不同施氮水平下菠萝蜜幼苗根系生长及氮素吸收特征

为探究酰胺态氮肥在菠萝蜜苗期的最佳施用量,本试验以马来西亚1号嫁接苗为试验材料,比较不同施氮量对菠萝蜜幼苗根系生长及氮素吸收积累的影响。结果表明:随着施氮量增加,菠萝蜜幼苗叶片、茎秆、地上部和整株生物量,叶片氮素累积量、茎秆氮素累积量和总氮素累积量均呈先升高后降低的趋势,且均在施氮量为N1(5g/株)时达最大值;根系生物量和根冠比在N1时达最小值。根系氮素累积量随着施氮量增加呈增长趋势。总根长、根系总表面积及根系体积随着施氮量增加呈降低趋势,其中N1水平与N0(0 g/株)无显著性差异。总根长、根系总表面积、根系体积与地上部干重呈显著正相关关系。施肥、地上部氮素累积量和总根长单个因子以及三者共同解释菠萝蜜苗生物量变化的比例为90.1%。综上,在本试验条件下,菠萝蜜幼苗适宜的施氮量为5 g/株,可作为菠萝蜜苗期施肥的参考值。

Root Growth and Nitrogen Uptake of Jackfruit Seedlings Under Different Nitrogen Levels

In order to explore a suitable application of amino nitrogen on jackfruit seedlings, this experiment used Malaysian No.1 grafted seedlings as the test materials to compare the effects of different nitrogen application on the root morphology and nitrogen accumulation of jackfruit seedlings. The results showed that with the increase of nitrogen level, the biomass of leaves, stems, shoots, total plant, and nitrogen accumulation of leaves, stems, total plant increased at first but decreased after the peak at N₁ (5 g/plant), while the biomass of roots and ratio of roots and shoots reached a minimum at N₁. The nitrogen accumulation in roots increased with the increase of nitrogen application. The total root length, total root surface area and total root volume decreased with the increase of nitrogen application, while there was no significant difference between N₁ and N₀ (0 g/plant). The total root length, total root surface area, total root volume were significantly positively correlated with dry weight of shoot. Fertilization, nitrogen accumulation of shoots and total root length and both of them accounted for 90.1% of the change in the biomass of jackfruit seedlings. In summary, the proper nitrogen nutrition was 5 g/plant in this experiment which could be used as a reference for jackfruit fertilization.