2.2.2. Plants nutrient analysis
Plant simples were ground using a ball mill (Retsol MM2000, Retsch,
Haan, Germany). Subsamples of shoots and roots were digested with a
mixture of nitric and perchloric acid (4:1) (Jin et al., 2012). The
concentrations of K in the digest solution was determined with a flame
photometer (Liu et al., 2020). The P concentration were measured by
SKALAR San++ continuous flowing analyzer after acidic
digestion (Xu et al., 2018). The concentrations of N in plant tissues
were determined using an Elementar CNS analyser (Vario EL III, Elementar
Analysensysteme GmbH, Germany) (Li et al., 2019b).
2.2.3. Available nutrientsin
the rhizosphere
The rhizosphere soils were collected by shaking the roots and the soil
adhering to the roots was considered as rhizosphere soil (Nazih et al.,
2001). All soil samples were stored in a refrigerator at 4 °C for
further analysis.
Soil
available N (NH4+ and
NO3-) was determined with the methods
described by Miah et al. (1998). Soil Olsen P was obtained by extraction
in NaHCO3 and analyzed by the Mo-Sb colorimetric method
(UV2550, Shimadzu, Japan) (Bao, 2000).
Available K was extracted with neutral 1 M NH4OAc, and
K concentration was measured by a flame photometer (Chen and Gabelman,
1995).