Plant Growth Regulators Application Enhance Tolerance to Salinity and Benefit the Halophyte Plantago coronopus in Saline Agriculture

Climate change, soil salinisation and desertification, intensive agriculture and the poor quality of irrigation water all create serious problems for the agriculture that supplies the world with food. Halophyte cultivation could constitute an alternative to glycophytic cultures and help resolve these issues. Plantago coronopus can be used in biosaline agriculture as it tolerates salt concentrations of 100 mM NaCl. To increase the salt tolerance of this plant, plant growth regulators such as polyamine spermidine, salicylic acid, gibberellins, cytokinins, and auxins were added in a hydroponic culture before the irrigation of NaCl (200 mM). In 45-day-old plants, dry weight, water content, osmolyte (sorbitol), antioxidants (phenols, flavonoids), polyamines (putrescine, spermidine, spermine (free, bound, and conjugated forms)) and ethylene were determined. In non-saline conditions, all plant regulators improved growth while in plants treated with salt, spermidine application was the most effective in improving growth, osmolyte accumulation (43%) and an increase of antioxidants (24%) in P. coronopus. The pretreatments that increase the sorbitol content, endogenous amines (bound spermine fraction), phenols and flavonoids may be the most effective in protecting to P. coronopus against stress and, therefore, could contribute to improving the tolerance to salinity and increase nutritional quality of P. coronopus.

Agronomic and Physiological Evaluation of Wheat Cultivars under Deficit Irrigation Condition

Improving crop productivity under drought conditions contributes largely to the sustainable agriculture globally. In this study, the agronomic traits and physiological processes related to osmolyte accumulation and reactive oxygen species (ROS) homeostasis during late growth stage in wheat under drought stress were studied. Three cultivars viz., Shimai 22 (drought tolerant), Zhongxinmai 99 (median drought-tolerant, control), and Shi 4185 (drought sensitive) sharing contrasting drought tolerance were grown under normal irrigation (NI: with irrigations prior to sowing, and at jointing and flowering stages) and deficit irrigation (DI, with irrigations prior to sowing and at jointing) conditions. Data regarding yields, osmolyte (i.e., proline and soluble sugar) contents, and antioxidant enzyme activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), and malondialdehyde (MDA) contents were recorded. Under deficit irrigation, the cultivars displayed modified agronomic and physiological traits. Among cultivars, Shimai 22 showed best agronomic traits (6.47 to 7.23% higher yield than control), osmolyte contents and AE activities (10.12 to 22.18% higher than control), and least MDA accumulation (12.30 to 17.06% lower than control). In contrast, Shi 4185 cultivar performed worst regarding above said traits. The transcripts of the genes in ��1-Pyrroline-5-carboxylate synthetase (P5CS) family that regulates proline biosynthesis and those in AE families that modulate ROS homeostasis were evaluated. Results revealed that the P5CS genes TaP5CS2 and TaP5CS5 and the AE ones TaSOD3, TaCAT2 and TaCAT5 were modified on transcripts across the cultivars under DI condition, showing to be significant upregulated compared with NI. These results suggested the essential roles of osmolyte accumulation and AE proteins in improving the drought tolerance of wheat during late growth stages. In addition, this study suggested that the elevated transcription efficiencies of distinct P5CS and AE family genes under water deprivation contribute to the enhanced drought tolerance in drought-tolerant cultivars. © 2021 Friends Science Publishers