| Drought stress is one of the main factors that affecte the yield of flax. To provide theoretical basis and technical guidance for scientific irrigation and yield improvement, the pot experiment, characterized by artificial water control and simulated drought stress and re-watering condition, was conducted in the Modern Agricultural Research Center of Southwest University from November 2014 to May 2015, with three different flax varieties(Inner Mongolia local varieties, Longya8, Zhouya10), the effects of drought stress and re-watering on growth and yield formation was studied at different growth stages, at the same time, the comparison of resistance to drought stress among the three flax varieties and the most sensitive stage of flax to drought stress was cleared. The conclusions were as follows:1. The results showed that, drought stress decreased the plant height, stem diameter, root diameter and root surface area of flax at different growth stages.Impact on Plant height and stem diametern descending order as follows: squaring > fir-shaped stage> seedling> final flowering. The effect of drought stress on the root diameter and surface area in budding stage topped the list of all period, and the decreasing range was 19.77%- 24.72% and 13.46%- 19.44% respectively, followed by final flowering stage, the effect of seedling stage and fir shaped stage was unnoticeable. The root length was increased by drought stress a t seeding stage and fir shaped stage, while decreased at budding and final flowering stage The plant height and stem diameter were increased after re-watering at different growth stages, plant height at seeding stage, fir shaped stage and final flowering stage had no significantly difference compared with the control level. But re-watering at budding stage showed little effect on plant height and stem diameter, respectively, 90.3%- 93.22% and 87.21%- 91.33% of controls, compared with the control group, the difference was significant.Re-watering at seeding stage and fir shaped stage, the root diameter and root surface area of the three flax varieties had no significantly difference compared with the control level and the compensation effect was obvious, but lower than the control level in the budding stage and the final flowering stage. Comparision among three flax vatieties in plant height, root length, stem diameter, root diameter and root surface area under drought stress at the same time, Longya8 was the least affected and showed large compensation effect after re-watering, Zhouya10 was the biggest affected and showed little compensation effect, while Inner Mongolia local variety somewhere in between the other two.2. Drought stress decreased canopy weight and root weight of flax at different growth stages, in sequence of budding stage > final flowering stage > fir shaped stage > seedling stage. Drought stress significantly decreased shoot weight and root weight at budding stage and final flowering stage, and decreased relativly little at seeding stage which had no significant difference with the control. Drought stress raised the root to shoot ratio of the three varieties and the budding stage increased the most, the increasing range was from 11.17% to 14.74%, and did not reach the significant level. Drought stress at the same time, the root to shoot ratio from big to small was Longya8 > Inner Mongolia local variety > Zhouya10. After re-watering, the biomass of root and shoot could be increased effectively, and the effect in the seedling stage was the most obvious, and the least effect in the budding stage. Re-watering effectively stimulated coordinate growth of root and shoot, and decreased.the root to shoot ratio3. Drought stress increased the content of chlorophyll at different growth stages.The effect showed the most significant in budding stage, and the range was from 14.01% to 20.29%. Re-watering decreased the chlorophyll content. Drought stress significantly increased the content of soluble sugar, free proline, soluble protein, and malondialdehyde(MDA), the activity of superoxide dismutase(SOD) and peroxidase(POD), and decreased the Catalase(C AT) activity.The osmotic adjustment substances and tective enzymes activity changed maximally at budding stage.The activities of antioxidant enzymes and osmotic substance of Longya8 changed most obvious, and Zhouya10,changed in the minimum, eventually most affected the plant performance and Inner Mongolia local variety somewhere in between the other two.After re-watering, the content of soluble sugar, free proline, soluble protein, MDA content and SOD, POD activity decreased, and CAT activity increased. The effects of osmotic substances and the partial antioxidative enzyme activity were the most significant in seedling stage, and the lowest in the budding stage.4. Among all those stages, the yield reduction at budding stage and final flowering stage was the biggest,the yield reduction was about 25%, and the seeding stage was the least.The descending order was budding stage > final flowering stage > fir shaped stage >seedling stage, and the three flax varieties was consistent. In the yield components, drought stress decreased the number of capsules per plant, fruit grain number and thousand grain weight at budding stage and final flowering stage in different degrees. Drought stress mainly reduced the number of capsules per plant at seedling stage and fir shaped stage, and budding stage and final flowering stage caused the yield decline mainly by reducing the number of capsules per plant, seed number per capsule and grain weight. “Longya8” had the least yeild reduced and higher drought resistance coefficient, but the largest yeild reduced, lower drought resistance coefficient of Zhouya10, and Inner Mongolia local variety somewhere in between the other two. The drought resistant order of the three flax varieties was Longya8 > Inner Mongolia local variety > Zhouya10, and the budding stage was the most sensitive stage to water, when suffered from drought stress, irrigation timing was important. |
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