Abstract

Aims

To test and compare the current methods of pretreatment/preservation/determination for plant foliar pH, and propose a method suitable for long-period sample preservation with little interfere with the stability of foliar pH. To establish the transformation equations of measured values with these different methods, and facilitate the comparability between the research results with such methods.

Methods

400 leaf samples from 20 species were collected in total for the four different methods of leaf pH determination: refrigerated (stored at about 4 ℃ for four days), frozen (stored at about -16 ℃ for four days), oven-dried, and the fresh green-leaf pH (the control). To explore the effects of different leaf: water mixing ratio on the determination results of foliar pH, we measured oven-dried green-leaf pH by leaf: water volume ratio of 1:8 and mass ratio of 1:10, and measured frozen senesced-leaf pH by mass ratio of 1:10 and 1:15. The standard major axis (SMA) regression (Mode Ⅱ) was used to analyze the relationship and present the conversion equation between the measured pH with different methods, and the SMA slope was then compared with unit to reveal the relative size of the measurements.

Important findings

Foliar pH of refrigerated and frozen green-leaves had no significant difference from that of fresh green-leaf, but oven-dried green-leaf pH always overrated fresh green-leaf pH. During the period of field sampling work, cryopreservation with a portable refrigerator is thus an advisable pretreatment choice for preserving the leaf samples, in order to get a precise pH after returning to the lab. For long-duration field sampling, freezing pretreatment is the optimal choice for leaf sample preservation; and refrigeration pretreatment is the best choice for the short-time preservation. The different leaf: water mixing ratio had significant influence on the measured foliar pH: High dilution reduced the proton concentration and increased the measured pH. Our research provided the conversion relationships between the existing pretreatment and measurement methods, in order to establish a connection among the results of pH reported by studies using different methods. Our study is expected to facilitate foliar pH research via analysis of the comparability and conversions among various current measurement methods; and thus, improve understanding of this interesting plant functional trait.

中文翻译：

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植物样品叶面pH值的预处理、保存和测定方法比较

摘要

目标

对现有植物叶面pH值的预处理/保存/测定方法进行测试和比较，提出一种适合长期样品保存且对叶面pH值稳定性影响较小的方法。用这些不同的方法建立测量值的变换方程，便于研究结果与这些方法的可比性。

方法

共采集了来自 20 个物种的 400 份叶片样品，用于四种不同的叶片 pH 测定方法：冷藏（约 4 ℃ 保存 4 天）、冷冻（约 -16 ℃ 保存 4 天）、烘干和新鲜绿叶 pH 值（对照）。为探讨不同叶水混合比对叶面 pH 测定结果的影响，我们以叶：水体积比 1:8 和质量比 1:10 测量烘干绿叶的 pH 值，并测量冷冻衰老- 叶的 pH 值按质量比为 1:10 和 1:15。采用标准长轴（SMA）回归（模式Ⅱ）分析不同方法测得的pH值之间的关系并给出转换方程，然后将SMA斜率与单位进行比较，以揭示测量值的相对大小。

重要发现

冷藏和冷冻绿叶的叶面pH值与新鲜绿叶没有显着差异，但烘干绿叶的pH值总是高估新鲜绿叶的pH值。因此，在现场采样工作期间，使用便携式冰箱进行冷冻保存是保存叶子样品的一个可取的预处理选择，以便在返回实验室后获得精确的 pH 值。对于长时间的野外采样，冷冻预处理是叶样保存的最佳选择；冷藏预处理是短期保存的最佳选择。不同的叶：水混合比对测量的叶 pH 值有显着影响：高稀释度降低了质子浓度并增加了测量的 pH 值。我们的研究提供了现有预处理和测量方法之间的转换关系，以便在使用不同方法的研究报告的 pH 值结果之间建立联系。我们的研究有望通过分析各种当前测量方法之间的可比性和转换来促进叶面 pH 研究；因此，提高对这种有趣的植物功能性状的理解。