不同水平和形态氮素供应对盆栽小菊外观品质和光合特性的影响

Effects of different nitrogen levels and forms on the appearance quality and photosynthesis characters of potted chrysanthemum with small inflorescences

研究了无土基质栽培的不同氮素水平(1,3,8,16,26mmol/L)和氮素形态配比(NH4+-N∶NO3--N分别为4∶0,1∶3,2∶2,3∶1,0∶4)对小菊外观品质、叶绿素含量和光合特性的影响。结果表明,氮素水平为16mmol/L时对小菊营养生长期较适宜,能显著提高株高、冠幅、植株鲜重和叶片数等;而8mmol/L氮素水平适于花发育期需求,利于提高单株花序数、花干重和延长花期,高浓度的氮素对花发育和开花不利,但提高叶绿素含量、净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr),降低胞间CO2浓度(Ci)。以NH4+-N部分代替NO3--N可显著提高小菊株高、冠幅、叶片数、植株鲜重和单株花序数量等指标,且在营养生长后期显著提高叶绿素含量和净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr),降低胞间CO2浓度(Ci),但对于花发育进度和整体花期无显著影响,研究表明,盆栽小菊NH4+-N∶NO3--N的适合比例为3∶1。

Substrate culture was employed to study the effects of different nitrogen levels （i.e.,1,3,8,16,26mmol·L^-1） and different ratios of nitrogen forms （i.e.,NH4^＋-N to NO3^--N,4∶0,1∶3,2∶2,3∶1,0∶4） on appearance quality,chlorophyll content and photosynthesis characters of chrysanthemum with small inflorescences. The results showed that 16 mmol·L^-1 nitrogen was optimal for vegetative growth,and it increased plant height,canopy,fresh weight and leaf numbers of plant. On the other hand,8 mmol·L^-1 nitrogen was optimal for reproductive growth,and it increased flower numbers,flower dry weight and prolonged the period of blooming. The flower development and its blooming were inhibited at higher level of nitrogen,but the chlorophyll content,net photosynthetic rate （Pn）,stomatal conductance（Gs） and transpiration rate （Tr） increased and the intercellular CO2 concentration（Ci） decreased. Plant height,canopy,leaf numbers,flowers numbers,flower dry weight were enhanced under NH4^＋-N condition as compared to NO3^--N. Furthermore,the chlorophyll content,net photosynthetic rate （Pn）,transpiration rate （Tr） and stomatal conductance（Gs） increased,but the intercellular CO2 concentration （Ci） obviously decreased during the late period of vegetative growth under NH4^＋-N condition. However,nitrogen forms didn＇t affect the progress of flower development or the blooming period. It was found that a ratio of 3∶1 of NH4^＋-N∶NO3^--N was optimal for potted chrysanthemum with small inflorescences.