Page 176 - 《广西植物》2025年第6期
P. 176

1 1 6 2                                广  西  植  物                                         45 卷
                ( 1. College of Forestryꎬ Southwest Forestry Universityꎬ Kunming 650224ꎬ Chinaꎻ 2. Key Laboratory of National Forestry and Grassland
                   Administration on Biodiversity Conservation in Southwest Chinaꎬ Southwest Forestry Universityꎬ Kunming 650224ꎬ Chinaꎻ 3. Key
                            Laboratory for Forest Resources Conservation and Utilization in the Southwest Mountainsꎬ Ministry of
                                      Educationꎬ Southwest Forestry Universityꎬ Kunming 650224ꎬ China )

                 Abstract: In order to investigate the growth of Pinus yunnanensis seedlings and the stoichiometric characteristics of
                 carbon (C)ꎬ nitrogen (N) and phosphorus (P) of different organs in response to shade and drought treatments and the
                 adaptive mechanismꎬ the growth of P. yunnanensis seedlings in shade and drought environments was measured and
                 analyzed in a potting controlled experiment using 1 ̄year ̄old P. yunnanensis seedlings as the subject. The experiment was
                 set up with two levels of 0% shade and 70% shadeꎬ and four moisture gradients of normal moisture (CKꎬ 80%±5%)ꎬ
                 light drought (LDꎬ 65%±5%)ꎬ moderate drought (MDꎬ 50%±5%) and severe drought (SDꎬ 35%±5%) were set to
                 determine the growth indexes of P. yunnanensis seedlings under shade and drought treatmentsꎬ as well as the Cꎬ Nꎬ and
                 P contents of leafꎬ stemꎬ coarse root and fine rootꎬ and calculate their stoichiometric characteristics. The results were as
                 follows: (1) Seedling heightꎬ ground diameter and biomass increment were the greatest under 0% shade and 70% shade
                 conditions with LDꎻ leaf biomass increment was significantly increased under the shade treatment ( 70% shade)
                 compared with no shade treatment (0% shade) in all drought stress treatments. (2) Compared with the normal water
                 treatmentꎬ with the increase of drought stress degreeꎬ the C content in each organ of P. yunnanensis seedlings under the
                 shade and drought interaction did not change significantlyꎻ the N content in leaf decreasedꎬ the N contents in stem and
                 coarse root increasedꎬ and the N content in fine root decreased and then increasedꎻ the P content in leaf and coarse root
                 decreasedꎬ and the P content in fine root increased. (3) The order of variability of each element was C<N<Pꎻ C element
                 had the smallest variability in stem and weak variability in stemꎬ coarse root and fine rootꎻ N element had the smallest
                 variability in leafꎻ P element had the largest variability in fine root. (4) There was a general correlation among the Cꎬ N
                 and P contents in each organ of P. yunnanensis seedlings. C content was negatively correlated between coarse root and
                 fine rootꎬ N content were positively correlated between leaf and fine rootꎬ stem and coarse rootꎬ and coarse root and fine
                 rootꎬ and P content was positively correlated between leaf and fine root. In summaryꎬ the growth of P. yunnanensis
                 seedlings in drought environment is mainly limited by N elementꎻ shade slows down the growth of P. yunnanensis
                 seedlings limited by N element. P. yunnanensis seedlings improve the habitat of seedlings by increasing the utilization
                 efficiency of N and Pꎬ and can alleviate the damage caused by drought stress. It is recommended that appropriate shade
                 be provided when cultivating P. yunnanensis seedlings in the forest understory in the future.
                 Key words: Pinus yunnanensisꎬ stoichiometric characteristicsꎬ drought stressꎬ shade stressꎬ variabilityꎬ correlation




                光照是植物进行光合作用的必备条件ꎬ水分                            互作对植物生长的影响存在四种假说:一是“ 相互
            是植物生长代谢过程中最重要的环境因子ꎬ当植                              作用理论”(Holmgren et al.ꎬ 1997)ꎬ认为中度遮阴
            物所在生长环境的水分条件和光照强度发生变化                              可以减缓干旱对植物生长的负面影响ꎬ但重度遮
            时ꎬ会导致其光合特性及形态结构发生改变( 刘建                            阴和高光照则会加重干旱对植物生长发育的影
            锋等ꎬ2011ꎻ邓秀秀等ꎬ2020)ꎮ 干旱通常会影响植                       响ꎻ二是“ 权衡理论” ( Smith & Hustonꎬ 1989)ꎬ认
            物的生长发育及生理过程ꎬ阻碍植物的呼吸作用ꎬ                             为植物在遮阴环境下生长ꎬ会向地上器官运输更
            进而 改 变 植 物 体 内 的 养 分 和 物 质 的 分 配 比 例               多的营养物质ꎬ减少营养物质向根系中转移ꎬ影响
            (Sainju et al.ꎬ 2017)ꎮ 有研究表明ꎬ遮阴减少了光                植物对水分的吸收ꎬ从而加重干旱对植物生长的
            能的供应ꎬ减弱了光合固碳的能力ꎬ以及改变水分                             影响ꎻ三是“促进理论” ( Quero et al.ꎬ 2006)ꎬ认为
            消耗值ꎬ进而影响植物的水分利用效率( 邓秀秀                             遮阴可以减轻植物生长受干旱的影响ꎬ改善植物
            等ꎬ2024)ꎻ遮阴会造成植株碳摄取困难ꎬ干扰植株                          在干 旱 环 境 下 的 生 长 状 况ꎻ 四 是 “ 独 立 理 论”
            的碳素分配ꎬ却在一定程度上减轻干旱对植株生                              (Holmgrenꎬ 2000)ꎬ认为遮阴与干旱互作对植物生
            长发育的影响(王林等ꎬ2020)ꎮ 同时ꎬ遮阴和干旱                         长发育不存在影响ꎮ
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