Effects of Salinity and Nutrient Addition on Mangrove Excoecaria agallocha

Abstract

Effects of salinity on seed germination and growth of young (1 month old) and old (2-year old) seedlings of Excoecaria agallocha were investigated. Combined effects of salinity and nutrient level were also examined on old seedlings. Seed germination was best at 0 and 5 psu salinity. 15 psu salinity significantly delayed root initiation and decreased final establishment rate. All seeds failed to establish at 25 psu salinity. Young seedlings performed best at 0 and 5 psu, but growth was stunned at 15 psu, and all seedlings died within 90 days at 25 psu. Old seedlings grew best at salinities below 5 psu and they survived the whole cultivation at 25 psu. This indicated that E. agallocha increased salt tolerance over time. Gas exchange was significantly compromised by salinities above 15 psu but evidently promoted by high nutrient. Proline accumulated considerably at high nutrient, and its contents increased from 0 to 15 psu but decreased at 25 psu salinity. Lipid peroxidation was aggravated by increasing salinity beyond 15 psu but markedly alleviated by nutrient addition. These responses indicated that E. agallocha was intolerant to high salinity but it can be greatly enhanced by nutrient addition.

Salinity strongly drives the survival, growth, leaf demography, and nutrient partitioning in seedlings of Xylocarpus granatum J. König

“…Reduced leaf production, decreased specific leaf area and increased leaf senescence with increased salinity is in accordance with the findings of Ball & Pidsley (1995) and Chen & Ye (2014). Leaf area reduction is considered to be the immediate response to salt stress (Parida & Das 2005, Reef & Lovelock 2015.…”

“…2a). Similarly, Ye et al (2005) found lower survival for Aegiceras corniculatum at 25 PSU, and Chen & Ye (2014) …”

“…For example, HoppeSpeer et al (2011), Mahmood et al (2014a), and Chen & Ye (2014) found maximum biomass in salinity ranging from 0 to 10 PSU (Rhizophora mucronata at salinity 8 PSU, Heritiera fomes and Excoecaria agallocha at salinity range 0 to 5 PSU). However, further increases in salinity can slow the biomass growth (Chen & Ye 2014, Mahmood et al 2014b. Reduction of leaf production accompanied with higher leaf mortality often leads to the death of the plant (Ball & Pidsley 1995, Suárez & Medina 2005.…”

Structure and Composition of Mangrove Associations in Tubli Bay of Bahrain as Affected by Municipal Wastewater Discharge and Anthropogenic Sedimentation

“…The average salinity levels were 13.72 dS m −1 , 19.57 dS m −1 , and 22.27 dS m −1 in Tubli, Sitra-1, and Sitra-2, respectively. In this context, it was reported that wastewater discharge had a positive effect on seedlings of mangroves through enhancement of growth and reducing the salt-induced damage to the physiological processes of plants [42].…”

Monitoring of Eco-Restoration of Mangrove Wetlands through Time Series Satellite Images: A Study on Krishna-Godavari Delta Region, East Coast of India

“…Most of the deforestation is by local communities for using the mangrove logs for construction of their houses (huts) and as firewood, as our field enquiries revealed. At some locations, the bare ground appears in light (white to pale blue) tone (Figure 2-c) due to salt encrustation in the areas where the mangrove vegetation declined and the land dried out, because extreme salinity can lead the death of mangrove plants (Chen and Ye 2014). The main reason for increased salinity regime in certin parts of mangrove ecosystem is construction of dams and barrages across rivers and consequent reduction in freshwater inputs into the system through the rivers (Spalding et al 1997).…”