Effect of waterlogging on photosynthesis and growth of finger millet (Eleusine coracana)

Abstract

Finger millet (Eleusine coracana (L.) Gaertn.) is an important cereal crop grown in most parts of Asia and Africa owing to its ability to adapt to stressful environments. The objective of this study was to examine the effect of waterlogging on photosynthesis and growth of finger millet. Plants were subjected to waterlogging by keeping pots filled with water from June 16 (transplanting) until November 12 (harvesting) in 2021 in Tokyo. After being subject to 13 days of waterlogging, net photosynthetic rate (P_n) decreased by 10.1% due to reduced stomatal conductance (g_s), transpiration rate, and relative chlorophyll content (SPAD). From July to September, long-term waterlogging increased P_n in the range of 4.9%–26.3%. The alleviation of high temperature, increase in SPAD and g_s, and other nonstomatal components were implicated as the cause of increased P_n in summer. These findings suggest that the effect of waterlogging on photosynthesis varies with the duration of waterlogging or the growing season. Plant height was significantly reduced by 27.9% during the first 13 days of waterlogging and remained lower throughout the waterlogging treatment than in irrigated conditions. Waterlogging also caused other morphological changes, such as a significant increase in the number of tillers (63.2%) and a 16.7% increase in the number of panicles. Grain yield decreased by 13.6%, but the reduction was not significant. Overall, finger millet has the potential to tolerate waterlogging and is a promising crop for both paddy and field farming.