Tolerance of crambe (Crambe abyssinica Hochst) to salinity and water stress during seed germination and initial seedling growth

ABSTRACT Crambe is an oilseed plant whose oil is suitable for various industrial purposes, such as production of biodiesel, plastics, rubbers, and cosmetics. There are reports of the rusticity of this species and its potential for growth in arid and semi-arid environments, where water scarcity and soil salinity are common. However, studies regarding the tolerance of its seeds to these stresses and the physiological responses triggered during germination and seedling establishment under these conditions are incipient. The objective of this study was to evaluate the tolerance of crambe seeds to water deficit and salt stress during germination and early seedling development, as well as to investigate the role of antioxidant enzymes on tolerance to these conditions. The seeds were exposed to water and salt stresses and their performance was analyzed. Seed water content, imbibition rate, percentage and speed of germination, and the base water potential for seed germination were evaluated. In the seedlings, the following measurements were made: root and shoot length, fresh and dry matter of roots and shoots, moisture content, and activity of the enzymes superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX). Water deficit and salt stress reduce the water uptake rate of the seeds, the germination and growth of seedlings. The crambe seeds had higher tolerance to salt stress than to water deficit. Absorption of salt and the action of the SOD and CAT antioxidant enzymes are part of the tolerance mechanisms of crambe seeds to salt stress.

摘要 海甘蓝（Crambe）是一种油料作物，其油脂可应用于生物柴油、塑料、橡胶及化妆品等多种工业生产场景。已有研究表明该物种具有良好的抗逆适应性，能够在水资源短缺、土壤盐渍化普遍存在的干旱与半干旱环境中生长。然而，针对该物种种子对上述逆境的耐受能力，以及胁迫条件下种子萌发与幼苗建成过程中触发的生理响应的相关研究仍较为匮乏。本研究旨在评估海甘蓝种子在萌发及幼苗早期生长阶段对水分亏缺与盐胁迫的耐受能力，并探究抗氧化酶（antioxidant enzymes）在其耐受上述逆境过程中的作用机制。实验中将种子置于水分胁迫与盐胁迫环境中，对其生长表现进行分析：测定了种子含水量、吸胀速率、萌发率与萌发速率，以及种子萌发所需的基准水势；同时针对幼苗，测定了根长与地上部长度、根及地上部的鲜重与干重、含水量，以及超氧化物歧化酶（SOD）、过氧化氢酶（CAT）与过氧化物酶（POX）的活性。研究结果显示，水分亏缺与盐胁迫会降低种子的吸水速率，抑制种子萌发与幼苗生长；且海甘蓝种子对盐胁迫的耐受能力高于水分亏缺胁迫。此外，盐分吸收以及SOD与CAT抗氧化酶的协同作用，是海甘蓝种子应对盐胁迫的耐受机制之一。