soil carbon dioxide flux and rice photosynthesis

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This article was downloaded by: [UTSA Libraries] On: 05 October 2014, At: 10:18 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Soil Science and Plant Nutrition Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tssp20 Soil carbon dioxide flux and rice photosynthesis Shouichi Yoshida a , Victoria Coronel a , Francisco T. Parao a & Evangelina de los Reyes a a International Rice Research Institute , Los Baños, Laguna , Philippines Published online: 29 Mar 2012. To cite this article: Shouichi Yoshida , Victoria Coronel , Francisco T. Parao & Evangelina de los Reyes (1974) Soil carbon dioxide flux and rice photosynthesis, Soil Science and Plant Nutrition, 20:4, 381-386, DOI: 10.1080/00380768.1974.10432609 To link to this article: http://dx.doi.org/10.1080/00380768.1974.10432609 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is

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Page 1: Soil carbon dioxide flux and rice photosynthesis

This article was downloaded by: [UTSA Libraries]On: 05 October 2014, At: 10:18Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH,UK

Soil Science and Plant NutritionPublication details, including instructions forauthors and subscription information:http://www.tandfonline.com/loi/tssp20

Soil carbon dioxide flux andrice photosynthesisShouichi Yoshida a , Victoria Coronel a , Francisco T.Parao a & Evangelina de los Reyes aa International Rice Research Institute , Los Baños,Laguna , PhilippinesPublished online: 29 Mar 2012.

To cite this article: Shouichi Yoshida , Victoria Coronel , Francisco T. Parao &Evangelina de los Reyes (1974) Soil carbon dioxide flux and rice photosynthesis, SoilScience and Plant Nutrition, 20:4, 381-386, DOI: 10.1080/00380768.1974.10432609

To link to this article: http://dx.doi.org/10.1080/00380768.1974.10432609

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all theinformation (the “Content”) contained in the publications on our platform.However, Taylor & Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness,or suitability for any purpose of the Content. Any opinions and viewsexpressed in this publication are the opinions and views of the authors, andare not the views of or endorsed by Taylor & Francis. The accuracy of theContent should not be relied upon and should be independently verified withprimary sources of information. Taylor and Francis shall not be liable for anylosses, actions, claims, proceedings, demands, costs, expenses, damages,and other liabilities whatsoever or howsoever caused arising directly orindirectly in connection with, in relation to or arising out of the use of theContent.

This article may be used for research, teaching, and private study purposes.Any substantial or systematic reproduction, redistribution, reselling, loan,sub-licensing, systematic supply, or distribution in any form to anyone is

Page 2: Soil carbon dioxide flux and rice photosynthesis

expressly forbidden. Terms & Conditions of access and use can be found athttp://www.tandfonline.com/page/terms-and-conditions

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Page 3: Soil carbon dioxide flux and rice photosynthesis

Soil Sci. Plant Nutr., 20 (4), 381-386, 1974

SOIL CARBON DIOXIDE FLUX AND RICE PHOTOSYNTHESIS

Shouichi YOSHIDA, Victoria CORONEL, Francisco T. PARAO, and Evangelina de los· REYES

International Rice Research Institute, Los Da~os, Laguna, PhiliPPines

Received April 5, 1914

Measurement of CO, concentratlon in air at 25 em below and 100 em above the canopy of a good rice crop Indicated that a severe COa deficit occurred around the photosynthetic surface of crop when light intensity was high. Soil C01 flux as measured by the soda lime method in a closed system ranged from 3.9 to 5.7 g·m-~. day-t under flooded conditions and from 6.0 to 8,6g·m-2 ·day-t under drained condi· tions. Cropped soil released more C02 than bare soil under both flooded and drained conditions. The estimated contribution of soil C02 to gross photosynthesis was 6~, for the flooded soil and 7% for the drained soil or a contribution of 9 and 12% to net dry matter production. These results together with other information indicate that atmospheric co~ is the most important source of co, in crop photosynthesis, soil co~ released into atmosphere Is second most important, and soil C011 absorbed by plant roots is almost negligible.

In photosynthesis in the field, the atmosphere.and the soil are the sources of carbon dioxide (C02). The possible contribution of soil COt flux to crop photosynthesis has been estimated for various upland crops in the temperate region. In one example, it ranged from 10% of net photosynthesis on a clear day to 100% on a cloudy day ( 5 ). In another, it ranged from 11 to 40% of net photosynthesis and from 8 to 26% of gross photosynthesis ( 4 ). Because of vigorous turbulent mixing of air, however, the contri· bution of soil COz flux to crop photosynthesis is considered not important under most weather conditions ( 4 ). But the contribution of soil COa flux to photosynthesis in crops grown in submerged soil (flood irrigated) such as rice has not been studied. Under flooded conditions, the diffusion of soil COa into the atmosphere may be impaired ( o) so completely that draining water from the field might increase the C02 diffusion into atmosphere ( 6). When semidwarf rice varieties are grown under good management they develop large leaf area indices and severe COt deficits may occur in the photo­synthetic surface of the crop on sunny days. Under such conditions draining the field to increase soil C02 flux could make more C02 available for crop photosynthesis.

