Optimum potassium dose for K use efficient cassava genotypes in an Ultisol of Kerala, India

Abstract

AbstractMineral nutrition is one of the most important strategies to increase crop yields as plant nutrients are one among the critical factors contributing to higher productivity though the efficiency of the applied fertilizers is low. An alternative to this issue is the screening of nutrient use efficient (NUE) genotypes within a crop species which are unique with respect to their efficiency in acquisition, transport and utilization of nutrients. In this regard, the germplasm collection of cassava at ICAR-CTCRI was considered initially in 2008 for screening K use efficient genotypes. Preliminary evaluation of 83 elite genotypes for their physiological efficiency for K resulted in the identification of six genotypes viz., Aniyoor, 7 III E3-5, Sree Sahya, 6-6, CR 43-8 and W-19. These were tested under a split plot design with four levels of K viz., K2O @ 0, 50,100 and 150 kg ha-1 to select the most promising K use efficient genotypes as well as their optimum K application requirement. This paper describes the parameters viz., tuber yield and NUE parameters like agronomic efficiency, physiological efficiency, agro physiological efficiency, apparent recovery efficiency, utilization efficiency, harvest index, K harvest index, K utilization ratio/K utilization for tuber, K uptake ratio and K utilization for biomass considered over three years of experimentation under the above four levels of K in arriving the best level/optimum dose of K application for these genotypes. The above data revealed that all these genotypes performed best under K2O @ 50 kg ha-1 which was on par with either 100 and 150 kg ha-1 K2O elucidating the advantage of reducing the dose of K for these genotypes. Keywords: Cassava genotypes, Nutrient use efficiency, K efficient, K uptake