Effect of Potassium Nitrate and Salinity on Growth and Endogenous Gibberellins of Glycine max Var. Daewonkong

Plant growth and development was affected greatly through salinity. Appropriate nutrients application on salinity condition can reduce its harmful effects and increased productivity of salinized soils. A pot experiment was carried out in 2007 in cs Lab., Department of Agronomy, Kyungpook National University, Korea to assess the effects of potassium nitrate on Gycine max (Var. Daewonkong) under different salinity levels. Experiment was complete randomized block design (CRBD), consisted of 9 treatments with 3 replications per treatment and each replication comprising 9plants. KNO3 and NaCl were applied to soybean plants 14 days after sowing (14 DAS). KNO3 was applied at the rates of 5.0 mM and 10.0 mM, each pot receiving150 ml of KNO3 solution. For salt stress induction, single dose of 300 ml of NaCl solution of 70 mM and 140 mM strength was given to the plants. Plant length, shoot and root fresh and dry weights were measured for harvested soybean plants while chlorophyll content was estimated in fully expanded leaves. Plant samples were harvested after 24 h of KNO3 and NaCl application for the analysis of endogenous bioactive Gibberellin. Results showed that all growth parameters (shoot length, fresh and dry shoot weight, fresh and dry root weight), chlorophyll content and endogenous bioactive GA1 and GA4 content of soybean cultivar Daewonkong were reduced under NaCl stress. KNO3 application enhanced shoot length, fresh and dry shoot weight, fresh and dry root weight, chlorophyll contents and endogenous bioactive GA1 and GA4 content as compared to control treatment.