氮素形态及配比对铁核桃苗生长及营养吸收的影响

摘要

Using NH4+-N,NO3--N and CO (NH2) 2 as nitrogen sources,the effect of nitrogen forms and the ratios on the plant size,biomass,root morphological characteristics,content and accumulation of elements in Juglans sigillata seedling was studied.The results showed that the nitrogen forms and the ratios had significant impact on seedling height,base diameter,root-shoot ratio,shoot and root biomass,root morphological trait,content and accumulation of elements in J.sigillata seedling.With the mixed supply of NH4+-N and NO3--N at the ratio of 1∶ 1,the seedling height,base diameter,root-shoot ratio,biomass of the entire plant,shoot and root,root total surface area,average diameter,root tip number,content and accumulation of elements in J.sigillata seedling were all at the maximum compared with other treatments.With the only supply of CO (NH2) 2,root total length and volume were the biggest,the biomass of the entire plant,shoot and root,the content and accumulation of elements in seedling were lower only than those with the mixed supply of NO3--N and NH4+-N at the ratio of 1∶ 1.With the only supply of NO3--N,the seedling was short and small,the biomass of the entire plant,shoot and root,root morphological parameters were all the lowest,and the content and accumulation of elements in seedling were the least.With the only supply of NH4+-N,most of the leaves in summer presented burning-shape necrosis,and the symptom was aggravated with increasing NH4+-N ratio.Meanwhile the seedling was slender,the tissue was not fully developed,the fibrous root was short and most fibrous roots showed necrosis,the biomass,root-shoot ratio and root total length,surface area,volume,average diameter and root tip number were smaller,and the accumulation of elements was also lower.J.sigillata seedling had no obvious preference to NH4+-N or NO3--N.The mixed supply of NO3--N and NH4+-N at the ratio of 1 ∶ 1 was able to boost the growth and nutrients absorption of J.sigillata seedling.CO (NH2) 2 was also good for growth and nutrients absorption of J.sigillata seedling.%采用盆栽试验方法,以铵态氮、硝态氮和尿素[CO(NH2)2]为氮源,研究氮素形态及配比对铁核桃苗植株大小、生物量、根系形态特征和苗木元素含量及积累量的影响.结果表明:氮素形态及配比对铁核桃苗木的高度、基径、根冠比值、地上部和根系的生物量、根系形态特性、苗木中元素含量及积累量有明显的影响.以50％NH4+-N+ 50％ N03--N为氮源的苗高、基径、根冠比值、整株及地上部和根系的生物量、根系的总表面积及平均直径、根尖数、苗木中元素含量及积累量都最大；单一供应CO(NH2)2的苗木根系总长度和总体积最大,苗木整株和地上部及根系的生物量、苗木中的元素含量及积累量仅低于50％ NH4+-N+ 50％ N03--N的处理；单一供应N03--N的苗木矮小,整株、地上部及根系的生物量和根系的形态及生长指标都最低,各种元素的含量及积累量也最少；单一供应NH4+-N时,在夏季叶片出现大量灼烧状坏死,其症状随NH4+-N的比例增加而加重,苗木也纤细,组织不充实,须根短,坏死较多,植株的生物量和根冠比及根系总长度、表面积、体积、平均直径和根尖数都较小,营养元素的积累量也较低.铁核桃对NH4+-N或N03--N没有明显的偏好.在NH4+-N与N03--N的比例各占50％时能够更好地促进铁核桃苗木的生长及营养的吸收,尿素也有较好的效果.