| This study was conducted to understand the genotype and major environmental effects of some important quality traits of sweetpotatoes (SP). It is expected that all results and findings may be used in screening or developing SP varieties with special quality and adaptation to the locally ecological environments, in classification of SP production bases with the specific purposes, and in improvement of cultivation technology. In our study from 1998 to 2000, more than 450 genotypes were tested, thousands of samples from different experiments, including national and provincial regional trials, 2-type hormone test, 5-application level of potassium fertilizer test, and 10-harvesting date test were determined by multiple new analytical methods, such as near infrared reflectance spectroscopy(NIRS), Rapid viscosity analyzer(RVA), Differential scanning calorimetry (DSC), X-ray diffraction, etc. The main results were as follows:l.A HCL hydrolysis-DNS method for SP starch content determination was improved by adjusting the DNS reagents and reducing pigment interfere effects. A new method to prepare samples for analysis was developed.2.A new direct distilled method to determine SP protein contents was developed.3.Some new quality indexes relevant to SP research and use, including crystallinity(CRY), big grain percent(BGP) and small grain percent(SGP) etc. were used in this study.4.The new NIRS calibration models were established, which could be used to determine many quality traits of SP storage roots and its starch rapidly and accurately. The relation coefficients of their calibration and prediction are 0.90 and 0.85 respectively. Among them, RVA and DSC indexes, and noodle quality parameters etc. were firstly analyzed by NIRS.5. A new statistic method of multiple variation analysis was applied to screen the very important quality traits of SPes. By using the method, dry matter content (DMC), amylose content(AC), dissoluble sugar content(DSC), P -amylase activity( & -AA) . General acceptability(GA), peak viscosity(PKV), breakdown viscosity(BDV)and setback viscosity(SBV) are identified as important storage root quality traits relative to SP eating quality, and AC,phosphorus content(PHC), BGP, SGP, PKV, SBV, CRY, Tr, AH, swelling degree(SWD), cooling(CL) and cooling resistance(CR) as important starch quality traits close to SP noodle quality.6. Genetic variation in both SP storage root quality and its starch quality was determined. Based on the results, the current Chinese SP varieties tested were classified, and their quality characters were evaluated. The difference in storage root quality of varieties bred in different growing regions, different breeding years was tested, local varieties and bred ones were also compared in storage root quality. Some excellent cultivars with higher storage root quality were selected.7. The main difference was found between SP storage root flour quality and starch quality. SP flour has A-, B- and C-types of RVA curve, but SP starch has only A-type RVA curve'. The pasting temperature and peak time of SP starch are lower than those of SP flour, but other main RVA indexes of the starch are higher than those of the flour. Thus the SP starch pasting properties could not be predicted by determining SP storage root RVA indexes.S.The different types of SP storage root quality were first identified so as to find out the quality characters of varieties with different quality types. Among them, varieties with high DMC are low in DSC, high in GA and other important quality traits. Also, cultivars with good eating quality are high in PHC, PPO and 0 -AA, high in the starch Tr, but low in the starch SGP.9.The quality types of SP noodle were classified according to different quality characters of noodles with different quality types. The qualified noodles have high SWD, but low in CL and CR. The SP varieties with high SWD noodles have high CL and CR, high in PKV, SBV and SGP, but low in BGP, CRY and AH; The cultivars with low CL have high BGP, middle grain percent(MGP) and T...
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