藏北高寒区越冬期间野生早熟禾根系生理特征及抗寒性比较

Comparison between physiological characteristics and cold resistance of wild Poa root during the overwintering period in alpine regions in northern Tibet

为研究藏北高寒区早熟禾属(Poa)野生种质田间越冬期的生理特征和抗寒强弱,以采集自藏北草原的3个野生种和引进1个栽培品种为试验对象,在海拔4 512 m环境条件下进行田间种植,并测定其根系中可溶性糖(soluble sugar,SS)、可溶性蛋白(soluble protein,SP)、丙二醛(MDA)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)5项指标越冬期间的变化,分析不同材料的低温生理适应性。结果表明,4种供试材料的越冬率均高于80%,且野生种的越冬率显著高于栽培品种(P<0.05)。入冬前(9月)至翌年返青期(5月),根系中SS、MDA含量和SOD、CAT活性总体表现为先升高后下降的趋势,峰值出现于最冷月(1月);SP含量呈现持续增加的变化趋势。中亚早熟禾(Poa litwinowiana)和渐尖早熟禾(P.attenuata)的SOD和CAT活性在最冷月显著(P<0.05)高于冷地早熟禾(P.crymophila)和青海冷地早熟禾。利用隶属函数法综合评价早熟禾属材料的抗寒性能,由强到弱顺序为中亚早熟禾>渐尖早熟禾>冷地早熟禾(野生种)>青海冷地早熟禾(栽培种)。

The objective of this research was to investigate the physiological characteristics and cold resistance of wild Poa during the overwintering period,and to analyze the physiological adaptability of Poa under chilling stress in alpine regions in northern Tibet.The experimental materials included wild Poa litwinowiana,P.attenuata,P.crymophila,and a cultivated variety(Poa crymophila‘Qinghai’).The soluble sugar(SS),soluble protein(SP),malondialdehyde(MDA),superoxide dismutase(SOD),and catalase(CAT)activities were measured in the field at an altitude of 4 512 m.The results showed that the overwintering rate of the 4 tested materials all reached 80%,and the overwintering rate of wild Poa was significantly higher (P < 0.05) than that of the cultivated variety. The contents of SS and MDA and the relative activities of SOD and CATincreased overall at first and then decreased from late autumn (September) until turning green the following year (May),reaching its maximum during the coldest month (January). The SP contents increased during the entire overwintering period.SOD and CAT of P. litwinowiana and P. attenuata in the coldest month were significantly higher (P < 0.05) than that of theothers. Through the membership function analysis, it was found that the order of cold-resistance of the Poa tested was asfollows: P. litwinowiana > P. attenuata > P. crymophila (wild varieties) > Poa crymophila ‘Qinghai’ (cultivated variety).