【作者】 刘丹；

【导师】 王晓凌；

【作者基本信息】 河南科技大学 ， 生态学， 2012， 硕士

【摘要】 牧草的耐牧性是牧草维持自身生存，维持草场持续生产和提高产草量的重要因素。本研究以一年生黑麦草为材料，采用遮光、断根等研究方法，通过探明去叶黑麦草母体非结构碳水化合物的损耗途径，以及根系吸收能力的变化，来揭示去叶黑麦草再生的根叶协调生长机制。然后以根叶协调生长机制为基础，通过检测再生叶、茬、根系以及根系伤流液中激素含量，并运用断根、喷施外源激素等研究方法，来探明根源细胞分裂素调控去叶黑麦草耐牧性的模式途径，从而验证根源细胞分裂素对去叶黑麦草再生的调控是影响其耐牧性的一个本质属性。主要研究结果如下：1.黑麦草根茎储备的可溶性碳水化合物、有机物质是促其再生的重要物质来源，地上部分再生也对根部有机物质有一定程度的消耗，较高的留茬高度有助于缓解对根部有机物质的消耗，维护相对较高的根系活力，可有效促进再生。多次去叶情况下，黑麦草叶片中细胞分裂素(ZR)含量与叶片再生生物量之间存在显著性的正相关关系。2.断根易引起黑麦草根系生物量被大量消耗，根系活力值降低，从而引起其根系中较低的ZR含量，根系中较低的ZR含量会导致再生叶片中ZR含量的降低，从而产生抑制再生叶片生长的作用。尽管去叶也可以刺激黑麦草根系和叶片中脱落酸(ABA)含量的升高，但黑麦草根系中的ABA含量与再生叶片中的ABA含量之间，并没有直接的联系。3.黑麦草多次去叶情况下，会引起根系生物量，以及可溶性碳水化合物的大量消耗，从而导致根系伤流量以及根系中ZR含量的降低。断根则更易引起根系伤流量和根系中ZR含量的降低，而喷施外源细胞分裂素易引起黑麦草叶片中较高的ZR含量。黑麦草再生叶片中较高含量的ZR易促进叶片的再生，且这种促进作用并非完全由根系的吸收能力和可溶性碳水化合物含量决定，但必须以它们为基础。4.多次去叶下，黑麦草新生叶中玉米素和玉米素核苷(Z+ZR)、玉米素和玉米素核苷以及异戊烯基腺嘌呤和异戊烯基腺苷(Z+ZR+IPA+IPS)含量与再生叶生物量之间均存在显著正相关关系；新生叶与伤流液中Z+ZR、Z+ZR+IPA+IPS含量，新生叶与根系中Z+ZR、Z+ZR+IPA+IPS含量之间均存在显著正相关关系。而黑麦草再生与根系的吸收能力的强弱，以及根系贮存的有机物含量并无直接的联系。与未断根相比，重度断根更易引起去叶黑麦草根系贮存有机物质含量的大幅下降，导致根系功能的衰竭，根系、伤流液和叶片中Z+ZR以及Z+ZR+IPA+IPS含量显著下降，从而抑制其再生。更多还原

【Abstract】 Grazing tolerance is important in continuation grassland production andimproving hay yield. In the current study, ryegrass was used as the subject materials,with the research method of shading, root breaking, proving the coordinationmechanism between roots and leaves though the study of non-structure carbohydratesloss ways and changes of root absorbing ability. Based on the coordination mechanismbetween roots and leaves, we used method of root breaking and exogenousphytohormone spraying, with exzaming the content of phytohormones in newly grownleave, stubble, root and root xylem sap, proving the way of root-derived zeatin andzeatin riboside in adjusting grazing tolerance of ryegrass, thus indicating that root-derived cytokinin in improving the grazing tolerance of ryegrass is a essential attribute.The main results are as follows.1. Soluble carbohydrate and organic matter stored in stems and roots areimportant sources for ryegrass to regenerate, and there were some consuming for rootbiomass to a certain degree. Compared with low stubble, the high stubble couldmaintain a relative high root function by relieving root biomass consuming inregeneration, and as a result increased regeneration effectively. There were asignificant positive correlation between ZR content and biomass in newly grownleaves under frequent defoliation.2. After leaf clipping, the root biomass of ryegrass was greatly consumed andthen root capacity declined, thereby resulting in a low ZR content in roots, which ledto the lower ZR content of newly grown leaves and as a result taking inhibitory effecton leaf growth. After leaf clipping, if the consumption of root biomass did not increase,the root capacity of ryegrass could get enhanced, resulting in a higher ZR content inroots, which could lead to a higher ZR content in newly grown leaves, thus promotingthe growth of the leaves. Although leaf clipping of ryegrass also could stimulate ABAincrease in roots, there did not existed evident direct relation between the ABA contents of roots and newly grown leaves and that the ABA content of roots did notdirectly or indirectly affected the growth of newly grown leaves.3. Under frequent defoliation, the biomass and soluble carbohydrate content inryegrass roots decreased, causing a decline of the ZR content in both xylem sap androots. Moreover, under frequent defoliation root breaking easily decrease the ZRcontent in the xylem sap and roots; however, exogenous cytokinin easily increased theZR content in the newly grown leaves and roots. High ZR content in the leavesimproved the regrowth of ryegrass, which was not determined by the absorptioncapacity of the roots.4. Under frequent defoliation, the Z+ZR and Z+ZR+IPA+IPS contents in leaveshad a significantly position correlation with the biomass of the newly grown leaves; asignificant positive correlation was observed between leaves and xylem sap, betweenleaves and roots in Z+ZR contents, between leaves and xylem sap in Z+ZR+IPA+IPScontents, between leaves and roots in Z+ZR+IPA+IPS contents. However the regrowthof ryegrass had no direct relationship with root absorbing ability or organic mattercontents stored in roots. Compared with no root breaking, severe root breaking easilycaused the exhaustion of root functions and decreasing of the Z+ZR andZ+ZR+IPA+IPS contents in roots, root xylem sap, as well as leaves, thereby restrainedregrowth of ryegrass.更多还原