甜瓜根系与叶片协同衰老过程中相关生理指标的变化

Changes of Physiological Indexes Related to the Synergistic Senescence Between Root and Leaf System in Muskmelon

以甜瓜“锦绣脆玉”为试材,测定了坐果期至成熟期根系活力与叶片SPAD值、根系和叶片可溶性蛋白质、丙二醛(MDA)含量及抗氧化酶活性,探讨甜瓜根系与叶片协同衰老的生理机制,以期为其生育后期早衰的合理调控提供参考依据。结果表明:从坐果期到成熟期,根系活力、叶片叶绿素含量以及根系与叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性和可溶性蛋白质含量均呈现先升高后降低的趋势,在坐果后10~20 d(果实膨大前期)达到最大值,丙二醛(MDA)含量和过氧化物酶(POD)活性均持续上升。从叶片和根系生理特性的相互关系上来看,叶片3种保护酶(SOD、CAT、POD)活性及可溶性蛋白质含量始终高于同期根系,而MDA含量却始终低于同期根系,且SOD、CAT活性和MDA含量差异达显著水平,根系中相关生理指标的变化幅度整体上均大于叶片。综上所述,在甜瓜生育后期,根系代谢能力下降和叶片光合产物亏缺,保护酶清除活性氧自由基能力降低,加重了脂膜过氧化程度,最终导致植株衰老;整体上来看,根系和叶片衰老具有密切相关性,且根系衰老速度相对较快,其衰老加剧了叶片衰老。

Taking‘Jinxiucuiyu'muskmelon as test material,the investigation of root vigor and leaf SPAD value,and soluble protein and malondialdehyde(MDA)contents,protective enzyme activities in root and leaf from sitting melon stage to maturing stage were determined,physiological mechanism of synergistic senescence between root and leaf system in muskmelon was studied,in order to provide reference for the reasonable regulation of premature aging in the later growth stage of muskmelon.The results showed that the root vigor,leaf chlorophyll contents,and the soluble protein contents,the superoxide dismutase(SOD),catalase(CAT)activities of root and leaf initially increased from low to high and then declined,which reached the maximum value at 10-20 days after fruit setting(early stage of fruit expansion),and that the MDA contents,peroxidase(POD)activities of root and leaf gradually increased.From the relationship of physiological characteristics between leaves and roots,the SOD,CAT,POD activities,and soluble protein contents of leaf were significantly higher than that of root the corresponding period,the MDA contents were less than that of root the corresponding period,and the SOD,CAT activities and MDA content between root and leaf were significantly different,In addition,the amplitude of relevant physiological changes in root was larger than that in leaf.In conclusion,the metabolic capacity was reduced of the root and leaf,and the photosynthetic products were deficient.Moreoverthe ability of protecting enzymes to scavenge reactive oxygen free radicals was reduced,aggravating the degree of membrane oxidation,and those led to the gradual senescence of plants duringthe late stage.In the aging process,the senescence of roots and leaves was closely related,and the senescence speed of roots was relatively fast,which aggravated the senescence of leaves.