STUDY ON STARCH IODINE TEST FOR DETERMINING MATURATION STAGE AT SEVERAL APPLE CULTIVARS IN CORRELATION WITH CLIMATIC FACTORS AT SCDP BISTRITA USING A ONE YEAR MODEL BY MEANS OF IMAGE ANALYSIS IN IMAGEJ

The objective of the present study was to evaluate the possibility to determine the starch index based on the starch iodine test and subsequent image analysis, subsequently to study the changes of the main fruit quality parameters (starch index, soluble sugars, weight, diameter) and the description of the ripening process according to climatic factors. Elaboration of a research model regarding maturation stage and ripening process differentiation among cultivar groups (autumn and winter cultivars) is critical in fruit growing. Results showed that at autumn cultivars ‘Auriu’, ‘Starkprim’, ‘Ionaprim’, ‘Auriu de Bistrita’) in 2013 starch hydrolysis begun slowly in early September (04.09.2013) presenting incipiently lower level values between 2.1-2.8 starch index and after a month these values increased to 6.2-6.6 due to the increase of mean average temperatures along with genetic factors. At the winter cultivars ('Golden delicious’, ‘Ionathan’, ‘Salva’, ’Starkrimson’) at harvest time it has been observed a small hydrolysis, the values being situated between 1.1-1.2 and after 30 days the values increased slowly to 2.1-2.8, the hydrolysis process being thus much slower when compared with autumn cultivars. The soluble sugar content varied between 12.6-18.4 ˚Brix at autumn cultivars, the maximum being registered at ‘Ionaprim’ cultivar (18.4 ˚Brix), followed by ‘Aura’ (16.3 ˚Brix), data registered at harvest day. At 30 days after the harvest day (04.09.13) the soluble sugar content varied between 13.8-18.6 ˚Brix with a small increasement. At winter cultivars it has been observed a lower degree of starch hydrolysis and implicitly a reduced content of soluble sugars situated between 14.2-15.2 ˚Brix at harvesting time. At 30 days after harvest day the soluble sugar content varied between 14.6-16.3 ˚Brix. The ripening processes is primary genetically determined but it is influenced also by the environmental factors, thus an appropriate modeling is a key step in order to interpolate the maturation stage with the sum of active temperatures.