Spad 502 plus instrument

Leaf chlorophyll content was non-destructively measured using a SPAD-502 Plus instrument (Konica-Minolta, Japan). The photosynthetic pigment was extracted with 80% acetone after crushing the leaves with liquid nitrogen. Chl a and Chl b contents were determined using the method described by Porra et al. (1989) (link). The carbon assimilation rate was measured in sunlight using the Rapid Photosynthesis Measuring System MIC-100 (Masa International, Japan; Tanaka et al., 2021 (link)).

Foliar chlorophyll content was measured non-destructively using a SPAD-502 Plus instrument (KONICA MINOLTA; http://www.konicaminolta.jp, last accessed 24 December 2017). For pigment extraction, leaves were ground in a mortar in liquid nitrogen and extracted using 80% acetone. Chla and Chlb levels were determined as described by Porra et al. (1989) . Maximum quantum yield (F_v/F_m) and the carbon fixation rate were measured using a LI-6400XT portable photosynthesis system (LI-COR; http://www.licor.com/, last accessed 24 December 2017) at 30 °C, with a CO₂ concentration of 400 ppm, humidity of 70–80%, and photon flux density of 2000 μmol m^–2 s^–1. Oxidation of P700 was measured using a Dual-PAM-100 chlorophyll fluorescence and P700 photosynthesis analyser (Walz; http://www.walz.com/, last accessed 24 December 2017). The antenna function of LHCI was estimated as the time required to reach two-thirds of the maximum P700 oxidation with far-red light (intensity 2). State transition (F_r) was determined as described by Lunde et al. (2000) (link) using a JUNIORPAM fluorometer (Walz). F_r is calculated using the following formula: F_r=[(F_i′–F_i)–(F_ii′– F_ii)]/(F_i′–F_i). F_i and F_ii are the fluorescence in the presence of PSI light in States 1 and 2, respectively, whereas F_i′ and F_ii′ are the fluorescence in the absence of PSI light in State 1 and 2, respectively.

The plant height of seedlings was measured with a ruler, and Electronic vernier calipers were used to measure stem thickness. The relative chlorophyll content in fully developed leaves, as indicated by SPAD (Soil and Plant Analyzer Development) value, was determined with a portable Konica SPAD-502Plus instrument (Konica Minolta Holdings Inc., Tokyo, Japan). Fresh plant roots from different treatment groups were collected and completely expanded onto the scanner platform (Epson Expression 1000XL, Seiko Epson Corporation, Nagano, Japan). Analyze the scanned root photos using WinRhizo Pro software (Regent Instruments Inc., Quebec, Canada) to obtain the roots’ total length, diameter, surface area, and volume. Afterward, dry the stem and root samples at 75 ° C for 4 days and further determine the dry mass of the stem and roots using an electronic balance.