以五优308（杂交籼稻）、甬优2640（籼粳杂交稻）、嘉优2号（杂交粳稻）为材料，通过2年的播种期试验和秧龄弹性试验，研究了3种不同类型的连作晚稻在金华地区作机插的安全齐穗期和适宜播栽期。试验结果表明，不同类型连作晚稻机插产量均随着播种期的推迟而降低；在18 d秧龄条件下，五优308、甬优2640和嘉优2号于7月3日、7月6日和7月9日之前播种，能安全齐穗，五优308产量最高，嘉优2号最耐迟播，但产量水平明显低于五优308和甬优2640；五优308在秧苗素质、秧龄弹性方面明显差于甬优2640，五优308适宜机插的秧龄为12~20 d，甬优2640为17~27 d。五优308秧龄超过21 d之后，抽穗期推迟，安全齐穗风险加大，产量水平明显低于甬优2640。

In two-year trial of different seeding times and seedling ages, the safe full heading date and appropriate seeding date of different types of late seasonal machine transplanted rice, such as indica hybrid rice Wuyou 308, indica-japonica hybrid rice Yongyou 2640 and japonica hybrid rice Jiayou No.2, were investigated. The results showed that the production of all the tested cultivars decreased with the delay of seeding time; Wuyou 308, Yongyou 2640 and Jiayou No.2 fully headed in the seedling age of 18 d when they are planted before June 3rd, June 6th and June 9th respectively. Jiayou No.2 showed the best tolerance to delayed seeding, but significantly lower production compared to Wuyou 308 （highest） and Yongyou 2640. Wuyou 308 had inferior seedling quality and narrower appropriate seedling range compared to Yongyou 2640. The optimum range of seedling age for machine transplanting of Wuyou 308 was 12 to 20 days, and that of Yongyou 2640 was 17 to 27 days. When the seedling age of Wuyou 308 was over 21 days, its heading stage will delay, the risk of being unable to full heading will increase, and lead to obviously lower production than Yongyou 2640.