Physiological and morphological responses of two sweet potatos (Ipomoea batatas (L.) Lam) to drought stress

摘要

In this study, two sweet potato (Ipomoea batatas (L.) Lam) cultivars (white-fleshed and orange-fleshed) were grown in greenhouse conditions. The drought stress levels were imposed by maintaining the soil water content at 25%, 50%, 75% and 100% of field capacity to evaluate the effects of drought on growth parameters (shoot and root dry weight, leaf area (LA), specific leaf area (SLA), relative water content (RWC), total chlorophyll proline and soluble sugars content in plant organs (leaf and root). The results showed that as drought increased, the amount of the above growth parameters in plant organs of both cultivars decreased. However, in all drought treatments, white-fleshed sweet potato had significantly higher shoot and root dry weight, leaf area (LA), specific leaf area (SLA) and relative water content (RWC) than orange-fleshed. The most reduction on dry weight was mainly in level 4 of stress 25% FC in two cultivars. Drought stress led to reductions in the relative leaf water content (RWC) by 25% FC. The lowest content of total chlorophyll and total nitrogen content was observed in drought conditions while between control and drought treatments there were significant differences. As drought increased, the amount of proline content of white-fleshed sweet potato was higher than orange-fleshed sweet potato. Also, drought increases soluble sugars contents. Therefore, it seems that white-fleshed sweet potato is more tolerance than orange-fleshed sweet potato.