CAJ | 학술논문

【目的】秋眠是紫花苜蓿（Medicago sativa）对晚秋生长环境变化的一种适应性反应，根系是紫花苜蓿越冬的主要功能器官，秋眠性与其越冬具重要关联，但对于如何通过根系性状的越冬特征来实现抗寒效应，仍不清楚。文章中从根系性状越冬反应的角度，探究秋眠性对紫花苜蓿抗寒性的作用过程。【方法】采用11个标准秋眠级紫花苜蓿品种为材料，以紫花苜蓿在中国适宜分布区中较为寒冷的中温带地区为例，通过标准主轴分析（standardized major axis，SMA）等方法，研究不同秋眠级紫花苜蓿各根系性状在越冬过程的差异化响应及其异速生长关系，进一步采用偏最小二乘回归（partial least squares regression，PLSR）等方法，研究不同秋眠型紫花苜蓿通过根系策略来实现其抗寒效应的关键作用因子。【结果】（1）随着秋眠性的减弱（即秋眠级提高），越冬紫花苜蓿根颈直径和侧根数显著减小（P＜0.05），秋眠性较强的紫花苜蓿具有增强储藏的表型特征，而主根直径、侧根直径等则随着秋眠性的减弱而显著趋于增大（P＜0.05），侧根数量与侧根的其他特性表现一定的权衡关系（P＜0.05）；（2）受秋眠级的影响，根系性状之间表现显著的异速生长关系，主要表现在根颈入土深度、侧根位置、侧根数等性状之间，其异速生长斜率与1存在显著差异（P＜0.05），不同根系性状在越冬期间对秋眠级具有不同的响应策略；（3）紫花苜蓿越冬率与秋眠级具有显著的负相关关系，但并非线性响应，而是呈现逻辑斯蒂曲线变化特征，1—5秋眠级趋于稳定在高越冬率水平（＞95%），中间级别5—8级的越冬率逐渐急剧减小（50%—70%），9—11级在中高纬度难以越冬（＜5%）；（4）影响紫花苜蓿越冬率的正向贡献因子是根颈直径、侧根数（P＜0.05），而主根直径、侧根直径等因子的提高反而降低了紫花苜蓿的抗寒性（P＜0.05），根系直径等性状并非决定抗寒能力的主导因子。【结论】不同秋眠级紫花苜蓿的根系性状表现出对越冬低温胁迫的差异化响应特征，不同性状具有异速生长关系；紫花苜蓿主要通过增加根颈直径和侧根数来提高其抗寒性，并不取决于根系其他表型性状的绝对大小；越冬期间，不同秋眠型紫花苜蓿根系策略的适应性变化，是实现其抗寒效应的重要途径。【目的】鞦眠是紫花苜蓿（Medicago sativa）對晚鞦生長環境變化的一種適應性反應，根繫是紫花苜蓿越鼕的主要功能器官，鞦眠性與其越鼕具重要關聯，但對于如何通過根繫性狀的越鼕特徵來實現抗寒效應，仍不清楚。文章中從根繫性狀越鼕反應的角度，探究鞦眠性對紫花苜蓿抗寒性的作用過程。【方法】採用11箇標準鞦眠級紫花苜蓿品種為材料，以紫花苜蓿在中國適宜分佈區中較為寒冷的中溫帶地區為例，通過標準主軸分析（standardized major axis，SMA）等方法，研究不同鞦眠級紫花苜蓿各根繫性狀在越鼕過程的差異化響應及其異速生長關繫，進一步採用偏最小二乘迴歸（partial least squares regression，PLSR）等方法，研究不同鞦眠型紫花苜蓿通過根繫策略來實現其抗寒效應的關鍵作用因子。【結果】（1）隨著鞦眠性的減弱（即鞦眠級提高），越鼕紫花苜蓿根頸直徑和側根數顯著減小（P＜0.05），鞦眠性較彊的紫花苜蓿具有增彊儲藏的錶型特徵，而主根直徑、側根直徑等則隨著鞦眠性的減弱而顯著趨于增大（P＜0.05），側根數量與側根的其他特性錶現一定的權衡關繫（P＜0.05）；（2）受鞦眠級的影響，根繫性狀之間錶現顯著的異速生長關繫，主要錶現在根頸入土深度、側根位置、側根數等性狀之間，其異速生長斜率與1存在顯著差異（P＜0.05），不同根繫性狀在越鼕期間對鞦眠級具有不同的響應策略；（3）紫花苜蓿越鼕率與鞦眠級具有顯著的負相關關繫，但併非線性響應，而是呈現邏輯斯蒂麯線變化特徵，1—5鞦眠級趨于穩定在高越鼕率水平（＞95%），中間級彆5—8級的越鼕率逐漸急劇減小（50%—70%），9—11級在中高緯度難以越鼕（＜5%）；（4）影響紫花苜蓿越鼕率的正嚮貢獻因子是根頸直徑、側根數（P＜0.05），而主根直徑、側根直徑等因子的提高反而降低瞭紫花苜蓿的抗寒性（P＜0.05），根繫直徑等性狀併非決定抗寒能力的主導因子。【結論】不同鞦眠級紫花苜蓿的根繫性狀錶現齣對越鼕低溫脅迫的差異化響應特徵，不同性狀具有異速生長關繫；紫花苜蓿主要通過增加根頸直徑和側根數來提高其抗寒性，併不取決于根繫其他錶型性狀的絕對大小；越鼕期間，不同鞦眠型紫花苜蓿根繫策略的適應性變化，是實現其抗寒效應的重要途徑。
【목적】추면시자화목숙（Medicago sativa）대만추생장배경변화적일충괄응성반응，근계시자화목숙월동적주요공능기관，추면성여기월동구중요관련，단대우여하통과근계성상적월동특정래실현항한효응，잉불청초。문장중종근계성상월동반응적각도，탐구추면성대자화목숙항한성적작용과정。【방법】채용11개표준추면급자화목숙품충위재료，이자화목숙재중국괄의분포구중교위한랭적중온대지구위례，통과표준주축분석（standardized major axis，SMA）등방법，연구불동추면급자화목숙각근계성상재월동과정적차이화향응급기이속생장관계，진일보채용편최소이승회귀（partial least squares regression，PLSR）등방법，연구불동추면형자화목숙통과근계책략래실현기항한효응적관건작용인자。【결과】（1）수착추면성적감약（즉추면급제고），월동자화목숙근경직경화측근수현저감소（P＜0.05），추면성교강적자화목숙구유증강저장적표형특정，이주근직경、측근직경등칙수착추면성적감약이현저추우증대（P＜0.05），측근수량여측근적기타특성표현일정적권형관계（P＜0.05）；（2）수추면급적영향，근계성상지간표현현저적이속생장관계，주요표현재근경입토심도、측근위치、측근수등성상지간，기이속생장사솔여1존재현저차이（P＜0.05），불동근계성상재월동기간대추면급구유불동적향응책략；（3）자화목숙월동솔여추면급구유현저적부상관관계，단병비선성향응，이시정현라집사체곡선변화특정，1—5추면급추우은정재고월동솔수평（＞95%），중간급별5—8급적월동솔축점급극감소（50%—70%），9—11급재중고위도난이월동（＜5%）；（4）영향자화목숙월동솔적정향공헌인자시근경직경、측근수（P＜0.05），이주근직경、측근직경등인자적제고반이강저료자화목숙적항한성（P＜0.05），근계직경등성상병비결정항한능력적주도인자。【결론】불동추면급자화목숙적근계성상표현출대월동저온협박적차이화향응특정，불동성상구유이속생장관계；자화목숙주요통과증가근경직경화측근수래제고기항한성，병불취결우근계기타표형성상적절대대소；월동기간，불동추면형자화목숙근계책략적괄응성변화，시실현기항한효응적중요도경。
