不同浓度指数施肥方法下马来沉香与土沉香苗期需肥规律

Nutrient upkate of Aquilaria malaccensis and Aquilaria sinensis seedlings in response to different exponential regimes

设置每株施N 0、1000、2000、3000、4000、5000 mg的6个氮素水平处理,进行珍贵树种马来沉香与土沉香苗期指数施肥试验,探讨不同氮素供应水平对其苗期生长、叶片养分含量以及根系形态指标的影响,旨在揭示马来沉香与土沉香苗期的氮素需求特征,确定其适宜施氮量。结果表明,马来沉香与土沉香苗期的地径、苗高以及生物量随着氮素供应水平的增加而增大,当每株施氮量大于3000 mg后其生长和生物量趋于稳定;施氮处理为3000mg/plant时的马来沉香与土沉香根系各生长和形态指标均显著大于其他处理;运用临界浓度法确定出马来沉香苗期叶片氮、磷、钾含量的临界值分别为35.55、1.75、17.99 g/kg,最适含量范围分别为35.55～53.11、1.75～2.73、17.99～26.63 g/kg;土沉香苗期叶片氮、磷、钾含量的临界值分别为37.78、3.08、18.89 g/kg,最适含量范围分别为37.78～58.56、3.08～4.44、18.89～29.28 g/kg。综合3种养分的最适含量范围,推断出马来沉香和土沉香苗期的最适施氮量均为3000 mg/plant。

Exponential nutrient delivery can bring about a steady state of nutrition in the plant and improve nutrient uptake,and hence accelerate seedling growth. An exponential fertilization trial was conducted with six N dose levels （applying a total of 0, 1000, 2000, 3000, 4000, 5000 mg/seedling in this experiment） of nitrogen to assess the effects on different nitrogen levels on growth and foliar nutrient status of Aquilaria malaccensis and Aquilaria sinensis seedlings with the different nitrogen levels. The objective of this study was to reveal the nitrogen demand and determine the optimal nitrogen amount for A. malaccensis and sinensis seedlings. It was indicated that ground diameter,height and biomass seedlings increased with the increase of nitrogen supply,up to 3000 mg/seedling,after then growth performance and biomass were unchanged and leaf area remarkable decreased. Critical level approach was used for identifying N,P and K deficiencies by means of foliar analysis in A. malaccensis seedlings,and the critical values of N,P,and K ？were 35.55, 1.75 and 17.99 g/kg,while their optimal concentrations ranged from 35.55 to 53.11, 1.75 to 2.73, 17.99 to 26.63 g/kg,respectively. And the critical values of N, P and K of A. sinensis were 37.78, 3.08 and 18.89 g/kg,while their optimal concentrations ranged from 37.78 to 58.56, 3.08 to 4.44, 18.89 to 29.28g/kg. Based on these data, it could be inferred that 3000 mg/seedling would be the optimal nitrogen amount for A. malaccensis and sinensis seedlings.