Abstract
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.
Highlights
Cowpea [Vigna unguiculata (L.) Walp.] is an important source of protein for human consumption in the North and Northeast regions of Brazil because of its low cost (Freire Filho et al, 2011)
According to the analysis of variance, there was a significant interaction between treatment with ascorbic acid (AsA) and the presence of salt (p ≤ 0.05), but there was no interaction between the tested genotypes (Table 1)
Germination of cowpea seeds was negatively influenced by salinity; in the absence of salt, germination was 95% for BRS Marataoã and 94% for Setentão
Summary
Cowpea [Vigna unguiculata (L.) Walp.] is an important source of protein for human consumption in the North and Northeast regions of Brazil because of its low cost (Freire Filho et al, 2011). It is grown by both subsistence farmers (and sold in small surplus volumes) and medium and large-scale producers that target the national and international markets (Freire et al, 2007). Increased salinity interferes with growth medium, germination and seedling development. This is likely to be due to reduced water uptake by plants as a result of excess salts, leading to a reduction in soil water potential. Together with the toxic effects of ions on seed protoplasm, such reduction impairs germination and germination speed, and causes the formation of seedlings with reduced growth, characterized by decreased length and lower biomass accumulation (Conus et al, 2009)
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