EFFECT OF LAB-173711, AN ABA ANALOG, ON LOW-TEMPERATURE RESISTANCE OF MUNG BEAN SEEDLINGS

The effect of LAB 173 711, a synthetic analogue of abscisic acid, has been evaluated on chilling-sensitive mung bean (Vigna radiata L. cv. Local V.) seedlings. Electrical conductivity was used for assessing the degree of chilling injury. Exposure of 8-day-old mung bean seedlings to 4-degrees-C for 35 h resulted in a 50% electrolyte leakage and induced irreversible chilling injury. The seedlings gained the best protection against chilling injury by pretreatment with LAB 173 711 (5 x 10(-4) M) for 3 days. The protection effect could be sustained for 4 days. The LAB 173 711 pretreatment at 28-degrees-C did not cause a significant difference in the electrolyte leakage over the ambient temperature (28-degrees-C) control. Application of LAB 173 711 at 28-degrees-C reduced visible injury and the treated seedlings had higher ethylene production and respiration rate over the untreated control. LAB 173 711 helped maintain the integrity of the cell membrane and thus reduced the leakage of soluble sugar and amino acids. These combined effects led to a higher chilling tolerance in the mung bean seedlings.