IR20 <strong>and</strong> 18 percent in Fujisaka 5 

when the <strong>light</strong> intensity was low <strong>and</strong> the <strong>temperature</strong> was high. Apparently, grain 

filling, <strong>and</strong> hence, the yield <strong>of</strong> IR20 is more likely to be reduced by adverse climatic 

environments than are those <strong>of</strong> Fujisaka 5 rice. 

DISCUSSION 


The length <strong>of</strong> the grain filling period markedly affects the yield <strong>of</strong> rice because it 

affects the maximum amount <strong>of</strong> solar energy available for grain filling. Additionally, 

it constitutes the last part <strong>of</strong> the rice plant's life cycle; this knowledge about the grain 

filling period can contribute to the overall <strong>und</strong>erst<strong>and</strong>ing <strong>of</strong> the total growth duration 

<strong>of</strong> rice varieties. 

Existing information on the effect <strong>of</strong> environmental factors <strong>and</strong> (or) plant physiological 

factors on the length <strong>of</strong> the grain filling period <strong>of</strong> rice is scarce. An.n et al. (1) 

reported that while the grain filling <strong>of</strong> a japonica rice was completed in about 25 days 

after anthesis at a daily mean <strong>temperature</strong> <strong>of</strong> 25°C, it took much longer when the daily 

mean <strong>temperature</strong> was 21 °C, <strong>and</strong> was not complete even after 75 days from anthesis 

when the daily mean <strong>temperature</strong> was 17°C. Their experiment was conducted in 

<strong>temperature</strong>-controlled glasshouse rooms where day <strong>and</strong> night <strong>temperature</strong>s were held 

constant. NAGATO <strong>and</strong> EBATA (11, 12) also measured the rate <strong>of</strong> grain filling <strong>und</strong>er 

different <strong>temperature</strong> regimes. When YAMAKAWA (24) planted 12 rice varieties in 

the field in Japan at different times so that these rice crops would be exposed to different 

daily mean <strong>temperature</strong>s during the ripening period, he showed that japonica rice 

ripened over 30 days when the daily mean <strong>temperature</strong> was about 29°C, while ripening 

took 53 days when the daily mean <strong>temperature</strong> was 18°e. The time for maturity was 

determined by visual examination in this experiment. 

In the present study, rice grains were fo<strong>und</strong> to mature faster than was expected, 

only 13 days were required for the upper grains <strong>of</strong> IR20 rice to reach the maximum 

weight when the daily mean <strong>temperature</strong> was 28°C, <strong>and</strong> 18 days for Fujisaka 5 rice. 

When the daily mean <strong>temperature</strong> was lower, 16°C, the upper grains <strong>of</strong> IR20 rice 

achieved maximum weight in 33 days, whereas those <strong>of</strong> Fujisaka 5 rice required 43 days. 

The critical low <strong>temperature</strong> for photosynthesis has been reported as IS.5°C for 

japonica rice (23) <strong>and</strong> between 20° <strong>and</strong> 25°e for indica rice (14). In the experiment 

<strong>of</strong> Aimi et al., the day <strong>and</strong> night <strong>temperature</strong>s were both 17°0 which is a subnormal 

<strong>temperature</strong> for photosynthesis <strong>of</strong> japonica rice, In our experiment, however, at a 

daily mean <strong>temperature</strong> <strong>of</strong> 16°0, the day <strong>temperature</strong> was held at 20°C, which is above 

the critical low <strong>temperature</strong> for photosynthesis <strong>of</strong> japonica rice. This difference in the 

<strong>temperature</strong> regimes may explain the variation in the results obtained in the present 

study <strong>and</strong> those <strong>of</strong> Aimi et aI, 

It is normally assumed that <strong>light</strong> intensity has little or no effect on the length <strong>of</strong> the



grain filling period. The present findings indicate that low <strong>light</strong> intensity extends the 

grain filling period <strong>of</strong> the grains <strong>of</strong> the whole panicle by about 5 days by affecting the 

filling <strong>of</strong> the grains on the lower branches <strong>of</strong> the rice panicle. Light intensity did not 

affect the length <strong>of</strong> the grain filling period <strong>of</strong> the grains on the upper branches <strong>of</strong> the 

rice panicle. 