Previous experiments ( 10) showed that C02 enrichment during the period from 33 to 14 days before flowering increased spikelet number, and hence grain yield. If

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Page 4: Soil carbon dioxide flux and rice photosynthesis

382 S. YOSHIDA, V. CORONEL, F.T. PARAO, and E. de los REYES

drainage can increase soil COa flux, it might be timed so that the increased soil COa flux would have a maximum effect on the spikelet number of a crop.

MATERIALS AND METHODS

Four lOx ll·m plots were set up lo make four different treatments with and without a crop under flooded condition and with and without a crop under drained condition. Twenty-day-old IRS seedlings were transplanted into the field at 30x 30-cm spacing and fertilized with 150 : 50 : 50 (N-Pa0,-K10) on February 4, 1973. All the plots were kept flooded about 10 em deep for 56 days, then some plots were drained. The experiment was ended 1 week later.

Sampling for dry weight and LAI was done before the start of the drainage treat· ment and at the end of the experiment. Forty-five hills were collected from five randomly selected areas in each plot and measured for leaf area according to the procedure of YosmoA et al. ( 11 ). All samples were dried to a constant weignt in a forced-draft oven at 70°C and then weighed.

To measure COa concentration in air as affected by crop photosynthesis, sample air was collected at 100 em above and 25 em below the crop surface. At each point, the inlet of a needle valve was positioned parallel to the crop surface and connected with Tygon tubing to a Plantass S4A Infrared Gas Analyzer (Beckman-Toshiba Co., Ltd.). Measurements were done on bright days, April 3, 5, and 6.

Soil C02 flux was measured every 24 hr by the soda-lime method described by MONTEITH et al, ( 4 ), A glass petri dish containing about 20 g of granulated soda-lime (analytical reagent grade, 5 mm in diameter) was oven-dried at 100°C for 2 hr, then cooled in a desiccator for 30 min and weighed. In the field, the soda-lime dish was quickly mounted on a wooden petri dish holder so that the dish was about 4 em above the soil surface for bare soil and about 4 em above the water surface for flooded soil within a plastic bucket whose diamet.'!r was about 24 em. For bare soil, the edges of the bucket were pressed below the soil surface. For flooded soil, the plastic bucket with four holes on the side about 5 em above the edge was pressed below the soil surface so that the holes on the side of the bucket were within water. The area covered by the bucket was about 450 cm1• After 24 hr, the soda-lime dish was removed, oven-dried at 100°C for 2 hr, cooled in a desiccator for 30 min and reweighed. The CO a flux was estimated by dividing the weight increase in the granulated soda-lime per day by the surface area covered by the plastic bucket.

Soil moisture content was expressed in weight of water lost at 105°C against dry soil weight. Soil temperature at 5 em below the soil surface was recorded on April 5 .

• RESULTS

Diurnal changes in CO: concentration in air below and above canopy The crop's LAI values were 5.0 at the beginning of the experiment and 6.0 at the

end {Table 1). These values are aufficient to enable the variety IRS to attain its maximum growth rate ( 1 ). Crop growth rate did not differ significantly between the flooded and drained plots. Since diurnal changes in COa concentration in the air above and below crop surface on both flooded and drained plots and on three different days

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Soil Carbon Dioxide Flux and Rice Photosynthesis 383

Table 1. Dry weight and leaf area Index (LAI) of rice crops.

April 2

LAl Dry wt. (g/m1)

------- ------Flooded Drained

5.0 5.0

583 583

April 9

LAI Dry wt. (g/m')

6.0 6.0

753 784

.24 29

u Difference in crop growth rate between the two treatments is not statistically significant.

s ~

8

350

340

330 100 em above canopy

320

310

300

290

280

270 0 ~600 0800 1000 1200 1400 1600 1800

Time Fig. 1. Diurnal changes in C01 concentration

In flooded rice field, April 3, 1973.

