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：盐胁迫会通过诱导活性氧（reactive oxygen species, ROS）过量产生，对植物生长与代谢造成不利影响。抗坏血酸（ascorbic acid, AsA）可通过抑制活性氧积累，保护细胞器与细胞免受氧化损伤。本研究旨在探究抗坏血酸对盐胁迫下豇豆的调控效应。
本试验选用两个豇豆品种（BRS Marataoã与Setentão）的种子，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；随后将种子播于湿润纸巾上，分别设置0.0（对照组）、1.5、3.0、4.5、6.0及7.5 dS·m⁻¹的盐胁迫梯度，将播种种盘置于25℃的台式发芽箱中培养。
试验采用完全随机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次重复，每次重复包含50粒种子。本试验测定的指标包括：发芽率、初次发芽数、发芽速率指数、幼苗地上部与根系长度、幼苗总干重，以及叶片与根系电解质渗漏率。
研究结果显示，针对BRS Marataoã品种，0.50 mM的抗坏血酸处理效果最优；而Setentão品种则以0.75 mM抗坏血酸处理为最佳，该浓度可在无盐胁迫及所有测试盐胁迫水平（包括最高胁迫梯度）下，培育出更健壮的幼苗，并减轻氧化胁迫引发的细胞膜损伤。