香蕉苗期氮素亏缺与补偿对植株生长和根系形态的影响

Effects of nitrogen deficiency and compensation of nitrogen

关键词:  氮素, 亏缺, 补偿效应, 香蕉, 根系形态

Key words:  nitrogen(N), deficiency, compensation effect, banana, root morphology

摘要:

为探究氮素亏缺及亏缺后补偿供氮对蕉苗生长及其根系形态特征的影响,该研究以主要栽培品种基因组类型(AAA型和ABB型)的香蕉品种为材料,通过石英砂基质培养结合氮素亏缺与补偿处理,分析其株高、叶长、叶宽、新增绿叶数、地上部和根系的鲜重和干物质质量、根长和根表面积及根体积等指标的变化。结果表明:(1)亏缺30 d,香蕉苗呈现明显的缺氮表型症状,株高、叶长、叶宽及新增绿叶数均显著降低,根系干物质积累增加,品种Ⅰ、Ⅱ根系干物质分别提高64.71%、87.50%,根冠比增加,总根表面积分别增加4.38%、11.85%,体积分别增加71.78%、66.55%。(2)亏缺68 d,干物质积累受到明显抑制,品种Ⅰ、Ⅱ全株干物质质量降低33.74%、42.04%,根系干物质质量与常规处理无显著差异,根系形态参数变化趋势与轻度亏缺一致。(3)亏缺后补偿供氮,缺氮症状消失,植株生长指标恢复正常水平; 品种Ⅰ、Ⅱ根系干物质质量显著增加51.22%、52.38%,根冠比显著高于常规处理,根系趋向正常形态生长,并且总根体积分别增加61.80%、45.92%; 轻度氮素亏缺后适时补偿供氮,缺氮蕉苗可恢复正常生长,根系干物质质量及体积显著高于常规处理且幼苗的长势更好。综上认为,生产中可以综合利用亏缺胁迫后补偿供氮的方式来培育香蕉苗,以利于其在田间栽培的生长。

Abstract:

In order to explore the effects of nitrogen(N)deficiency and compensation of nitrogen(N)nutrient on growth and root morphology of banana. In this experiment, two main cultivated variety genome types(AAA and ABB)were used as materials, plant height, leaf length, leaf width, number of new green leaves, fresh weight and dry matter mass of shoot and roots, root length, root surface area and root volume were studied by using quartz sand matrix culture combined with N deficiency and compensation treatment. The results were as follows:(1)The plant height, leaf length, leaf width and number of new green leaves decreased significantly, after 30 d N deficiency of varieties I and Ⅱ, dry matter mass of roots increased by 64.71% and 87.50%, and root-shoot ratio increased, total root surface area and volume increased by 4.38% and 11.85%,71.78% and 66.55%, respectively.(2)After 68 d N deficiency of varieties I and Ⅱ, dry matter mass of the whole plant decreased by 33.74% and 42.04%, and there was no significant differences between the deficiency treatment and the conventional treatment. The change trend of root morphological parameters was consistent with that of mild deficiency.(3)After the deficiency, N supply was compensated, the symptom of N deficiency disappeared, and the plant growth indexes returned to normal level. The dry matter mass of the varieties Ⅰ and Ⅱ increased by 51.22% and 52.38%, and the root-shoot ratio was significantly higher than that of the conventional treatments. Roots tended to grow in normal shape, and total root volume increased by 61.80% and 45.92%, respectively. The dry matter mass and volume of roots increased significantly than the conventional treatments and the plant growth vigor was better when the N compensation was timely after mild N deficiency. To sum up, the method of deficiency compensation can be comprehensively used in the production to promote the growth of banana seedlings in the field.