结实期干湿交替灌溉对稻米品质及籽粒中一些酶活性的影响

Effect of Dry-wet Alternate Irrigation on Rice Quality and Activities of Some Enzymes in Grains during the Filling

在土培池和大田试验条件下,观察了结实期干湿交替灌溉对武育粳3号(粳稻)和扬稻6号(籼稻)米质和籽粒中淀粉合成关键酶活性的影响以及它们之间的关系。与对照(保持水层)相比,轻干-湿交替灌溉(土壤干至土壤水势为-25kPa时复水)增加了结实率和粒重,降低了垩白粒率和垩白度,提高了淀粉的最高黏度和崩解值,减小了热浆黏度、最终黏度和消减值。重干-湿交替灌溉(土壤干至土壤水势为-50kPa时复水)的结果则相反,两品种结果趋势一致。轻干-湿交替灌溉增加了籽粒中蔗糖合成酶(SuS)、腺苷二磷酸葡萄糖焦磷酸化酶(AGP)、淀粉合成酶(StS)和淀粉分支酶(SBE)活性,重干-湿交替灌溉则降低了上述各酶的活性。不同灌溉方式对籽粒中酸性转化酶(AIV)活性影响较小。SuS、AGP、StS和SBE活性与粒重、最高黏度、崩解值呈显著正相关,与垩白度和消减值呈显著负相关。上述结果说明结实期轻干-湿交替灌溉可以改善稻米品质,SuS、AGP、StS和SBE在籽粒形成中起重要作用。

Improvement in rice quality is an important target in the production. This study investigated whether the practice of dry-wet alternate irrigation during the grain filling period could improve the grain quality and whether the key enzymes in sucrose-to-starch conversion in rice grains are involved in this process. Two rice cultivars, Wuyujing 3 （japonica） and Yangdao 6 （indica）, were grown in cement tank and paddy field. Well-watered （control）, moderate dry-wet alternate irrigation （soil was re-watered when soil water potential reached at - 25 kPa）, and severe dry-wet alternate irrigation （soil was re-watered when soil water potential reached at - 50 kPa） were imposed from heading to maturity. Compared with the control, the moderate dry-wet alternate irrigation increased filled-grain percentage and grain weight （Table 1）, improved the milling quality （Table 2）, and reduced chalky kernels and chalkiness （Table 3）. It also increased peak viscosity and breakdown values and decreased hot viscosity, final viscosity and setback values （Table 4）. The results were reversed for the severe dry-wet alternate irrigation. The two irrigation methods had little effects on the cooking and nutrient qualities. The two cultivars behaved the same. Activities of sucrose synthase （SuS）, adenine diphosphoglucose pyrophosphorylase （AGP）, starch synthase （StS） and starch branching enzyme （SBE） in the grains were significantly enhanced by the moderate dry-wet alternate irrigation, but reduced by the severe dry-wet alternate irrigation （Table 5）. No significant difference in acid invertase （AIV） activities in the grains was observed among the treatments. Activities of SuS, AGP, StS, and SBE were significantly and positively correlated with grain weight, peak viscosity, and breakdown values, whereas significantly and negatively correlated with chalkiness and setback values （Table 6）. The results suggested that a moderate dry-wet alternate irrigation improves rice quality, and the enhanced activities of SuS, AGP, StS, and SBE play a vital role in the process.