Screening for Drought Tolerance in Thirty Three Taro Cultivars

Abstract

Taro [Colocasia esculenta (L.) Schott] is a root crop which is an important staple food in many regions of the world, producing 10.5 million tonnes on 1.4 million hectares a year. The crop is cultivated in wet (rain fed) or irrigated conditions, requiring on average 2,500 mm water per year, and in many countries it is cultivated in flooded plots. It is estimated that taro production could decrease by 40% as a result of the increase in drought and other severe events. In this work, thirty three accessions, including local cultivars, selected and hybrid lines were submitted to long duration drought stress and screened for tolerance. Twelve physiological, morphological and agronomic traits were measured at harvest, and subject to multivariate analysis. Stress indices, Water Use Efficiency and Factorial Analysis were useful for discriminating accessions regarding drought tolerance and yield stability, and drought tolerant and susceptible cultivars were identified. Our results confirm that different taro cultivars have different drought avoidance and tolerance strategies to cope with water scarcity. Better yield performers minimised biomass and canopy loss, while tolerance was observed in cultivars that presented low potential yield, but efficiently transferred resources to enhance corm formation. Among the 33 accessions, two local cultivars showed high yield stability and could be considered as suitable parents for breeding programs, while two others are well adapted to drought, but with overall low yield potential.

Effect of Irrigation Levels and Foliar Spraying With Seaweed Extract, Potassium Silicate and Abscisic Acid on Growth, Corm Yield and Quality of Taro

“…According to the FAO definition (FAO, 1994), taro is the 5 th crop between the main six crops that accumulate starch in roots, tubers, rhizomes, corms and stems which commonly consumed as human and animal food, and as manufactured food products. Meanwhile, it needs high water requirements thus shows least water use efficiency (Uyeda et al 2011; Ganança et al 2018).…”

Phenotypic flexibility and drought avoidance in taro (Colocasia esculenta (L.) Schott)

“…WUE was the ratio between the total plant dry biomass and total water used per plant, expressed in g/L (Ganança et al, 2018).…”

“…WUE is an usual measure of the plant drought resistance, with the more tolerant accessions usually showing higher WUE (Gouveia et al, 2019a;Ganança et al, 2018). Linked to stomatal aperture, WUE could represent the ratio of biomass (produced by CO 2 assimilation in photosynthesis) to water loss by transpiration (Igamberdiev et al, 2004).…”

“…Water scarcity is currently one of the most devastating abiotic stresses with a great impact on crop productivity, and populations' food security and subsistence, which is expected to be aggravated with ongoing climatic changes (Ganança et al, 2018;Ganança et al, 2015). Taro needs a high water supply to obtain optimal yields, about 2,500 mm rainfall per year (Ganança et al, 2018). Therefore, water scarcity and severe weather events were expected to affect negatively this crop productivity (Ganança et al, 2015).…”

“…Water use efficiency (WUE) is essential for plant drought tolerance discrimination. The most tolerant taro accessions can increase or maintain WUE under drought, improving or showing a small decrease in total plant biomass (TPB) and yield (Gouveia et al, 2019a;Ganança et al, 2018). Drought can lead to a nutrient deficiency, since the amount of water availability and nitrogen (N) absorption are strongly correlated (Duman, 2012).…”