Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/4/2019
Publication Date: 1/6/2021
Citation: Gealy, D.R., Rohila, J.S. 2021. Effect of AWD irrigation on yield components and biological responses of recurrent inbred lines from a weed-suppressive indica x tropical japonica mapping population. Proceedings of 38th Rice Technical Working Group Meeting, February 24-27, 2020, Orange Beach, Alabama. p 135. Electronic Publication
Technical Abstract: Alternating-wetting-drying (AWD) is a conservation irrigation management system that is being implemented in commercial rice production in the USA. Among its potential advantages are the ability to reduce irrigation costs and increase water use efficiency, thus extending the viability of underground aquifers while maintaining economical productivity of the rice industry. Currently, our understanding of yield losses under AWD stress is limited. For this field study, 14 recombinant inbred lines (RILs; F10) were chosen from a collection of 330 RILs from a PI 312777 x Katy mapping population based on their diverse and unique plant traits. PI 312777 is naturally high-yielding, weed-suppressive, and AWD stress-tolerant compared with Katy. The selected RILs were evaluated for two years under AWD and conventional flooded (FLD) irrigation systems for yield components and AWD-stress tolerance. The experiment was conducted in 2017 and 2018 as a split plot design with four replications, main plots of conventionally flooded (FLD) or AWD irrigation, and subplots of the parents, RILs, and five standard cultivars as checks. Rice was drill-seeded 2-cm deep in Dewitt silt loam soil into plots 4-m long with six, 18-cm-wide rows on May 9 of 2017 and 2018 at Stuttgart, AR. Pre-flood nitrogen fertilizer was broadcast-applied as urea at 110 kg ha-1 N, followed by the initial ‘permanent’ flood application to all plots on June 20, 2017 and June 7-8, 2018. All other cultural and weed control practices were performed generally as in conventional rice production. Drain/reflood cycles in AWD plots were implemented July 14/July 21-24 and July 28/Aug. 25, 2017; and July 5/July 17-18, 2018 (a 2nd AWD cycle could not be implemented in 2018 due to extended periods of rainfall). The first and 2nd AWD cycles reached minimum percent soil volumetric water content (VWC) at approximately 10 and 13 weeks after emergence, respectively, and were intended to establish ‘severe AWD’ conditions in plots (VWC ~15-20%; except when rain sometimes prevented adequate drying). To determine relative levels of plant stress, leaf temperature and C assimilation rate data were recorded in all plots when ~minimum VWC was reached in AWD plots. Yield components were determined from 1-m of row several days before bulk harvesting the whole plot for final yield, which was done Oct. 4-17, 2017 and Sept 14 to Oct. 12, 2018 depending on the maturity of the RILs.