For field rice crops in the tropics, where the daily mean <strong>temperature</strong> varies between 

25° <strong>and</strong> 30°C, the duration <strong>of</strong> ripening is reported to be about 30 days after flowering 

(20). The duration <strong>of</strong> ripening is considered the sum <strong>of</strong> the length <strong>of</strong> the grain filling 

period for the first-flowering spikelet, difference in days between the first <strong>and</strong> last flowering 

spikelets on the same panicle, <strong>and</strong> the duration <strong>of</strong> panicle emergence. In the 

present study, the percentage fertility was 94 to 92 percent in IR20 rice <strong>and</strong> 81 to 9(} 

percent in Fujisaka 5 rice, when the plants were allowed to remain in the glasshouse 

room at 25°C for 3 days after the first spikelet flowering in each panicle. This indicates. 

that 3 days are about enough between the time <strong>of</strong> anthesis <strong>of</strong> the first spikelet <strong>and</strong> fertilization 

<strong>of</strong> the last spikelet on the same panicle. 

Panicle emergence takes 14 days in the field crop <strong>of</strong>IR20 rice at Los Banos, Philippines. 

Thus, the sum <strong>of</strong> each term, i.e., (13+3+14), becomes 30 days for an IR20 rice 

crop at Los Banos. However, when flowering (or heading) or a rice crop in the field is. 

defined in agronomic terms as the time when 50 percent <strong>of</strong> the panicles <strong>of</strong> a rice crop 

has emerged, the length <strong>of</strong> the grain filling period for IR20 rice as a field crop at Los. 

Banos is 23 days. 

The optimum daily mean <strong>temperature</strong> <strong>of</strong> 20° to 22°C (J, 3) reported for the ripening 

<strong>of</strong> japonica rice agrees with the results <strong>of</strong> statistical analysis <strong>of</strong> the effects <strong>of</strong> climatic 

factors on rice yield (2, 7-9). Despite the fact that different varieties <strong>of</strong> rice, locations~ 

<strong>and</strong> techniques were used, the optimum <strong>temperature</strong>s reported were remarkably similar. 

This may be because in Japan there may not be any differences among japonica 

rice varieties in response to <strong>temperature</strong> during ripening. Based on this premise, the 

results <strong>of</strong> the present study can be compared with those reported in Japan. 

In this study, the optimum daily mean <strong>temperature</strong> for grain filling was fo<strong>und</strong> torange 

from 19° to 25°C for IR20 rice <strong>and</strong> from 16° to 22°C in Fujisaka 5 rice. There 

appears to be no sharp optimum <strong>temperature</strong> for grain filling, only a <strong>temperature</strong> range 

that is optimum for grain filling. In their statistical analyses <strong>of</strong> effects <strong>of</strong> <strong>temperature</strong> 

on rice yield, MURATA (9), HANYU et al. (2), <strong>and</strong> MURAKAMI (8) developed similar 

parabolic equations in which the daily mean <strong>temperature</strong> <strong>and</strong> solar radiation or sunshine 

hours are used as climatic parameters. :Murata's equation is: 

r =s [1.20-0.021 (t-21.5)2] 

where Y is grain yield (kg/lO a), S<strong>and</strong> t are solar radiation (calc· m- 2 • day-I), <strong>and</strong> 

<strong>temperature</strong> (0C), respectively, in August <strong>and</strong> September. When 2BoC is substituted for 

t, a 74 percent reduction in yield is obtained as compared with the maximum yield 

achieved with a daily mean <strong>temperature</strong> <strong>of</strong>21.5°C. However, our experimental results. 

show that the grain weight <strong>of</strong> Fujisaka 5 rice was reduced by only about 11 percent at 

28°C as compared with the maximum weight achievable. Recently, MURATA (JO}



reported the results <strong>of</strong> one field experiment in which the grain weight varied from 24 g at 

a daily mean <strong>temperature</strong> <strong>of</strong> 22°C to about 21 g at 28°C, about a 13 percent reduction. 

Probably, the equation obtained by statistical analysis may help to explain yield differ 

-ences attributable to climatic components in certain ecological regions, but apparently, 

the equation is not appropriate for the general relationship between parameters used 

<strong>and</strong> yield. Some unexpressed or unrecognized factors associated with <strong>temperature</strong> 

~hanges might be involved in the <strong>temperature</strong> term <strong>of</strong> the equation. 

