Combination of the prematured, theovermatudred wiht the matured fruis prevails and is spoiling Thai export marked. Besides, the fruit-selling incomes is decreased becaused byers do not believe in the furit qualiny, thus lower and set a single price level. Porbliem on agricultural labor also becomes critical, ie. labor scarcity and increasing wages. It is therefore difficult ot find professional workers to inspect fruit quality from orchards to markets. This research project well recognizes such problem and aima to study mechanixm to physically indentify fruit maturity and then to develop an istrument to relatively chect the maturity. Reseadrch work plan compriser 2 years. The first year aims to develop the instrumentation and measurement system (IMS) to experimrnt with water melon to acquire data enough ot correlate between paramenters of acoustic response and those of truit physiology and define the criteria to control the fruit maturity. Year no. 2 aims to design protoype of maturity indication instrument (MII), build up, test and improve the prototype. Engineering and economeic evalation will be performed. The project will be carried out with the Japanese Expert (Dr. H. TAKAO) who is keen on Instrumentation and Measurement for fruit and vegetable Quality Control (Especially on MII for Japanese fruits) , and tested with Flora Fruit Company (Thai). Tlhe project will cost about 1.88 million baht for 2 years of operation.