Effects On Physi-chemical Traits Of Rice Quality Of Aging In Indica-japonica Hybrid Rice

It would play a very important role in the breeding and extension in indica-japonica hybrid rice to study the effects on physi-chemical traits of aging progress in rice quality. In this study, two experiment were designed, nature aging at room temperature in short-term or long-term storage, as well as artificial aging at high temperature and high humidity, for certain indica-japonica hybrid rice cultivars and other types of rice cultivars. Some physic-chemical traits were determined using various reasonable methods, which amylose content (AC) was essayed by the national standard method. AC and amylopectin content (Ap) were measured by the method of dual-wavelength. RVA profile traits were analyzed using RVA-tecmaster instrument. Gel consistency (GC) and alkali spreading value (ASV) of rice quality were determined using the standard method approved by Agriculture Department, and some samples were tested by professional agency for twelve physic-chemical index. All of these studies were aimed to find the underling ways of change of physic-chemical traits index during nature or artificial aging progress in indica-japonica hybrid rice, and the difference express against to other types of rice cultivars. The main results are as follows:In the long term natural aging experiment, the AC value of low AC indica-japonica cultivars were increased by 2.37% after thirty-two month storage, which was two times higher than that of indica-indica hybrid rice. The changes of AC value were not obvious in short-term storage experiment, but the GC and ASV were decreased slightly to result in to be worse in quality, meanwhile chalky rice rate (CRR) and chalkiness degree (CD) were also declined to be better for rice quality. The changing between GC and chalky rice ratio was significantly correlated in indica-japonica hybrid rice Zheyoul 8. The changing between ASV and CRR or CD were significantly or negatively correlation in indica-indica hybrid rice Lianyoupeijiu.In the artificial aging experiment, AC value was increased in indica-japonica hybrid rice, which was shown the same trends as in the long term nature storage experiment. The changes of RVA profile traits in indica-japonica hybrid rice were as follows:decreased peak viscosity (PKV) and breakdown viscosity (BDV), and increased hot paste viscosity (HPV), cool paste viscosity (CPV), pasting temperature (PaT), setback viscosity (SBV) and consistence values (CSV). The changing trends of RVA profile traits in indica-japonica hybrid rice was similar to that of japonica-japonica hybrid rice and convention japonica late rice, and was obvious different with indica-indica hybrid rice.Comparison of relationship between the rice quality physi-chemical index and the characters of RVA profile in japonica-japonica hybrid rice to indica-japonica hybrid rice, results were shown that the correlation of AC values to HPV is significantly positive in indica-japonica hybrid rice, but it is not significant in japonica-japonica hybrid rice. On the contrary, the correlation between AC values and PeT was different with the former results. The analyses of correlation changes were conducted, it was shown that the correlation between GC to PKV or HPV is significantly positive in indica-japonica hybrid rice. Analysis on the correlation between characters of RVA profile and AC, GC, ASV in rice quality in indica-japonica, it were shown that GC is significantly positive correlation with PKV or HPV, and ASV is significantly positive correlation with PaT.Preliminary research revealed the change feature of physi-chemical traits in the aging process in indica-japonica hybrid rice. It would have profound reference facts support these researches on breeding and extension in indica-japonica hybrid rice.