Objective]Fall dormancy of alfalfa (Medicago sativaL.) is an adaptive strategy in response to change of temperature and lighting in the growth environment in late autumn. Roots, as the main functional organ of alfalfa, play a vital role in surviving the winter. Although previous studies have shown that there are significant correlations between fall dormancy and cold resistance, the overwintering characteristics of alfalfa roots on cold resistance are not clearly understood. The aim of this study was to determine the role of fall dormancy on winter hardiness in consideration of aspects of root traits.[Method] Eleven alfalfa standard check cultivars were chosen and grown in semi-arid temperate regions, which is an appropriate area for alfalfa cultivation in China. Using the standardized major axis (SMA) method, the allometric scaling of different root traits in response to fall dormancy in the process of overwintering was studied. Furthermore, using partial least square regression (PLSR) and other methods, the master regulators of the effects of alfalfa with different fall dormancy types on cold resistance in root phenotypic traits were analyzed.[Result]The results showed that with increasing fall dormancy rating, from one to 11, the collar diameter and lateral root number of wintering alfalfa significantly decreased (P<0.05). More dormant alfalfa was accompanied with enhanced storage phenotypic characteristics. However, taproot diameter and lateral root diameter significantly increased (P<0.05) as alfalfa became more non-dormant. Tradeoffs were found between lateral root number and other lateral root traits (P<0.05). Affected by fall dormancy ratings, root traits performed notable allometric scaling of different parts, mainly in collar depth, lateral root position, and lateral root number. Significant differences (P<0.05) existed between allometric scopes and one (P<0.05). Therefore, different root traits had differentiation strategies during the overwintering process. There were significantly negative correlations between the alfalfa winter survival rate and fall dormancy rating. The negative correlation could be fitted by logistic curve but not by a linear equation. Alfalfa cultivars with a fall dormancy (FD) rating of 1-5 tended to have a higher winter survival rate (>95%), 6-8 FD tended to have a sharply decreased winter survival rate (50%-70%), and 9-11 rarely survived in winter (<5%). Collar diameter and lateral root number were positive contribution factors in the alfalfa winter survival rate (P<0.05), but the taproot diameter and lateral root diameter, negative contribution factors, were not main factors that decided the winter hardiness in alfalfa (P<0.05).[Conclusion]Root traits of alfalfa with different fall dormancy ratings performed differentiation strategies in response to low-temperature stress in winter, followed by allometric relationships among different traits. Alfalfa enhanced its winter survival rate mainly through increasing collar diameter and lateral root number, and did not depend on the absolute size of other root phenotypic traits. Overall, during wintering, adaptive changes of root traits of alfalfa with different fall dormancy ratings are a primary pathway to improve winter survival.