ORYZALIN-INDUCED TARO (COLOCASIA ESCULENTA L.) TETRAPLOID AND DIPLOID ASSESSMENT FOR GROWTH AND AGRONOMIC TRAITS

Abstract

Taro (Colocasia esculenta L. cv. Pontianak) is a popular and widely cultivated cultivar in the Indonesian farming community. In taro Pontianak, manipulating the ploidy level by chromosome doubling can enhance its genetic diversity. The latest study aimed to evaluate the oryzalin-induced polyploid taro cv. Pontianak compared with its diploid in terms of growth, anatomical, cytological, morphological, and agronomic traits in the greenhouse and the field. In vitro shoots of taro cv. Pontianak were soaked using a liquid medium supplemented with oryzalin with a concentration of 30 and 60 μM for one day. After five times of subcultures, flow cytometry analysis proceeded to determine their ploidy levels. The diploid (2n = 2x) and tetraploid (2n = 4x) plantlets were then acclimatized in the greenhouse for six to eight weeks and hardened for two months before planting in the field for 10 months. Squashing the root tip to ensure the ploidy levels of taro seedlings helped measure the chromosome numbers. Observing the growth, anatomical, and agronomic traits of diploid and tetraploid plants occurred during the hardening process until harvest time. The 30 μM oryzalin treatment produced tetraploid and mixoploid shoots; none from the 60 μM treatment. Oryzalininduced tetraploid taro exhibited some morphological characteristics of tetraploid plants, such as, longer stomata size and low density. Tubers of tetraploid plants tended to have increased protein, ash, and water content compared with their diploid counterpart. However, tetraploid taro showed a slower growth rate both in the greenhouse and the field. Additionally, it gave lower yields than diploids in some agronomic characteristics, including delayed flowering time, lower plant fresh weight, and smaller tubers. This study provides information that oryzalin-induced tetraploid taro could exhibit increasing and decreasing nutritional-agronomic traits (as mentioned above) compared with its diploid.