Analysis of trace metal distribution in plants with lab-based microscopic X-ray fluorescence imaging

Table 1 Mann–Whitney U test statistics for significant differences at the 0.05 probability level (marked with asterisks sign) in OJIP parameters between X-ray exposed and non-exposed adjacent area (the same size and bordering the exposed area) of pepper leaves (n = 4)

Chl fluorescence parameters	N	Median	U	Z	Asymp. Prob > \|U\|
Φ_Po
Area under X-ray	4	0.985	3	− 1.29904	0.19393
Adjacent area	4	0.993
Φ_RE1o
Area under X-ray	4	1.23	12	1.01036	0.31232
Adjacent area	4	1.1
Φ_ET2o
Area under X-ray	4	0.951	0	− 2.16506	0.03038*
Adjacent area	4	0.991
Φ_PSII
Area under X-ray	4	0.823	4	− 1.01036	0.31232
Adjacent area	4	0.883

The Z value represents standardized value corrected for the presence of ties in case of similar values which are assigned to the same rank. Asymp. Prob > |U| indicates the asymptotic significance; when it is lower than the statistical threshold, the alternative hypothesis that the two distributions are different, is accepted. Φ_Po—maximum quantum yield of primary PSII photochemistry, Φ_ET2o—quantum yield of the electron transport flux from Q_A to Q_B, and Φ_RE1o—quantum yield of the electron transport flux until PSI electron acceptors according to Stirbet and Govindjee [33]. Φ_PSII- operating PSII efficiency according to Küpper et al. [25]

ISSN: 1746-4811