摘要
【目的】探讨缺氮及恢复供氮对香蕉苗生长及其根系形态参数的影响,为香蕉苗期形态诊断和氮肥管理提供依据。【方法】通过石英砂培养试验,对比研究了缺氮程度和恢复供氮后香蕉苗表型性状、地上部和根系的干物质质量、根系形态参数等的变化。【结果】缺氮后香蕉苗呈现明显的缺氮症状;恢复供氮32 d后,香蕉苗缺氮症状消失,表型恢复正常性状。但是,缺氮程度、缺后恢复供氮对香蕉生长的影响不同,轻度缺氮不会抑制地上部生长,反而刺激根系生长,显著增加了根系干物质质量;中度缺氮时,明显抑制了香蕉苗生长,地上部干物质质量降低了19.25%,而根系干物质质量无明显变化,缺氮对根系的促生作用减弱。缺氮后,香蕉苗的总根长和直径<2 mm细根的根长明显减小,轻度、中度缺氮时,香蕉苗的总根长分别为正常处理的58.3%和49.7%。但是,缺氮明显增加了香蕉苗平均根直径、总体积和直径>2 mm的根系体积,轻度、中度缺氮期,香蕉苗的平均直径和总体积分别为正常处理的1.85倍和2.01倍、1.62倍和1.31倍。缺氮香蕉苗恢复供氮32 d后,缺氮表型性状完全消失,地上部和整株干物质质量分别增加了6.08%和5.24%;根系趋向正常生长,总根长特别是细根长度显著增加,平均根直径和总体积显著降低,但是,复氮处理的香蕉苗的干物质质量、根系长度、平均根直径和总体积仍达不到正常处理香蕉苗的水平。【结论】香蕉缺氮的表型性状能及时反映香蕉的氮素营养状况,缺氮对香蕉表型性状的影响通过及时补充氮肥可在短期恢复,但干物质质量、根系生长的恢复期滞后于表型性状恢复期。在香蕉栽培过程,香蕉苗期要综合考虑土壤肥力和营养特性合理施肥,避免先缺再补的施肥措施。
[Objective]The purpose of the paper was to understand the effects of nitrogen deficiency and restoration of nitrogen nutrients on banana seedling growth,root morphological parameters and development of typical deficiency symptoms in order to provide theoretical basis for banana N nutrition diagnosis and fertilization.[Methods]The experimental design was a randomized complete block with 3 treatments.The treatments were supplied in quartz sand culture in a pot experiment.The three treatments were banana supplied complete Hoagland nutrient solution(control,T1),minus nitrogen(-N)nutrient solution(T2)and restoration of nitrogen involving resupply whole nutrients solution after N deficiency symptoms were observed(T3).Each banana seedling with 6 green leaves was transplanted to a pot of 13 cm(bottom)to 16 cm(top)in diameter and 15 cm in height.The banana seedling was rinsed with deionized water for one week before treatments were implemented.T1,T2 and T3 had 90,33 and 15 pots as 90,33 and 15 repetitions respectively.The banana seedlings of the control were irrigated with modi-fied complete Hoagland nutrient solution,in which the molar ratio of N and K2O changed into 1:2.T2 supplied Hoagland nutrient solution of N deficiency.T3 was applied with Hoagland nutrient solution of N deficiency until typical mild N deficiency symptoms developed in 50 percent of banana seedlings,when they were supplied complete Hoagland nutrient solution.Morphological characteristics of banana seedlings were observed every day after the treatments.The nitrogen deficiency symptoms and time of its appearance were recorded in detail.Chlorosis of the leaves was obvious,which was regarded as mild nitrogen deficiency symptoms.When the plants showed slow and weak growth,they were considered to have moderate nitrogen deficiency symptom.Stagnated plant growth with some dead leaves was classified as severe nitrogen deficiency symptom.Sampling of seedlings showing mild and moderate nitrogen deficiency was conducted at 31 days and 67 days after nitrogen defi
作者
刘芳
林李华
张立丹
樊小林
孙少龙
LIU Fang;LIN Lihua;ZHANG Lidan;FAN Xiaolin;SUN Shaolong(College of Natural Resources and Environment,South China Agricultural University,Guangzhou 510642,Guangdong,China)
出处
《果树学报》
CAS
CSCD
北大核心
2019年第1期67-75,共9页
Journal of Fruit Science
基金
国家重点研发计划(2017YFD0200701)
省级重大科研项目(2016KZDXM029)
国家现代农业产业技术体系建设专项-(CARS-31-06)
关键词
香蕉苗
缺氮
复氮
干物质质量
根系形态
Banana seedling
N deficiency
N resupply
Dry matter
Roots morphology
