苏打盐碱胁迫对水稻幼苗生长及氮代谢关键酶的影响

Effects of Soda Saline-alkali Stress on Growth and Nitrogen Metabolism Key Enzyme of Rice

为明确水稻不同秧龄苗在苏打盐碱胁迫下的生长和氮代谢差异,以"长白9"为试验材料,设置不同秧龄L1(3叶秧龄)、L2(4叶秧龄)、L3(5叶秧龄),以50 mmol/L的混合盐碱进行胁迫,研究苏打盐碱胁迫(0~48 h)下水稻不同秧龄苗的生理响应、物质积累和氮素吸收特性。结果表明:苏打盐碱胁迫显著提高了水稻各秧龄苗脯氨酸和可溶性糖含量,3叶秧龄苗响应时间更早,涨幅更大,随秧龄的增大,渗透调节能力变弱;苏打盐碱胁迫显著提高了水稻各秧龄苗叶片及根中Na^+积累量和Na^+/K^+,3叶秧龄苗峰值更高,随秧龄的增长离子平衡能力逐渐增强。从氮素代谢来看,苏打盐碱胁迫显著抑制了水稻不同秧龄苗的氮素吸收和转化,降低了叶片和根系硝酸还原酶(NR)和谷氨酰胺合成酶(GS)活性,抑制了地上部氮素积累和植株干物质积累。5叶秧龄苗NR和GS活性的下降显著小于其他秧龄,并通过小幅上调叶片谷氨酸脱氢酶(GDH)活性来增强GDH代谢途径,以适应盐碱胁迫对氮素吸收造成的影响。5叶秧龄苗地上部、根系干质量以及地上部氮素积累量所受影响也明显小于其他秧龄。这说明,苏打盐碱地水稻移栽选择大叶秧龄苗有利于增强秧苗抗性,能保证更高效的氮素吸收和物质积累。

In order to clarify the differences in growth and nitrogen metabolism of rice seedlings of different ages under soda saline-alkaline stress, Changbai 9 was used as test material, rice seedlings of different ages, L1(3-leaf seedling age), L2(4-leaf seedling age) and L3(5-leaf seedling age), were stressed with 50 mmol/L mixed saline alkali, and the physiological response, material accumulation and nitrogen absorption characteristics of the rice seedlings were studied after soda saline-alkali stress(0-48 h). The results showed that soda saline-alkali stress significantly increased the content of proline and soluble sugar in rice seedlings, the response time of the 3-leaf seedlings was earlier and the increase was greater, and with the increase of age, the osmotic adjustment ability became weaker;Soda saline-alkali stress significantly increased Na^+ accumulation and Na^+/K^+ in leaves and roots of rice seedlings of all ages, the peak value of 3-leaf seedlings was higher, and the ion balance was gradually enhanced with the growth of rice seedlings. From the perspective of nitrogen metabolism, soda saline-alkali stress significantly inhibited nitrogen uptake and transformation in different seedling ages, the activities of NR and GS in leaves and roots were reduced, and nitrogen accumulation in shoots and dry matter accumulation in plants were inhibited. The decrease of NR and GS activities in the 5-leaf seedlings was significantly less than that of other seedlings, and the GDH metabolic pathway was enhanced by slightly up-regulating the GDH activity of leaves, so as to adapt to the effects of saline-alkali stress on nitrogen uptake. The effects of 5-leaf seedlings on shoot dry weight, root dry weight and nitrogen accumulation were also significantly less than those of other seedling ages. The above results show that transplanting rice in soda saline-alkaline land to select ageing seedlings with large leaves is beneficial to enhance seedling resistance and ensure more efficient nitrogen absorption and material accumulation.