甘蔗种茎热水处理脱除宿根矮化病菌及其对再生苗的影响

Effects of seedcane hot water treatment on elimination of Leifsonia xyli subsp.xyli and performance of sugarcane seedlings

50℃2 h热水处理黑皮果蔗、黄皮果蔗和粤糖93-159双芽段种茎,结果表明:黑皮果蔗全部丧失出苗能力;黄皮果蔗出苗时间延迟,但最终出苗率与对照无差异;而粤糖93-159出苗率和出苗速度均不受影响。两个品种的热处理再生苗生长早期株高和茎径均显著低于对照,但随着生长时间的增加,这种差异逐渐缩小。采用高灵敏度的巢式PCR技术检测再生植株体内的宿根矮化病菌,在再生苗生长前期的120 d内所有经热处理植株均呈阴性,其后部分植株呈阳性,至播种200 d时,黄皮果蔗阳性率为50%,粤糖93-159阳性率为100%。试验还发现,种茎热水处理能增强再生植株中后期抗旱能力。本研究指出,虽然种茎热水处理能减少生长早期再生苗体内宿根矮化病菌含量但难以实现所有种茎完全脱菌,在进行脱菌效果评价时,要对生长中后期的再生苗进行检验;生产上采用该措施防病,要充分考虑不同品种耐热性能的差异。

Seedcane cuttings with two buds of three sugarcane varieties, Red Stalk Badila, Yellow Stalk Badila and YT93-159, were treated with hot water at 50 C for 2 hours. The effects of this treatment on Leifsouia xyli subsp. xyli （Lxx）, the causal agent of sugarcane ratoon stunting disease, and the performance of sugarcane seedlings were determined. For seedcane germination, no difference in YT93 159, significant delay in Yellow Stalk Badila, and ab- solute loss in Red Stalk Badila were observed. For seedling growth, inhibition in plant height and stem diameter appeared in early stage but not in late stage in both YT93-159 and Yellow Stalk Badila. In Lxx detection by highly sensitive nested-PCR technique, no positive seedlings were found in both YT93-159 and Yellow Stalk Badila during 120 days of the early growing period, but positive plants increased after 120 days, with 50% positive rate in Yellow Stalk Badila and 100% in YT93-159 at the 200th day after sowing. It was also observed that the drought-tolerability of seedlings was enhanced by hot water treatment. This study indicated that it is difficult to completely eliminate I.xx from all seedcanes by hot water treatment, though the titer of pathogens was decreased in all seedlings during early growing stage. The detection for pathogens should be conducted during late growing stage of the seedlings for evalu ating I.xx elimination, and the distinction of heat-tolerance between different varieties must be taken into consideration if hot water treatment was used by growers.