Objective A high-quality, drought-resistant restorer rice line was bred.

Method 'Huanghuazhan' as female parent and 'Lvhan 1' as male parent were used for the hybridization. The F₁ hybrid was backcrossed with Huanghuazhan to obtain BC₁F₁ followed by repeated backcrossing held in Hefei and Bengbu, Anhui as well as Lingshui, Hainan. From BC₁F₁ to BC₁F₅ generations, water stress test, molecular marker detection, phenotypic and agronomic traits selection, yield evaluation, and drought resistance determination were performed to scrutinizingly screen the candidates to arrive at a finalized select breed.

Result In 2016, the selected DJ639 was officially named 'Lvhan 639' for its outstanding drought tolerance, grain quality, and yield, with a drought index of 0.85 (moderate drought tolerance) and grain quality reaching the Grade 2 premium rice standard; its mean yields in the 2019 and 2020 production trials were 9327.3 and 9031.2 kg·hm⁻², 9.57% and 11.91% higher than the control Lvhan 1, respectively. It showed moderate resistance to rice blast. It was approved by Anhui Provincial Crop Variety Approval Committee in 2021 (Approval No. : Wanshendao 20212003), and obtained the new plant variety right in 2023 (CNA20191000485). The two combinations of 'Lvhanliangyou 21' and 'Wanhanliangyou 25' were approved by Anhui Provincial Crop Variety Approval Committee in 2022.

Conclusion The newly bred Lvhan 639 of high quality, drought and disease resistance, yield, and combining ability was considered amply suitable for extended cultivation.