Alleviation of aqueous nitrogen loss from paddy fields by growth and decomposition of duckweed (Lemna minor L.) after fertilization

A Preliminary Study of the Impacts of Duckweed Coverage during Rice Growth on Grain Yield and Quality

“…But in areas with limited fertilizer input, competition between duckweed and rice seedlings may occur, which affects the rice growth, tiller formation, and final yield [ 14 ]. In a recent report, duckweed coverage significantly increased the rice yield by 13.2% and 16.9% when urea and biogas slurry were applied, respectively; however, the yield increase was smaller and non-significant when slow-release fertilizer or no fertilizer was applied [ 22 ]. Unfortunately, neither the tiller formation nor the panicle number was reported in other studies ( Table S1 ), except for a study by Wang et al [ 26 ].…”

“…Duckweed coverage in a paddy field, particularly at the early rice-growth stage, forms a physical barrier that directly blocks ammonia volatilization, allowing relatively more N to be retained in the surface water and soil for the growth of the duckweed and rice [ 19 , 20 ]. In addition, duckweed coverage decreases the water temperature and pH, which slows ammonia volatilization, especially at the early growth stage of rice [ 19 , 21 , 22 ]. At the middle and late growth stages, rice-leaf shading accelerates duckweed decomposition, releasing N and other minerals into the rice paddy [ 23 ].…”

“…At the middle and late growth stages, rice-leaf shading accelerates duckweed decomposition, releasing N and other minerals into the rice paddy [ 23 ]. Therefore, duckweed coverage could increase the nitrogen-use efficiency by decreasing N loss through volatilization or runoffs, showing significant ecological and economic benefits [ 19 , 20 , 22 ].…”

“…Although a number of studies have investigated the effects of the duckweed coverage in paddies on the rice growth and yield, no consensus has been reached because positive [ 19 , 20 ], negative [ 14 ], and no significant effects [ 27 , 28 ] of duckweed on the rice yield have been reported ( Table S1 ). The effects of the duckweed treatment on the rice yield seem to be dependent on soil types [ 29 ], duckweed species [ 26 ], and fertilizer applications [ 22 ]. Duckweed coverage significantly increased the rice yield by 13.2% and 16.9% when urea and biogas slurry were applied, respectively; however, no significant yield increase was found when slow-release fertilizer or null fertilizer was applied [ 22 ].…”

“…The effects of the duckweed treatment on the rice yield seem to be dependent on soil types [ 29 ], duckweed species [ 26 ], and fertilizer applications [ 22 ]. Duckweed coverage significantly increased the rice yield by 13.2% and 16.9% when urea and biogas slurry were applied, respectively; however, no significant yield increase was found when slow-release fertilizer or null fertilizer was applied [ 22 ]. This suggests that duckweed–rice interactions vary with the nutrient availability in the growth environment.…”