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
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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NO 3 --N∶NH 4 +-N=100∶0(硝酸钙42.16 g·盆 -1)、NO 3 --N∶NH 4 +-N=75∶25(硝酸钙31.62 g·盆 -1, 碳酸氢铵7.06 g·盆 -1)、NO 3 --N∶NH 4 +-N= 50∶50(硝酸钙21.08 g·盆 -1, 碳酸氢铵14.12 g·盆 -1)、NO 3 --N∶NH 4 +-N=25∶75(硝酸钙10.54 g·盆 -1, 碳酸氢铵21.19 g·盆 -1)、NO 3 --N∶NH 4 +-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: NO 3 --N∶NH 4 +-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NH 4 +-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% NO 3 --N处理的脐橙叶片Pn也极显著低于NO 3 --N∶NH 4 +-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NH 4 +-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。NO 3 --N和NH 4 +-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 NO 3 --N∶NH 4 +-N at 100∶0 (CaNO 3·4H
2O 42.16 g·pot -1), NO 3 --N∶NH 4 +-N at 75∶25 (CaNO 3·4H 2O 31.62 g·pot -1and NH4HCO3 7.06 g·pot -1), NO 3 --N∶NH 4 +-N at 50∶50 (CaNO 3·4H 2O 21.08 g·pot -1and NH 4HCO 314.12 g·pot -1), NO 3 --N∶NH 4 +-N at 25∶75 (CaNO 3·4H 2O 10.54 g·pot -1and NH 4HCO 321.19 g·pot -1), and NO 3 --N∶NH 4 +-N at 0∶100 (NH 4HCO 328.25 g·pot -1or CO(NH 2) 210.71 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 NO 3 --N and NH 4 +-N at the ratio of 75∶25, contents of Chl. a, Chl. b and Car. and P nwere significantly higher than those under other nitrogen sources treatments. P n, T r, WUEand G sof Newhall navel orange at 10:00 reached highest values with 4.81 μmol(CO 2)·m -2·s -1, 2.30 mmol(CO 2)·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, WUEand G sall decreased with increasing NH 4 +-N/NO 3 --N ratio. Under sole NO 3 --N (NO 3 --N∶NH 4 +-N=100∶0), P nwas 3.53 μmol(CO 2)·m -2·s -1, significantly lower than that under mixed NO 3 --N and NH 4 +-N dose (NO 3 --N∶NH 4 +-N=75∶25). Under the sole CO(NH 2) 2, the contents of Chl. a, Chl. b and Car. and P nwere lowest, and P nwas only 3.07 μmol(CO 2)·m -2·s -1. No significant differences were noted in Newhall navel orange P nunder the sole NH 4 +-N and CO(NH 2) 2. Also no significant differences were noted in LCPand LSPof Newhall navel orange among different nitrogen resources treatments. Both points were respectively maintained at 861.51 μmol·m -2·s -1and 10.09 μmol·m -2·s -1. Mixed dose of NO 3 --N and NH 4 +-N at the ratio of 75∶25 was beneficial to Newhall navel orange in terms of Pn improvement.
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