Water and Fertilizer Utilization and Characteristics of Rice Root Growth under Rainwater Storage Irrigation

Root system is the main organ for absorbing water and nutrients and its morphological characteristics are related to the development status of above ground part and final grain yield of rice. This study investigated utilization of water and fertilizer under rainwater storage irrigation (RI) and changes of root growth indicators. Results showed that, the averaged root weight for RI was lower than conventional flooding irrigation (CI), while the main root length for RI was higher. The white root ratio (the percentage of white root) was reduced relatively slower in whole growth stage Rainfall utilization efficiency (RUE) for RI was 2.6 and 3.5 times CI in 2013 and 2014, showing a rather better rainfall utilization efficiency. Water utilization efficiency (WUE) for RI was almost twice and 1.5 times of CI in 2013 and 2014, respectively. The irrigation regimes showed significant effect on RUE and WUE. Nitrogen use efficiency (NUE) for CI was 8.5 and 8.7% higher than RI in 2013 and 2014, respectively. Nitrogen accumulation in above ground part of rice plant and WUE both showed positive correlation with root activity, while NUE showed no relevance to root activity. Therefore, under rainwater storage irrigation mode, root activity and WUE was promoted, preventing premature aging of roots in the late growth stage of rice. (C) 2020 Friends Science Publishers