JIA-2019-11

2460 XU Bing-qin et al. Journal of Integrative Agriculture 2019, 18(11): 2457–2471 cell turgor (Nayyar and Walia 2003). In this study, soluble sugar and proline contents of both of the cultivars increased significantly under drought stress. Soluble sugar contents increased by 10.22–19.36% in DM and by 1.71–74.45% in HN following 24 to 72 h of drought treatment (Fig. 1-B and Appendix B). For DM, the proline content had linear growth and after 72 h drought duration, it nearly doubled comparing to the 0 h control (Fig. 1-C and Appendix B). The proline content in HN also increased, reaching 31.87, 65.14, and 91.48% after 24, 48, and 72 h, respectively, greater than the 0 h control (Fig. 1-C and Appendix B). MDA is the main product of cytoplasmic membrane peroxidation, and its content can directly reflect the tissue membrane lipid peroxidation (Okcu 2005). For DM, the MDA content increased by 40.23% after 24 h, remained unchanged at 48 h, and then increased by 114.96% after 72 h, showing the time-course of drought stress caused cell membrane injuries in leaves (Fig. 1-D andAppendix B). But MDA content in HN had no significant changes with drought duration (Fig. 1-D and Appendix B). ABA and JA are the key hormones regulating drought adaptive responses (McAdam and Brodribb 2016). ABA content in the two cultivars showed different trends. In DM, it dramatically increased after 24 h, reaching 38.38% of the Fig. 1 Comparisons of relative water content (RWC, A), total soluable sugar (B), proline (C), malondialdehyde (MDA, D), and abscisic acid (ABA, E), and jasmonic acid (JA, F) contents with the osmotic stress duration. Error bars represent SE ( n =5). The letters above the histogram indicate the statistical significance according to the LSD test at the level of 0.05 ( P <0.05). The experiments were repeated twice. 0 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040 0.045 e e e e b a c d MDA content (µmol g –1 FW) MDA 60 65 70 75 80 85 h g f e d c b RWC (%) a 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 g e d g c b ABA content (µg g –1 FW) 0 0.05 0.10 0.15 0.20 f h g f e d c b a Proline content (mg g –1 FW) 0 2 4 6 8 10 12 14 16 18 20 d Total soluble sugar content (mg g –1 FW) c b a h g f e – 0 24 48 72 0 24 48 72 – 0 24 48 72 0 24 48 72 – 0 24 48 72 0 24 48 72 – 0 24 48 72 0 24 48 72 Time (h) Time (h) – 0 24 48 72 0 24 48 72 – 0 24 48 72 0 24 48 72 0 10 20 30 40 50 60 g g f e d c b a JA content (µg g –1 FW) DM HN B A D C F E