高寒半湿润地区不同苜蓿品种越冬期根系生理及构型特征

Root Physiology and Characteristics of Different Alfalfa Varieties During Overwintering in Alpine Sub-humid Area

为明确在青藏高原海拔3500 m半湿润地区不同苜蓿(Medicago sativa L.)品种越冬期根系生理及构型特征与越冬率的关系,选取10个不同苜蓿品种,在越冬不同时期,测定根及根颈中超氧化物歧化酶、过氧化物酶、过氧化氢酶活性和丙二醛、脯氨酸、可溶性糖含量,并在越冬前挖取根系以获取根系形态特征。结果表明:返青前根颈中可溶性糖含量变化比根部剧烈;越冬率较高的苜蓿品种根系分支模式更接近于叉状分支;返青前根部脯氨酸含量、越冬初根颈可溶性糖含量、总根长、总根表面积、主根平均直径与越冬率呈极显著正相关关系(P<0.01),返青前根颈脯氨酸含量、总根体积、根尖数、分叉数与越冬率呈显著正相关关系(P<0.05);主成分分析显示分叉数、总根表面积、总根长对苜蓿越冬率影响较大。参试苜蓿在该地自然越冬过程中,根颈生理活动比根部敏感,根系发达、扩展性强的‘WL319HQ’、‘皇后’、‘太阳神’、‘驯鹿’等品种具有较好的越冬适应性。

To clarify the relationship between root physiological and root configuration and overwintering rate of different alfalfa(Medicago sativa L.)varieties in the semi-humid region of the Qinghai-Tibet Plateau at an altitude of 3500 m.10 different alfalfa varieties were planted in this area.The activity of superoxide dismutase,peroxidase,catalase,and the content of malondialdehyde,proline,soluble sugars in roots and crown were determined at different stages of overwintering.The root system was picked before overwintering to obtain root morphological characteristics.The results showed that before turning green,the content of soluble sugar in the crown changed more drastically than that in roots.Alfalfa varieties with a higher overwintering rate were closer to dichotomous branches and had better cold resistance.The proline content in the roots before turning green,the soluble sugar content in the crown at the beginning of overwintering,total root length,root surface area,average taproot diameter were significantly positively correlated with the overwintering rate(P<0.01).Proline content in the crown before turning green,root volume,root tips,root forks were significantly positively associated with the overwintering rate(P<0.05).Principal component analysis showed that the root forks,root surface area,and total root length had a greater influence.During the natural overwintering process at this area,the root crown physiological activities was more sensitive than the roots of alfalfa.The varieties‘WL319HQ’,‘Alfaqueen’,‘Sun-god’and‘AC Caribou’had well-developed root systems and strong expansion with better overwintering adaptability.