水稻根和籽粒细胞分裂素和脱落酸浓度与籽粒灌浆及蒸煮品质的关系

以10个不同基因型水稻品种和杂交稻组合为材料，分析了结实期水稻根系和籽粒细胞分裂素和脱落酸（ABA）浓度的变化及其与籽粒灌浆速率和稻米蒸煮品质的关系。结果表明，灌浆早期(花后0～12 d)根和籽粒玉米素＋玉米素核苷（Z＋ZR）浓度以及灌浆中期（花后13～26 d）根和籽粒ABA浓度与籽粒起始生长势、平均灌浆速率、最大灌浆速率、糙米重呈显著或极显著正相关（r＝0.726* ~ 0.984**），与活跃灌浆期呈显著或极显著负相关(r＝－0.749* ~ －0.834**)。灌浆中、后期（花后27~40 d）根和籽粒Z＋ZR浓度与活跃灌浆期呈显著或极显著正相关(r＝0.689* ~ 0.932**)，但灌浆后期Z＋ZR浓度与灌浆速率呈极显著负相关(r＝－0.826** ~ －0.927**)。灌浆中期和后期根和籽粒Z＋ZR浓度与胶稠度及碱化值呈显著或极显著正相关（r＝0.722* ~ 0.896**），与直链淀粉含量呈显著或极显著负相关（r＝－0.633* ~－0.778**）。灌浆中期根和籽粒ABA浓度与胶稠度及碱化值呈极显著负相关（r＝－0.883** ~ －0.913**），与直链淀粉含量呈显著或极显著正相关（r＝0.803** ~ 0.871**）。不同灌浆期ZR或ABA处理对籽粒灌浆、稻米胶稠度和直链淀粉含量的影响，与内源激素同灌浆特征参数和稻米蒸煮品质指标的关系基本吻合。表明根和籽粒细胞分裂素和ABA对籽粒灌浆和稻米蒸煮品质起调控作用，其调控的正、负效应取决于灌浆的时期。

Concentrations of Cytokinin and Abscisic Acid in Roots and Grains and Its Relationship with Grain Filling and Cooking Quality of Rice

Cytokinin and abscisic acid (ABA) are two kinds of important plant hormones. Their roles in the grain filling and quality of rice, however, are not fully understood. The objective of this study was to determine changes in concentrations of zeatin (Z) + zeatin riboside (ZR) and ABA in both the roots and grains during grain filling, grain filling characteristics and the indexes for cooking quality using ten rice cultivars (including hybrids and lines) grown in nutrient solution. The results showed that the change in concentrations of Z+ZR and ABA in roots and grains exhibited a single peak curve during the grain filling period. The Z + ZR concentration in roots was very high at early grain filling stage and reached a peak at 3–9 d after anthesis (DAA), and that in grains at 9–12 DAA. ABA concentrations in roots and grains were rather low at early grain filling stage, then increased with grain filling, and reached a peak at 15–18 DAA in roots and at 15–21 DAA in grains. Concentrations of Z + ZR in roots and grains at early grain filling stage (0–12 DAA) and ABA at the mid stage (13–26 DAA) were significantly or very significantly correlated with the initial grain growth potential, mean grain filing rate, maximum grain filling rate and brown rice weight (r=0.726* ~ 0.984**), whereas significantly and negatively correlated with active grain filling period (r=－0.749* ~ －0.834**). Z+ZR concentrations at the mid or late grain filling stage (27–40 DAA) significantly or very significantly correlated with active grain filling period (r=0.689* ~ 0.932**) but those at the late stage negatively correlated with grain filling rate (r=－0.826** ~ －0.927**). The gel consistency and alkali spreading value of rice were significantly or very significantly correlated with Z+ZR concentrations in roots and grains at mid and late grain filling stages (r = 0.722* ~ 0.896**), whereas significantly and negatively correlated with ABA concentrations at mid grain filling stage (r=－0.883**~－0.913**). The correlations between amylose content and the concentrations of Z+ZR and ABA were reversed to the correlations of gel consistency with the two hormones. When roots were treated with 10^-7 mol/L ZR or with 10^-7 mol/L ABA at 0-6, 14–20 and 24–30 DAA, respectively, the effects of the exogenous hormones on grain filling and the cooking quality were consistent with the relationships of the two endogenous hormones with the grain filling parameters and indexes for cooking quality. The results suggest that cytokinin and ABA play important roles in the regulation of grain filling and quality of rice, and the direction of effects may dependent on grain filling stages.