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【目的】明确棉花轻简化基质育苗技术下的幼苗离床耐受生理相关特性,为其安全存放和运输保护提供理论支持。【方法】设置了育苗基质添加保水剂和不添加保水剂的处理,以中棉所50为材料,研究了29 d苗龄的幼苗不同离床和复水条件下的相关生理指标变化。【结果】室内条件下棉苗离床的耐受过程中,幼苗叶片逐步失水,引起从叶片外部表层细胞结构到内部生理的一系列变化,最终影响移栽成活率。其中,离床3 d内是安全期,叶片含水量的损失不到5%,且及时复水后能达到幼苗离床前初始状态的98%以上,移栽成活率均在99%以上;此时叶片表层细胞结构相对完整,细胞连接相对平滑,保卫细胞相对饱满。离床5 d为临界期,此时复水仅能达到初期的93%左右;第5至7天叶片失水最快,这个阶段相对含水率日均下降15百分点;当失水降到50%以下(11 d后)时,叶片表层细胞皱缩较严重,细胞壁皱褶明显,气孔塌陷较深,复水后恢复能力弱。失水过程中真叶内脯氨酸、丙二醛含量和过氧化物酶活力随离床时间增加而上升/增加,过氧化氢酶和超氧化物歧化酶活力变化在前5 d上升,5 d后开始下降。【结论】保水剂有利于维持离床棉苗体内水分,缓解离床期干旱胁迫。
【Objective】 The purpose of this study is to identify the physiologically relevant characteristics of seedling exudation in cotton seedling under the light simplified matrix seedling technology and to provide theoretical support for its safe storage and transport protection. 【Method】 The treatments of adding water-retaining agent and non-adding water-retaining agent were set up in nursery substrate. The changes of related physiological indexes of seedlings of 29-day-old seedling under different bed separation and rehydration conditions were studied using Zhongmianshu 50 as material. 【Result】 During the tolerance of cotton seedlings to bed separation under indoor conditions, seedling leaves gradually lost water, causing a series of changes from the outer surface cell structure to the internal physiology of the leaves and finally affecting the survival rate of transplanting. Among them, within 3 days from bed is a safe period, the loss of leaf water content less than 5%, and in time after rehydration seedlings can reach more than 98% of the initial state before bed, survival rate of transplanting more than 99%; this When the leaf surface cell structure is relatively complete, cell connection is relatively smooth, relatively full guard cells. 5 d from the bed for the critical period, rehydration at this time can only reach about 93% of the initial; the first 5 to 7 days leaves the fastest water loss, the average relative water content at this stage decreased by 15 percentage points; when the water loss to 50% Below (after 11 days), the cell surface folds shrink more seriously, with obvious cell wall folds, deep pore collapse and weak recovery after rehydration. Proline, malondialdehyde (MDA) content and peroxidase activity in true leaves during water loss increased / increased with increasing bed-separation time, and the changes of catalase and superoxide dismutase activities increased in the first 5 days. 5 d began to decline. 【Conclusion】 The water-retaining agent is good for maintaining the water content of cotton seedlings in bed and alleviating the drought stress in bed-leaving.