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- Title
Comparative Physiological Responses of Rice Seedlings Under Salinity, Alkalinity, and Saline-Alkalinity Conditions.
- Authors
Maganizo Kamanga, Rowland
- Abstract
Salt-alkalization is becoming an increasingly challenging environmental and socioeconomic problem as it considerably reduces crop growth and productivity. However, studies have often skewed towards neutral salinity stress, hence plants' physiological responses to saline-alkalinity remain unclear. Here we unravel this gap by dissecting key physiological responses of rice, using cultivar Hinohikari under salinity stress, alkaline stress and saline-alkaline stress. Our results show that the sensitivity of rice to salt stress is aggravated under high pH than low pH conditions. For example, by day 16 of stress imposition, severe saline-alkalinity (SSA) and severe alkalinity (SA) had reduced shoot dry mass by 370 and 235%, respectively, whereas neutral salinity stress had reduced it by 59% only. Physiologically, saline-alkaline stressed plants were nearly 6 times more chlorotic in younger leaf blades, as a result of a 182% reduction in Fe concentration. In tandem, older leaf blades were 4 times more chlorotic as a result of Na+ toxicity induced senescence by accumulating 727% more Na+ under severe SSA than under salinity stress. This high rhizospheric pH induced Na+ hyperaccumulation was at the expense K+ that leaked excessively in the roots, resulting into improper K:Na balances. Furthermore, SSA exposed plants exhibited compromised membrane integrity particularly in leaves, which was associated with 4 times, and 2.6 times more H2O2 accumulation than control and neutral salinity stressed plants, respectively. These results are consistent with previous reports, and further accentuate the lethality of combined growth media high pH and Na for plant growth, and provides avenues for targeting useful traits for breeding and enhancing plants' tolerance to mixed saline-alkaline stress. Future research should further consider unravelling more on the molecular signatures underlying these physiological responses.
- Subjects
PLANT breeding; PLANT growth; OXIDATIVE stress; SALINITY; ALKALINITY
- Publication
Gesunde Pflanzen, 2024, Vol 76, Issue 6, p1721
- ISSN
0367-4223
- Publication type
Academic Journal
- DOI
10.1007/s10343-024-01049-w