This study investigated the physiological mechanism underlying cold resistance differences between two rye(Secale cereale)cultivars,White BK-1 and Dongmu-70,during seed germination and seedling stages.The results showed that seed germination rate,germination potential,root length,stem length,and seedling biomass were all significantly greater in White BK-1 compared to Dongmu-70 under cold stress(4℃),indicating superior cold tolerance.Low temperature exposure resulted in damage to pho-tosynthetic tissues within rye mesophyll cells,leading to a significant decrease in net photosynthetic rate(Pn).White BK-1 exhibited a smaller reduction in Pn and a faster recovery rate after stress alleviation.Chlorophyll content in rye leaves initially increased with prolonged cold stress,followed by a subsequent decline.Additionally,chlorophyll a/b ratio decreased under cold conditions.Malondialdehyde(MDA)content increased in rye leaves under cold stress,but to a lesser extent in White BK-1.Exposure to cold stress triggered the accumulation of osmotic regulators in rye leaves,while antioxidant enzyme activity exhibited a biphasic response,initially increasing and then declining.White BK-1 displayed a more robust response to cold stress by maintaining higher levels of soluble sugars and proline accumulation,as well as sustaining greater Pn and antioxidant enzyme activity.
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