Chemical induced prolongation of seed viability and stress tolerance capacity of mung bean seedlings

Mung bean(Vigna radiata L. Welczek cv. PS-16) seeds lost viability at a rap id rate under accelerated ageing condition at 99.5% relative humidity (RH) and 32 +/- 2 degrees C temperature for 30 days. Pretreatment of seeds with sodium dikegulac (Na-Dk, 2,3:4-6 di-0-isopropylidene-alpha-L-xylo-2 hexalof uranosate) for 8 hours and seed treatment with Eucalyptus oil throughout th e ageing period of 30 days remarkably slowed the fall of germination and re duced the time (h) required for 50% germination (T-50). The chemicals also hardened the seeds under adverse storage environment by increasing percent germination and by decreasing T-50 hours after 7 days of PEG-induced water stress treatment (1.0 MPa) for 48 h. Speed of seed germination under stress treatment was significantly slowed down in control seed lots aged for 15 d ays and this was relieved by treatment with Na-Dk or Eucalyptus oil. The Na -Dk and Eucalyptus oil induced changes of germination behaviour of seeds we re associated with parallel changes of seedling growth and metabolism under stress condition. Significant reduction of shoot and root length, epicotyl girth and leaf area of seedlings, raised from 15 day-aged seeds, as a resu lt of stress treatment was diminished in Na-Dk and Eucalyptus oil treated s amples. The chemicals checked the loss of seedling potential as evident fro m higher chlorophyll, protein and RNA levels as well as higher activity of catalase and lower activity of IAA-oxidase. Influence of the chemicals on s tress tolerance capacity of mung bean seedlings in addition to their role o n deferment of storage deterioration on seeds is discussed.