One complicating factor in <strong>temperature</strong> studies is the possibility that the day or 

the night <strong>temperature</strong> has a specific physiological role (22), in which case the daily 

mean <strong>temperature</strong> may not be meaningful. Day <strong>temperature</strong> is obviously important 

for photosynthesis. As noted earlier, the difference in the duration <strong>of</strong> grain filling between 

the present results at a daily mean <strong>temperature</strong> <strong>of</strong> 16°C <strong>and</strong> those <strong>of</strong> Aimi et al. 

at a daily mean <strong>temperature</strong> <strong>of</strong> 17°C may be better <strong>und</strong>erstood in terms <strong>of</strong> the differ 

-ence in day <strong>temperature</strong>. 

High night <strong>temperature</strong> has been shown to have deleterious effects on the ripening 

-<strong>of</strong> rice (4, 11,25,26), such as lowering the final grain weight <strong>and</strong> increasing the in 

~idence <strong>of</strong> chalky grains <strong>and</strong> other poor quality grains. While a high night <strong>temperature</strong> 

increases respiration, which might account for the imp<strong>air</strong>ed ripening (27), Moss 

.et al. (6) demonstrated that a high night <strong>temperature</strong> increased respiration in the night, 

<strong>and</strong> that this in turn, caused an increase in photosynthesis during the day. Hence, it 

is difficult to ascribe the adverse effect <strong>of</strong> high night <strong>temperature</strong> on grain filling to 

increased respiration. Furthermore, high day <strong>temperature</strong>s may cause results similar 

to those <strong>of</strong> high night <strong>temperature</strong>s. 

Fig. 7. 

24 

22 

...... 

110 

:::: 20 

.s:; 

110 

"; 

c: 18 

.~ 

§ 16 

- 

14 

12 

0 __-11-___ 

°_"",,- 

D 

Experimer1 

123 

IR20 .,. 

Fu;SOI



To better <strong>und</strong>erst<strong>and</strong> how <strong>temperature</strong> during the grain filling period affects grain 

weight, the grain weight was plotted against the daily mean <strong>temperature</strong>, regardless <strong>of</strong> 

the day <strong>and</strong> night <strong>temperature</strong>s (Fig. 7). There was a smooth <strong>and</strong> consistent pattern in 

the changes in grain weight as affected by the daily mean <strong>temperature</strong> in both IR2(} 

<strong>and</strong> Fujisaka 5 rices, except with Fujisaka 5 when the difference between the day <strong>and</strong> 

night <strong>temperature</strong> was 18°0. The maximum grain weight <strong>of</strong> Fujisaka 5 rice was. 

achieved at the low <strong>temperature</strong> range, while the grain weight <strong>of</strong> IR20 remained high 

<strong>and</strong> stable at the high <strong>temperature</strong> range. This implies that <strong>temperature</strong>, regardless. 

<strong>of</strong> day or night, affects grain weight, <strong>and</strong> such effect <strong>of</strong> <strong>temperature</strong> is best related tathe 

daily mean <strong>temperature</strong>. Thus, within the <strong>temperature</strong> range between 14° <strong>and</strong> 

34°0, the daily mean <strong>temperature</strong> appears to be the most meaningful expression by 

which to describe the effect <strong>of</strong> <strong>temperature</strong> on ripening <strong>of</strong> IR20 <strong>and</strong> Fujisaka 5 rices. 

In the continent type <strong>of</strong> climate, large differences in the day <strong>and</strong> night <strong>temperature</strong>s 

are common (15). A night <strong>temperature</strong> <strong>of</strong> 15°0 has been reported to prevent 

or delay panicle initiation <strong>of</strong> rice even when the day <strong>temperature</strong> is maintained at 30°C 

or 33°0 (16-18). In the present experiment, however, the large difference <strong>of</strong> lBoe 

between day <strong>and</strong> night <strong>temperature</strong>s appeared to have an adverse effect on the ripening 

<strong>of</strong> Fujisaka 5 rice rather than a low night <strong>temperature</strong> per se. 

At Los Banos, Philippines, high yields are normally achieved in experimental 

fields in the dry season when rice matures in April or May. These two months are 

characterized by high <strong>temperature</strong>s <strong>and</strong> high solar radiation. In terms <strong>of</strong> yield components, 

high yields in the dry season crop are clearly associated with a large grain 

number per square meter (29). In addition, however, high <strong>temperature</strong> does not 

appear to have any noticeable adverse effects on grain filling, probably because IR2() 

rice <strong>and</strong> other indica varieties are well adapted to high <strong>temperature</strong>s during the grain 

filling period (Fig. 7). 

