兰州百合连作障碍效应及机制研究

为探讨兰州百合连作障碍效应及作用机制,以正茬及不同连作年限土壤为试验对象,利用盆栽试验,动态研究了连作对百合生长、光合特性及抗氧化酶系统的影响,并利用GC-MS技术分析了正茬及不同连作年限土壤中自毒成分的种类及含量。结果显示,苗期、鳞茎膨大期及成熟期连作对百合的生长均存在抑制作用,且随着连作年限的延长作用程度增强。同一生长阶段,随连作年限的增加,百合植株中CAT和SOD含量逐渐下降,POD活性先升高后降低,MDA含量持续升高。叶绿素总量(Chl)、净光合速率(P_n)、气孔导度(G_s)及蒸腾速率(T_r)呈下降趋势,而胞间CO₂浓度(C_i)持续升高。从正茬、连作2年和连作4年土壤中分别鉴定出9种、15种、17种化感自毒物质,主要包括:2,3-丁二醇、间苯二甲酸二辛酯、2,2'-亚甲基双-(4-甲基-6-叔丁基苯酚)和对苯二甲酸二辛酯。其中,对苯二甲酸二辛酯在连作2年和4年土壤中含量均达最高值,分别为33.24%和41.43%。连作通过影响百合植株的光合作用能力,破坏抗氧化酶代谢平衡,从而抑制百合植株的生长,导致连作障碍的发生;连作条件下多种次生代谢物引起的自毒作用是导致兰州百合连作障碍产生的主要原因之一。

Problems associated with continuous cropping of Lilium davidii var.unicolor

To explore the negative effects of continuous cropping on the growth of Lanzhou lily (Lilium davidii var.unicolor),we conducted a pot experiment using soil containing fresh Lanzhou lily stubble and soil from fields where Lanzhou lily had been cultivated for 2 or 4 years.The growth indexes,photosynthetic characteristics,and antioxidant enzyme activity of Lanzhou lily plants were evaluated,and the types and contents of autotoxic substances in soil from fields continuously cropped with Lanzhou lily for 2 or 4 years was analyzed by gas chromatography-mass spectrometry (GC-MS).The results showed that the growth of Lanzhou lily was inhibited by continuous cropping at the seedling stage,bulb enlargement stage,and maturity stage,and the inhibitory effect increased with increasing number of continuous cropping years.At the same growth stage,with increased number of continuous cropping years,the activity of catalase and superoxide dismutase decreased,the activity of peroxidase increased and then decreased,the malondialdehyde content increased,the total chlorophyll content,net photosynthetic rate,stomatal conductance,and transpiration rate decreased gradually,and the intercellular CO2 concentration increased.We identified 9 compounds in soil containing stubble,and 15 and 17 compounds in soil where Lanzhou lily had been continuously cropped for 2 and 4 years,respectively.These compounds included 2,3-butanediol,dioctyl isophthalate,2,2′-methylenebis-(4-methyl-6-tert-butylphenol),and dioctyl terephthalate.The highest contents of dioctyl terephthalate were in soil where Lanzhou lily was continuously cropped for 2 and 4 years (33.24％ and 41.43％,respectively).Continuous cropping inhibited the growth of Lanzhou lily by affecting its photosynthetic capacity and disrupting the metabolic balance of antioxidant enzymes,ultimately leading to reduced performance under continuous cropping.The autotoxicity of several secondary metabolites that accumulated under continuous cropping was one of the main causes of the reduced performance of Lanzhou lily.