Characterization of the Water Economy of Sugarcane Transgenic Genotypes

Aims: Study designed to characterize water economy of a group of sugarcane transgenic lines grown in a rain-sheltered, well-watered, and water-stressed conditions.

Study Design: Randomized complete block with 3 replications.

Place and Duration of Study: The study was conducted at the Texas A&M AgriLife Research and Extension Center in Corpus Christi during 2012 and early 2013.

Methodology: Stem cuts of 14 transgenic lines and two non-transgenic background genotypes (NTBGs) were hand-planted in 13.5-L pots. The study had two phases. In the 1st phase, lines were subjected to a well-watered regime of 1.3 L d-1. In the 2nd phase, lines were exposed to water deficits by reducing irrigation to 0.65 L every other day. At the end of both phases, plants were harvested to determine biomass and leaf area.

Results: Under well-watered conditions the higher nominal water use efficiency (NWUE) attained by lines 15 and 133 over the NTBG was related to their higher production of biomass, which was not paralleled by an increase in whole-plant transpiration. Lines 132 and 20, which showed NWUE not different than their NTBG, exhibited lower and higher cumulative whole-plant transpirations, respectively. Under water stress, lines 11 and 163 had lower NWUE than their respective NTBGs, as a result of lower biomass production not paralleled by a lower whole-plant transpiration. Lines 132 and 112 had NWUE not different than the respective NTBGs, but they both exhibited lower cumulative whole-plant transpiration and lower biomass production.

Conclusion: The study helped characterize the water economy of 14 transgenic sugarcane lines. Under well-watered conditions, lines 15 and 133 exhibited higher NWUE, line 132 was more water-conservative, and line 20 was more water-prodigal than the NTBG. Under water stress, lines 11 and 163 had lower NWUE and lines 132 and 112 were less tolerant to water stress than their respective NTBGs.