不同形态氮源及其配比对石灰性黄壤上纽荷尔脐橙光合特性的影响

Effects of nitrogen forms and ratios on photosynthetic characteristics of Newhall navel orange in calcareous yellow soils

    摘要
  • 摘要: 采用盆栽方法, 在避雨透光棚内, 研究不同形态氮源及其配比NO3--N∶NH4+-N=100∶0(硝酸钙42.16 g·盆-1)、NO3--N∶NH4+-N=75∶25(硝酸钙31.62 g·盆-1, 碳酸氢铵7.06 g·盆-1)、NO3--N∶NH4+-N= 50∶50(硝酸钙21.08 g·盆-1, 碳酸氢铵14.12 g·盆-1)、NO3--N∶NH4+-N=25∶75(硝酸钙10.54 g·盆 -1, 碳酸氢铵21.19 g·盆-1)、NO3--N∶NH4+-N=0∶100(碳酸氢铵28.25 g·盆-1)、尿素10.71 g·盆-1对枳砧纽荷尔脐橙叶片光合速率(Pn)日变化、光合色素含量、叶片光补偿点和光饱和点的影响, 为柑橘的氮素营养及施肥管理提供科学依据。结果表明: NO3--N∶NH4+-N为75∶25处理的脐橙叶片中叶绿素a(Chl. a)、叶绿素b(Chl. b)和类胡萝卜素(Car.)含量和全天Pn都显著或极显著高于其他氮源配比处理, 上午10:00脐橙叶片的Pn、Tr、WUE和Gs均是最高的, 极显著高于其他氮源处理, 其Pn、Tr、WUE和Gs分别为4.81 μmol(CO2)·m-2·s-1、2.30 mmol(H2O)·m-2·s-1、2.09和0.09 mol·m-2·s-1。随着NH4+-N比例的增加, 脐橙叶片中Chl. a、Chl. b和Car.的含量与Pn、Tr、WUE和Gs均逐渐下降。100% NO3--N处理的脐橙叶片Pn也极显著低于NO3--N∶NH4+-N为75∶25处理, 其Pn仅为3.53 μmol(CO2)·m-2·s-1。单一尿素氮处理(施用10.71 g·盆-1尿素)的脐橙叶片中Chl. a、Chl. b、Car.和Pn含量最低, 其Pn为3.07 μmol(CO2)·m-2·s-1, 与单纯施用NH4+-N处理无显著性差异。不同氮源处理的脐橙叶片光饱和点和光补偿点均无显著性差异, 其值分别维持在861.51 μmol·m-2·s-1和10.09 μmol·m-2·s-1左右。NO3--N和NH4+-N混合比例为75∶25时有利于提高纽荷尔脐橙Pn。

     

    Abstract: A pot experiment was conducted in a rain-light shad to provide scientific basis for citrus nitrogen nutrient and fertilizer management via analysis of the effects of different nitrogen forms and ratios NO3--N∶NH4+-N at 100∶0 (CaNO3·4H2O 42.16 g·pot-1), NO3--N∶NH4+-N at 75∶25 (CaNO3·4H2O 31.62 g·pot-1 and NH4HCO3 7.06 g·pot-1), NO3--N∶NH4+-N at 50∶50 (CaNO3·4H2O 21.08 g·pot-1 and NH4HCO3 14.12 g·pot-1), NO3--N∶NH4+-N at 25∶75 (CaNO3·4H2O 10.54 g·pot-1 and NH4HCO3 21.19 g·pot-1), and NO3--N∶NH4+-N at 0∶100 (NH4HCO3 28.25 g·pot-1 or CO(NH2)2 10.71 g·pot-1). Also the daily changes in photosynthetic rates (Pn), photosynthetic pigments (Chal. a, Chl. b, Car.) contents, light compensation point (LCP) and light saturation point (LSP) of Newhall navel orange grafted in trifoliate orange were analyzed. The results showed that under the mixed dose of NO3--N and NH4+-N at the ratio of 75∶25, contents of Chl. a, Chl. b and Car. and Pn were significantly higher than those under other nitrogen sources treatments. Pn, Tr, WUE and Gs of Newhall navel orange at 10:00 reached highest values with 4.81 μmol(CO2)·m-2·s-1, 2.30 mmol(CO2)·m-2·s-1, 2.09 and 0.09 mol·m-2·s-1, respectively. The contents of Chl. a, Chl. b and Car., and Pn , Tr, WUE and Gs all decreased with increasing NH4+-N/NO3--N ratio. Under sole NO3--N (NO3--N∶NH4+-N=100∶0), Pn was 3.53 μmol(CO2)·m-2·s-1, significantly lower than that under mixed NO3--N and NH4+-N dose (NO3--N∶NH4+-N=75∶25). Under the sole CO(NH2)2, the contents of Chl. a, Chl. b and Car. and Pn were lowest, and Pn was only 3.07 μmol(CO2)·m-2·s-1. No significant differences were noted in Newhall navel orange Pn under the sole NH4+-N and CO(NH2)2. Also no significant differences were noted in LCP and LSP of Newhall navel orange among different nitrogen resources treatments. Both points were respectively maintained at 861.51 μmol·m-2·s-1 and 10.09 μmol·m-2·s-1. Mixed dose of NO3--N and NH4+-N at the ratio of 75∶25 was beneficial to Newhall navel orange in terms of Pn improvement.

     

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