Sodium Nitroprusside Alleviates Moderate Drought Stress in Beet (Beta vulgaris L. subsp. vulgaris) by Modulating Its Photosynthetic Capacity

Beet growth and sugar production are strongly impacted by drought. Nitric oxide (NO) donors, such as sodium nitroprusside (SNP), have shown promising results in the alleviation of drought stress; however, these effects were not evaluated in beet. The aim of this study was to evaluate the effects of SNP on the morphophysiology and sugar content of beets for human consumption under moderate and severe drought stresses, as well as the role of SNP in the recovery of plants upon re-watering. For this, two experimental sets were performed. In the first, beet plantlets were irrigated with 80% of water holding capacity (WHC-well-watered), 15% WHC (moderate stress), or water restricted (severe stress) up to 36 days after sowing (DAS). In the second, beets were irrigated with 80% WHC, 15% WHC, re-watered after water restriction, or late water restriction (from 44 to 66 DAS). In both sets, beets were leaf sprayed with 100-mu M SNP or water. The gas exchanges, photosynthetic pigments, chlorophyll fluorescence, electrolyte leakage, water content, and growth were determined in both developmental stages, and sugar content was determined in 66-d-old plants. 15% WHC and water restriction reduced growth and photosynthetic capacity of plants in both developmental stages, with 36-d-old plantlets being more sensitive than 66-d-old beet plants. SNP reversed the negative effects of 15% WHC but not those of water restriction. Re-watering fully recovered growth and photosynthetic capacity of drought-stressed beets independently of SNP. In summary, SNP alleviated moderate drought stress in beet by modulating its photosynthetic capacity.

Automated summary

This study aimed to evaluate the effects of the NO donor SNP on the morphophysiology and sugar content of beets under moderate and severe drought stresses, as well as its role in the recovery of plants after re-watering. The results showed that SNP alleviated moderate drought stress in beets.