不同秋眠级紫花苜蓿品种抗寒性对新疆北疆地区覆雪厚度的响应

Relationship between cold resistance of alfalfa,degree of fall-dormancy and snow cover thickness in Northern Xinjiang

由于北疆地区冬季气候寒冷,常出现极端降雪情况,使得苜蓿遭受冷害和冻害的威胁,导致苜蓿生产性能下降,对畜牧业生产造成巨大损失。为探究不同秋眠级的紫花苜蓿品种抗寒性、越冬率及干草产量对北疆地区冬季覆雪厚度的响应,明确不同覆雪厚度下不同秋眠级苜蓿品种各抗寒指标的动态变化规律。选取秋眠级为1级的紫花苜蓿品种驯鹿、3级的康赛、5级的巨能551、7级的赛迪7和9级的WL656HQ,覆雪厚度设置为0、10及15 cm,对紫花苜蓿根冠层土壤温度变化、土壤表层(1~10 cm)日温度变化、表层土壤(0~15 cm)平均含水率变化、根颈中抗寒生理指标变化及越冬率进行观测和分析。发现冬季积雪可以维持紫花苜蓿的根冠部及根颈下土壤层的温度动态平衡,使得各秋眠级紫花苜蓿品种的越冬率在覆雪条件下均显著提高(P<0.05);与不覆雪相比,覆雪后各紫花苜蓿的丙二醛含量有所降低,可溶性蛋白、可溶性碳水化合物含量及干草产量均有所增加。通过主成分综合分析发现,覆雪15 cm处理下,秋眠级为5级的巨能551的越冬率、抗寒性指标及干草产量等综合评分表现优异,比较适宜在新疆北疆地区进行推广种植。

The climate in the north of Xinjiang Province is cold and extreme snowfall often occurs in winter that contributes to alfalfa cold injury and freezing injury with a decline in alfalfa stand production and consequent reduction in animal production potential.This study explored the variation in cold resistance,overwintering survival rate and hay yield of alfalfa(Medicago sativa)varieties with different fall-dormancy scores and with different snow-cover-thickness treatments in Northern Xinjiang.Alfalfa varieties tested were:AC Caribou(Dormancy score 1),Concept(Dormancy score 3),Magnum 551(Dormancy score 5),Sardi 7(Dormancy score 7),and WL656HQ(Dormancy score 9)and the experiment included snow cover thickness treatments of 0,10,and 15 cm,achieved using plastic frames and addition or removal of snow to control snow depth on the experiment plots.Data collected included daily soil temperature in the root cap and in the surface layer(1-10 cm),average water content in the surface layer(0-15 cm),plant physiological indexes of cold resistance in the root and neck and overwintering survival rate of alfalfa plants.It was found that winter snow helped to maintain the temperature balance of the soil layer around the cap and neck of root of alfalfa,and the overwintering survival rates of alfalfa varieties with high fall dormancy were significantly increased under snow cover(P<0.05).Compared with no snow covering,malondialdehyde content of alfalfa decreased,while soluble protein,water soluble carbohydrate content and hay yield increased with snow covering.Principal component analysis indicated that under 15 cm snow cover,Magnum 551 with fall-dormancy score 5 had excellent overall score for overwintering survival rate,cold resistance index and hay yield.Hence this variety is recommended as suitable for cultivation in northern Xinjiang.