CAJ | 학술논문

【目的】研究土壤干旱对华北落叶松幼苗生长与生理的影响，揭示该种的苗期耐旱性与生长策略，预测干旱气候对幼苗更新的影响，为评估未来气候变化下该种的种群动态与制定合理的经营措施提供理论支撑，同时也为干旱地区的人工林营造特别是苗木管护提供依据。【方法】以当年生华北落叶松幼苗为试验材料，在盆栽条件下，采用称重控水法，将土壤相对含水量分别控制在最大田间持水量的70%～80%(对照)、50%～60%(轻度干旱)、35%～50%(中度干旱)和20%～35%(重度干旱)，研究不同干旱处理对华北落叶松幼苗生长、叶绿素含量、抗氧化系统和渗透调节的影响，分析幼苗耐旱性，确定该种的干旱胁迫阈值。【结果】轻度干旱对华北落叶松幼苗针叶和幼茎的伸长生长影响较小，中度和重度干旱显著抑制针叶和茎的伸长生长，3种干旱处理均明显促进侧根的发生与伸长，干旱时幼苗的针叶长与主根长紧密相关；针叶的叶绿素总量和叶绿素 a含量对轻度干旱无明显反应，随干旱加强而持续下降，重度干旱时叶绿素b含量下降，但3种干旱强度下的叶绿素a、叶绿素 b含量之比无明显变化；随干旱加强，华北落叶松幼苗的SOD酶和POD酶活性持续增强，丙二醛和脯氨酸含量持续增加，可溶性蛋白质含量下降，茎的可溶性糖含量持续增加，针叶和根的可溶性糖含量先增后减；干旱条件下幼苗的抗氧化系统和脯氨酸含量在3种营养器官之间紧密相关。【结论】华北落叶松当年生幼苗的生长和生理作用几乎不受轻度干旱的影响或仅受较小影响，但受中度和重度干旱的影响显著。干旱条件下，华北落叶松幼苗采取减少地上部分生长、优先满足根系的生长策略，并启动抗氧化系统和积累脯氨酸来减轻干旱造成的伤害，具一定的耐旱性；针叶的生理变化先于形态变化，未出现针叶变黄脱落的现象；中度和重度干旱限制了针叶的碳摄取与根部的碳储藏，势必影响到幼苗的存活，推测华北落叶松当年生幼苗的干旱胁迫阈值应小于最大田间持水量的35%。山西省5月份的月均降雨量相当于本试验的中度干旱处理，接近于重度干旱处理，华北落叶松幼苗的生长显著受春旱影响，且未来区域气候的干旱化趋势下(降水量减少30%)，这种影响作用将更加严重。【目的】研究土壤榦旱對華北落葉鬆幼苗生長與生理的影響，揭示該種的苗期耐旱性與生長策略，預測榦旱氣候對幼苗更新的影響，為評估未來氣候變化下該種的種群動態與製定閤理的經營措施提供理論支撐，同時也為榦旱地區的人工林營造特彆是苗木管護提供依據。【方法】以噹年生華北落葉鬆幼苗為試驗材料，在盆栽條件下，採用稱重控水法，將土壤相對含水量分彆控製在最大田間持水量的70%～80%(對照)、50%～60%(輕度榦旱)、35%～50%(中度榦旱)和20%～35%(重度榦旱)，研究不同榦旱處理對華北落葉鬆幼苗生長、葉綠素含量、抗氧化繫統和滲透調節的影響，分析幼苗耐旱性，確定該種的榦旱脅迫閾值。【結果】輕度榦旱對華北落葉鬆幼苗針葉和幼莖的伸長生長影響較小，中度和重度榦旱顯著抑製針葉和莖的伸長生長，3種榦旱處理均明顯促進側根的髮生與伸長，榦旱時幼苗的針葉長與主根長緊密相關；針葉的葉綠素總量和葉綠素 a含量對輕度榦旱無明顯反應，隨榦旱加彊而持續下降，重度榦旱時葉綠素b含量下降，但3種榦旱彊度下的葉綠素a、葉綠素 b含量之比無明顯變化；隨榦旱加彊，華北落葉鬆幼苗的SOD酶和POD酶活性持續增彊，丙二醛和脯氨痠含量持續增加，可溶性蛋白質含量下降，莖的可溶性糖含量持續增加，針葉和根的可溶性糖含量先增後減；榦旱條件下幼苗的抗氧化繫統和脯氨痠含量在3種營養器官之間緊密相關。【結論】華北落葉鬆噹年生幼苗的生長和生理作用幾乎不受輕度榦旱的影響或僅受較小影響，但受中度和重度榦旱的影響顯著。榦旱條件下，華北落葉鬆幼苗採取減少地上部分生長、優先滿足根繫的生長策略，併啟動抗氧化繫統和積纍脯氨痠來減輕榦旱造成的傷害，具一定的耐旱性；針葉的生理變化先于形態變化，未齣現針葉變黃脫落的現象；中度和重度榦旱限製瞭針葉的碳攝取與根部的碳儲藏，勢必影響到幼苗的存活，推測華北落葉鬆噹年生幼苗的榦旱脅迫閾值應小于最大田間持水量的35%。山西省5月份的月均降雨量相噹于本試驗的中度榦旱處理，接近于重度榦旱處理，華北落葉鬆幼苗的生長顯著受春旱影響，且未來區域氣候的榦旱化趨勢下(降水量減少30%)，這種影響作用將更加嚴重。
【목적】연구토양간한대화북락협송유묘생장여생리적영향，게시해충적묘기내한성여생장책략，예측간한기후대유묘경신적영향，위평고미래기후변화하해충적충군동태여제정합리적경영조시제공이론지탱，동시야위간한지구적인공림영조특별시묘목관호제공의거。【방법】이당년생화북락협송유묘위시험재료，재분재조건하，채용칭중공수법，장토양상대함수량분별공제재최대전간지수량적70%～80%(대조)、50%～60%(경도간한)、35%～50%(중도간한)화20%～35%(중도간한)，연구불동간한처리대화북락협송유묘생장、협록소함량、항양화계통화삼투조절적영향，분석유묘내한성，학정해충적간한협박역치。【결과】경도간한대화북락협송유묘침협화유경적신장생장영향교소，중도화중도간한현저억제침협화경적신장생장，3충간한처리균명현촉진측근적발생여신장，간한시유묘적침협장여주근장긴밀상관；침협적협록소총량화협록소 a함량대경도간한무명현반응，수간한가강이지속하강，중도간한시협록소b함량하강，단3충간한강도하적협록소a、협록소 b함량지비무명현변화；수간한가강，화북락협송유묘적SOD매화POD매활성지속증강，병이철화포안산함량지속증가，가용성단백질함량하강，경적가용성당함량지속증가，침협화근적가용성당함량선증후감；간한조건하유묘적항양화계통화포안산함량재3충영양기관지간긴밀상관。【결론】화북락협송당년생유묘적생장화생리작용궤호불수경도간한적영향혹부수교소영향，단수중도화중도간한적영향현저。간한조건하，화북락협송유묘채취감소지상부분생장、우선만족근계적생장책략，병계동항양화계통화적루포안산래감경간한조성적상해，구일정적내한성；침협적생리변화선우형태변화，미출현침협변황탈락적현상；중도화중도간한한제료침협적탄섭취여근부적탄저장，세필영향도유묘적존활，추측화북락협송당년생유묘적간한협박역치응소우최대전간지수량적35%。산서성5월빈적월균강우량상당우본시험적중도간한처리，접근우중도간한처리，화북락협송유묘적생장현저수춘한영향，차미래구역기후적간한화추세하(강수량감소30%)，저충영향작용장경가엄중。
[Objective]Larix principis-rupprechtii,a deciduous conifer tree species,is an important forest component and timber resource in subalpine of North China. This species is mainly distributed in subalpine regions of Shanxi province where droughts have occurred frequently in recent decades. In this study, drought effects on seedling growth and physiological responses of L. principis-rupprechtii were carried out to analyze its drought resistance and growth strategy at early stage. This study intends to provide a basis for afforestation,especially for seedling management and protection of this species. It can also efficiently predict regeneration of the species under the drying climate. [Method]A potted experiment