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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR AND GENETIC ENHANCEMENT OF ABIOTIC STRESS TOLERANCE IN SORGHUM

Location: Plant Stress and Germplasm Development Research

Title: Water and radiation use efficiencies in sorghum

Authors
item Narayanan, Sruthi -
item Aiken, Robert -
item Xin, Zhanguo
item Prasad, Vara -
item Yu, Jianming -

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 19, 2013
Publication Date: May 1, 2013
Citation: Narayanan, S., Aiken, R., Xin, Z., Prasad, V., Yu, J. 2013. Water and radiation use efficiencies in sorghum. Crop Science. 105(3):649-656.

Interpretive Summary: Agriculture accounts for 70 % of all freshwater withdrawals worldwide and ranks as the biggest water consumer in the world. To meet the rapidly expanding requirements of water for food, feed, fiber, and biofuel production, both rain-fed and irrigated agriculture needs to use water more efficiently. Producing more crop per drop is key to sustainably meet the need of 9 billion people for food and fuel in a world, where rain, temperature, and drought become increasingly unpredictable. Increasing crop water use efficiency (WUE), the amount of biomass produced per unit water consumed, can enhance crop productivity and yield potential. Eight sorghum (Sorghum bicolor (L.) Moench) genotypes, which differ in canopy architecture, were evaluated under field conditions for transpiration efficiency (TE) and radiation use efficiency (RUE). Canopy level WUE was estimated as the slope of the regression of above-ground biomass on cumulative water use for specified sampling intervals. RUE was estimated as the slope of the regression of above ground biomass on the simulated cumulative intercepted photosynthetically active radiation. Internode length was calculated as the ratio of plant height to total leaf number at maturity. Sorghum genotypes, grown under field conditions, showed significant differences in (a) biomass production, (b) water use, (c) intercepted radiation, (d) water productivity, and (e) RUE. WUE and RUE were more strongly correlated to biomass production than to water use or intercepted radiation, respectively. RUE was positively correlated to WUE and tended to increase with internode length. These results demonstrate that increased utilization of radiation can increase water productivity in plants. Sorghum canopies with increased light transmission to mid-canopy layers can increase RUE and also have the potential to increase crop productivity and WUE.

Technical Abstract: Increasing crop water use efficiency (WUE), the amount of biomass produced per unit water consumed, can enhance crop productivity and yield potential. The objective of this study was to evaluate the factors affecting water productivity among eight sorghum (Sorghum bicolor (L.) Moench) genotypes, which differ in canopy architecture. This study hypothesized that sorghum genotypes differing in WUE measured in greenhouse also differ in WUE and radiation use efficiency (RUE; the amount of biomass produced per unit of intercepted radiation which is suitable for photosynthesis) in field; and that increased WUE and RUE could be associated with differences in canopy architecture. Canopy level WUE was estimated as the slope of the regression of above-ground biomass on cumulative water use for specified sampling intervals. RUE was estimated as the slope of the regression of above ground biomass on the simulated cumulative intercepted photosynthetically active radiation. Internode length was calculated as the ratio of plant height to total leaf number at maturity. Sorghum genotypes, grown under field conditions, showed significant differences in (a) biomass production, (b) water use, (c) intercepted radiation, (d) water productivity, and (e) RUE. WUE and RUE were more strongly correlated to biomass production than to water use or intercepted radiation, respectively. RUE was positively correlated to WUE and tended to increase with internode length. These results demonstrate that increased utilization of radiation can increase water productivity in plants. Sorghum canopies with increased light transmission to mid-canopy layers can increase RUE and also have the potential to increase crop productivity and WUE.

Last Modified: 8/22/2014
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