钙、镁缺乏对香蕉幼苗生长及养分吸收的影响

Effects of calcium and magnesium deficiency on banana seedling growth and nutrient absorption

为探讨钙、镁缺乏对香蕉幼苗生理生化指标及养分吸收、运输及分配的影响,以宝岛蕉幼苗为试验材料进行养分胁迫沙培试验。结果表明,叶片是对钙、镁胁迫发生响应最敏感的部位。钙胁迫先在新叶出现缺素症状,沿叶边缘出现枯斑;镁胁迫则先在下部叶片出现叶脉之间失绿黄化的症状。钙、镁缺乏不影响幼苗的茎粗和叶片数,但均会显著降低叶片叶绿素含量。缺钙抑制幼苗株高的生长。钙、镁缺乏均显著降低宝岛蕉幼苗的光合作用强度,钙胁迫下光合作用的限制因素是非气孔因素,而镁胁迫下光合作用同时受到气孔因素和非气孔因素的限制。钙、镁缺乏均抑制宝岛蕉幼苗全株的干物质积累量,缺镁处理的影响大于缺钙处理;钙、镁胁迫还改变了香蕉幼苗养分分配,缺钙抑制N、P、K向叶部运输,缺镁抑制K、Mg在茎部的积累,最终抑制宝岛蕉幼苗叶部和茎部的生长、促进根部的生长,导致根冠比增加。钙、镁缺乏均不利于香蕉幼苗对其他养分的吸收。香蕉栽培过程中,合理施用氮、磷、钾肥的同时要混合使用钙、镁肥才能获得高产。

In order to investigate the effects of Ca and Mg deficiency on physiological and biochemical indexes,nutrient absorption,transportation and distribution of banana seedlings,a sand culture experiment was conducted on banana seedlings under nutrient deficiency.The results showed that:leaf was the most sensitive part to Ca and Mg deficiency.Ca deficiency first showed deficiency symptoms in new leaves and dry spots along leaf edges.Mg deficiency first appeared in the lower leaf between the veins of chlorosis symptoms.The deficiency of Ca and Mg did not affect the stem diameter and leaf number of seedlings,but both significantly reduced chlorophyll content.Ca deficiency inhibited the growth of seedling height.Both Ca and Mg deficiency significantly reduced the photosynthetic intensity of banana seedlings.The limiting factor of photosynthesis under Ca deficiency was non-stomatal factor,while the limiting factor was both stomatal factor and non-stomatal factor under Mg deficiency.Ca and Mg deficiency inhibited the dry matter accumulation of the whole plant,and the effect of Mg deficiency was greater than that of Ca deficiency.Ca deficiency also changed nutrient allocation in banana,Ca deficiency inhibited the transport of N,P and K to leaves,and Mg deficiency inhibited the accumulation of K and Mg in stems,which ultimately inhibited the growth of leaves and pseudostems of banana seedlings and promoted the growth of roots,leading to the increase of root to shoot ratio.Lack of Ca and Mg is not conducive to the absorption of other nutrients in bananas.In banana cultivation process,application of nitrogen,phosphorus and potassium fertilizer should be combined with calcium and magnesium fertilizer to obtain high yield.