with one-year-old seedlings of L. principis-rupprechtii was carried out with four water regimes by controlling soil water content using weighing method. Light drought ( LD ) was treated as 50% -60%,moderate drought ( MD ) as 35% -50%,severe drought ( SD) as 20% -35%,and control ( CK) as 70% -80% of field water carrying capacity, respectively. For each treatment,length of needles,stems and primary roots of the seedlings were measured,and lateral roots of each seedling were counted and measured to analyze drought effects on elongation growth of vegetative organs. Physiological indexes, including needle chlorophyll contents, antioxidants, i. e. SOD, POD activities and malondialdehyde ( MDA) contents,and osmotic substances,i. e. proline,soluble sugar and protein were also measured to analyze seedling physiological changes. Then drought resistance of the one-year-old seedling was analyzed and drought stress threshold was estimated on the basis of above indexes. [Result]Elongations of needles and stems of L. principis-rupprechtii seedlings were significantly restrained by both the moderate and severe drought stress,but not significantly by light drought. The formation and elongation of lateral roots were promoted by all drought stresses. There was close correlation between primary root length and needle length under soil drought. Contents of total chlorophyll and chl a were not changed by light drought,but constantly decreased with increasing drought intensity. The Chl b content was decreased by severe drought while chl a / chl b was not significantly affected by drought. With increased drought level,activities of SOD and POD were both significantly promoted and contents of MDA and proline were remarkably increased,but soluble protein contents significantly decreased. Soluble sugar content of stems was continually rising by increased drought,while the sugar contents of needles and roots were increased by light drought but decreased by moderate and severe drought. The antioxidant system and proline contents of three organs ( root,stem and needle) were closely related.[Conclusion]Light drought had no or only slight effects on the elongation growth and physiological indexes of seedlings,while moderate and severe drought had significant negative effects. One-year-old seedlings of L. principis-rupprechtii were of some drought resistance,fulfilled by the adaptive strategy that reduced the aboveground growth and gave priority to the root growth. The utility of antioxidant system and proline accumulation were also efficient responses to alleviate the seedling impacts by drought. Morphological change of needles was less distinct and less than physiological changes. No needles turned yellow or shed during the trail of 120 days. Carbon uptake of needles and carbon storage of roots were both affected by moderate and severe drought,which would lead to carbon starve and even to death of seedlings. It is estimated that the drought stress threshold of the relative water content of soil is less than 35% of field water carrying capacity. Mean monthly rainfall of May in Shanxi is roughly equal to the moderate and severe drought in this trail,thus seedling growth of L. principis-rupprechtii is substantially affected by the spring drought. The effect would be strengthened by the drying climate in future, saying the rainfall reducing by 30% of the present amount.