ASSESSMENT OF POTASSIUM USE EFFICIENCY IN FCV TOBACCO GENOTYPES UNDER NLS CONDITIONS

Abstract

Potassium (K) is the key nutrient required in large quantity for optimum yield and quality of tobacco (Nicotiana tobacum L.) grown on K deficient Alfisols under NLS conditions. Identification and use of genotypes efficient in K uptake and utilization may be a promising strategy to improve yield and reduce costly input of K fertilizers (SOP) in FCV tobacco production. A field experiment on K deficient Alfisols at CTRI Regional station, Jeelugumilli was conducted to evaluate FCV tobacco genotypes for their potassium use efficiency. Treatments for the field experiment included eighteen FCV tobacco genotypes (16/103, Mc Nair-12, CM-12, Kanchan, NLSH-1, NLST-2, NLST-3, NLST-4, TOBIOS-2, RT-301, RT-36-1, RT-42-1, RT-47-1, RT-51-2, RT-57-1, RT67-3, RT-90-1, RT-102-1) grown with and without 120 kg K2O/ha. Plants were harvested treatment wise at the age of 65 DAT. Data on dry matter yield, K concentration and uptake in different plant parts were recorded. K use efficiency was computed in terms of agronomic efficiency (AE), physiological efficiency (PE), recovery efficiency (RE) and internal use efficiency (IUE). Results revealed that in absence of K addition, all the genotypes showed a significant reduction in biomass production. Among the genotypes highest shoot biomass was recorded for RT-51-2 highest biomass. Genotypes showed differential yield response to applied potassium. Among the genotypes RT-51-2, RT-57-1and TOBIOS2 recorded higher AE and RT-57-1, RT-47-1, RT-673 and Kanchan showed greater PE. The RE and IUE were highest in RT-51-2 and NLST-3 respectively. Based on AE and IUE genotypes are classified as efficient and responsive (ER), non efficient and responsive (NER), efficient and non-responsive (ENR) and non-efficient and non-responsive (NENR). In this study ER genotypes were Mc Nair-12, RT-42-1, RT67- 3 and RT-102-1. Genotypes including 16/103, CM-12, NLSH-1, NLST-3 and RT-90-1 are categorized as ENR. The genotypes viz., Kanchan, TOBIOS-2, RT-36-1, RT-47-1, RT-51-2, and RT-57-1 come under NER category. The NENR was represented by NLST2, NLST-4 and RT-30-1. ER genotypes are to be selected while evolving the varieties for higher potassium use efficiency.