干旱胁迫下钠复合肥对霸王(Zygophyllum xanthoxylum)根系生长的促进作用

霸王(Zygophyllum xanthoxylum)是荒漠区广为分布的一种多浆旱生植物。采用盆栽育苗的方法,初步评价了干旱胁迫下Na+对霸王根系生长的贡献,探讨了一种新型钠复合肥对霸王根系形态、生理学指标的影响。结果显示,钠复合肥能显著促进霸王根系的生长并提高其抗旱性:(1)正常浇水时,钠复合肥对霸王的促进作用主要体现在株高的增加和侧根的增长上,根系活力显著增强;(2)自然干旱15d后,钠复合肥使得霸王根系活跃吸收面积显著提高24%,促进主根的加粗和伸长以吸收更多的水分和矿质养分;(3)干旱胁迫下,钠复合肥处理使霸王根部Na+浓度保持较高水平,K+浓度下降42%。因此认为,干旱前钠复合肥显著促进了霸王侧根的生长和根系活力的提高,干旱后钠复合肥通过促进根系活跃吸收面积的扩大和主根的生长以提高霸王的抗旱性,其主要原因是根和叶中积累了较多的Na+、而非K+。

A Sodium Compound Fertilizer Promotes Root Growth in Zygophyllum xanthoxylum under Drought Stress

Zygophyllum xanthoxylum is a succulent xerophyte that widely lives in desert area. The effects of a newly invented sodium compound fertilizer on both morphological and physiological indices relevant to root growth were investigated in pots experiments in order to evaluate the contribution of Na⁺ to root growth of Z. xanthoxylum under drought stress. The results indicated that the sodium compound fertilizer significantly enhanced root growth as well as drought resistance of Z. xanthoxylum: (1) The sodium compound fertilizer mainly improved plant height, promoted the growth of lateral roots and enhanced root activity significantly under well irrigated condition; (2) The sodium compound fertilizer significantly improved root active absorbent area by 24% and increased taproot diameter and elongation to uptake sufficient water and mineral nutrition after 15 days' drought treatment; (3) Ion analysis showed that Na⁺ concentration in roots of Z. xanthoxylum under drought stress was maintained at a high level, however, K⁺ concentration decreased by 42% by the sodium compound fertilizer. Therefore, it is proposed that Na⁺ could significantly improve lateral root growth and root activity under well irrigated condition, whereas, enhance root active absorbent area and taproot growth to improve the drought tolerance of Z. xanthoxylum under water stress, which was mainly caused by the higher accumulation of Na⁺, not K⁺, in roots and leaves of Z. xanthoxylum.