Light intensity effects on the growth and biomass production of submerged macrophytes in different water strata

This study investigated the effects of light intensity on growth and biomass production of three submerged macrophyte species including Hydrilla verticillata, Vallisneria natans, and Ceratophyllum demersum in different water strata. For this purpose, water was classified into six strata designed: 5 cm, 30 cm, 60 cm, 90 cm, 120 cm, and 150 cm in the field under natural conditions. Results revealed that very high and very low heat intensity affected the growth of submerged macrophyte species differently. The growth of macrophytes was inhibited because of the high light intensity at 5 cm water strata. However, at 150-cm water strata, the macrophytes were died due to low light penetration. Among macrophyte species, the biomass production of Hydrilla verticillata and Ceratophyllum demersum was highest in the water strata at 90 cm, while Vallisneria natans were died in water strata of 120 cm due insufficient illumination. Furthermore, Hydrilla verticillata and Ceratophyllum demersum showed resilience and grown normally in later stages. The highest height of Vallisneria natans (35.3 cm), including Hydrilla verticillata (45.8 cm) and Ceratophyllum demersum (28.2 cm), was observed in water strata at 30, 60, and 60 cm. This study revealed that high and low light intensity affects the chlorophyll contents of macrophytes that results an impact on their growth and biomass production.