不同供镁浓度对芝麻生长及养分累积的影响

 为促进芝麻高产营养与栽培，探讨不同镁浓度对芝麻生长和养分累积的影响。以品种中芝13为材料，设置5个供镁浓度处理（0、50、100、500和1 000μmol/L），30d后测定不同处理芝麻生物量、根系形态参数、氮磷钾含量等指标。结果显示：不同供镁浓度对芝麻生长有着不同程度的影响，镁在100μmol/L及以下时，芝麻出现缺素症状，表现为植株矮小、老叶失绿黄化，根系生长受阻。芝麻植株生物量随着供镁浓度增加而增加，根系生长对镁浓度的变化尤为敏感，缺镁抑制根系生长。与1 000μmol/L相比，3个缺镁浓度（0、50和100μmol/L）处理下根系干重分别减少97.83%、93.88%和86.65%，且侧根长、侧根数、根表面积、根体积以及根平均直径显著降低。同时，随着镁浓度增加，芝麻叶片和根系中氮、磷、钾累积量显著上升，说明适宜供镁有利于芝麻生长和养分累积。此外，与供镁浓度500μmol/L相比，1 000μmol/L处理下的芝麻植株，叶片与根系中钙的积累量均显著降低，暗示芝麻在钙和镁吸收方面可能存在拮抗关系

Effect of magnesium on sesame (Sesamum indicum L.) growth and nutrient accumulation

For high yield nutrition of sesame (Sesamum indicum L.), effects of magnesium (Mg) on nutrient accumulation was investigated using culitvar Zhongzhi 13. Aquaculture was carried out with 5 Mg concentrations treatments, including 0, 50 μmol/L, 100 μmol/L, 500 μmol/L, and 1 000 μmol/L. Sesame plant biomass, root morphological parameters and the content of macronutrient (nitrogen, phosphorus and potassium) were measured after 30 days of different Mg treatments. Results showed that different Mg concentrations had different effects on sesame growth. The plants exhibited typical symptoms of Mg deficiency under 100 μmol/L. They had short stature with chlorotic and yellowish old leaves, and their roots were slowed down. Biomass of sesame plants increased with the Mg concentration, but root growth was particularly sensitive to the change of Mg concentration. Magnesium deficiency inhibited root growth and development. Compared with 1 000 μmol/L, root growth were dramatically suppressed by 97.83%, 93.88% and 86.65% in root dry weight under 0 μmol/L, 50 μmol/L and 100 μmol/L Mg respectively. Lateral root length, lateral root number, root surface area, root volume and the average diameter of roots were also significantly reduced under 3 Mg-deficiency treatments. For other nutrients, nitrogen (N), phosphorus (P) and potassium (K) accumulations in leaves and roots were dramatically enhanced with the increase of Mg. It indicated that the optimal Mg concentration is beneficial to other nutrients of sesame plants. Furthermore, compared with 500 μmol/L, the accumulations of calcium (Ca) in leaves and roots were significantly decreased under 1 000 μmol/L, illustrating an antagonistic effect between Ca and Mg absorption in sesame plants.