Sweet Potato and Taro Resilient to Submergence and Stresses:Sustainable Livelihood in Fragile Zones Vulnerable to Climate Changes

Sweet potato (Ipomoea batatas L.) and Taro [Colocasia esculenta (L.) Schott] are the important submergence and stress tolerant tuber crops used as staple or subsistence food by millions of people in developing nations. Both tubers and leaves of these crops are an alternative source of dietary energy. The visibility of these crops as life support crops species have been enhanced during post super cyclone in Odisha and Tsunami in coastal states of India. Genetic diversity of these crops and, their wide distribution and potential to adapt in harsh environmental condition advocate for their further exploitation to develop stress tolerant crops with valued traits. Gene flow through conventional breeding is hindered owing to flowering behaviours, cytogenetical anomalies in taro and hexaploidy coupled with self incompatibility in sweet potato.

To make these crops more resilient, an extensive study was taken up integrating conventional and non conventional methods to tap the vast potential of genetic diversity in isolating the stress tolerant sweet potato and taro genotypes. The varietal gene bank of sweet potato maintained at Regional Centre farm were also tested under in situ to study tolerance to environmental stresses.

In vitro and in vivo screening and evaluation of 171 sweet potato genotypes and their successive evaluation under in situ salt stress (6.0-8.0 dSm^-1) in coastal Odisha and West Bengal resulted in identification of eleven salt tolerant genotypes packed with high yield (>15 t ha^-1), starch (16-20%), beta carotene (5-14 mg/100g) and anthocyanin (85mg/100g). Induced flooding resulted in identifying submergence tolerant 3 sweet potato genotypes. Further, the survival of some of the varieties of sweet potato over dry period reflects their tolerance to drought stress and can be adapted for cultivation in high lands, where such conditions prevail. Similarly screening of 174 taro genotypes through in vitro-in vivo screening, evaluation under integrated stress and validation of results under in situ stress resulted in identifying five stress tolerant taros including two submergence tolerants. Results on isozymes, DNA polymorphisms and cluster analysis are encouraging for gene pool enrichment for stress tolerant superior types to cope with harsh climate and their impact on livelihood security.