Abstract:
Abstract: In this study, the Korla fragrant pear in the mature period was focused to investigate its mature rule and the variation tendency in the physical and chemical indicators with the increase of the effective accumulated temperature, as well as establish the quantitative assessment method for the maturity level. The pears chosen for the test had no mechanical damages and no pests, and the sizes were basically the same (diameter of 55-65 mm), which were picked on the campus of the Tarim University, with an age of 12 years. The area was located between 80°30′ - 81°58′ E and 40°22′ - 40°57′ N. A total of 1 200 pears were for the test, among which 800 were used to establish a mathematical model, picked in 2012 and 2013, and 400 for the validation of the model, picked in 2014. Based on the preliminary selection tests for indicators and the production situation surveys for Korla fragrant pear, the evaluation indexes were fruit hardness, soluble solid content, chlorophyll and vitamin C content, and the variations in various indexes with the increase of effective accumulated temperature during the mature period were detected. The Data was analyzed with the Excel software and SigmaPlot software. A similar variation tendency was found between the indicators, which was a slow change at first and then followed by a rapid change until steady after the mature. Hence, this study set up a mathematical model for the mature rule of the Korla fragrant pear and proposed a quantitative assessment method for the relationships between maturity rule and physical and chemical indicators. It was shown that the model could depict the relationships between the effective accumulated temperature that fragrant pear required during the mature period and the physical and chemical indicators. The model was obvious significant (P<0.0001), and interrelationships among accumulated temperature, maturity level, and physical and chemical indicators could be well evaluated and predicted with the high correlation coefficient (r > 0.998). Furthermore, five levels of effective accumulated temperature (3000, 3200, 3400, 3600 and 3800℃) were selected to testify the developed mathematical model by calculating the fruit hardness, soluble solid content, chlorophyll content and vitamin C content. For the same fragrant pear, maturity levels indicated by different indicators were similar and the maximum relative deviation was 2.14, which was in an acceptable range. This result also verified the conclusion that the variations in various indicators during the period of mature could be expressed with the same mathematical model. Finally, the results can offer the references in the determination of proper harvest date, the assessment of maturity level, and the prediction of physical and chemical indicators for the Korla fragrant pear; moreover, the results can be helpful in guidance of a timely harvest according to different post-harvest processing methods as well as to the quantitative study of fruit maturity level. The evaluation method of pear maturity proposed in this study can be used to express the mature law of the pear, evaluate maturity level and complete mutual prediction according to effective accumulated temperature and physical and chemical indicators. However, in the practical application it has some limitations for different growing environments and different field management approaches. So the calibration test is required in a particular area before this method is used. Only in this way, the method can accurately express the maturity level of the pear and determine the best picking time.