Leaf potassium status for drought tolerance: The hunt for promising sesame (Sesamum indicum L.) accessions

Sesame (Sesamum indicum L.) an oilseed crop predominantly cultivated under rainfed conditions in India, is very often exposed to varying intensities and frequencies of drought stress. The leaf potassium content (KC) is known to play a key role in leaf stomatal movement (a direct response to increase or decrease in the osmotic potential of the guard cells) and the plant's ability to withstand drought. The accumulation of potassium (K) varies within a plant species which mainly depends on available soil, plant water status, and external environments. A set of 71 sesame germplasm accessions along with two national checks were assessed to quantify the KC and its association with other traits such as leaf area (LA), relative water content (RWC), leaf dry weight (LDW), and seed weight (SW) under irrigated (WW) and intermittent drought stress (WS) conditions during 2018 and 2019. Though the leaf traits, total dry matter (TDM), RWC, and yield attributing components were found to decrease significantly under drought, the KC was reported to increase by 13 to 14% among accessions across the years tested. The regression analysis suggested a significant positive relationship between seed weight (SW) and KC (R-2=0.87 and R-2=0.76) under the WS situation during both the years. Besides, KC exhibited a significant positive association with RWC, LDW, LA, SW and negative association with total dry matter (TDM). The per se performance revealed that three accessions, IC 204789, IC 205311, and IC 205206 were the most promising with maximum KC, RWC, and seed weight under WS conditions.