Assessment of drought resistance among wild rice accessions using a protocol based on single-tiller propagation and PVC-tube cultivation

Abstract To assess the variation in drought resistance among wild rice accessions, a protocol was developed based on single-tiller propagation and PVC-tube cultivation. Severe water stress was applied at late vegetative growth stage. The responses of eight accessions of Oryza rufipogon and one accesstion of O. officinalis were evaluated by measuring the morphological and physiological traits, including leaf rolling score, leaf water potential, free proline content, chlorophyll content, above-ground biomass, maximum root depth, maximum root length, root weight, deep root percentage and root/shoot ratio. Wild rice accessions showed differential abilities to tolerate and recover from the water deficit. The accession of O. officinalis had much stronger drought tolerance than all O. rufipogon accessions. Two O. rufipogon accessions (Or03, Or08) from Hainan (as a tropical island) had the best performance under drought stress, while two other accessions of (Or15, Or33) from Guangdong and Jiangxi provinces were sensitive to water deficit. The results revealed the preliminary evidences that O. rufipogon accessions from tropical area have stronger drought resistance than accessions from sub-tropical areas. Keywords: biomass; drought resistance; root system; vegetative stage; wild rice. Abbreviations: T1, T2-drought stress for 20 days, 28 days; T3-one month after restored irrigation; SWC-soil water content (SWC1 and SWC2 mean the measurements at T1 and T2, similarly for other traits); FPC-free proline content; LWP-leaf water potential; LCC-leaf chlorophyll content; LRS-leaf rolling score; RD -maximum root depth; RL-maximum root length; SRV-shallow root volume; DRV -deep root volume; SRW-shallow root weight; DRW-deep root weight; RW-root weight as the sum of SRW and DRW; AGB-above-ground biomass per tube