Abstract:

To screen high-efficiency seedling-raising agents suitable for early-spring seedling raising of ratoon rice in the southern Henan rice region，and alleviate low-temperature stress caused by late spring cold and the damage of sheath blight，this experiment took Taoyou Xiangzhan， the main cultivar of ratoon rice in southern Henan， as the test material. A low-temperature stress environment was simulated in an artificial climate chamber，with five treatments（CK，pure soil；Z，Longqi brand seedling-raising agent；Y，self-developed seedling-raising agent；X，Dr. Xu brand seedling-strengthening adjuvant；S，Chengbiao brand sulfur）set up. The regulatory effects of different treatments on seedling quality and physiological and biochemical indices were compared，and the stress resistance mechanism and application value of the self-developed formula were clarified. The results showed that under low temperature stress，compared with CK，all treatments could improve the seedling quality，among which the Y and Z treatments had better effects. The stem base width of the seedlings in treatments Y and Z significantly （p<0.05） increased by 41.2% compared with CK. The fresh weight of stems and roots in treatment Y significantly increased by 148.1% and 41.2% compared with CK. The total root length，total root surface area，and total root volume significantly increased by 67.6%，55.2%，and 100.0%， respectively， compared with CK. The incidence of seedling blight was reduced by 58.67 percentage points compared with CK. Treatment Y activated the antioxidant system：the activities of peroxidase（POD），catalase（CAT）and superoxide dismutase（SOD） significantly increased by 45.56%，58.48%，35.45% compared with CK，respectively；the malondialdehyde（MDA）content significantly decreased by 28.6%，the proline and soluble sugar content were increased by 61.08%，72.88%， respectively， compared with CK，effectively maintaining cell membrane integrity and osmotic adjustment capacity. The results showed that the self-developed seedling raising agent Y significantly enhanced the low-temperature tolerance and blight resistance of ratoon rice seedlings in southern Henan，providing theoretical basis and technical support for safe early-spring seedling raising of regional ratoon rice.

Key words: ratoon rice, early-spring seedling raising, low-temperature stress, seedling quality