Soli COa Dux (f•m-2 •day-I) lOr-;:;-_-:-:---;~-....:..._.:_ ___ ---. 8 Bare soil

6 ~~------~~--~ --·----...... rained 4 Flooded? ... --------

l%"--'----'---L.-........1--_.....L..._..t__j

8 Cropped soil

6

4 2

80 60

._ ___ ... _______ , _______ _j

Bare & cropped soil

o~r~--,2r-~s~~ .. --~s---+s--~7 Days arter "drained plots" were drained

Fig. 2. COa flux from bare and cropped sol1 and soil water content under flooded and dralned conditions.

were similar to each other, only one example is presented in Fig. 1. Early morning, the C01 concentration was high but it decreased sharply with time. The decrease was more pronounced below the canopy, and the differences in COt concentration below and above the canopy were as large as 40 ppm when the sun neared its zenith. This indicates that severe COa deficits occurred around the photosynthetic surface of crop when light intensity was high. Under such a condition, it would be reasonable to assume that soil COa moving to crop surface· could be efficiently used for photosynthesis, Toward evening the difference between the COa concentration above and below the canopy decreased. Eventually, the COJ concentration below the canopy became higher because of the COa released by the plant through respiration.

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Page 6: Soil carbon dioxide flux and rice photosynthesis

384 S. YOSHIDA, V. CORONEL, F.T. PARAO, and E. de los REYES

Soil COz flux Both bare and cropped soil had almost identical moisture contents. As shown in

Fig. 2 soil moisture content decreased from 114% to 79% by 1 week after drainage. Soil COa flux ranged from 3.0 to 5.7 g·m-•·day-1 under flooded conditions and from 6.0 to 8.6g·m-2·day-1 under drained conditions. In both bare and cropped soil, drainage increased soil COa flux by 40 to 50%. Cropped soil released more COa than bare soil under both flooded and drained conditons. This can largely be attributed to root respiration of the crop. No special observation was tnade on blue-green ~lgae on the soil surface which was rather predominant in this field. All aquatic weeds were removed prior to the start of soil COa measurement.

Crmtributio11 of soil C02 flux to rice photosynthesis The following assumptions were used to estimate the contribution· of soil C02 flux

to rice photosynthesis. 1. co~ released frorrr soil during daytime is used in photosynthesis. 2. Daytime lasts 12- hr from 0600 to 1800. 3. The temperature quotient for COs production in the soil is Q,o=3 ( 4 ). (Recorded mean soil temperatures for flooded and drained soil were 30.0 and 28.5"C during daytime, and 28.1 and 24.5<>C at night). Knowing mean soil temPeratures for day and night, and using Q,o=3, we can compute ratio of C02 production rates for day and night by the ~allowing formula :

R I ::::QJ1fl0=3Jt/JO lh

were Rt and Rz are rates of soil COs production for day and night, respectively, and Jt is difference in temperature between daytime and nighttime hours.

Since the C02 production per day is the sum of daytime and nighttime production, and since we assume that daytime and nighttime hours are equally 12 hr, we can estimate C02 production during daytime hours as :

Rt co~ production during daytime hours=COa production per day X ~(R~ + R~)

4. Net dry matter production can be obtained by subtracting 10% from crop growth rate. That allows for mineral content. 5. Gross photosynthesis can be estimated by dividing net dry matter by 0.6. In our previoull study ( 1 ), we found that respiration of a rice crop can be related to gross photosynthesis as :

Respiration =0.4 x gross photosynthesis. Therefore,

Net dry matter=0.6 x gross photosynthesis.

6. co~ can be converted to dry matter by multiplying grams of co~ by !~ . i.e.,

(ClUJ). ~" 11 0 CO~ , assuming that all dry matter is carbohydrate of the ~orm (C 2 ) ••

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Soil Carbon Dioxide Flux and Rice Photosynthesis 385

Table 2. Carbon balance between rice photosynthesis and soil C01 flux,

Net dry matter production (g Clla0·m-1 ·day-1)

Gross photosynthesis (g CH20·m-2·day-1)

Soil C02 flux during daytime (g CHaO·m-1 ·day-1)

Estimated contribution of soil COl to: Net dry matter production (%)

Gross photosynthesis (%)

Flooded

22 36 2.0

9

6

·-~---------

Drained

26 44 3.2

12 7

Using these assumptions, the estimated contribution of soil co.~~ to gross photo· synthesis was 6% for the flooded soil and 7% for the drained soil (Table 2) : its contribution to net dry matter production was 9% for the flooded soil and 12% for the drained soil.

