Drought resistance of new synthetic hexaploid wheat accessions evaluated by multiple traits and antioxidant enzyme activity

Drought is a severe threat to wheat production. Synthetic hexaploid wheat (SHW, AABBDD) has great potential for improving resistance to various stresses of bread wheat. The drought resistance of thirty-four new SHWs and a control (bread wheat cultivar Jinmai47) were evaluated under two water regimes, i.e., well watered (WW) and water stressed (WS), in two consecutive years. Compared with the cultivar Jinmai47 under WW conditions, SHWs displayed increased plant height (PH), larger flag leaf area (FLA), longer spikes (SL) and more biomass plant−1 (BMPP), but SHWs displayed fewer grains spike−1 (GNPS) and less thousand-grain weight (TGW), resulting in lower grain yield plant−1 (GYPP) and a lower harvest index (HI). The membership function value of drought resistance (MFVD) analysis and drought resistance index (DI) under the two water regimes revealed six SHW lines (SHW1, SHW3, SHW10, SHW16, SHW21 and SHW34) identified with higher drought resistance. Our results also showed higher activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT), in WS plots than in WW plots. SHWs with higher drought resistance exhibited higher activities of antioxidant enzymes (SOD, POX and CAT) in both WW and WS plots. SHWs exhibiting excellent agronomic traits and increased drought resistance could further be applied to stress resistance studies and wheat breeding programmes.