Effects of nitric oxide and silicon application on growth and productivity of pepper under salinity stress

Background: Salinity is one of the most prevalent abiotic stresses which adversely affect plant growth, yield, and fruit quality by restricting water uptake and disrupting metabolic activities. Nitric oxide (NO) can be used to alleviate the adverse effects of salinity stress on plant growth and yield; however, limited knowledge is available on the frequency of NO application. There are limited studies on determining frequency of NO application to alleviate adverse effects of salinity stress on plant growth.Methods: This study was conducted to determine the frequency of NO application and associated impacts on pepper growth under salinity stress. The plants were grown in perlite medium and irrigated with a nutrient solution having 0 and 100 mM NaCl salinity. Salinity stress was imposed one month after planting, and simultaneously 2 mM silicon (Si) and 100 mu M NO were applied at 0-, 7-,14- and 28-days interval after imposing salinity.Results: Yield and plant growth were reduced by salinity stress, whereas proline and MDA (malondialdehyde) in the leaves were increased. The Si application increased stem diameter and dry weight, whereas decreased plant height and root length. Furthermore, Si application decreased stomatal conductivity under salinity-free conditions, while increased it under salinity stress. Application of NO at 7-and 14 -days interval increased most of the studied traits, whereas decreased plant height, leaf dry weight, stomatal conductivity, and proline content.Conclusions: While nitric oxide applied at 7-day intervals decreased marketable yield, application at 14 -day intervals increased it by-16.5%. Based on the results, it is thought that weekly application of Si and NO application at 14-days interval could increase marketable yield of pepper under saline environments. (c) 2022 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).