The soil C02 flux is primarily determined by soil organic matter content and soil microbial activity which depends on soil temperature and soil water content. The soil used in this experiment contained abount 2% organic matter, not an extreme value for paddy soils in the tropics. When a soil has higher organic matter, it will release more COa in the atmosphere and the contribution of soil COa flux may become greater than we found in this experiment. Crop growth rate in this experiment was measured under bright sunny days, but in the wet season the crop growth rate would be smaller hence the contribution of soil C0.11 flux to photosynthesis would be greater. Assumin~ gross photosynthesis of a rice crop on cloudy days in the wet season to be half that on bright sunny days in the dry season, the contribution of soil CO, flux to rice photosynthesis would be 10% under flooded conditions and 15% under drained conditions.

DISCUSSIONS

Figure 1 presents evidence that a good rice crop suffers from C02 shortage for photosynthesis on sunny. days, and that air turbulence is not sufficient to supply a constant COa concentration to the photosynthetic surface of the rice crop. Since photosynthesis is proportional to COa concentration around 300 ppm ( 2 ), a drop in C02 concentration as large as 40 ppm is quite critical. Thus, on sunny days the effect of high solar radiation on photosynthesis will be partially counteracted by decreased COa concentration. UCHJJIMA et al. ( 9) recorded a C02 concentration drop as large as 100ppm for a corn crop when the LAI was large and the wind speed was low.

In our experiment, soil COa flux ranged from 3.9 to 5.7 g. m-•·day-1 under flooded conditions, These values are much larger than those reported in other studies, TANAKA et al. (8) reported that no COa flux was detected from a flooded soil where all straw from a previous rice crop had been removed. They found COa flux at a rate of 6.6 g·m-'·day~1 for a flooded soil where 12 t/ha of straw had been incorporated. MURATA et al. ( 6) also reported that COa flux from flooded soils ranged from 0.2 to 2.2 g· m-a.day-1 when compost had been incorporated in amounts varying from 7.5 to

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Page 8: Soil carbon dioxide flux and rice photosynthesis

386 S. YOSHIDA, V. CORONEL, F.T. PARAO, and E. de los REYES

56.3 t/ha. The apparent discrepancy between our values of soil COs flux from flooded soil and those obtained by others may be attributed to the techniques employed. In the soda~Iime method, soda-lime granules absorb col as it is released from soil in a closed system. In other words, soda-lime granules act like crop stands in photosynthesis. On the other hand, when soil COa flux is measured in an open system, it is likely to be underestimated by turbulent mixing.

The estimated contributions of soil COa flux to rice photosynthesis are about the same as those reported for upland crops ( 4, 5). Less than 10% contribution of soil COs flux to gross photosynthesis is expected for a good rice crop under sunny days. There­fore, the atmospheric supply of C02 assumes a far greater importance as a source of C01 in crop photosynthesis.

There used to be much speculation on the Importance of the COs absorbed by plant roots in dry matter production. Available information indicated that the amounts of COa absorbed by plant roots range from much less than 1% of total uptake of COa by the leaves for peas and barley ( 7) to 1 or 2% of total plant carbon for rice ( 3 ), In conclusion, atmospheric C02 is the most important source of COa in crop photosynthesis in rice, soil COa released into atmosphere is next most important source, and soil co~ absorbed by plant roots is an almost negligible source.

REFERENCES

1) COCK, ].II. and YOSHIDA, S., Soil Sci, Plant Nutr,, 19, 53 (1973) 2) GAASTRA, P., Msdsdsl. Landbouwhoguchool Wagsningen, 159, 13 (1959) 9) MITSUI, S. and KURIHARA, K., Soil Sci. Plant Nutr., 8, 226 (1962) () MONTE1TU, J.L., SZEIC, G., and YABUKJ, K., J. APP. Ecol., 1, 321 (1964) 5) MoSS', D.N., MUSGRAVE, R.B., and LEMON, E.R., Crop Sci., 1, 83 (1961) 6) MURATA, Y., 0SADA, A., and lYAMA, ]., Agriculture and Horticulture, 32, 11 (1957) 7) STOLWJJK, J,A.J, and THIMAN, K.V., Plant Physiol., 32, 513 (1957) 8) TANAKA, A., KAWANO, K., and YAMAGUCUI, ]., Int. Rics Res. /nst. T1ch. Bull., 1 (1966) 9) UCUI11MA, A., UOAGAWA, T., liORlE, T., and KOBAYASHI, K., f, Agr. Meterol., 23, 99 (1967)

10) YOSHIDA, S., Soil Sd, Plant Nutr., 19, 311 (1973) 11) YOSIUDA, S., FORNO, D.A., COCK, J,H., and GOMEZ, K.A., Laboratory Manual for Physio(og•

teal Studies of Rice, 2nd ed., Int. Rice Res. Inst., Los Bafios, Laguna, Philippines, 70 p. (1972) D

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