With 10 rice cultivars (lines) as materials, the changes in activities of adenosine diphosphoglucose pyrophosphorylase(ADPGPase), starch synthase (SSase) and starch branching enzyme (Q-enzyme) in the grains during grain filling, and theirrelationships with the filling rate, gel consistency (GC), alkali spreading value (ASV) and amylose content (AC) werestudied. The results showed that changes in activities of ADPGPase, SSase and Q-enzyme exhibited a single peak duringgrain filling, and the time of the activity peaks for the former two enzymes was earlier than that of the maximum grain-fillingrate (Tmax), and the time reaching the peak for Q-enzyme was synchronous with Tmax. The activities at early grain fillingstage, and the mean and maximum activities of each enzyme during grain filling period were positively and significantly orvery significantly correlated with the mean and maximum grain filling rate and starch content (mg grain-1) in the grains.Activities of ADPGPase at all grain filling stages and those of Q-enzyme at the early and mid filling stages were notsignificantly correlated the cooking quality (GC, ASV and AC). SSase activities at the early filling stage were significantlyand negatively correlated with GC and ASV, and positively correlated with AC. Activities of SSase at mid and late grainfilling stages and Q-enzyme at the late filling stage were significantly and positively correlated with GC and ASV, andnegatively correlated with AC. Spraying zeatin or abscisic acid at early grain filling stage could obviously regulate theactivities of ADPGPase, SSase and Q-enzyme in the grains.
This study was designed to elucidate the relationship between root chemical signals and the quality of rice. Various ricegenotypes were used. Zeatin (Z) + zeatin riboside (ZR), abscisic acid (ABA), 1-aminocylopropane -1-carboxylic acid(ACC), and organic acids in roots during grain filling and the appearance quality, cooking/eating quality were investigated.The correlations among them were analyzed. The results showed that Z + ZR concentrations in the roots at mid- and late-grain-filling stages were significantly and positively correlated with the gel consistency and alkali spreading value (r =0.72* - 0.90**), whereas negatively correlated with the amylose content (r = -0.68* - -0.78**). ABA concentrations in rootsat mid- grain-filling stage were significantly and negatively correlated with the gel consistency and alkali spreading value(r = -0.90** - -0.91**), and positively correlated with the amylose content (r = 0.87**). ACC concentrations in root exudatesat mid-grain-filling stage were very significantly correlated with the percentage of chalky grains and chalkiness (r = 0.97**- 0.98**), and those at late-grain-filling stage were significantly correlated with chalkiness and chalky size (r = 0.69* -0.96**). The more the malic acid and succinic acid exuded from roots for a cultivar, the greater the breakdown values andthe smaller the setback values in the starch profile, and the results were reversed for a cultivar with more tartaric acid andcitric acid exuded from roots during the grain-filling period. The cultivar with more lactic acid in exudates had smaller gelconsistency and alkali spreading values, but had greater amylose content. When roots were treated with exogenous ZR,ABA, and ACC during grain filling, effects of the chemicals on the rice quality were consistent with the relationships ofthe endogenous hormones (Z + ZR, ABA, and ACC) with the quality indexes. Using rape cake as organic fertilizer canincrease the concentrations of malic acid and succinic acids exuded from roots as well as the breakdown v
YANG Jian-chang CHANG Er-hua ZHANG Wen-jie WANG Zhi-qin LIU Li-jun
