Abstract:

In order to investigate the effects of water stress on the morphology and structure of cucumber root system and its response mechanism to water stress, we selected the cucumber variety ‘Xinchun 4’ as the test material for a pot experiment. Four treatments, namely, normal water supply (CK), mild stress (T1), moderate stress (T2), and severe stress (T3), were set to study the effects of different levels of water stress on the root architecture, antioxidant enzymes and osmotic regulating substances of the cucumber root system. The results showed that the plant height, stem thickness and leaf area of cucumber seedlings did not decrease under T1 treatment compared with normal water supply, while T2 and T3 treatments showed strong inhibition of cucumber growth and development, and T1 treatment increased the total length, total surface area, total mean diameter and number of root tips of the cucumber root system by 10.6%, 29.2%, 8.9% and 10.4%, respectively. In terms of root physiological activities, root vigor, SOD, POD and CAT activities, as well as MDA content and proline content tended to increase with the increase of water stress, while root soluble protein content tended to decrease with the increase of water stress. In conclusion, it can be seen that under mild water stress, the root system of cucumber seedlings can improve its adaptive ability to water stress by regulating the activities of antioxidant enzymes, osmoregulatory substances and soluble protein concentration, in order to maintain its normal physiological and metabolic functions.

Key words: cucumber, roots, water stress, antioxidant enzyme activity, malonaldehyde, proline, soluble protein