A simple evapotranspiration model of a paddy field in tropical Asia

Yoshida, Shigemitsu

doi:10.1080/00380768.1979.10433148

Cited by 5 publications

(5 citation statements)

References 6 publications

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“…Potential evapotranspiration (ET o ) was between 2 and 3 mm d -1 , which is close to the values reported in earlier studies [ 18 , 19 ] for the wet season in the Philippines ( Fig 1B ). Crop ET increased with crop development and attained a maximum at about flowering stage, with about 6 mm d -1 for the 390 ppmv treatment.…”

Section: Resultssupporting

confidence: 90%

Atmospheric CO2 concentration effects on rice water use and biomass production

et al. 2017

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Numerous studies have addressed effects of rising atmospheric CO2 concentration on rice biomass production and yield but effects on crop water use are less well understood. Irrigated rice evapotranspiration (ET) is composed of floodwater evaporation and canopy transpiration. Crop coefficient Kc (ET over potential ET, or ETo) is crop specific according to FAO, but may decrease as CO2 concentration rises. A sunlit growth chamber experiment was conducted in the Philippines, exposing 1.44-m2 canopies of IR72 rice to four constant CO2 levels (195, 390, 780 and 1560 ppmv). Crop geometry and management emulated field conditions. In two wet (WS) and two dry (DS) seasons, final aboveground dry weight (agdw) was measured. At 390 ppmv [CO2] (current ambient level), agdw averaged 1744 g m-2, similar to field although solar radiation was only 61% of ambient. Reduction to 195 ppmv [CO2] reduced agdw to 56±5% (SE), increase to 780 ppmv increased agdw to 128±8%, and 1560 ppmv increased agdw to 142±5%. In 2013WS, crop ET was measured by weighing the water extracted daily from the chambers by the air conditioners controlling air humidity. Chamber ETo was calculated according to FAO and empirically corrected via observed pan evaporation in chamber vs. field. For 390 ppmv [CO2], Kc was about 1 during crop establishment but increased to about 3 at flowering. 195 ppmv CO2 reduced Kc, 780 ppmv increased it, but at 1560 ppmv it declined. Whole-season crop water use was 564 mm (195 ppmv), 719 mm (390 ppmv), 928 mm (780 ppmv) and 803 mm (1560 ppmv). With increasing [CO2], crop water use efficiency (WUE) gradually increased from 1.59 g kg-1 (195 ppmv) to 2.88 g kg-1 (1560 ppmv). Transpiration efficiency (TE) measured on flag leaves responded more strongly to [CO2] than WUE. Responses of some morphological traits are also reported. In conclusion, increased CO2 promotes biomass more than water use of irrigated rice, causing increased WUE, but it does not help saving water. Comparability with field conditions is discussed. The results will be used to train crop models.

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Section: Resultssupporting

confidence: 90%

Atmospheric CO2 concentration effects on rice water use and biomass production

et al. 2017

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“…The mean seasonal value of ET obtained was in the range of the major areas of rice in Asia and America. In the Philippines, 7 mm•day -1 was an average requirement during the submerged period [37]. In fact, ET falls within the range given by many authors, which varies between 4 and 9 mm•day -1 [27,30,36].…”

Section: Rice Evapotranspiration Measuredsupporting

confidence: 58%

“…The average KCp found under our conditions was around the unit value (1.06). Some authors showed that the average ET from a rice field was lower than the pan evaporation and it ranged between 0.90 and 0.98 [9,16,37].…”

Section: Determination Of Rice Crop Coefficient Based On Et 0 and Epmentioning

confidence: 99%

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Estimation of rice evapotranspiration using a microlysimeter technique and comparison with FAO Penman-Monteith and Pan evaporation methods under Moroccan conditions

et al. 2003

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This paper reviews field measurements of evapotranspiration from paddy rice fields (ET) in an experimental station in the Gharb region of Morocco, during the summer seasons in 1995 and 1996. The results showed that the seasonal average water consumption of rice was 6.7 mm•day-1 with a maximum value of 8.3 mm•day-1 during the panicle enlargement stage (R2). The average daily ET for 1996 was compared with US Class 'A' open pan evaporation (Ep) and with reference evapotranspiration (ET 0) calculated using a validated FAO Penman-Monteith equation. Both methods gave good estimates of ET with a correlation coefficient of 0.78 (P < 0.001, slope = 1.06) with Ep and 0.79 with ET 0 (P < 0.001, slope = 1.3). The derived mean crop coefficients were 1.06 and 1.3, respectively, for the average of the two years. The cumulated ET over the growing season was nearly equal to the cumulated Ep, and greater by about 20% of cumulated ET 0. This superiority might be attributed to an advective energy transferred from areas surrounding the rice zone activated by wind speed. rice (Oryza sativa) evapotranspiration / crop coefficient / reference ET Résumé-Calcul de l'évapotranspiration du riz sous les conditions marocaines : recherche d'une relation simple entre l'évapotranspiration calculée expérimentalement et l'évapotranspiration de référence estimée à partir de l'équation FAO Penman-Montheith et l'évaporation bac. Cet article traite de l'évapotranspiration du riz (ET) mesurée expérimentalement au niveau du champ dans la région rizicole au nord-ouest du Maroc durant la période estivale de 1995 et 1996. Les résultats obtenus ont été comparés à ceux de l'évaporation à partir d'un bac ouvert class 'A' (Ep) et avec l'évapotranspiration de référence calculée à partir de l'équation FAO Penman-Monteith (ET 0) calibrée sous les conditions marocaines. Les résultats obtenus ont été comparés à l'ET 0 et à l'Ep. Des coefficients culturaux ont été alors établis. Les résultats obtenus ont montré que la moyenne saisonnière des besoins en eau du riz était de 6,7 mm•jour-1 avec un maximum atteint de 8,3 mm•j-1 durant la deuxième décade du grossissement de la panicule avant l'épiaison. L'ET saisonnière en 1996 a montré une corrélation très hautement significative avec les deux modèles, de 0,78 (P < 0,001, pente = 1,06) avec Ep et 0,79 avec ET 0 (P < 0,001, pente = 1,3). les coefficients culturaux moyens des deux années, étaient respectivement de 1,06 (Kcp = ET•Ep-1) et 1,3 (KC 0 = ET•ET 0-1). L'ET cumulée durant la saison de croissance égalise avec l'Ep cumulée et dépasse l'ET 0 cumulée de 20 %. Cette supériorité pourrait provenir d'une énergie advective transmise des zones sèches, entourant la zone rizicole, activée par le déplacement des vents. riz (Oryza sativa) évapotranspiration / coefficient cultural / évapotranspiration de référence

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“…Rising temperatures increase evapotranspiration (Figure 5(b) and Figure 6) of plants and wetlands in the Lamto area, which explains the positive relationship between mean annual temperature and evapotranspiration (Table 2) during specific periods of the study, most notably in the middle of 2010 and the last five years, which have been extremely hot and dry. Our results corroborate well with those studies [86], who claimed an energy exchange between the soil and the plant canopy due to plants consuming net radiation via the photosynthesis channel, which is transformed into evapotranspiration. Our findings indicate a link between evapotranspiration and temperature caused by solar radiation and the requirements of chlorophyllous plants for biosynthetic metabolic processes, as described by the authors [87] [88] [89].…”

Section: Discussionsupporting

confidence: 93%