Effects of water use efficiency on plant dry matter in NERICA and Japanese rice cultivars under drought conditions

Abstract

NERICA (New Rice for Africa) was produced by crossing Asian rice (Oryza sativa L.) and African rice (Oryza glaberrima Steud.) and recorded to be drought tolerance. This study aimed to examine the transpiration and water use efficiency affected plant aboveground dry matter in total 29 cultivars including 23 NERICA, 1 indica-type and 5 japonica-type cultivars. Seedlings were transplanted 2 plants per pot (1/5000 a Wagner pot) on June 14, 2021. When the flag leaf appeared, three water treatments with three replications were imposed for 14 days. The control plot (C) was watered daily to maintain the water content per pot at field capacity (SW). The water content of medium dry pots (MD) and hard dry pots (HD) were maintained at 40% and 10% of SW, respectively. Surface of the pots was covered to eliminate the evaporation. Samples for dry matter measurement were collected on the same day starting and ending water treatment. Water use efficiency (WUE) was significantly different among cultivars when soil moisture treatments were included, and the same observation on soil moisture treatments when included cultivars. NERICA 4 showed the lowest WUE while NERICA 9 and Hokuriku 193 had the highest WUE. Cultivars with higher transpiration rate (Tr) had higher dry matter production (ΔDW). Under high vapor pressure deficit, ΔDW was more correlated with transpiration corrected by vapor pressure deficit (Tr/VD) than with WUE.