Does simultaneous phosphorus fertilization negate the suppressive effect of nitrogen fertilization on polyphenol oxidase activity?
Does simultaneous phosphorus fertilization negate the suppressive effect of nitrogen fertilization on polyphenol oxidase activity?
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DOI：
10.1016/j.geoderma.2022.116287
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发表时间：
2023-02
期刊：
影响因子：
6.1
通讯作者：
Taiki Mori;N. Imai;K. Kitayama
中科院分区：
文献类型：
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作者：
Taiki Mori;N. Imai;K. Kitayama
施氮后柠檬酸类有机质的分解受阻已被广泛报道，但其机制尚不清楚。“P-耗竭假说”表明，抑制分解的N施肥发生如下：N施肥刺激微生物竞争磷（P）的收购，导致磷缺乏木质素分解和多酚氧化酶（PPO）活性的同时抑制。这一假设可以通过同时施N和P肥以及检查是否通过额外的P肥来否定施N对PPO活性的抑制来检验。在这里，我们通过文献研究的荟萃分析来验证这一假设。为了获得更多的数据，这一分析，在婆罗洲的两个低地龙脑香雨林进行了同步N和P施肥的田间施肥实验。基于磷耗竭假说，我们假设施氮会抑制PPO活性，但同时施磷会消除这种负面影响。然而，荟萃分析不支持P耗竭假说。在11项研究中，有6项（包括我们的田间试验）没有证明氮肥对PPO活性的抑制作用，因此无法验证这一假设。只有5项研究报道了N施肥对PPO活性的抑制作用，其中3项不支持P耗竭假说，因为P施肥并没有否定N施肥对PPO活性的抑制作用。总体而言，我们的分析表明，磷耗竭假说不能全面解释的机制，氮施肥对PPO活性的负面影响。
Hindered decomposition of recalcitrant organic matter after nitrogen (N) fertilization is widely reported, but the underlying mechanisms remain unclear. The “P-depletion hypothesis” suggests that suppression of decomposition by N fertilization occurs as follows: N fertilization stimulates microbial competition for phosphorus (P) acquisition, leading to P deficiency in lignin decomposers and simultaneous suppression of polyphenol oxidase (PPO) activity. This hypothesis can be tested through simultaneous N and P fertilization and examination of whether the suppression of PPO activity with N fertilization is negated by additional P fertilization. Here, we tested this hypothesis through meta-analysis of literature studies. To obtain additional data for this analysis, a field fertilization experiment with simultaneous N and P fertilization was conducted in two lowland dipterocarp rain forests in Borneo. Based on the P-depletion hypothesis, we hypothesized that N fertilization would suppress PPO activity, but the negative impact would disappear with simultaneous P treatment. However, the meta-analysis did not support the P-depletion hypothesis. Out of 11 studies, 6 (including our field experiment) did not demonstrate suppressive effects of N fertilization on PPO activity, so the hypothesis could not be tested. Only five studies reported suppressive effects of N fertilization on PPO activity, three of which did not support the P-depletion hypothesis because P fertilization did not negate the suppression of PPO activity caused by N fertilization. Overall, our analysis indicates that the P-depletion hypothesis cannot comprehensively explain the mechanism underlying the negative impact of N fertilization on PPO activity.