模拟三峡库区消落带土壤水分条件下的桑树幼苗生长状况

模拟三峡库区消落带土壤水分变化特征,设置土壤含水量分别为田间最大持水量的40%～50%、70%～80%、90%～100%的干旱(DH)、正常水分(CK)、渍水(WH)3个处理组,研究不同土壤水分条件对桑树实生幼苗生长的影响,探讨桑树对三峡库区消落带土壤水分变化的适应能力。桑树幼苗在3种土壤水分条件下生长30 d后,幼苗叶水势、根冠比、根表面积、侧根数量、根系活力、受害指数均出现差异:干旱组的叶水势比正常水分组低18.0%,渍水组的叶水势比正常水分组高54.0%;干旱组的根冠比较正常水分组高24.9%,渍水组的根冠比较正常水分组低17.6%;干旱组和渍水组的根表面积分别比正常水分组高45.9%和25.4%;干旱组和渍水组的侧根数量分别比正常水分组高85.8%和43.6%;干旱组和渍水组的根系活力分别比正常水分组低13.9%和78.9%;干旱组和渍水组的受害指数分别比正常水分组高50%和100%。研究结果显示,随着土壤水分含量的降低,桑树幼苗叶水势表现出明显的下降趋势,而根冠比呈增加趋势,证实桑树具有适应三峡库区消落带全年干旱和水淹交替的土壤水分变化的能力,尤其具有抗干旱能力。

Mulberry Seedling Growth Under Virtual Soil Moisture Condition in Hydro-fluctuation Belt of the Three Gorges Reservoir Area

In order to discuss the adaptive capability of mulberry to soil moisture variation in hydro-fluctuation belt of the Three Gorges Reservoir Area,the effect of soil water condition on mulberry seedling growth was investigated through simulating soil moisture variation patterns in hydro-fluctuation belt of the Three Gorges Reservoir Area by setting three treatment groups with soil water content of 40% ~50%(drought hardening,DH),70% ~80%(normal water,CK),and 90% ~100%(waterlogging hardening,WH) of the maxi-mum field capacity respectively.After mulberry seedlings had been grown under these three soil moisture conditions for 30 d,the seedlings showed difference in leaf water potential,root/shoot ratio,root surface area,lateral root number,root vigor,and degree of damage.The leaf water potential in drought hardening group was 18.0% lower than that in normal water group,but that in waterlogging hardening group was 54.0% higher than that in normal water group.The root/shoot ratio in drought hardening group was 24.9% higher than that in normal water group,but that in waterlogging hardening group was 17.6% lower than that in normal water group.The root surface area in drought hardening group and waterlogging hardening group was 45.9% and 25.4% higher than that in normal water group respectively.The lateral root number in drought hardening group and waterlogging hardening group was 85.8% and 43.6% higher than that in normal water group respectively.The root vigor in drought hardening group and waterlogging hardening group was 13.9% and 78.9% lower than that in normal water group respectively.The degree of damage in drought hardening group and waterlogging hardening group was 50% and 100% higher than that in normal water group respectively.These results show that,with the reduction of soil water content,the leaf water potential of mulberry seedlings showed a marked decline trend,and the root/shoot ratio showed an increasing trend,demonstrating that mulberry has the adaptive capability to annual soil moisture alternation between drought and water logging in hydro-fluctuation belt of the Three Gorges Reservoir Area and especially has high drought resistance.