Salt tolerance during the seedling production stage of Catharanthus roseus, Tagetes patula and Celosia argentea

ABSTRACT The guarantee of water supply for irrigated agriculture in the semi-arid region must necessarily involve the use of lower quality water, such as brackish water. The objective of the present work was to evaluate the tolerance to salinity of the ornamental species Catharanthus roseus, Tagetes patula and Celosia argentea, using different methods. The experiment was conducted in a randomized block, arranged in a 10 x 3 factorial scheme, corresponding to 10 saline concentrations of irrigation water (ECw 0.5; 1.0; 1.5; 2.0; 2.5; 3.0; 3.5; 4.0; 5.0 and 6.0 dS m-1) and 3 ornamental species. Four salinity tolerance assessment methods were tested, using relative values or percentages of reduction in quantitative and qualitative analyses. The different methods show the highest sensitivity to salinity of C. roseus, in the seedling production stage, compared to T. patula and C. argentea species. The methods of threshold salinity and ORN index led to similar results in terms of classification of salt tolerance, with C. roseus classified as sensitive and T. patula and C. argentea as moderately sensitive. The method of Fageria (1985) allowed good separation of the species, with tolerance limits of 1.5, 2.5 and 3.5 dS m-1, respectively for C. roseus, T. patula and C. argentea. It is obvious from the comparison with literature data that the seedling production stage is more sensitive to salt stress, and it is necessary to carry out new studies aimed at attenuating the effects of stress at this stage, through the use of management techniques.

摘要 半干旱地区灌溉农业的供水保障，必然需要使用低品质水源，例如咸淡水（brackish water）。本研究旨在通过多种方法评估观赏植物长春花（Catharanthus roseus）、孔雀草（Tagetes patula）及青葙（Celosia argentea）的耐盐性。试验采用随机区组设计，设置10×3因子试验方案，涵盖10个灌溉水电导率（Electrical Conductivity of Irrigation Water, ECw）梯度：0.5、1.0、1.5、2.0、2.5、3.0、3.5、4.0、5.0及6.0 dS·m⁻¹，以及3种供试观赏植物。本试验共测试4种耐盐性评价方法，评价指标均为定量与定性分析中的相对值或降幅百分比。结果显示，相较于孔雀草与青葙，各评价方法均表明长春花在育苗阶段对盐胁迫的敏感性最强。盐度阈值法与ORN指数法在耐盐性分类结果上趋于一致：长春花被划为盐敏感型，孔雀草与青葙则为中度盐敏感型。法盖里亚（Fageria, 1985）法可有效区分各供试物种的耐盐性，长春花、孔雀草、青葙的耐盐极限分别为1.5、2.5及3.5 dS·m⁻¹。结合已有文献数据可知，育苗阶段对盐胁迫更为敏感，未来需开展相关研究，通过栽培管理技术缓解该阶段的盐胁迫负面影响。