Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 1, 1999
Publication Date: N/A
Interpretive Summary: Considerable research has shown that plants respond similarly to soil drying regardless of the species. However similar experiments have not been conducted to examine specifically how sugarcane responds to soil drying. Additionally, sugarcane has a fundamentally different root structure than other species that have been studied for response to soil drying. Sugarcane eroots have special structures that serve as air passageways from the shoot to the root tips. These passageways are particularly important in allowing plants to withstand flooded conditions. Agricultural Research Service scientists in Gainesville, FL conducted experiments to determine if these special air passageways in sugarcane roots caused sugarcane to respond differently than other plant species to soil drying. The results of the experiments indicated that some sugarcane cultivars had significant differences in their response to soil drying, however the response of all sugarcane cultivars examined were well withing the range reported for plan species that do not have the special air passageways in their roots. Thus it was concluded that the air passageways in the roots offer no particular advantage or disadvantage in how a plant responds to soil drying.
Technical Abstract: With few exceptions, plant processes across species have the same general pattern of decreased activity with soil drying. The current research was undertaken to examine the pattern of transpiration response to soil drying in sugarcane (Saccharum officinarum L.). This question is particularly intriguing for sugarcane because its roots have aerenchyma and this water- deficit response has not been reported for a species with root aerenchyma. Four sugarcane genotypes were grown in 4.1-L pots sealed to prevent water loss except by transpiration. Pots were weighed on a daily basis and the weights used to calculate transpiration and available soil water expressed as the fraction of transpirable soil water (FTSW). Plateau regression was used to determine the FTSW threshold at which transpiration begins to decline (i.e. stomata begin to close). FTSW thresholds for all four genotypes were found to be in the range of 0.30 to 0.38. We concluded that sugarcane transpiration response to a drying soil is no different than tha published for species that do not possess root aerenchyma.