覆雪厚度对不同秋眠级苜蓿抗寒性及越冬率的影响

本试验旨在研究覆雪厚度对不同秋眠级紫花苜蓿抗寒性及越冬率的影响,选择秋眠级分别为2级的皇后(Alfaqueen)、5级的巨能551(Magna551)、8级的WL525HQ和10级的赛迪10(Sardi10)紫花苜蓿,设定0,10和15 cm三个覆雪厚度处理,通过动态观测紫花苜蓿根冠处及田间土层(1~10 cm)的温度、根颈中丙二醛(MDA)、可溶性糖(WSC)和可溶性蛋白(SP)含量及越冬率。结果表明,无积雪覆盖时低秋眠级(2和5级)紫花苜蓿越冬率分别为:64%和59%;而高秋眠级(8和10级)紫花苜蓿全部死亡。覆雪厚度10 cm即可以保证除秋眠级10(赛迪10)外的苜蓿安全越冬,且越冬率均在90%以上。随着覆雪厚度的增加,积雪对紫花苜蓿根冠及根颈下土层温度有显著影响,能显著提高各秋眠级紫花苜蓿的越冬率(P<0.05),降低MDA的含量,增加非/极非秋眠型的紫花苜蓿根颈中SP和WSC的含量。运用隶属函数综合评价,无覆雪条件下苜蓿品种的抗寒性及越冬率顺序为:皇后>巨能551;覆雪厚度10 cm下苜蓿的抗寒性及越冬率顺序为:巨能551>皇后>WL525HQ>赛迪10;覆雪厚度15 cm下苜蓿的抗寒性及越冬率顺序为:巨能551>皇后=WL525HQ=赛迪10。

Effects of snow cover thickness on cold resistance and winter survival rates in alfalfa cultivars with different fall dormancies

Four alfalfa cultivars with different fall dormancies (rating 2 Alfaqueen,rating 5 Magna551,rating 8 WL525HQ,and rating 10 Sardi10)were used to study the effects of different snow cover thicknesses on cold resistance and overwintering survival rates.The four cultivars were maintained with 0,10,and 15 cm winter snow depths.Temperatures were monitored for alfalfa canopy-level and soil surface (1-10 cm).Dynamic vari-ation in malondialdehyde (MDA),soluble sugar (WSC)and soluble protein (SP)contents in collar and stand counts were recorded each fall and spring to assess winter injury.The results showed that without snow cover the winter survival rates of low fall dormancy alfalfa (2,5)were 64% and 59% respectively,while all the high fall dormancy alfalfa (8,10)died.With the exception of alfalfa with fall dormancy 10 (Sardi10),a snow cover thickness of 10 cm can ensure the winter safety of alfalfa,with the winter survival rate recorded at over 90%. Increasing snow cover thickness significantly moderated temperatures at alfalfa canopy-level and soil surface. Increased cover significantly improved the winter survival rate of different alfalfa (P <0.05).It increased the SP and WSC content of alfalfa collars in the non-and extremely non-fall dormancy cultivars,and decreased the MDA content.Membership function analysis showed that without snow cover the order of cold resistance and winter survival rate of the alfalfa cultivars was Alfaqueen>Magna551;with snow cover thickness of 10 cm,the order of cold resistance and winter survival rate was Magna551 >Alfaqueen>WL525HQ>Sardi10;and with snow cover thickness of 15 cm,the order was Magna551>Alfaqueen=WL525HQ=Sardi10.