Diagnosis and confirmation of subsoil acidity induced multi nutrient disorders in Tannia (Xanthosoma sagittifolium L. Schott) grown in an Ultisol, Kerala, India

Abstract

Aroids are a group of tropical tuber crops which includes taro, tannia and elephant foot yam. Tannia(Xanthosoma sagittifolium L. Schott) belonging to the family Araceae is considered as a remunerativeintercrop in the partial shaded conditions of plantations. The tubers, consisting of corm and cormelsas well as the leaves are edible, and have good nutraceutical properties, but many of them are yet tounravel. The leaves are rich sources of phytochemicals and minerals like P, Ca and K. Being a shadetolerant and acid sensitive crop, when it is grown in potentially acidic aluminium (Al) rich laterite soils,they are prone to the occurrence of some nutritional disorders which was suspected as subsoil acidityinduced Mg, K and Ca deficiency. Experiments conducted in the nutrient omission pot trial gave theinference of the same which was further confirmed through soil and plant analysis. More confirmationon the occurrence of the antagonistic effect of excess K on the deficiency of Mg and Ca too was evolvedby conducting experiments in lysimeter tanks followed by the analysis of the soil filled in lysimeter tanksand the symptomatic leaf samples. Though both experiments were done to confirm the susceptibilityof the crop to potential acidity manifested in the form of interveinal chlorosis, typical of Mg deficiency,and associated K and Ca disorders. The growth and yield data of the crop recorded indicated the needto replenish the soil with required quantities of nutrients viz., K, Ca and Mg at an application rate ofK2O @ 100 kg ha-1 along with lime@1 t ha-1 and MgSO4 @100 kg ha-1. Since acidity being the primarycause and K being the crucial nutrient in affecting the yield, further experiments conducted revealeddolomite as the best soil ameliorant @ 1 t ha-1 and K2O @ 150 kg ha-1.Keywords: Tannia, Nutrient disorder, Subsoil acidity, Nutrient deficiency, Lysimeter