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Neglecting rice milling yield and quality underestimates economic losses from high-temperature stress.

Lyman NB, Jagadish KS, Nalley LL, Dixon BL, Siebenmorgen T - PLoS ONE (2013)

Bottom Line: These dramatic losses result from reduced paddy yield and increased percentages of chalky and broken kernels, which together decrease the quantity and market value of milled rice.Recently published estimates show paddy yield reductions of up to 10% across the major rice-producing regions of South and Southeast Asia due to rising temperatures.The results of our study suggest that the often-cited 10% figure underestimates the economic implications of climate change for rice producers, thus potentially threatening future food security for global rice producers and consumers.

View Article: PubMed Central - PubMed

Affiliation: Department of Agricultural Economics and Agribusiness, University of Arkansas, Fayetteville, Arkansas, United States of America.

ABSTRACT
Future increases in global surface temperature threaten those worldwide who depend on rice production for their livelihoods and food security. Past analyses of high-temperature stress on rice production have focused on paddy yield and have failed to account for the detrimental impact of high temperatures on milling quality outcomes, which ultimately determine edible (marketable) rice yield and market value. Using genotype specific rice yield and milling quality data on six common rice varieties from Arkansas, USA, combined with on-site, half-hourly and daily temperature observations, we show a nonlinear effect of high-temperature stress exposure on yield and milling quality. A 1 °C increase in average growing season temperature reduces paddy yield by 6.2%, total milled rice yield by 7.1% to 8.0%, head rice yield by 9.0% to 13.8%, and total milling revenue by 8.1% to 11.0%, across genotypes. Our results indicate that failure to account for changes in milling quality leads to understatement of the impacts of high temperatures on rice production outcomes. These dramatic losses result from reduced paddy yield and increased percentages of chalky and broken kernels, which together decrease the quantity and market value of milled rice. Recently published estimates show paddy yield reductions of up to 10% across the major rice-producing regions of South and Southeast Asia due to rising temperatures. The results of our study suggest that the often-cited 10% figure underestimates the economic implications of climate change for rice producers, thus potentially threatening future food security for global rice producers and consumers.

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Related in: MedlinePlus

Nonlinear response of mean milled rice outcomes of tested genotypes given 1°C, 2°C, and 4°C increases in mean growing-season temperature.Average milled non-chalky head rice (red), chalky head rice (blue), and broken rice (green) per hectare were derived from estimated changes in paddy and milling quality outcomes, by scenario, using sample mean values of paddy and milling quality outcomes as baselines. Estimated changes in mean paddy and milling quality outcomes illustrated in Figures 2 and 3 were used to calculate the milled mass per hectare values illustrated above. Estimated changes in paddy yield from the baseline were calculated using the pooled sample of paddy yield trials and do not vary across cultivar. These changes are presented in Figure 2. Total milling revenue ($1,000 ha−1) is presented at the end of each bar. We used the sample means of milled medium-grain (Bengal and Jupiter) and long-grain (XL723, Wells, LaGrue, and Cypress) U.S. rice prices from 2007–2010, the sample period, for the price of non-chalky head rice, and the sample mean of Arkansas brewers’ milled rice prices over the 2007–2010 period for the price of broken and chalky-head rice kernels.
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pone-0072157-g003: Nonlinear response of mean milled rice outcomes of tested genotypes given 1°C, 2°C, and 4°C increases in mean growing-season temperature.Average milled non-chalky head rice (red), chalky head rice (blue), and broken rice (green) per hectare were derived from estimated changes in paddy and milling quality outcomes, by scenario, using sample mean values of paddy and milling quality outcomes as baselines. Estimated changes in mean paddy and milling quality outcomes illustrated in Figures 2 and 3 were used to calculate the milled mass per hectare values illustrated above. Estimated changes in paddy yield from the baseline were calculated using the pooled sample of paddy yield trials and do not vary across cultivar. These changes are presented in Figure 2. Total milling revenue ($1,000 ha−1) is presented at the end of each bar. We used the sample means of milled medium-grain (Bengal and Jupiter) and long-grain (XL723, Wells, LaGrue, and Cypress) U.S. rice prices from 2007–2010, the sample period, for the price of non-chalky head rice, and the sample mean of Arkansas brewers’ milled rice prices over the 2007–2010 period for the price of broken and chalky-head rice kernels.

Mentions: CHK, MRY and HRY largely determine the value of a unit of paddy rice, but the quantity of milled rice output per unit area harvested depends on paddy yield. Figure 3 illustrates XL723’s susceptibility to chalky kernel formation while maintaining high head rice potential per hectare due to its high yield. Cypress, the relatively low-yielding, high quality long-grain cultivar compares very well in non-chalky head rice production despite having a baseline yield disadvantage. The baseline estimate of XL723’s non-chalky milled head rice is higher than Cypress’s because of XL723’s 31% baseline paddy yield advantage over Cypress. The relative proportions of non-chalky and chalky head rice, and broken rice change as average growing-season temperature increases from the baseline level by 1°C, 2°C, and 4°C. Given a 4°C increase, Cypress is estimated to produce over 0.6 t ha−1 more non-chalky head rice than XL723 and roughly 1.2 t ha−1 more than LaGrue or Wells.


