"Tissue culture screening method identified salt tolerant swamp taro varieties"
Out of seven swamp taro (Cyrtosperma merkusii) varieties investigated using tissue culture screening methods, four were identified as salt tolerant by the Centre for the Pacific Crops and Trees (CePaCT) of the Secretariat of the Pacific Community (SPC) in one of its research. Three varieties are from Kiribati (Natutebubua, Teimanra and Kaiura) and one from Fiji (Via kai).
The varieties used were sourced originally from the two countries and conserved at CePaCT. The research validated past studies by CePaCT looking to optimise screening protocols for different crops.
The tolerance of these varieties were assessed based on their responses to four treatments during four weeks duration of the research using two different screening approaches - addition of varied salt concentrations initially in the culture medium, and incremental addition of varied salt concentrations weekly to culture medium. The exercise imitates similar scenario of salt inundation occurring in the swamp taro pits.
The latter approach (incremental additional of 1% salt weekly) was optimal where varieties identified as tolerant exhibited higher mean values of tolerance to all treatments even up to a total of 4% based on five morphological parameters (plant length, root length, corm size, scorching of leaves, number of emerging leaves and suckers produced) used in the assessment. The first approach showed opposite results.
The varieties identified will be further evaluated in Kiribati and other atoll countries for their real responses in the field and to validate correlation between varietal responses in tissue culture versus field responses.
Swamp taro is the staple crop of the atoll countries and is one of the crops severely affected by the current drought impacting outer islands of the Marshall Islands, thus food security is greatly threatened. Increased soil salinity and high temperatures are worsened during drought periods.
Other Pacific island atoll countries such as Kiribati, Tokelau and Tuvalu have all had similar problems when faced with their worst drought experience, hence more requests received by CePaCT for salt tolerant crop varieties.
This makes this research very timely and extremely important. The research develops a quick screening method for identifying varieties for field validation and assists with selection of varieties that will form the basis of a breeding program for improved resilience of swamp taro varieties to salinity.
The research was carried out by Ms Takena Redfern-Viala of Kiribati under her Greg Urwin Pacific Leadership Program as well as linking to project activities of the SPC AusAID International Climate Change Adaptation Initiative project. Valerie Saena Tuia of SPC Genetic Resources supervised the research.