Background Qinghai-Tibet Plateau is known for characteristics of high altitude, low rainfall and varying temperature, and the crops in this area are susceptible to abiotic stresses such as drought, basic salt and freeze-thaw that caused damages in different perspectives such as the permeability of biological membrane, osmotic adjustment, and antioxidant enzyme system. Hordeum vulgare L. is an indispensable crop in plateau and plays an important role in agricultural ecosystem as well.Result In this experiment, H. vulgare L. was used as experimental material and the physiological characteristics soluble protein (SP) content, malondialdehyde (MDA) content, antioxidant enzyme activity and relative water content (RWC) of seedlings were examined under freeze-thaw condition combined with drought and alkali stress.Conclusion Research results indicated that under the combined stresses of basic salt and drought, H. vulgare L. seedlings were damaged by lipid peroxidation, weakened superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activities, while enhanced osmotic adjustment ability in plants cell. It was suggested that, in agricultural management, the simultaneous occurrence of two stresses, basic salt and drought, should be avoided in the early stage of H. vulgare L. planting to reduce the physiological stress on plants.
Secale cereale L. (rye) as an overwinter forage usually harvested in the autumn, widely grows in the northeastern China, where the temperature varies widely from day to night. In this area, the crop is confronted with not only freeze–thaw stress, but also the soil salinization. In this study, the rye seedlings under alkaline salt (AS) stress were subjected to both cutting treatment (CT) after growing for 7 days and freeze–thaw (FT) stress(10/−5°C) after 6 days regrowth. The changes of soluble protein (SP), malondialdehyde (MDA), relative water content (RWC), catalase (CAT) and superoxide dismutase (SOD) activities in seedlings were studied to analyze the physiological effects of FT and AS stress with CT. The results indicated, under the combined stress, the enzyme activity and RWC decreased and the soluble protein and MDA content increased. Cutting treatment led to the accumulated of MDA, increase of enzyme activity and decrease of RWC in seedlings. The finding from the study indicates that the CT could aggravate the membrane peroxidation under the combined stress of FT and AS and enhance the osmotic adjustment ability of rye and activated the antioxidant enzyme system. The rye having been cut is more sensitive to the compound stress.
The freeze-thaw (FT) and drought in early spring in Northeast China are two main ecological stresses to forage grasses. In this paper, Secale cereale L. grown under 2 d drought-stress (mild, moderate, and severe treat) with 5, 10 and 15% polyethylene glycol (PEG-6000) concentrations. The temperature gradient was set to 10, 5, 0, -5, 0, 5 and 10ºC after FT treatment. The content of protein, soluble sugar and MDA increased with a trend of combined stress>FT>drought stress, indicating that the damage of rye under single FT stress was higher than that under the single drought stress. Under drought stress, FT could aggravate the damage to rye. At T7 (10ºC) in the thawing stage, compared with the CK, the pattern of the decrease of RWC and chlorophyll and the increase of protein and MDA content was severe combined stress>FT>moderate combined stress>moderate drought stress. The results of this study showed that a proper drought treatment before FT stress could alleviate the physiological damage to the forage leaf.
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