Neglecting rice milling yield and quality underestimates economic losses from high-temperature stress.

Lyman NB, Jagadish KS, Nalley LL, Dixon BL, Siebenmorgen T - PLoS ONE (2013)

Nonlinear response of mean milled rice outcomes of tested genotypes given 1°C, 2°C, and 4°C increases in mean growing-season temperature.Average milled non-chalky head rice (red), chalky head rice (blue), and broken rice (green) per hectare were derived from estimated changes in paddy and milling quality outcomes, by scenario, using sample mean values of paddy and milling quality outcomes as baselines. Estimated changes in mean paddy and milling quality outcomes illustrated in Figures 2 and 3 were used to calculate the milled mass per hectare values illustrated above. Estimated changes in paddy yield from the baseline were calculated using the pooled sample of paddy yield trials and do not vary across cultivar. These changes are presented in Figure 2. Total milling revenue ($1,000 ha−1) is presented at the end of each bar. We used the sample means of milled medium-grain (Bengal and Jupiter) and long-grain (XL723, Wells, LaGrue, and Cypress) U.S. rice prices from 2007–2010, the sample period, for the price of non-chalky head rice, and the sample mean of Arkansas brewers’ milled rice prices over the 2007–2010 period for the price of broken and chalky-head rice kernels.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3750041&req=5

pone-0072157-g003: Nonlinear response of mean milled rice outcomes of tested genotypes given 1°C, 2°C, and 4°C increases in mean growing-season temperature.Average milled non-chalky head rice (red), chalky head rice (blue), and broken rice (green) per hectare were derived from estimated changes in paddy and milling quality outcomes, by scenario, using sample mean values of paddy and milling quality outcomes as baselines. Estimated changes in mean paddy and milling quality outcomes illustrated in Figures 2 and 3 were used to calculate the milled mass per hectare values illustrated above. Estimated changes in paddy yield from the baseline were calculated using the pooled sample of paddy yield trials and do not vary across cultivar. These changes are presented in Figure 2. Total milling revenue ($1,000 ha−1) is presented at the end of each bar. We used the sample means of milled medium-grain (Bengal and Jupiter) and long-grain (XL723, Wells, LaGrue, and Cypress) U.S. rice prices from 2007–2010, the sample period, for the price of non-chalky head rice, and the sample mean of Arkansas brewers’ milled rice prices over the 2007–2010 period for the price of broken and chalky-head rice kernels.
Mentions: CHK, MRY and HRY largely determine the value of a unit of paddy rice, but the quantity of milled rice output per unit area harvested depends on paddy yield. Figure 3 illustrates XL723’s susceptibility to chalky kernel formation while maintaining high head rice potential per hectare due to its high yield. Cypress, the relatively low-yielding, high quality long-grain cultivar compares very well in non-chalky head rice production despite having a baseline yield disadvantage. The baseline estimate of XL723’s non-chalky milled head rice is higher than Cypress’s because of XL723’s 31% baseline paddy yield advantage over Cypress. The relative proportions of non-chalky and chalky head rice, and broken rice change as average growing-season temperature increases from the baseline level by 1°C, 2°C, and 4°C. Given a 4°C increase, Cypress is estimated to produce over 0.6 t ha−1 more non-chalky head rice than XL723 and roughly 1.2 t ha−1 more than LaGrue or Wells.

Bottom Line: These dramatic losses result from reduced paddy yield and increased percentages of chalky and broken kernels, which together decrease the quantity and market value of milled rice.Recently published estimates show paddy yield reductions of up to 10% across the major rice-producing regions of South and Southeast Asia due to rising temperatures.The results of our study suggest that the often-cited 10% figure underestimates the economic implications of climate change for rice producers, thus potentially threatening future food security for global rice producers and consumers.

View Article: PubMed Central - PubMed

Affiliation: Department of Agricultural Economics and Agribusiness, University of Arkansas, Fayetteville, Arkansas, United States of America.

ABSTRACT
Future increases in global surface temperature threaten those worldwide who depend on rice production for their livelihoods and food security. Past analyses of high-temperature stress on rice production have focused on paddy yield and have failed to account for the detrimental impact of high temperatures on milling quality outcomes, which ultimately determine edible (marketable) rice yield and market value. Using genotype specific rice yield and milling quality data on six common rice varieties from Arkansas, USA, combined with on-site, half-hourly and daily temperature observations, we show a nonlinear effect of high-temperature stress exposure on yield and milling quality. A 1 °C increase in average growing season temperature reduces paddy yield by 6.2%, total milled rice yield by 7.1% to 8.0%, head rice yield by 9.0% to 13.8%, and total milling revenue by 8.1% to 11.0%, across genotypes. Our results indicate that failure to account for changes in milling quality leads to understatement of the impacts of high temperatures on rice production outcomes. These dramatic losses result from reduced paddy yield and increased percentages of chalky and broken kernels, which together decrease the quantity and market value of milled rice. Recently published estimates show paddy yield reductions of up to 10% across the major rice-producing regions of South and Southeast Asia due to rising temperatures. The results of our study suggest that the often-cited 10% figure underestimates the economic implications of climate change for rice producers, thus potentially threatening future food security for global rice producers and consumers.

Show MeSH
Related in: MedlinePlus