Maize Radiation Use Efficiency under Optimal Growth Conditions

Abstract

and Amthor (1999) suggested that the RUE era in crop modeling should be closed. Accurate measurement of crop growth and radiation use efficiencyA number of factors contribute to the variation in (RUE) under optimal growth conditions is required to predict plant reported estimates of RUE (Sinclair and Muchow, 1999). dry matter accumulation and grain yield near the genetic growth potential. Research was conducted to quantify the biomass and leafEstimates of RUE depend on whether radiation is meaarea index (LAI) accumulation, extinction coefficient, and RUE of sured as total solar radiation or as PAR. While some maize (Zea mays L.) under conditions of optimal growth. Maize was authors suggest that conversion of RUE based on solar grown in two environments over five growing seasons (1998)(1999)(2000)(2001)(2002).radiation to that based on PAR is achieved simply by Total aboveground biomass at maturity ranged from 2257 g m Ϫ2 in multiplying by the fraction of total solar radiation that 1998 to 2916 g m Ϫ2 in 2001; values that are considerably greater than is photosynthetically active (usually 0.5, Sinclair and the biomass achieved in most previous studies on RUE in maize. Muchow, 1999), it has been pointed out that the appro-Peak LAI ranged from 4.8 to 7.8. Maize extinction coefficients during priate multiplication factor depends on canopy LAI vegetative growth (k ) were within the range of recently published (Bonhomme, 2000). The radiation intercepted by a crop values (0.49 Ϯ 0.03), with no clear pattern of differences in k among years. Seasonal changes in interception of photosynthetically active is different from that absorbed by it and, therefore, radiation (PAR) were similar across all but one year. Estimates of introduces variation in RUE calculations. In agreement RUE were obtained using the short-interval crop growth rate method with Sinclair and Muchow (1999), Bonhomme (2000) and the cumulative biomass and absorbed PAR (APAR) method. suggests that assuming 85% of intercepted PAR (IPAR) Values of RUE obtained using the two methods were 3.74 (Ϯ0.20) g is absorbed by the leaf canopy is accurate when canopy MJ Ϫ1 APAR and 3.84 (Ϯ0.08) g MJ Ϫ1 APAR, respectively, and did LAI is large, but the value is smaller when canopies not vary among years. This compares to a published mean RUE are less dense. Variation in estimates of RUE can be for maize of 3.3 g MJ Ϫ1 of intercepted PAR (Mitchell et al., 1998).substantially reduced by measuring both intercepted Moreover, RUE did not decline during grain filling. Differences in and absorbed radiation continuously during a sampling

Intercepted solar radiation by maize crops subjected to different tillage systems and water availability levels

“…In addition to weather conditions, a natural reduction of incoming solar radiation is expected to happen after the middle of the summer season, as a consequence of the solar declination. Decreases in intercepted PPFD may also be expected in maize crops during the grain-filling period due to leaf senescence (Maddoni & Otegui, 1996;Collinson et al, 1999;Lindquist et al, 2005).…”

“…bras., Brasília, v.45, n.12, p. 1331-1341, dez. 2010 is often a critical step in crop simulation models which aims at estimating increases in daily biomass and kernel number (Lindquist at al., 2005).…”

“…This efficiency depends on the leaf area index (LAI) and on the extinction coefficient, which is related to the canopy structure, especially concerning the shape of the leaf and its inclination (Norman & Campbell, 1989;Varlet-Grancher et al, 1989;Lindquist et al, 2005). Alterations in the extinction coefficient that shows a constant LAI tend to promote alterations in the intercepted solar radiation, and hence, in the potential accumulation of biomass (Lindquist et al, 2005).…”

Multi-scale evaluation of light use efficiency in MODIS gross primary productivity for croplands in the Midwestern United States

“…Typical ε * GPP in site-scale studies range from 2.40 to 4.24 gC MJ −1 for C4 crops and 1.41 to 1.96 gC MJ −1 for C3 crops (Chen et al, 2011;Kalfas et al, 2011;Lindquist et al, 2005;Singer et al,2011;Turner et al, 2002), while ε * GPP in many large-scale modeling efforts are about 0.604-1.08 gC MJ −1 for croplands (Bradford et al, 2005;Heinsch et al, 2003;Lobell et al, 2002;Zhao and Running, 2010). Note that the ε * GPP values prescribed in many large-scale biogeochemical models are only approximately half of those in a number of small-scale studies.…”

Comparison of performance of tile drainage routines in SWAT 2009 and 2012 in an extensively tile-drained watershed in the Midwest

“…The Soil and Water Assessment Tool (SWAT), a physically based and watershed-scale hydrological model, has been widely used to simulate land use change impacts on water quantity and quality (Basheer et al, 2016;Guo et al, 2015;Luo et al, 2012;Shope et al, 2014;Teshager et al, 2016;Wang et al, 2016;Yin et al, 2016), but studies on simulation of tile drainage impact at field and watershed scales using the new tile drainage routine from SWAT2012 are few (Boles et al, 2015;Du et al, 2005Du et al, , 2006Moriasi et al, 2005Moriasi et al, , 2012. For instance, Sui and Frankenberger (2008) quantified the impact of tile drains on nitrate loss in an extensively tiledrained watershed, and showed that simulated nitrate loss results by SWAT2005 could be used for simulation of nitrate reductions at the watershed scale.…”