REFERENCES 

1) Anu, R., SAWAMURA, H., <strong>and</strong> KmolNo, S., Physiological studies on the mechanism <strong>of</strong> crop plants. The 

effect <strong>of</strong> the <strong>temperature</strong> upon the behavior <strong>of</strong> carbohydrates <strong>and</strong> related enzymes during the ripening 

<strong>of</strong> rice plant, Proc. Crop Sci. Soc. Japan, 27 (4),405-407 (1959) 

2) llANYu,J., UCHIJIMA, T., <strong>and</strong> SUGAWAJlA, S., Studies on the agro-climatological method for expressing 

the paddy rice products (Part I). An agro-climatic index for expressing the quantity <strong>of</strong> ripening <strong>of</strong>" 

the paddy rice, Bull. Nat. Tolwku Agr. Exp. Sta., 34, 27-36 (1966) 

3) MATSUSHIMA, S., MANAKA, K., <strong>and</strong> TSUNODA, K., Analysis <strong>of</strong> developmental factors determining yield 

<strong>and</strong> yield prediction <strong>and</strong> culture improvement <strong>of</strong> lowl<strong>and</strong> rice. XXXIX. On mechanism <strong>of</strong> ripening 

(5). XL. On the mechanism <strong>of</strong> ripening (6), Proc. Crop Sci. Soc. Japan, 25, 203-206 (1957) 

4) MATSl.JSHIMA, S. <strong>and</strong> TSUNODA, K., Analysis <strong>of</strong> developmental facton determining yield <strong>and</strong> its application 

to yield prediction <strong>and</strong> culture improvement <strong>of</strong> lowl<strong>and</strong> rice. XLV. <strong>Effects</strong> <strong>of</strong> <strong>temperature</strong> 

<strong>and</strong> its daily range in different growth stages upon the growth, grain yield <strong>and</strong> its constitutional factors. 

Proc. Crop Sci. Soc. Japan, 26, 243-244 (1958) 

5) MATSUSHIMA, S. <strong>and</strong> TANAKA, T., Analysis <strong>of</strong> developmental factors determining yields <strong>and</strong> its appli-



cation to yield prediction <strong>and</strong> culture improvement <strong>of</strong>lowl<strong>and</strong> rice. LV. Early discrimination <strong>of</strong> 

non-fertilized rice grains, Proc. Crop Sci. Soc. Japan, 28, 365-366 (1960) 

6) Moss, D.N., MUSGRAVE, R.B., <strong>and</strong> LEMON, E.R., Photosynthesis <strong>und</strong>er field conditions. III. Some 

effects <strong>of</strong> <strong>light</strong>, carbon dioxide, <strong>temperature</strong>, <strong>and</strong> soil moisture on photosynthesis, respiration, <strong>and</strong> 

transpiration <strong>of</strong> corn, Crop Sci., 1, 8~7 (1961) 

7) MUNAKATA, K., KAWASAKI, 1., <strong>and</strong> KARIYA, K., Quantitative studies on the effects <strong>of</strong> the climatic 

facton on the productivity <strong>of</strong> rice, Bull. Chugoku Agr. Exp. Sta., No. 14,59-95 (1967) 

8) MURAKAMI, T., Paddy rice ripening <strong>and</strong> <strong>temperature</strong>, Japan Agr. &s. Q.,7 (1), 1-5 (1973) 

9) MURATA, Y., On the influence <strong>of</strong> solar radiation <strong>and</strong> <strong>air</strong> <strong>temperature</strong> upon the local differences in the 

productivity <strong>of</strong> paddy rice in Japan, Proc. Crop Sci. Soc. Japan, 35, 59-63 (1964) 

10) MURATA, Y., Productivity <strong>of</strong> rice in different climatic regions <strong>of</strong> Japan, Presented at the symposium 

"Climate <strong>and</strong> Rice" at the International Rice Research Institute, Los Banos, Laguna, Philippines, 

September 24-27, 1974 (Mimeo.) 

