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United States Department of Agriculture

Agricultural Research Service

Title: In-vitro Screening for Salt Tolerance in Hibiscus Species

Authors
item Sakhanokho, Hamidou
item Pounders, Cecil
item Kelley, Rowena - MISS STATE UNIV

Submitted to: Southern Nursery Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 11, 2007
Publication Date: November 16, 2007
Citation: Sakhanokho, H.F., Pounders Jr, C.T., Kelley, R.Y. 2007. In-vitro Screening for Salt Tolerance in Hibiscus Species. Southern Nursery Association Proceedings Vol.52 pg. 339-343.

Interpretive Summary: Salinity constitutes one of the major stress factors affecting plant growth. This is a concern in many areas of the world, including the U.S. Gulf Coast where extreme weather events such as hurricanes and coastal floodings can periodically increase soil salinity. Evaluating and selecting for salt tolerance using conventional breeding methods can be labor intensive because it is a complex trait controlled by several genes. Tissue culture techniques, which allow for the processing of large numbers of samples in a short period of time, have been used to screen and/or produce salt-tolerant lines and plants in several agronomic crops sugarcane, but very little research has been undertaken to assess salinity tolerance of ornamental plants. The objective of this study was to use in vitro meristem culture to evaluate and select hibiscus plants for salt tolerance. The species evaluated included red and green variants of Hibiscus acetosella, Hibiscus dasycalyx, and Hibiscus aculeatus. H. acetosella is native to tropical west Africa and grown as an ornamental for the attractiveness of its deep burgundy red, maple-like leaves. H. dasycalyx, also known as the Neches River rose mallow, is a federally listed candidate endangered species that is native to Texas. H. aculeatus (rosemallow, comfortroot, or Pineland hibiscus) is a hardy species with light yellow flowers and red eye. It is native to the lower coastal plains of southeastern North America. Various salt concentrations (0-1%) were used, and increasing salinity adversely affected both shoot growth and root formation. The latter trait is generally highly affected by salt and also positively correlated with salt tolerance at the whole plant level. Interestingly, the highest level of salt tolerance was found in the threatened species, H. dasycalyx. Individual salt tolerant plants within each species were identified and selected for further evaluation under greenhouse conditions.

Technical Abstract: Salinity constitutes a major abiotic stress factor affecting plant growth in many areas of the world, including the U.S. Gulf Coast where extreme weather events such as hurricanes and coastal floodings can periodically increase soil salinity. The objective of this study was to use in vitro meristem culture to evaluate and select hibiscus plants for salt tolerance. The species evaluated included red and green variants of Hibiscus acetosella, Hibiscus dasycalyx, and Hibiscus aculeatus. H. acetosella is native to tropical west Africa and grown as an ornamental for the attractiveness of its deep burgundy red, maple-like leaves. H. dasycalyx, also known as the Neches River rose mallow, is a federally listed candidate endangered species that is native to Texas. H. aculeatus (rosemallow, comfortroot, or Pineland hibiscus) is a hardy species with light yellow flowers and red eye. It is native to the lower coastal plains of southeastern North America. Five salt concentrations (0.1%, 0.2%, 0.4%, 0.8%, and 1% (w/v)), were used in addition to the control treatment that contained no salt. The number of plants that rooted at day 10, 20, and 30 in each treatment was recorded as well as plant height after 30 days of in vitro culture. Both root formation and shoot growth were adversely affected by increasing salinity in all three species. In the control treatment, shoot growth was significantly higher in both variants of H. acetosella than in either H. aculeatus or H. dasycalyx. H. dasycalyx performed as well as both H. acetosella variants for shoot height at 0.2% NaCl concentration, but at 0.4% NaCl concentration, H. dasycalyx performed better than any of the two other species for the same trait. At 0.8 and 1% NaCl concentrations, there were no differences among the species for shoot height. For root development, a trait highly affected by salt and positively correlated with salt tolerance at the whole plant level, H. dasycalyx performed better than any other species under saline conditions after 30 days. In addition, there was very little callus formation even at higher salt concentrations in H. dasycalyx as compared to the other species. Individual salt tolerant plants within each species were identified and selected for further evaluation under greenhouse conditions.

Last Modified: 9/10/2014
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