干旱胁迫下江南油杉幼苗生长与耗水特性

Growths and Water Consumption Characteristics of Keteleeria fortunei var.cyclolepis Seedlings under Drought Stress

为探究干旱胁迫下江南油杉(Keteleeriafortuneivar.cyclolepis)幼苗生长与耗水特性,为江南油杉苗期水分管理、干旱修复技术探索提供理论依据,以2年生江南油杉幼苗为材料,采用盆栽控水法,设置适宜水分(CK)及轻度(T1)、中度(T2)和重度(T3)干旱4种处理,分别为田间最大持水量的75%~80%、55%~60%、35%~40%和15%~20%,研究不同干旱程度下江南油杉幼苗生长变化和耗水特性。结果表明,30~40天时,苗高生长随干旱程度加深呈下降趋势,轻度干旱处理的地径生长表现最好,且其地径增长率显著高于其他处理;轻度干旱处理有利于茎和根生物量的积累。30~40天时,根冠比随干旱程度加深呈上升趋势。平均日耗水量和周耗水量及总耗水量均随干旱程度加深呈下降趋势。轻度干旱处理的日耗水量在胁迫后期达到最高值,之后与中度和重度干旱处理的日耗水量相近,均处于较低水平;轻度干旱环境下,江南油杉幼苗对土壤水分的利用效率较高,说明江南油杉幼苗有一定耐旱能力。综合考虑苗木生长和耗水特性,将土壤水分含量控制在田间最大持水量的55%~60%能保持江南油杉幼苗正常的生长发育,并有利于茎和根生物量的积累,还能实现土壤水分高效利用,达到节水育苗和旱地生态修复的目标。

In order to investigate growths and water consumption characteristics of Keteleeria fortunei var.cyclolepis seedlings under drought stress,and provide theoretical basis for water management of K.fortunei var.cyclolepis at seedling stage and exploration of drought restoration technology,taking 2-year-old K.fortunei var.cyclolepis seedlings as materials,appropriate water(CK)and mild(T1),moderate(T2)and severe(T3)drought treatments by potted water control method were set,with 75%-80%,55%-60%,35%-40%and 15%-20% of maximum field capacity respectively.Growth changes and water consumption characteristics of K.fortunei var.cyclolepis seedlings under different drought degrees were studied.Results showed that growth of seedling height decreased with deepening of drought degrees from 30 to 40 days.Under mild drought treatment,growth of ground diameter was the best from 30 to 40 days,and growth rate of ground diameter was significantly higher than those of other treatments.Mild drought treatment was beneficial to accumulations of stem and root biomass.From 30 to 40 days,root-shoot ratio increased with deepening of drought degrees.Average daily and weekly water consumptions and total water consumption decreased with deepening of drought degrees.Under mild drought treatment,daily water consumption reached the highest at later stage of stress,and after the highest value,daily water consumptions were similar to daily water consumptions under moderate and severe drought treatments,which were at lower levels.Under mild drought environment,K.fortunei var.cyclolepis seedlings had highly efficient utilization for soil moisture,which indicated that K.fortunei var.cyclolepis seedlings had certain drought tolerance ability.Considering growths and water consumption characteristics of seedlings,controlling soil moisture content at 55%-60% of maximum field capacity could maintain normal growths of K.fortunei var.cyclolepis seedlings,facilitate accumulations of stem and root biomass,realize highly efficient utilization for soil moisture,and achieve goal of water-saving seedling and dry land ecological restoration.