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

葛会敏; 樊卫国

doi:10.3724/SP.J.1011.2013.00401

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 (P_n), 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 P_n were significantly higher than those under other nitrogen sources treatments. P_n, T_r, WUE and G_s 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 P_n , T_r, WUE and G_s all decreased with increasing NH₄⁺-N/NO₃^--N ratio. Under sole NO₃^--N (NO₃^--N∶NH₄⁺-N=100∶0), P_n 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 P_n were lowest, and P_n was only 3.07 μmol(CO₂)·m^-2·s^-1. No significant differences were noted in Newhall navel orange P_n 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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