Many scientists believe that taro is an orphan crop which needs drastic genetic changes in breeding. But when comparing to highly improved seed propagated species such as wheat, rice and maize, the breeding of taro is usually considered as a relatively simple, says Dr Anton Ivancic, Professor of Genetics, Plant Improvement and Botany of Cultivated Plants at the University of Maribor, Slovenia, EU.
Professor Ivancic says a breeder has to obtain viable hybrid seeds, germinate them, obtain mature plants and evaluate them.
“If he finds a superior plant(s) he has to prove it and the work is more or less completed. If we neglect mutations and epigenetic changes, the genetic structure of the selected plant(s) will remain unchanged due to vegetative propagation (i.e., due to continuous mitosis),” Professor Ivancic said when giving a seminar at NARI Bubia on February 17 2015.
He said the major problems associated with taro breeding (and breeding of other aroids) are:
- poor flowering ability of the parental material;
- difficulties associated with seed germination,
- slow growth of seedlings and a relatively long vegetation period;
- discontinuous work (breeding programs are frequently interrupted, terminated and restarted);
- insufficient theoretical knowledge and practical work experience of breeders (frequent changes of breeders, not many people remain breeders for a longer period of time);
- inefficient selection methods, and
- inappropriate breeding facilities, environmental conditions and financial support.
Professor Ivancic, who has spent many years in PNG in the past, said the existing taro breeding programs appear to be very similar.
“They are based on artificial or natural recombination of superior genotypes, relatively simple selection procedure followed by clonal propagation.
“The neglected approaches are interspecific hybridisation, polyploidisation, mutagenesis, genetic engineering, marker assisted selection and epigenetic breeding approach. Most of the breeding programs are associated with Colocasia esculenta and not much has been done on Alocasia macrorrhizos, Colocasia gigantea and Cyrtosperma merkusii,” he said.
The genetic breeding in PNG should also involve Amorphophallus paeoniifolius, Xanthosoma sagittifolium and X. violaceum, he said.
Each breeding includes three main steps:
- creation of genetic variation,
- selection of superior genotypes in genetically variable populations and
- realisation of a new cultivar (field trials and chemical evaluation in order to test the value of the selected genotype(s), registration, multiplication, marketing). Hybridisation is still considered to be the most efficient and the most reliable method of creating genetic variation.
The seminar was given to discuss theoretical issues and practical problems associated with the genetic breeding of taro and other aroids: genetically inherited traits and environmental conditions influencing flowering, artificial induction of flowering, hybridization techniques, hybridisation schemes, seed germination, selection methods and their efficiency, neglected breeding approaches and maintenance of genetic identity of cultivars.
NARI has an ongoing breeding program on staple foods such as taro and sweet potato. Earlier breeding work on taro resulted in the release of four improved varieties with resistant to the Taro Leaf Blight disease.
Professor Ivancic spent two weeks with NARI researchers both at Bubia and Aiyura.