Submitted to: Field Crops Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/9/2008
Publication Date: 5/10/2008
Citation: Xin, Z., Payton, P.R., Franks, C.D., Burke, J.J. 2008. A simple method to determine transpiration efficiency in sorghum. Field Crops Research. 107(2):180-183. Interpretive Summary: Fresh water resource has become increasingly scarce. Thus, enhancing water use efficiency is a critical research goal to sustaining agricultural productivity. However, progress in improving water use efficiency in crops is severely limited by the lack of high throughput and reproducible method suitable for screening large number of plant accessions to select the lines with superior water use efficiency. We have developed a high throughput and cost effective method to determine water use efficiency in sorghum. This method can reliably detect genetic difference in 14 selected sorghum lines. The method should be easily adapted to determine water use efficiency in other crops.
Technical Abstract: [Sorghum bicolor (L.) Moench] is a widely-grown cereal grain and a dietary staple for more than 500 million people worldwide, grown primarily in arid and semi-arid regions. Crop modeling analysis indicates that a small improvement in transpiration efficiency (TE) could have a large impact on sorghum yield and yield stability. While sorghum is known to vary genetically in TE, it has not been possible to exploit this variability in breeding programs, largely due to the lack of robust and high-throughput methodologies to determine TE. We have developed a mini-lysimetric method that directly measured whole plant TE in sorghum during early seedling stage under greenhouse conditions. TE in sorghum lines can be accurately determined in a 6-inch pot by using a commercial potting mix with high water-holding capacity without the need for re-watering. The genetic variation in TE of 11 inbred lines and three hybrids were evaluated under two conditions that differed significantly in relative humidity. Although relative humidity had a large impact on TE, similar genotypic rankings were observed across experiments by the mini-lysimetric assay. Despite the advantage of hybrid vigor, the three hybrids used in this study were not the highest in TE rank, suggesting a need and potential to improve TE in sorghum. Post photosynthetic metabolic processes may contribute to a large part of the whole plant level TE since the genetic variation in TE could not be accounted for by leaf-level instantaneous TE derived from gas exchange measurements. Our method offers a high throughput and affordable way to determine whole plant level TE in sorghum.