高羊茅根系、叶片和根颈对冷锻炼的响应差异

Different responses of the roots,leaves and crowns in tall fescue(Festuca arundinacea)on cold acclimation

以高羊茅 (FestucaarundinaceaSchreb .cv .Barlex)为材料 ,对其植株根系、叶片、根颈及植株整体在冷锻炼期间的抗冻性变化及其生理基础进行了比较研究。结果显示 :冷锻炼 (昼夜温度 4 / 2℃ )期间高羊茅植株各部位抗冻性在逐渐提高的总趋势下呈现不同的变化 ,其中根系LT50 (半致死温度 )变化最小 ,根颈和叶片的LT50 下降幅度远大于根系。以植株表观死亡率求得的LT50 与叶片LT50 相近 ;以真实死亡率求得的LT50 能反映根颈修复冷冻胁迫伤害、产生新生分蘖的能力。冷锻炼期间高羊茅叶片、根颈和根系的可溶性糖含量逐渐升高 ,可溶性糖含量由高到低依次为根颈、叶片、根系 ,与各部位抗冻性的变化趋势基本一致。根颈可溶性糖含量可以作为高羊茅冷锻炼响应的一个评价指标。

The differences of freezing tolerance among roots,leaves and crowns and their responses to cold acclimation in tall fescue(Festuca arundinacea Schreb.cv.Barlex)were studied.Taking the freezing tolerance of whole plants(showing by the low temperature at which 50% of lethal plants)as a standard,the changes of freezing tolerance in plants were monitored during 10 days artificial cold acclimation in growth chamber(day/night,4/2 ℃).The results showed that the freezing tolerance of tall fescue was gradually enhanced,especial of leaves and crowns,and followed by the increasing of the content of soluble sugar and the decreasing of water content after 10 days' cold acclimation.Compared with the increasing freezing tolerance of whole plants,the LT 50 of leaves was the most close to the LT 50 calculated by apparent death rate of plants,but remarkable different from that by true death rate,which reflected the capability of regrowing new tillers from the crowns.It is suggested that crowns and their contents of soluble sugar may be the critical part of tall fescue for determination of the plant freezing tolerance.