11) NAGATO, K. <strong>and</strong> EBATA, M., <strong>Effects</strong> <strong>of</strong> <strong>temperature</strong> in the ripening period upon the development <strong>and</strong> 

qualities <strong>of</strong>lowl<strong>and</strong> rice kernels, Prot. Crop Sci. Soc. Japan, 28, 275-278 (1960) 

12) NAGATO, K. <strong>and</strong> EBATA, M., <strong>Effects</strong> <strong>of</strong> <strong>temperature</strong> during the ripening period on the development 

<strong>and</strong> the quality <strong>of</strong> rice kernels, Proc. Crop Sci. Soc. Japan, 34, 59-66 (1965) 

13) NAKAYAMA, II., Panicle senescence in rice plant, Bull.lIokuriku Natl. Agr. Exp. Sla., No. 16, 15-57 (1974) 

14) OSADA, A., Studies on the photosynthesis <strong>of</strong> indica rice, Prot. Crop Sci. Soc. Japan, 33, 69-76 (1964) 

15) OWEN, P.C., The climate <strong>of</strong> the sub-coastal plains <strong>of</strong> Northern Australia: A comparison with those <strong>of</strong> 

other rice-growing areas, J. Austr. Inst. Agr. Sci., 33 (4),247-253 (1967) 

16) OWEN, P.C., The growth <strong>of</strong>f our rice varieties as affected by <strong>temperature</strong> <strong>and</strong> photoperiod with uniform 

daily periods <strong>of</strong> day<strong>light</strong>, Exp. Agr., 5, 85-90 (1969) 

17) OWEN, P.C., <strong>Effects</strong> <strong>of</strong> night <strong>temperature</strong> on growth <strong>and</strong> development <strong>of</strong>IR8 rice, Exp. Agr., 8, 213- 

218 (1972a) 

18) OWEN, P.C., <strong>Effects</strong> <strong>of</strong> cool periods (15°C) at night on Taichung Native 1 rice, Exp. Agr., 8,289-294 

(1972b) 

19) SATAKE, T., Circular dense-culture <strong>of</strong> rice plant in pots, the purpose <strong>of</strong> obtaining many uniform 

panicles <strong>of</strong> main sterns, Proc. Crop Sci. Soc. Japan, 41, 361-362 (1972) 

20) TANAKA, A. <strong>and</strong> VERGARA, B.S., Growth habit <strong>and</strong> ripening <strong>of</strong> rice plants in relation to the environmental 

conditions in the Far East, IRC Newsl. Spec. Issue, 26-42 (1967) 

21) TANAKA, M., Studies on the growth <strong>of</strong> lowl<strong>and</strong> rice caused by cool water irrigation <strong>and</strong> delayed 

heading, Bull. Aomori Agr. Exp. Sta., 7, 1-107 

22) WENT, F.W., The Experimental Control <strong>of</strong> Plant Growth, The Ronald Press Comp., New York, 343 p. 

23) YAMADA, N., MURATA, Y., OSADA, A., <strong>and</strong> hAMA, J., Photosynthesis <strong>of</strong> rice plant, Proc. Crop Sci. Soc. 

Japan,23 (3), 214-222 (1955) 

24) YAMAKAWA, Y., Studies on the ecological variations <strong>of</strong> the growth <strong>of</strong> rice plant caused by the shifting 

<strong>of</strong> cultivation .eason in warm region in Japan, Agr. Bull. Saga Univ., 14, 23-159 (1962) 

25) YAMAMOTO, K., Studies on ripening <strong>of</strong> rice (Part I), Agr. HQrt. (Tokyo), 29, 1161-1163 (1954) 

26) YAMAMOTO, K., Studies on ripening <strong>of</strong> rice (Part II), Agr.lIort. (Tokyo), 29, 1303-1304 (1954) 

27) YAMAMOTO, K., Studies on ripening <strong>of</strong> rice (Part III), Agr.lIort. (Tokyo), 29, 1425-1427 (1954) 

28) YosnIDA, S., CocK,J.lI., <strong>and</strong> PARAO, F.T., Physiological aspects <strong>of</strong> high yields, in International Rice 

Research Institute, Rice Breeding, Los Banos, Laguna, Philippines, 1972. pp.455-469 

29) YOSIIIDA, S. <strong>and</strong> PARAO, F.T., Climatic influence on yield <strong>and</strong> yield components <strong>of</strong>lowl<strong>and</strong> rice in the 

tropics, Presented at the symposium "Climate <strong>and</strong> Rice" at the International Rice Research Institute, 

Los Banos, Laguna, Philippines, September 24-27, 1974 (Mimeo.)

Yoshida und Hara - 1977 - Effects of air temperature and light on grain fill

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