Ascorbic acid of cowpea seeds under saline stress

Abstract: Salinity adversely affects plant growth and metabolism by triggering increased production of reactive oxygen species (ROS). Ascorbic acid (AsA) is known to protect organelles and cells against ROS by preventing accumulation. The objective of this study was to study the effects of AsA on cowpea beans under saline stress. Cowpea seeds of the cultivars (BRS Marataoã and Setentão) were conditioned at concentrations of 0.0 (control); 0.25; 0.50; 0.75 and 1.00 mM AsA and seeded on paper towels, moistened at saline levels of 0.0 (control); 1.5; 3.0; 4.5; 6.0 and 7.5 dS.m-1, packed in a bench germinator at 25 °C. The statistical design adopted was a completely randomized 2 × 5 × 6 factorial design (cultivar x ascorbic acid x saline levels) with four replicates of 50 seeds per treatment. The analyzed variables were percentage of germination, first germination count, germination speed index, shoot and root length, total seedling dry weight, and leaf and root electrolyte leakage. Ascorbic acid at concentrations of 0.50 mM for BRS Marataoã and 0.75 mM for the Setentão, enabled the development of more vigorous seedlings and the reduction of membrane damage caused by oxidative stress both in the absence of salt and at the saline levels tested, including the highest one.

摘要：盐胁迫可通过诱导活性氧（ROS）过量产生，对植物生长与代谢造成不利影响。抗坏血酸（AsA）可通过抑制活性氧积累，保护细胞器与细胞免受ROS介导的氧化损伤。本研究旨在探究抗坏血酸对盐胁迫下豇豆的调控效应。本实验选用品种为BRS Marataoã与Setentão的豇豆种子，分别以0.0（对照组）、0.25、0.50、0.75及1.00 mM的抗坏血酸溶液进行浸种预处理，随后将种子播于纸巾之上，并用0.0（对照组）、1.5、3.0、4.5、6.0及7.5 dS·m⁻¹的盐溶液润湿纸巾，最后将播种后的纸巾放置于25℃的台式发芽箱中培养。本实验采用完全随机2×5×6因子设计（品种×抗坏血酸浓度×盐胁迫水平），每个处理设置4次生物学重复，每次重复包含50粒种子。本实验测定的指标包括发芽率、初次发芽计数、发芽速率指数、地上部与根系长度、幼苗总干重，以及叶片与根系的电解质渗漏率。研究结果显示，对于BRS Marataoã品种，采用0.50 mM的抗坏血酸处理即可培育出更健壮的幼苗；而对于Setentão品种，0.75 mM的抗坏血酸处理则可达到相同效果。该处理方案无论在无盐胁迫条件下，还是在所有测试的盐胁迫水平（包括最高胁迫组）中，均可有效减轻氧化应激引发的细胞膜损伤。