SYSTEM ANALYSIS OF PLANT TRAITS TO INCREASE GRAIN YIELD ON LIMITED WATER SUPPLIES.

Authors: Sinclair, Thomas; MUCHOW, RUSSELL - CSIRO, BRISBANE AUSTRALIA

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: Soil water deficits, or drought, are a common feature of crop production and this leads to a loss in yield. A number of traits have been suggested for incorporation into plants to maximize yields in water-limited environments. It is very difficult, however, to sort out the potential impact of a change any single trait would have on the overall performance of the crop. This study, involving a USDA-ARS scientist located at Gainesville, FL, used a crop model to assess the potential yield changes that could be expected in changing a number of plant traits. The trait that was consistently found to result in yield increases is an increase in crop rooting depth. Deeper roots allowed access by the plant to water reserves deeper in the soil and alleviated the severe consequences of developing drought. Combining a number of traits associated with sorghum plants resulted in greater yields than maize traits when yield levels were below 550 g m-2 (90 bu/A). Above this yield level, however, maize traits resulted in the greater yields.

Technical Abstract: Crop growth in commercial situations usually requires a maximizing of grain yield on limited available water resources, and this results in a maximizing of the ratio of yield to evapotranspiration. A system analysis was undertaken to identify those plant traits that might be altered to improve crop yield in a water-limited environment. A mechanistic maize (Zea mays L.) model was used to simulate yield across 20 y at Columbia, MO. Since sorghum is known to be better adapted to drier environments a number of individual plant traits were adjusted in the maize model to represent sorghum (Sorghum bicolor L.). For the tested environments, it was found that decreasing leaf size and increasing seed growth rate both resulted in decreased yield and decreased ratio of grain yield to evapotranspiration. On the other hand, increasing depth of water extraction resulted in increased yields and increased ratio of grain yield to evapotranspiration. Combining sorghum-like traits in the maize model also increased yield and increased ratio of grain yield to evapotranspiration when averaged for all years. For all seasons where simulated yield was less than about 550 g m 2, grain yields were greater in crops with sorghum-like traits than maize traits.