Correlating sentinel-2-derived NDVI with the amount of visible color changes and seed fall of Glasswort (Salicornia herbacea L.) during it's ripening stage

Abstract

Glasswort (Salicornia herbacea) is an annual succulent plant that grows widely around intertidal zone of Gomishan Lagoon in eastern boarders of the Caspian Sea in Iran. Due to its medicinal, industrial, and economic values, tendency of its plantation is growing in recent years. One of the challenges to manage a glasswort farm is to know the appropriate date to harvest since glasswort seeds ripe quickly and seed fall happens considerably by little shake. One way of defining appropriate harvesting date can be found through correlating the amount of visible greenness of the plant, and it's ripening stage with NDVI values derived from remote sensing imageries . This experimental research was conducted to answer this problem by relating the changes in Glasswort visually estimated color classes and its amount of seedfall to the amount of Normalized difference Vegetation Index (NDVI) values that were obtained from Sentinel-2 remotely sensed imagery during the seedfall period of Glasswort community either in the field or in its natural habitat. The maximum NDVI values of 41 Sentinel-2 images during 2018-2020 within Glasswort phenological period were extracted and were correlated with the color class of the plant and the weight of seedfall in sample plots. Results showed a strong correlation between NDVI and brownness color class of the plant (R2=0.80) and a strong negative correlation with amount of its seed fall (R2=-0.83).

Keywords

• normalized difference vegetation index
• harvesting dates
• seedfall
• halophyte plantation
• saline agriculture