入侵程度对日本菟丝子和小叶女贞生长及生理代谢的影响

Effects of Invasion Degree on Growths and Physiological Metabolisms of Cuscuta japonica and Ligustrum quihoui

为探究日本菟丝子(Cuscuta japonica)入侵程度对自身生长的影响和对小叶女贞(Ligustrum quihoui)绿篱的危害,为选择除草剂施药部位和降低药害提供参考,以日本菟丝子覆盖度为依据,划分4个入侵度,分别为轻度(<10%)、中度(10%≤~30%)、重度(30%≤~50%)和超重度(>50%)。测定日本菟丝子的侵染方式、茎性状和吸器状态及小叶女贞的枝条密度、茎叶性状和伤害率,并测定两种植物的可溶性糖(SS)、蔗糖(SU)、淀粉(ST)和丙酮酸(PA)含量及硝酸还原酶(NR)活性,分析入侵程度对日本菟丝子和小叶女贞生长和生理代谢的影响。结果表明,小叶女贞绿篱为日本菟丝子的理想寄主,年入侵增长率超过150%。随入侵程度增加,日本菟丝子侵染深度极显著降低,侵染密度极显著增加,趋于对小叶女贞表层幼茎、叶和顶芽的侵害,极显著增加新叶、幼茎和顶芽的伤害率;重度入侵加剧老叶的伤害率。入侵程度越高越限制小叶女贞的分生和再生能力,重度和超重度入侵极显著降低小叶女贞枝条密度。日本菟丝子可根据入侵程度调节茎长、茎粗、分枝数及吸器直径和数量,入侵程度较高时表现出觅养与自疏。小叶女贞通过提高SS、SU和PA含量及NR活性抵御轻、中度入侵,重度和超重度入侵会造成不可逆的伤害。总而言之,日本菟丝子可自我调节生长能力、生理代谢和侵染方式,降低种内竞争和呼吸消耗,加强对小叶女贞绿篱的危害。防治日本菟丝子时,可依侵染深度选择施药部位和施药方式;侵染越重,除草剂施药部位应越趋表面。

In order to explore effects of invasion degree of Cuscuta japonica on growth of C.japonica and damage to Ligustrum quihoui hedge,and provide reference for selecting application sites of herbicides and reducing phytotoxicity,according to coverage of C.japonica,4 invasion degrees were divided,including light(<10%),moderate(10%≤-30%),severe(30%≤-50%)and super severe(>50%).By determining infection pattern,stem traits and haustorium status of C.japonica,branch density,characters and damaged rates of leaves and stems of L.quihoui,and contents of SS,SU,ST and PA and NR activity of two plants,effects of invasion degree on growths and physiological metabolisms of C.japonica and L.quihoui were analyzed.Results showed that L.quihoui hedge was ideal host for C.japonica,with annual invasion growth rate more than 150%.With increase of invasion degree,infection depth of C.japonica decreased extremely significantly,and infection density increased extremely significantly.Damage to L.quihoui tended to young stems and leaves and terminal buds.Damaged rates of new leaves,young stems and terminal buds of L.quihoui increased extremely significantly.Severe invasion exacerbated damaged rate of old leaves.The greater the invasion degree was,the more limited for meristematic and regeneration abilities of L.quihoui.Severe and super severe invasion extremely significantly reduced branch density of L.quihoui.C.japonica could adjust stem length,stem diameter,number of branches,haustorium diameter and number according to invasion degree.When invasion degree was higher,C.japonica showed nourishment and self thinning.L.quihoui could resist light to moderate invasion by increasing contents of SS,SU and PA and NR activity,which could be damaged irreversibly in severe and super severe invasion.In conclusion,C.japonica could regulate growth ability,physiological metabolism and infection pattern to reduce intraspecific competition and respiration consumption,and strengthen damage to L.quihoui hedge.When preventing C.japonica,application sites of herbicides and methods could be chosen by infection depth.The heavier the infection of C.japonica on L.quihoui hedge was,the more the surface of herbicides should be applied.